2021
Yu Kovtun; T. Wauters; A. Goriaev; S Möller; D Lopez-Rodriguez; K. Crombé; S Brezinsek; A Dinklage; D Nicolai; Ch Linsmeier; M. Van Schoor; J Buermans; S Moon; R. Ragona; P Petersson
Comparative analysis of the plasma parameters of ECR and combined ECR + RF discharges in the TOMAS plasma facility Journal Article
In: Plasma Physics and Controlled Fusion, vol. 63, no. 12, pp. 125023, 2021.
@article{2031,
title = {Comparative analysis of the plasma parameters of ECR and combined ECR + RF discharges in the TOMAS plasma facility},
author = {Yu Kovtun and T. Wauters and A. Goriaev and S Möller and D Lopez-Rodriguez and K. Crombé and S Brezinsek and A Dinklage and D Nicolai and Ch Linsmeier and M. Van Schoor and J Buermans and S Moon and R. Ragona and P Petersson},
url = {https://doi.org/10.1088/1361-6587/ac3471},
doi = {10.1088/1361-6587/ac3471},
year = {2021},
date = {2021-12-01},
journal = {Plasma Physics and Controlled Fusion},
volume = {63},
number = {12},
pages = {125023},
publisher = {IOP Publishing},
abstract = {The toroidal magnetized system (TOMAS) plasma facility aims at complementary research on wall conditioning methods, plasma production and plasma–surface interaction studies. This paper explores for the first time the parameters in helium electron-cyclotron resonance (ECR) plasma and combined ECR + radio-frequency (RF) discharges in TOMAS. The ECR discharge in this work, at 2.45 GHz and 87.6 mT, is the main one for creating and maintaining the plasma, while the addition of RF power at 25 MHz allows to broaden the achievable electron temperature and density at a given gas flow, as evidenced by triple Langmuir probe measurements. This effect of the combined ECR + RF discharge provides flexibility to study particular aspects of wall conditioning techniques relevant to larger devices, or to approach plasma conditions relevant to fusion edge plasmas for particular surface interaction studies.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
V. Maquet; A. Druart; A. Messiaen
Analytical edge power loss at the lower hybrid resonance: ANTITER IV validation and application to ion cyclotron resonance heating systems Journal Article
In: Journal of Plasma Physics, vol. 87, no. 6, pp. 905870617, 2021.
@article{2033,
title = {Analytical edge power loss at the lower hybrid resonance: ANTITER IV validation and application to ion cyclotron resonance heating systems},
author = {V. Maquet and A. Druart and A. Messiaen},
year = {2021},
date = {2021-12-01},
journal = {Journal of Plasma Physics},
volume = {87},
number = {6},
pages = {905870617},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Sunwoo Moon; Per Petersson; Per Brunsell; Marek Rubel; A. Goriaev; R. Ragona; Sören Möller; Sebastijan Brezinsek; Dirk Nicolai; Christian Linsmeier; Yurii Kovtun; T. Wauters
Characterization of neutral particle fluxes from ICWC and ECWC plasmas in the TOMAS facility Journal Article
In: Physica Scripta, vol. 96, no. 12, pp. 124025, 2021.
@article{2030,
title = {Characterization of neutral particle fluxes from ICWC and ECWC plasmas in the TOMAS facility},
author = {Sunwoo Moon and Per Petersson and Per Brunsell and Marek Rubel and A. Goriaev and R. Ragona and Sören Möller and Sebastijan Brezinsek and Dirk Nicolai and Christian Linsmeier and Yurii Kovtun and T. Wauters},
url = {https://doi.org/10.1088/1402-4896/ac2494},
doi = {10.1088/1402-4896/ac2494},
year = {2021},
date = {2021-12-01},
journal = {Physica Scripta},
volume = {96},
number = {12},
pages = {124025},
publisher = {IOP Publishing},
abstract = {Electron- (ECWC) and ion- (ICWC) cyclotron wall conditioning are essential means for controlled fusion to modify the surface state of plasma-facing components in order to reduce impurity generation and fuel accumulation in the wall. Development of ECWC and ICWC requires characterization of neutral particle fluxes generated in discharges, because neutrals enhance the homogeneity of the conditioning, which may contribute to remote or shadowed areas, especially in the presence of a permanent magnetic field (e.g. W7-X, ITER). A time-of-flight neutral particle analyzer (ToF-NPA) with 4.07 m flight distance is employed to measure time- and energy-resolved low energetic (<1 keV) neutral particle distributions. The ToF-NPA setup tested at the EXTRAP T2R reversed field pinch was installed at the TOMAS toroidal plasma facility to determine low energy neutral particle fluxes while investigating the impact of the gas pressure in the instrument and compatibility with low count rates during EC- and ICWC discharges. TOMAS has a major radius of 0.78 m and provides various plasma operation conditions: toroidal magnetic field up to 0.12 T, EC frequency 2.45 GHz with the power of 0.6–6 kW, IC frequency of 10–50 MHz with the power of up to 6 kW. Early results on the characterization of three phases (EC only, EC + IC, and IC only) of hydrogen discharges demonstrate: (i) the low energy (10–725 eV) neutrals distribution has been determined by the NPA system, (ii) the mixed EC + IC phase produces the highest population of neutral particles, while the EC only provides one order of magnitude lower rate, (iii) the neutrals produced in IC only have higher average energy (28 eV) than EC only (7 eV) and EC + IC (16 eV).},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
E. R. Solano; G. Birkenmeier; E. Delabie; C. Silva; J. C. Hillesheim; A. Boboc; I. S. Carvalho; P. Carvalho; M. Chernyshova; T. Craciunescu; E. Luna; J. M. Fontdecaba; R. Henriques; P. Jacquet; I. Jepu; A. Kappatou; D. King; M. Lennholm; E. Lerche; E. Litherland-Smith; A. Loarte; M. Maslov; F. Parra Diaz; V. Parail; E. Pawelec; F. G. Rimini; A. Shaw; P. Siren; G. Szepesi; Ž. Štancar; E. Tholerus; S. Vartanian; B. Viola; H. Weisen; JET Contributors
L-H transition threshold studies in helium plasmas at JET Journal Article
In: Nuclear Fusion, vol. 61, no. 12, pp. 124001, 2021.
@article{2034,
title = {L-H transition threshold studies in helium plasmas at JET},
author = {E. R. Solano and G. Birkenmeier and E. Delabie and C. Silva and J. C. Hillesheim and A. Boboc and I. S. Carvalho and P. Carvalho and M. Chernyshova and T. Craciunescu and E. Luna and J. M. Fontdecaba and R. Henriques and P. Jacquet and I. Jepu and A. Kappatou and D. King and M. Lennholm and E. Lerche and E. Litherland-Smith and A. Loarte and M. Maslov and F. Parra Diaz and V. Parail and E. Pawelec and F. G. Rimini and A. Shaw and P. Siren and G. Szepesi and Ž. Štancar and E. Tholerus and S. Vartanian and B. Viola and H. Weisen and JET Contributors},
url = {https://doi.org/10.1088/1741-4326/ac2b76},
doi = {10.1088/1741-4326/ac2b76},
year = {2021},
date = {2021-12-01},
journal = {Nuclear Fusion},
volume = {61},
number = {12},
pages = {124001},
publisher = {IOP Publishing},
abstract = {We present a study of the power threshold for L–H transitions (P LH) in almost pure helium plasmas, obtained in recent experiments at JET with an ITER-like wall (Be wall and W divertor). The most notable new result is that the density at which P LH is minimum, , is considerably higher for helium than for deuterium and hydrogen plasmas. We discuss the possible implications for ITER in its pre-fusion operating power phase.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Z. Stancar; Z. Ghani; J. Eriksson; A. Žohar; S. Conroy; Y. O. Kazakov; T. Craciunescu; K. Kirov; M. Nocente; L. Garzotti; V. Radulović; P. Sirén; V. Kiptily; Y. Baranov; G. Szepesi; M. Dreval; M. Gorelenkova; H. Weisen; E. Militello-Asp; L. Snoj; JET Contributors
Experimental validation of an integrated modelling approach to neutron emission studies at JET Journal Article
In: Nuclear Fusion, vol. 61, no. 12, pp. 126030, 2021.
@article{2036,
title = {Experimental validation of an integrated modelling approach to neutron emission studies at JET},
author = {Z. Stancar and Z. Ghani and J. Eriksson and A. Žohar and S. Conroy and Y. O. Kazakov and T. Craciunescu and K. Kirov and M. Nocente and L. Garzotti and V. Radulović and P. Sirén and V. Kiptily and Y. Baranov and G. Szepesi and M. Dreval and M. Gorelenkova and H. Weisen and E. Militello-Asp and L. Snoj and JET Contributors},
url = {https://doi.org/10.1088/1741-4326/ac3021},
doi = {10.1088/1741-4326/ac3021},
year = {2021},
date = {2021-12-01},
journal = {Nuclear Fusion},
volume = {61},
number = {12},
pages = {126030},
publisher = {IOP Publishing},
abstract = {An integrated modelling methodology for the calculation of realistic plasma neutron sources for the JET tokamak has been developed. The computational chain comprises TRANSP plasma transport and DRESS neutron spectrum calculations, and their coupling to the MCNP neutron transport code, bridging plasma physics and neutronics. In the paper we apply the developed methodology to the analysis of neutron emission properties of deuterium and helium plasmas at JET, and validate individual modelling steps against neutron diagnostic measurements. Two types of JET discharges are modelled—baseline-like and three-ion radio-frequency scenarios—due to their diversity in plasma heating, characteristics of the induced fast ion population, and the imprint of these on neutron emission properties. The neutron emission modelling results are quantitatively compared to the total neutron yield from fission chambers, neutron emissivity profiles from the neutron camera, neutron spectra from the time-of-flight spectrometer, and neutron activation measurements. The agreement between measured and calculated quantities is found to be satisfactory for all four diagnostic systems within the estimated experimental and computational uncertainties. Additionally, the effect of neutrons not originating from the dominating D(D, n)3He reactions is studied through modelling of triton burnup DT neutrons, and, in mixed D-3He plasmas, neutrons produced in the 9Be(D, nγ)10B reaction on impurities. It is found that these reactions can contribute up to several percent to the total neutron yield and dominate the neutron activation of samples. The effect of MeV-range fast ions on the neutron activation of 115In and 27Al samples is measured and computationally validated.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Anna Widdowson; J Paul Coad; Yevhen Zayachuk; Ionut Jepu; Eduardo Alves; Norberto Catarino; Victoria Corregidor; Matej Mayer; Stepan Krat; Jari Likonen; Kenichiro Mizohata; Chris Rowley; Miroslaw Zlobinski; Marek Rubel; David Douai; Kalle Heinola; T. Wauters; Laura Dittrich; Sunwoo Moon; Per Petersson; Aleksandra Baron-Wiechec; Liga Avotina
Evaluation of tritium retention in plasma facing components during JET tritium operations Journal Article
In: Physica Scripta, vol. 96, no. 12, pp. 124075, 2021.
@article{2035,
title = {Evaluation of tritium retention in plasma facing components during JET tritium operations},
author = {Anna Widdowson and J Paul Coad and Yevhen Zayachuk and Ionut Jepu and Eduardo Alves and Norberto Catarino and Victoria Corregidor and Matej Mayer and Stepan Krat and Jari Likonen and Kenichiro Mizohata and Chris Rowley and Miroslaw Zlobinski and Marek Rubel and David Douai and Kalle Heinola and T. Wauters and Laura Dittrich and Sunwoo Moon and Per Petersson and Aleksandra Baron-Wiechec and Liga Avotina},
url = {https://doi.org/10.1088/1402-4896/ac3b30},
doi = {10.1088/1402-4896/ac3b30},
year = {2021},
date = {2021-12-01},
journal = {Physica Scripta},
volume = {96},
number = {12},
pages = {124075},
publisher = {IOP Publishing},
abstract = {An assessment of the tritium (T) inventory in plasma facing components (PFC) during JET T and deuterium-tritium (DT) operations is presented based on the most comprehensive ex situ fuel retention data set on JET PFCs from the 2015-2016 ILW3 operating period is presented. The global fuel retention is 4.19 × 1023 D atoms, 0.19% of injected fuel. The inner divertor remains the region of highest fuel retention (46.5%). The T inventory in PFCs at the end of JET operations is calculated as 7.48 × 1022 atoms and is informative for accountancy, clean-up efficacy and waste liability assessments. The T accumulation rate at the upper inner divertor during JET DT operations has been used to assess the requirements and frequency of operation of a new laser induced desorption diagnostic to be installed on JET for the final DT experiments in 2023.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
S. Kamio; V. E. Moiseenko; Yu. V. Kovtun; H. Kasahara; K. Saito; R. Seki; M. Kanda; G. Nomura; T. Seki; Y. Takemura; T. Wauters; R. Brakel; A. Dinklage; D. Hartmann; H. Laqua; T. Stange; A. Alonso; S. Lazerson; R. Ragona; J. Ongena; H. Thomsen; G. Fuchert; I. E. Garkusha
First experiments on plasma production using field-aligned ICRF fast wave antennas in the large helical device Journal Article
In: Nuclear Fusion, vol. 61, no. 11, pp. 114004, 2021.
@article{2027,
title = {First experiments on plasma production using field-aligned ICRF fast wave antennas in the large helical device},
author = {S. Kamio and V. E. Moiseenko and Yu. V. Kovtun and H. Kasahara and K. Saito and R. Seki and M. Kanda and G. Nomura and T. Seki and Y. Takemura and T. Wauters and R. Brakel and A. Dinklage and D. Hartmann and H. Laqua and T. Stange and A. Alonso and S. Lazerson and R. Ragona and J. Ongena and H. Thomsen and G. Fuchert and I. E. Garkusha},
url = {https://doi.org/10.1088/1741-4326/ac277b},
doi = {10.1088/1741-4326/ac277b},
year = {2021},
date = {2021-11-01},
journal = {Nuclear Fusion},
volume = {61},
number = {11},
pages = {114004},
publisher = {IOP Publishing},
abstract = {The results of the first experimental series to produce a plasma using the ion cyclotron range of frequency (ICRF) in the large helical device (LHD) within the minority scenario developed at Uragan-2M (U-2M) are presented. The motivation of this study is to provide plasma creation in conditions when an electron cyclotron resonance heating start-up is not possible, and in this way widen the operational frame of helical machines. The major constraint of the experiments is the low RF power to reduce the possibility of arcing. No dangerous voltage increase at the radio-frequency (RF) system elements and no arcing has been detected. As a result, a low plasma density is obtained and the antenna-plasma coupling is not optimal. However, such plasmas are sufficient to be used as targets for further neutral beam injection (NBI) heating. This will open possibilities to explore new regimes of operation at LHD and Wendelstein 7-X (W7-X) stellarator. The successful RF plasma production in LHD in this experimental series stimulates the planning of further studies of ICRF plasma production aimed at increasing plasma density and temperature within the ICRF minority scenario as well as investigating the plasma prolongation by NBI heating.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
V. G. Kiptily; M. Fitzgerald; Y. O. Kazakov; J. Ongena; M. Nocente; S. E. Sharapov; M. Dreval; Ž. Štancar; T. Craciunescu; J. Garcia; L. Giacomelli; V. Goloborodko; H. J. C. Oliver; H. Weisen; JET Contributors
Evidence for Alfvén eigenmodes driven by alpha particles in D-3He fusion experiments on JET Journal Article
In: Nuclear Fusion, vol. 61, no. 11, pp. 114006, 2021.
@article{2028,
title = {Evidence for Alfvén eigenmodes driven by alpha particles in D-3He fusion experiments on JET},
author = {V. G. Kiptily and M. Fitzgerald and Y. O. Kazakov and J. Ongena and M. Nocente and S. E. Sharapov and M. Dreval and Ž. Štancar and T. Craciunescu and J. Garcia and L. Giacomelli and V. Goloborodko and H. J. C. Oliver and H. Weisen and JET Contributors},
url = {https://doi.org/10.1088/1741-4326/ac26a2},
doi = {10.1088/1741-4326/ac26a2},
year = {2021},
date = {2021-11-01},
journal = {Nuclear Fusion},
volume = {61},
number = {11},
pages = {114006},
publisher = {IOP Publishing},
abstract = {Alfvén eigenmodes (AEs) driven by energetic alpha particles can lead to enhanced fast ion transport and losses, thereby degrading the plasma performance in ITER and future magnetic confinement fusion reactors. Unexpectedly, AEs with negative toroidal mode numbers, which are currently not considered for ITER, were observed in dedicated experiments with fusion-born alpha particles on the tokamak Joint European Torus (JET). The paper provides evidence for a complex interplay between fast ions, monster sawtooth crashes and AEs. Our results highlight the need for an improved description of the synergies between different fast ion phenomena in future burning plasmas.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
A. A. Teplukhina; M. Podesta; F. M. Poli; G. Szepesi; Y. O. Kazakov; P. J. Bonofiglo; M. Gorelenkova; M. Nocente; J. Ongena; Z. Stancar; JET Contributors
Fast ion transport by sawtooth instability in the presence of ICRF–NBI synergy in JET plasmas Journal Article
In: Nuclear Fusion, vol. 61, no. 11, pp. 116056, 2021.
@article{2029,
title = {Fast ion transport by sawtooth instability in the presence of ICRF–NBI synergy in JET plasmas},
author = {A. A. Teplukhina and M. Podesta and F. M. Poli and G. Szepesi and Y. O. Kazakov and P. J. Bonofiglo and M. Gorelenkova and M. Nocente and J. Ongena and Z. Stancar and JET Contributors},
url = {https://doi.org/10.1088/1741-4326/ac2524},
doi = {10.1088/1741-4326/ac2524},
year = {2021},
date = {2021-11-01},
journal = {Nuclear Fusion},
volume = {61},
number = {11},
pages = {116056},
publisher = {IOP Publishing},
abstract = {JET experiments have shown that the three-ion scenarios using waves in the ion cyclotron range of frequencies (ICRF) is an efficient way to build fast ion population through beam ion acceleration by radio frequency (RF) waves. Such a heating scheme is applied to plasmas with at least two thermal ion species. Analysis of mixed discharges with complex heating schemes requires a workflow that allows to model thermal and fast ion transport consistently. This paper is dedicated to modelling of a mixed plasma discharge with significant fraction of fast ions and contributes to development of fast ion transport models. For interpretive analysis with the TRANSP code a JET hydrogen–deuterium plasma discharge with neutral beam injection (NBI) and ICRF heating has been chosen. The task is complicated by NBI–ICRF synergy and plasma magnetohydrodynamic activity, like sawtooth crashes. D beam ions accelerated by RF waves form a high energy tail in fast ion distribution. Significant difference between the neutron rate computed by TRANSP and measured one is observed if the same diffusivity for electrons and ions is assumed. Sensitivity studies show that uncertainties in input plasma parameters and thermal ion transport models are crucial for modelling mixed plasma discharges and increased D transport is required to reach the plasma composition consistent with diagnostic measurements at the plasma edge. Fast ion redistribution by a sawtooth instability is characterised by non-resonant transport due to reconnection of magnetic field lines and resonant transport caused by resonance interaction between the instability and fast ions. With ORBIT simulations it has been shown that resonant interaction strongly affects fast ions of high energies, like beam ions accelerated by RF waves and fusion products. For the considered case, fast ion profiles simulated by ORBIT remain peaked after the sawtooth crashes.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Jiahao Li; R. Ragona; Yuntao Song; Qingxi Yang; Chao Yu; J. Hillairet; T. Batal; JM Bernard; Zhaoxi Chen; Hao Xu; Jian Chen; Shilin Chen; Ning Li
Development of TWA mock-up for TITAN Journal Article
In: Fusion Engineering and Design, vol. 171, pp. 112549, 2021, ISSN: 0920-3796.
@article{2026,
title = {Development of TWA mock-up for TITAN},
author = {Jiahao Li and R. Ragona and Yuntao Song and Qingxi Yang and Chao Yu and J. Hillairet and T. Batal and JM Bernard and Zhaoxi Chen and Hao Xu and Jian Chen and Shilin Chen and Ning Li},
url = {https://www.sciencedirect.com/science/article/pii/S0920379621003252},
doi = {https://doi.org/10.1016/j.fusengdes.2021.112549},
issn = {0920-3796},
year = {2021},
date = {2021-10-01},
journal = {Fusion Engineering and Design},
volume = {171},
pages = {112549},
abstract = {The challenge of tokamak auxiliary heating method ICRH is to couple large amount of power through the plasma boundary, where an evanescence layer has to be crossed, without exceeding the voltage standoff at the antenna. Travelling Wave Array antenna has been proposed for ICRH of future fusion reactor such as DEMO in view to decrease the antenna power density. However, so far the voltage standoff of a TWA antenna in the ICRH frequency range (30–60 MHz) has never been demonstrated. A TWA mock-up has been designed and will be tested in the CEA/IRFM testbed TITAN to assess its compatibility to RF high power operation. In this paper, the main characteristics of the TWA mock-up are reported in detail. In addition, some near-field RF analyses are presented, containing reflection characteristics, port voltage, electric field and k// spectrum. Meanwhile, the structural evaluation of the antenna during its lifting process is carried out to check with safety requirements. The assembly strategy of the whole structure is also explained elaborately to ensure the fluency and correct integration of the TWA mock-up. Finally, the RF assessment of antenna straps critical dimensions is briefly described.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
A R Field; S Aleiferis; E Belonohy; P Carvalho; I Coffey; D Frigione; L Garzotti; L Horvath; Hyun-Tae Kim; M Lennholm; E. Lerche; P Lomas; C G Lowry; J Mailloux; F Rimini; C M Roach; M Sertoli; Z Stancar; G Szepesi; D. Van Eester
The impact of fuelling and W radiation on the performance of high-power, ITER-baseline scenario plasmas in JET-ILW Journal Article
In: Plasma Physics and Controlled Fusion, vol. 63, no. 9, pp. 095013, 2021.
@article{2023,
title = {The impact of fuelling and W radiation on the performance of high-power, ITER-baseline scenario plasmas in JET-ILW},
author = {A R Field and S Aleiferis and E Belonohy and P Carvalho and I Coffey and D Frigione and L Garzotti and L Horvath and Hyun-Tae Kim and M Lennholm and E. Lerche and P Lomas and C G Lowry and J Mailloux and F Rimini and C M Roach and M Sertoli and Z Stancar and G Szepesi and D. Van Eester},
url = {https://doi.org/10.1088/1361-6587/ac1567},
doi = {10.1088/1361-6587/ac1567},
year = {2021},
date = {2021-09-01},
journal = {Plasma Physics and Controlled Fusion},
volume = {63},
number = {9},
pages = {095013},
publisher = {IOP Publishing},
abstract = {Sustained operation of high-performance, ITER-baseline scenario plasmas at the high levels of input power () required to achieve ∼15 MW of D-T fusion power in JET-ILW requires careful optimisation of the fuelling to avoid an unacceptable disruption rate due to excessive radiation, primarily from W impurities, which are sputtered by edge-localised modes (ELMs) from the divertor targets. By using a train of ELM-pacing pellets from a high-frequency pellet injector to promote regular ELMs, which flush W and other impurities from the confined plasma, such high-performance plasmas can be sustained (for ∼5 s) while maintaining a high normalised confinement factor H 98,y2 ∼ 1, which would otherwise be degraded by reducing the pedestal confinement if a higher rate of D2 gas fuelling were used instead of the pellets to mitigate the W contamination. The causes underlying the improved performance and energy confinement obtained using this combined, gas and pellet fuelling scheme is investigated here in some detail.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
G. P. Glazunov; D. I. Baron; S. M. Maznichenko; V. E. Moiseenko; M. N. Bondarenko; M. V. Gnidenko; V. Yu. Gribanov; A. L. Konotopskiy; Yu. V. Kovtun; M. M. Kozulya; A. Yu Krasyuk; V. M. Listopad; N. V. Limar; A. V. Lozin; F. I. Ozherelev; V. K. Pashnev; R. O. Pavlichenko; N. P. Ponomarenko; E. V. Syusko; A. I. Lyssoivan; T. Wauters; A. Goriaev; I. E. Garkusha
Thermal desorption diagnostics in the Uragan-2M stellarator Journal Article
In: Fusion Engineering and Design, vol. 170, pp. 112716, 2021, ISSN: 0920-3796.
@article{2025,
title = {Thermal desorption diagnostics in the Uragan-2M stellarator},
author = {G. P. Glazunov and D. I. Baron and S. M. Maznichenko and V. E. Moiseenko and M. N. Bondarenko and M. V. Gnidenko and V. Yu. Gribanov and A. L. Konotopskiy and Yu. V. Kovtun and M. M. Kozulya and A. Yu Krasyuk and V. M. Listopad and N. V. Limar and A. V. Lozin and F. I. Ozherelev and V. K. Pashnev and R. O. Pavlichenko and N. P. Ponomarenko and E. V. Syusko and A. I. Lyssoivan and T. Wauters and A. Goriaev and I. E. Garkusha},
url = {https://www.sciencedirect.com/science/article/pii/S0920379621004920},
doi = {https://doi.org/10.1016/j.fusengdes.2021.112716},
issn = {0920-3796},
year = {2021},
date = {2021-09-01},
journal = {Fusion Engineering and Design},
volume = {170},
pages = {112716},
abstract = {The improved thermal desorption diagnostics has been manufactured, installed and tested in the Uragan-2M (U-2M) stellarator [1], [2], [3], [4], [5] for in-situ characterisation a stainless steel (SS) wall outgassing rate and a number of molecular layers of residual gases on its surface in four different positions. The detailed description of this diagnostics, the location of thermal desorption stainless steel probes, the methodology of determining the outgassing rates and the number of molecular layers of residual gases on the probe surfaces are presented. It has been found that the difference between of the data taken from the probes being at different position in the U-2M vacuum chamber lies within the measurement accuracy. Using the present diagnostics together with the mass-spectrometer measurements, some studies were made to investigate the release of gases from the thermal desorption probes before and after radio frequency (RF) or glow discharge (GD) cleaning with hydrogen, helium and argon plasmas. It has been observed that hydrogen sorption by the SS probes surface during the discharge cleaning leads to significant hydrogen desorption even at the temperature of 250-300$,^circ$C. In this case, hydrogen can be the one of the main gases which desorbs. After U-2M glow discharge cleaning with Ar plasma, the thermal desorption experiment has shown Ar as a significant component which is desorbed from the SS probe surface. Two kinds of desorbed Ar were registered with two different activation energies. The characteristics of the U-2M vacuum system are presented, too, including the block scheme, the list of pumps used to attain the ultimate vacuum, the equipment for measuring the total and partial pressures of residual gases.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
J. Hillairet; P. Mollard; L. Colas; W. Helou; G. Urbanczyk; J. -M. Bernard; J. -M. Delaplanche; F. Durand; N. Faure; P. Garibaldi; G. Lombard; C. Bourdelle; C. Desgranges; E. Delmas; R. Dumont; A. Ekedahl; F. Ferlay; M. Goniche; C. Guillemaut; G. T. Hoang; P. Maget; R. Volpe; Y. Song; Q. Yang; Z. Chen; Y. Wang; H. Xu; S. Yuan; Y. Zhao; F. Durodie; E. Lerche; R. Ragona; N. Bertelli; M. Ono; S. Shiraiwa; V. Bobkov; C. Klepper; C. Lau; E. Martin; B. Lu; R. Maggiora; D. Milanesio; K. Vulliez; G. Wallace; WEST Team
WEST actively cooled load resilient ion cyclotron resonance heating system results Journal Article
In: Nuclear Fusion, vol. 61, no. 9, pp. 096030, 2021.
@article{2024,
title = {WEST actively cooled load resilient ion cyclotron resonance heating system results},
author = {J. Hillairet and P. Mollard and L. Colas and W. Helou and G. Urbanczyk and J. -M. Bernard and J. -M. Delaplanche and F. Durand and N. Faure and P. Garibaldi and G. Lombard and C. Bourdelle and C. Desgranges and E. Delmas and R. Dumont and A. Ekedahl and F. Ferlay and M. Goniche and C. Guillemaut and G. T. Hoang and P. Maget and R. Volpe and Y. Song and Q. Yang and Z. Chen and Y. Wang and H. Xu and S. Yuan and Y. Zhao and F. Durodie and E. Lerche and R. Ragona and N. Bertelli and M. Ono and S. Shiraiwa and V. Bobkov and C. Klepper and C. Lau and E. Martin and B. Lu and R. Maggiora and D. Milanesio and K. Vulliez and G. Wallace and WEST Team},
url = {https://doi.org/10.1088/1741-4326/ac1759},
doi = {10.1088/1741-4326/ac1759},
year = {2021},
date = {2021-09-01},
journal = {Nuclear Fusion},
volume = {61},
number = {9},
pages = {096030},
publisher = {IOP Publishing},
abstract = {Three identical new WEST ion cyclotron resonance heating (ICRH) antennas have been designed, assembled then commissioned on plasma from 2013 to 2019. The WEST ICRH system is both load-resilient and compatible with long-pulse operations. The three antennas have been successfully operated together on plasma in 2019 and 2020, with up to 5.8 MW of coupled power. The load resilience capability has been demonstrated and the antenna feedback controls for phase and matching have been developed. The breakdown detection systems have been validated and successfully protected the antennas. The use of ICRH in combination with lower hybrid has triggered the first high confinement mode transitions identified on WEST.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
P. Huynh; E. Lerche; D. Van Eester; J. Garcia; T. Johnson; J. Ferreira; K. K. Kirov; D. Yadykin; P. Strand; JET Contributors; EUROfusion-IM Team
European transport simulator modeling of JET-ILW baseline plasmas: predictive code validation and DTE2 predictions Journal Article
In: Nuclear Fusion, vol. 61, no. 9, pp. 096019, 2021.
@article{2022,
title = {European transport simulator modeling of JET-ILW baseline plasmas: predictive code validation and DTE2 predictions},
author = {P. Huynh and E. Lerche and D. Van Eester and J. Garcia and T. Johnson and J. Ferreira and K. K. Kirov and D. Yadykin and P. Strand and JET Contributors and EUROfusion-IM Team},
url = {https://doi.org/10.1088/1741-4326/ac0b34},
doi = {10.1088/1741-4326/ac0b34},
year = {2021},
date = {2021-09-01},
journal = {Nuclear Fusion},
volume = {61},
number = {9},
pages = {096019},
publisher = {IOP Publishing},
abstract = {The European transport simulator is a fusion machine simulator useful for making predictions of high-performance fusion plasmas, in particular for DT reactors. Recent developments introducing self-consistent simulations of combined RF + NBI heating schemes in which majority, minority and beam ions are simultaneously heated is documented. The predictive simulations are first validated by comparison with the experimental data on a DD JET baseline plasma. In order to prepare the next JET DTE2 experimental campaign, extrapolations of fusion performance on DT plasma from DD plasma are made with a particular focus on ion cyclotron resonance heating (ICRH) computation. Traditional ion cyclotron range of frequency heating models do not permit the study of Coulomb collisional interaction of various ion species simultaneously including neutral beam injection ions, and generally forces one to consider only minority populations. Accounting for multi-population interaction is made possible here by solving coupled sets of Fokker–Planck equations for all ion species adopting the non-linear collision operator for arbitrary distribution functions, accounting for effects, such as the self-collisions of majority (or large minority) populations. To answer the question whether H minority scheme or 3He minority ICRH scheme is better for boosting the DT fusion performance, minority concentration scans are produced.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
P. Dumortier; F. Durodié; P. Jacquet; E. Lerche; I. Monakhov; C. Noble; P. Puglia
JET ILA full array and polychromatic operation Journal Article
In: Fusion Engineering and Design, vol. 169, pp. 112489, 2021, ISSN: 0920-3796.
@article{2018,
title = {JET ILA full array and polychromatic operation},
author = {P. Dumortier and F. Durodié and P. Jacquet and E. Lerche and I. Monakhov and C. Noble and P. Puglia},
url = {https://www.sciencedirect.com/science/article/pii/S0920379621002659},
doi = {https://doi.org/10.1016/j.fusengdes.2021.112489},
issn = {0920-3796},
year = {2021},
date = {2021-08-01},
journal = {Fusion Engineering and Design},
volume = {169},
pages = {112489},
abstract = {The JET ILA is an Ion Cyclotron Resonance Heating (ICRH) antenna composed of four resonant double loops (RDLs) arranged in a 2 toroidal by 2 poloidal compact array. It has been operated in a range of frequencies from 29 to 51 MHz, but mostly on half array. Some full array pulses were achieved but without all control loops implemented. All control algorithms (first and second stage matching, toroidal and poloidal phasing, totalling 22 feedback loops) have now been implemented and recently allowed to operate the full array at 33 MHz and 42 MHz up to 4 MW. It also allowed for the first time to perform a poloidal phase scan of the antenna at 37 MHz, with dipole toroidal phasing. Although full array operation has mostly proven reliable at 33 MHz, it has proven unstable at 42 MHz in several occasions due to the high level of mutual coupling between the different RDLs inherent to a compact array. To decouple the control of the top and bottom halves, first tests were successfully performed with polychromatic – or dual frequency – operation of the ILA (operation at 2 different frequencies around a central frequency).},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
R. Lunsford; C. Killer; A. Nagy; D. A. Gates; T. Klinger; A. Dinklage; G. Satheeswaran; G. Kocsis; S. A. Lazerson; F. Nespoli; N. A. Pablant; A. Stechow; A. Alonso; T. Andreeva; M. Beurskens; C. Biedermann; S. Brezinsek; K. J. Brunner; B. Buttenschön; D. Carralero; G. Cseh; P. Drewelon F. Effebverg; T. Estrada O. P. Ford; O. Gruklke; U. Hergenhahn; U. Höefel; H. Knauer; M. Krause; M. Krychowiak; S. Kwak; A. Langenberg; U. Neuner; D. Nicolai; A. Pavone; A. Puig Sitjes; K. Rahbarnia; J. Schilling; J. Svensson; T. Szepesi; H. Thomsen; T. Wauters; T. Windisch; V. Winters; D. Zhang; L. Zsuga; W7-X Team
Characterization of injection and confinement improvement through impurity induced profile modifications on the Wendelstein 7-X stellarator Journal Article
In: Physics of Plasmas, vol. 28, no. 8, pp. 082506, 2021.
@article{2021,
title = {Characterization of injection and confinement improvement through impurity induced profile modifications on the Wendelstein 7-X stellarator},
author = {R. Lunsford and C. Killer and A. Nagy and D. A. Gates and T. Klinger and A. Dinklage and G. Satheeswaran and G. Kocsis and S. A. Lazerson and F. Nespoli and N. A. Pablant and A. Stechow and A. Alonso and T. Andreeva and M. Beurskens and C. Biedermann and S. Brezinsek and K. J. Brunner and B. Buttenschön and D. Carralero and G. Cseh and P. Drewelon F. Effebverg and T. Estrada O. P. Ford and O. Gruklke and U. Hergenhahn and U. Höefel and H. Knauer and M. Krause and M. Krychowiak and S. Kwak and A. Langenberg and U. Neuner and D. Nicolai and A. Pavone and A. Puig Sitjes and K. Rahbarnia and J. Schilling and J. Svensson and T. Szepesi and H. Thomsen and T. Wauters and T. Windisch and V. Winters and D. Zhang and L. Zsuga and W7-X Team},
year = {2021},
date = {2021-08-01},
journal = {Physics of Plasmas},
volume = {28},
number = {8},
pages = {082506},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
V. Maquet; V. Bobkov; A. Messiaen; M. Usoltceva
Preliminary RF characterization of DEMO in-port ion cyclotron heating system for toroidal and poloidal geometry variations Journal Article
In: Fusion Engineering and Design, vol. 169, pp. 112508, 2021, ISSN: 0920-3796.
@article{2019,
title = {Preliminary RF characterization of DEMO in-port ion cyclotron heating system for toroidal and poloidal geometry variations},
author = {V. Maquet and V. Bobkov and A. Messiaen and M. Usoltceva},
url = {https://www.sciencedirect.com/science/article/pii/S0920379621002842},
doi = {https://doi.org/10.1016/j.fusengdes.2021.112508},
issn = {0920-3796},
year = {2021},
date = {2021-08-01},
journal = {Fusion Engineering and Design},
volume = {169},
pages = {112508},
abstract = {Ion cyclotron Resonance Heating (ICRH) is one of the auxiliary heating schemes considered for the future DEMOnstration Power Plant (DEMO). The ICRH system in DEMO should couple 50 MW using three equatorial ports. Compared to the ITER one, the current DEMO port design has a smaller toroidal and a larger poloidal extent. One of the ICRH pre-conceptual design options for DEMO, an in-port antenna based on the current ITER design, is investigated using the ANTITER II code. To make optimal use of the port larger poloidal extent, the possibility to use quadruplets instead of the ITER triplets is explored. The impact on the power coupling is evaluated for two different antenna geometry considering a possible toroidal extension of the antenna in the blanket. The ITER matching-decoupling system is adapted to the new antenna front geometries considered.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
G. Urbanczyk; L. Colas; J. Hillairet; E. Lerche; N. Fedorczak; J. Morales; J. Gunn; V. Ostuni; S. Heuraux; D. Vezinet; V. Bobkov; C. Desgranges; A. Ekedahl; P. Mollard; G. Lombard; B. Pegourie; T. Loarer; W. Helou; C. C. Klepper; E. A. Unterberg; M. Usoltceva; P. Devynck; C. Yan; J. G. Li; K. Wang
RF wave coupling, plasma heating and characterization of induced plasma-material interactions in WEST L-mode discharges Journal Article
In: Nuclear Fusion, vol. 61, no. 8, pp. 086027, 2021.
@article{2020,
title = {RF wave coupling, plasma heating and characterization of induced plasma-material interactions in WEST L-mode discharges},
author = {G. Urbanczyk and L. Colas and J. Hillairet and E. Lerche and N. Fedorczak and J. Morales and J. Gunn and V. Ostuni and S. Heuraux and D. Vezinet and V. Bobkov and C. Desgranges and A. Ekedahl and P. Mollard and G. Lombard and B. Pegourie and T. Loarer and W. Helou and C. C. Klepper and E. A. Unterberg and M. Usoltceva and P. Devynck and C. Yan and J. G. Li and K. Wang},
url = {https://doi.org/10.1088/1741-4326/ac0d11},
doi = {10.1088/1741-4326/ac0d11},
year = {2021},
date = {2021-08-01},
journal = {Nuclear Fusion},
volume = {61},
number = {8},
pages = {086027},
publisher = {IOP Publishing},
abstract = {Plasma heating in the full tungsten (W) environment in a steady-state tokamak (WEST) relies on electromagnetic waves in both the lower hybrid (LH) and ion cyclotron range of frequencies (ICRF). The present study focuses mostly on the optimization of discharges heated with ICRF, by reporting different methods to first optimize wave coupling, optimize their absorption and reduce the impurity production. It is shown that ICRF coupling can be optimized by moving the plasma closer to antennas, increasing the plasma density, wave frequency and LH power. We show that the absorption efficiency correlates with the hydrogen concentration with the existence of an optimum between 7% and 10% as expected for a minority heating scenario. Absolutely calibrated visible spectroscopy sightlines were used to monitor ion fluxes in different locations as part of an effort to quantitatively estimate the contribution of different impurity sources to the core contamination by tungsten. It is typically found that in discharges with high total RF-power (above 5 MW of LH and 3 MW of ICRF), divertor and antenna limiter sources can reach a similar order of magnitude during the ICRF phase.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
A. R. Polevoi; A. Loarte; R. Bilato; N. N. Gorelenkov; Y. O. Kazakov; E. Polunovskiy; A.Tchistiakov; E. Fable; V. Kiptily; A. V. Krasilnikov; A. Y Kuyanov; R. Nazikian; S. D. Pinches; M. Schneider
Impact of suprathermal ions on neutron yield at Pre-DT phase of ITER operation Journal Article
In: Nuclear Fusion, vol. 61, no. 7, pp. 076008, 2021.
@article{2017,
title = {Impact of suprathermal ions on neutron yield at Pre-DT phase of ITER operation},
author = {A. R. Polevoi and A. Loarte and R. Bilato and N. N. Gorelenkov and Y. O. Kazakov and E. Polunovskiy and A.Tchistiakov and E. Fable and V. Kiptily and A. V. Krasilnikov and A. Y Kuyanov and R. Nazikian and S. D. Pinches and M. Schneider},
url = {https://doi.org/10.1088/1741-4326/abfa33},
doi = {10.1088/1741-4326/abfa33},
year = {2021},
date = {2021-07-01},
journal = {Nuclear Fusion},
volume = {61},
number = {7},
pages = {076008},
publisher = {IOP Publishing},
abstract = {An assessment of neutron production during the pre-fusion power-operation (PFPO) phase has been carried out for a representative set of plasma scenarios predicted by the ITER Research Plan. A range of heating systems, namely neutral beam injection (NBI) (hydrogen), electron cyclotron resonance heating (ECRH), and ion cyclotron resonance heating (ICRH) are planned to be used for PFPO studies in helium, hydrogen, and mixed hydrogen–helium plasmas. Fast ions (protons and 3He) originating from NBI and ICRH systems can increase neutron production in PFPO plasmas by directly interacting with intrinsic Be impurities or through secondary processes, as also evidenced at JET. The generation of fast ions in ITER PFPO scenarios has been modelled using the ASTRA-NBI and TORIC-SSFPQL codes. A significant impact of the synergy between hydrogen NBI and hydrogen-minority ICRH on neutron production in helium plasmas is reported. In addition, the stability of the toroidicity-induced Alfvén eigenmodes (TAE) is analyzed for PFPO plasmas with a high pressure of suprathermal ions and a weak reversed shear. The possible impact of sawtooth oscillations and TAEs on neutron production is discussed, based on a linear stability analysis.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
R. Ragona; J. Hillairet; F. Durodié; C. Yu; P. Mollard; Q. Yang; H. Xu; T. Batal; J. Li; A. Messiaen; J-M. Bernard; G. Lombard; Y. Song
RF network analysis of the WEST TWA mock-up in TITAN Journal Article
In: Fusion Engineering and Design, vol. 168, pp. 112615, 2021, ISSN: 0920-3796.
@article{2016,
title = {RF network analysis of the WEST TWA mock-up in TITAN},
author = {R. Ragona and J. Hillairet and F. Durodié and C. Yu and P. Mollard and Q. Yang and H. Xu and T. Batal and J. Li and A. Messiaen and J-M. Bernard and G. Lombard and Y. Song},
url = {https://www.sciencedirect.com/science/article/pii/S0920379621003914},
doi = {https://doi.org/10.1016/j.fusengdes.2021.112615},
issn = {0920-3796},
year = {2021},
date = {2021-07-01},
journal = {Fusion Engineering and Design},
volume = {168},
pages = {112615},
abstract = {WEST represents the ideal device to test a reactor relevant travelling wave array (TWA) due to its long pulse capability and full metal wall configuration. Moreover, the already installed ICRF high power launchers will allow a direct comparison between a classical in-port antenna and the TWA. The design and exploitation of a high power (2 MW) TWA mock-up to be tested in TITAN represent the first step towards its integration in WEST. This paper presents the progress in the RF characterization of this high power mock-up. An integrated modelling scheme based on the full-wave code HFSS and on Python packages for RF circuit simulations is developed and used to parametrically analyse the response of the mock-up inside TITAN. The sensitivity of the antenna to geometrical deformations, e.g. thermal dilatation or manufacturing tolerances, is analysed. The use of trimmers to compensate those deformations is discussed and results from a manufactured trimmer test-bed are presented. A diagnostic system is proposed to measure electric field and current on the straps. Aspects like sensitivity and calibration are briefly discussed. In conclusion, the next steps of the project are outlined.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
T. Batal; R. Ragona; J. Hillairet; C. Yu; J-M. Bernard; P. Mollard; F. Farina; M. Firdaouss; Q. Yang
Design and thermal-structural analysis of a high power ICRH travelling wave array antennas Journal Article
In: Fusion Engineering and Design, vol. 166, pp. 112325, 2021, ISSN: 0920-3796.
@article{2014,
title = {Design and thermal-structural analysis of a high power ICRH travelling wave array antennas},
author = {T. Batal and R. Ragona and J. Hillairet and C. Yu and J-M. Bernard and P. Mollard and F. Farina and M. Firdaouss and Q. Yang},
url = {https://www.sciencedirect.com/science/article/pii/S0920379621001010},
doi = {https://doi.org/10.1016/j.fusengdes.2021.112325},
issn = {0920-3796},
year = {2021},
date = {2021-05-01},
journal = {Fusion Engineering and Design},
volume = {166},
pages = {112325},
abstract = {Travelling wave array (TWA) antennas have been proposed for the ICRH (Ion Cyclotron Resonance Heating) antennas of fusion reactors in view to decreasing the antenna voltage and associated electric field. This paper reports the progress of the design and structural analysis of an actively cooled high power TWA antenna for WEST. First, the design of a non-cooled mock-up that will be tested in the TITAN facility is presented. The main objective is to assess the voltage stand-off of the antenna at power and electric field levels relevant for future nominal operation in a fusion device. The main characteristics of the mock-up are detailed and the results from thermal and structural analysis of the mock-up tested in TITAN are presented. In the second part, the compatibility with WEST environment for an actively-cooled TWA antenna is assessed. Mechanical, electromagnetic, thermal and hydraulics constrains (.i.e VDE, plasma radiation, toroidal magnetic field ripple…) are listed in a system loads specification. A Virtual Reality analysis using IRFM tools has been performed to check compliance of the design in term of assembly inside the WEST vacuum vessel.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
E. Panontin; D. Rigamonti; M. Nocente; A. Dal Molin; A. Browslawski; T. Craciunescu; G. Croci; N. Cruz; J. Figueiredo; L. Giacomelli; G. GOrini; M. Gosk; G. Kaveney; Y. O. Kazakov; V. Kiptily; S. Korolszuk; A. Murari; E. Perelli Cippo; M. Salewski; A. Urban; I. Zychor; M. Tardocchi; JET Contributors
First spatially resolved measurements of the D-3 He a- particle source with the upgraded JET gamma-ray camera Journal Article
In: Review of Scientific Instruments, vol. 92, no. 5, pp. 053529, 2021.
@article{2015,
title = {First spatially resolved measurements of the D-3 He a- particle source with the upgraded JET gamma-ray camera},
author = {E. Panontin and D. Rigamonti and M. Nocente and A. Dal Molin and A. Browslawski and T. Craciunescu and G. Croci and N. Cruz and J. Figueiredo and L. Giacomelli and G. GOrini and M. Gosk and G. Kaveney and Y. O. Kazakov and V. Kiptily and S. Korolszuk and A. Murari and E. Perelli Cippo and M. Salewski and A. Urban and I. Zychor and M. Tardocchi and JET Contributors},
year = {2021},
date = {2021-05-01},
journal = {Review of Scientific Instruments},
volume = {92},
number = {5},
pages = {053529},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
V. Bobkov; M. Usoltceva; H. Faugel; A. Kostic; R. Maggiora; D. Milanesio; V. Maquet; R. Ochoukov; W. Tierens; F. Zeus; W. Zhang
Development of pre-conceptual ITER-type ICRF antenna design for DEMO Journal Article
In: Nuclear Fusion, vol. 61, no. 4, pp. 046039, 2021.
@article{2011,
title = {Development of pre-conceptual ITER-type ICRF antenna design for DEMO},
author = {V. Bobkov and M. Usoltceva and H. Faugel and A. Kostic and R. Maggiora and D. Milanesio and V. Maquet and R. Ochoukov and W. Tierens and F. Zeus and W. Zhang},
year = {2021},
date = {2021-04-01},
journal = {Nuclear Fusion},
volume = {61},
number = {4},
pages = {046039},
abstract = {ICRF antenna development for DEMO for the pre-conceptual phase is carried out by merging the existing knowledge about multi-strap ITER, JET and ASDEX upgrade antennas. Many aspects are taken over and adapted to DEMO, including the mechanical design and RF performance optimization strategies. The minimization of ICRF-specific plasma-wall interactions is aimed at by optimizing the feeding power balance, a technique already proven in practice. Technological limits elaborated for the components of ITER ICRF system serve as a guideline in the current design process. Several distinctive aspects, like antenna mounting, integration with the neighboring components or adaptation for neutron environment, are tackled individually for DEMO.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
J. Chew; P. Gibbon; D. Brömmel; T. Wauters; Y. Gribov; P. Vries
Three-dimensional first principles simulation of a hydrogen discharge Journal Article
In: Plasma Physics and Controlled Fusion, vol. 63, no. 4, pp. 045012, 2021.
@article{2013,
title = {Three-dimensional first principles simulation of a hydrogen discharge},
author = {J. Chew and P. Gibbon and D. Brömmel and T. Wauters and Y. Gribov and P. Vries},
year = {2021},
date = {2021-04-01},
journal = {Plasma Physics and Controlled Fusion},
volume = {63},
number = {4},
pages = {045012},
abstract = {Townsend discharge theory is commonly used to describe and approximate the ionisation fraction growth rate in the very early phase of plasma initiation in tokamak devices via ohmic breakdown. The prediction of the ionisation fraction growth rate is done most commonly with continuum or kinetic models, which in turn boil down to the relation between the first Townsend's coefficient α, pressure p and electric field strength E (namely, α/p and E/p). To date there are few computational models that attempt to simulate the ionisation fraction growth rate via explicit modelling of each ionisation event through electron-neutral collisions. This is largely due to the challenge of addressing the exponential growth of charged particles from ionisation processes, combined with the high computational cost of N-body simulation. In this work, a new fully three-dimensional, first-principles model of a Townsend hydrogen discharge is demonstrated and benchmarked against prior experimental findings. These tests also include comparisons of three separate models for the scattering angle and their impact on the obtained α/p and mean electron drift velocity. It is found that isotropic scattering combined with restricting the freed electron's scattering angle along the incident electron's velocity vector during ionisation events gives the closest agreement of α/p compared to experimental measurements.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
D. Van Eester; E. Lerche; Ph. Hyunh; T. Johnson; JET contributors; EUROfusion-IM team
A fast tool for ICRH+NBI modelling within the EU-IM framework A fast tool for ICRH+NBI modelling within the EU-IM framework Journal Article
In: Journal of Plasma Physics, vol. 87, no. 2, pp. 855870202, 2021.
@article{2008,
title = {A fast tool for ICRH+NBI modelling within the EU-IM framework A fast tool for ICRH+NBI modelling within the EU-IM framework},
author = {D. Van Eester and E. Lerche and Ph. Hyunh and T. Johnson and JET contributors and EUROfusion-IM team},
editor = {Journal Plasma Physics},
year = {2021},
date = {2021-04-01},
booktitle = {A fast tool for ICRH+NBI modelling within the EU-IM framework A fast tool for ICRH +NBI modelling within the EU-IM framework},
journal = {Journal of Plasma Physics},
volume = {87},
number = {2},
pages = {855870202},
abstract = {Most if not all tokamak heating scenarios involve multiple ion populations being heated simultaneously. To allow the simulation of various aspects of physics dynamics determining the characteristics of operational scenarios in a flexible way, speedy yet sufficiently accurate models are needed, and they should be connected to each other via a `backbone'. Under the umbrella of EUROfusion's Integrated Modelling efforts, such a structure is provided. The present paper focuses on one physics aspect: auxiliary heating. After solving the wave equation or beam source equation, this requires solving a set of coupled Fokker–Planck equations for the various populations involved. The adopted modules – enabling accounting for the Coulomb collisional interaction of several non-Maxwellian (minority, majority and beam) populations – are discussed and a practical example of their use is provided: the JET `baseline' scenario heating a minority of 3He
3He ions in a balanced D+ + T mix heated by D and T neutral beams.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
3He ions in a balanced D+ + T mix heated by D and T neutral beams.
K. K. Kirov; E. Belonohy; C. D. Challis; J. Eriksson; D. Frigione; L. Garzotti; L. Giacomelli; J. Hobirk; A. Kappatou; D. Keeling; D. King; E. Lerche; P. J. Lomas; M. Nocente; C. Reux; F. G. Rimini; A. C. C. Sips; D. Van Eester; JET Contributors.
Analysis of the fusion performance, beam–target neutrons and synergistic effects of JET's high-performance pulses Journal Article
In: Nuclear Fusion, vol. 61, no. 4, pp. 046017, 2021.
@article{2009,
title = {Analysis of the fusion performance, beam–target neutrons and synergistic effects of JET's high-performance pulses},
author = {K. K. Kirov and E. Belonohy and C. D. Challis and J. Eriksson and D. Frigione and L. Garzotti and L. Giacomelli and J. Hobirk and A. Kappatou and D. Keeling and D. King and E. Lerche and P. J. Lomas and M. Nocente and C. Reux and F. G. Rimini and A. C. C. Sips and D. Van Eester and JET Contributors.},
year = {2021},
date = {2021-04-01},
journal = {Nuclear Fusion},
volume = {61},
number = {4},
pages = {046017},
abstract = {Achieving high neutron yields in today's fusion research relies on high-power auxiliary heating in order to attain required core temperatures. This is usually achieved by means of high neutral beam (NB) and radio frequency (RF) power. Application of NB power is accompanied by production of fast beam ions and associated beam–target (BT) reactions. In standard JET operational conditions, deuterium (D) NBs are injected into D plasmas. The injected beams comprise D atoms at full, one-half and one-third injected energy. Typically, the full energy of the injected D beams is between 90 and 120 keV, providing 1.4–2.0 MW of heating, which is about half of the injected power. Half-energy D beams carry about one-third of the injected power and the rest of the power is carried by the third energy fraction of D beams. Under these conditions, thermal fusion reactions, i.e. those between plasma ions, and BT reactions are of the same order of magnitude. This study addresses important issues regarding the impact of density, central electron and ion temperatures and their ratio, Ti(0)/Te(0), on fusion performance, measured by the total neutron yield and BT neutron counts. NB/RF synergistic effects are discussed as well. It is demonstrated that thermal fusion gain increases linearly with normalised plasma pressure, βN, and confinement, Btτ. The BT neutrons are, however, more difficult to predict and this task in general requires numerical treatment. In this study, BT neutrons in JET's best-performing baseline and hybrid pulses are analysed and the underlying dependencies discussed. Central fast ion densities are found to decrease with increased density and density peaking. This is attributed to poorer beam penetration at high density. The BT reactions however are unchanged and can even increase if operating at higher core temperatures. An increase in the central ion temperature and Ti(0)/Te(0) ratio leads to higher total and BT reaction rates whilst simultaneously the ratio of the BT to total neutron decreases significantly. NB/RF synergistic effects are found to have a negligible impact on total neutron rate. This can be explained by the reduced beam penetration in high-density conditions leading to lower central fast ion density.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
A. Messiaen; V. Maquet; J. Ongena
Ion cyclotron resonance heating fast and slow wave excitation and power deposition in edge plasmas with application to ITER Journal Article
In: Plasma Physics and Controlled Fusion, vol. 63, no. 4, pp. 045021, 2021.
@article{2006,
title = {Ion cyclotron resonance heating fast and slow wave excitation and power deposition in edge plasmas with application to ITER},
author = {A. Messiaen and V. Maquet and J. Ongena},
url = {https://doi.org/10.1088/1361-6587/abdf2b},
doi = {10.1088/1361-6587/abdf2b},
year = {2021},
date = {2021-04-01},
journal = {Plasma Physics and Controlled Fusion},
volume = {63},
number = {4},
pages = {045021},
publisher = {IOP Publishing},
abstract = {The antenna power coupling to the plasma centre and its possible deleterious coupling to the plasma edge are key parameters in an ion cyclotron resonance heating system. The influence on these parameters by the confluence between the slow and the fast magnetosonic waves is studied for the case of large machines. Until now, the modelling of the scrape off layer region has been calculated by ANTITER II, which contains only the fast wave description and where the confluence with the slow wave (S wave) is approximated by the Alfvén resonance. In the present study, a complete modelling of the slow and fast waves is made by ANTITER IV. The modelling by the two codes is compared and shows the important role of the Alfvén and the lower hybrid resonances for the excitation of large fields and associated power deposition at the edge of the plasma even far from the antenna location. The ANTITER IV modelling is thereafter applied to the case of the ITER antenna with a reference density profile and heating parameters. A comparative study is made for the edge power deposition and the excitation of large fields for different toroidal phasing cases of the antenna. This study also takes into account the tilting of the antenna array with respect to the total magnetic field in front of the antenna. If the Faraday screen is field-aligned, the excitation of the S wave occurs at the wave confluence; however, in the case of non-alignment the antenna directly excites the S wave. This effect is studied and quantified. All edge effects, even the direct excitation of S waves, can be strongly reduced by tailoring the current distribution in the straps of the antenna array. Resulting cases for the minimisation of edge power deposition in ITER and the reactor are studied.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
G. Pucella; P. Buratti; E. Giovannozzi; E. Alessi; F. Auriemma; D. Brunetti; D. R. Ferreira; M. Baruzzo; D. Frigione; L. Garzotti; E. Joffrin; E. Lerche; P. J. Lomas; S. Nowak; L. Piron; F. Rimini; C. Sozzi; D. Van Eester; JET Contributors.
Onset of tearing modes in plasma termination on JET: the role of temperature hollowing and edge cooling Journal Article
In: Nuclear Fusion, vol. 61, no. 4, pp. 046020, 2021.
@article{2010,
title = {Onset of tearing modes in plasma termination on JET: the role of temperature hollowing and edge cooling},
author = {G. Pucella and P. Buratti and E. Giovannozzi and E. Alessi and F. Auriemma and D. Brunetti and D. R. Ferreira and M. Baruzzo and D. Frigione and L. Garzotti and E. Joffrin and E. Lerche and P. J. Lomas and S. Nowak and L. Piron and F. Rimini and C. Sozzi and D. Van Eester and JET Contributors.},
year = {2021},
date = {2021-04-01},
journal = {Nuclear Fusion},
volume = {61},
number = {4},
pages = {046020},
abstract = {In this work the onset of tearing modes in the termination phase of plasma pulses on JET is investigated. It is shown that the broadening or the shrinking of the current density profile, as a consequence of a core hollowing or an edge cooling of the electron temperature profile, strongly increases the probability of destabilizing a 2/1 tearing mode also in absence of an external trigger (e.g. a sawtooth crash). Two parameters are defined to highlight changes in the shape of the temperature profile that can lead to MHD instabilities and an empirical stability diagram is introduced into the space of the two new parameters. A large data-set of pulses carried out in the high-current scenario at JET with ITER-like wall is analyzed and criteria for the development of disruption alerts based on the two risk indicators for MHD instabilities are discussed, taking into account the different dynamics of the observed phenomena leading to the onset of 2/1 tearing modes.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
M. Usoltceva; V. Bobkov; H. Faugel; T. Franke; A. Kostic; R. Maggiora; D. Milanesio; V. Maquet; R. Ochoukov; W. Tierens; F. Zeus; W. Zhang
DEMO ion cyclotron heating: Status of ITER-type antenna design Journal Article
In: Fusion Engineering and Design, vol. 165, pp. 112269, 2021, ISSN: 0920-3796.
@article{2007,
title = {DEMO ion cyclotron heating: Status of ITER-type antenna design},
author = {M. Usoltceva and V. Bobkov and H. Faugel and T. Franke and A. Kostic and R. Maggiora and D. Milanesio and V. Maquet and R. Ochoukov and W. Tierens and F. Zeus and W. Zhang},
url = {https://www.sciencedirect.com/science/article/pii/S0920379621000454},
doi = {https://doi.org/10.1016/j.fusengdes.2021.112269},
issn = {0920-3796},
year = {2021},
date = {2021-04-01},
journal = {Fusion Engineering and Design},
volume = {165},
pages = {112269},
abstract = {The ITER ICRF system will gain in complexity relative to the existing systems on modern devices, and the same will hold true for DEMO. The accumulated experience can help greatly in designing an ICRF system for DEMO. In this paper the current status of the pre-conceptual design of the DEMO ICRF antenna and some related components is presented. While many aspects strongly resemble the ITER system, in some design solutions we had to take an alternative route to be able to adapt to DEMO specific. One of the key points is the toroidal antenna extent needed for the requested ICRF heating performance, achieved by splitting the antenna in halves, with appropriate installation. Modelling of the so far largest ICRF antenna in RAPLICASOL and associated challenges are presented. Calculation are benchmarked with TOPICA. Results of the analysis of the latest model and an outlook for future steps are given.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
R H S Budé; D. Van Eester; J Dijk; R J E Jaspers; A B Smolders
Accelerating simulations of electromagnetic waves in hot, magnetized fusion plasmas Journal Article
In: Plasma Physics and Controlled Fusion, vol. 63, no. 3, pp. 035014, 2021.
@article{2001,
title = {Accelerating simulations of electromagnetic waves in hot, magnetized fusion plasmas},
author = {R H S Budé and D. Van Eester and J Dijk and R J E Jaspers and A B Smolders},
url = {https://doi.org/10.1088/1361-6587/abd619},
doi = {10.1088/1361-6587/abd619},
year = {2021},
date = {2021-03-01},
journal = {Plasma Physics and Controlled Fusion},
volume = {63},
number = {3},
pages = {035014},
publisher = {IOP Publishing},
abstract = {Accurate simulations of the behavior of RF waves in hot, magnetized fusion plasmas have traditionally been computationally demanding due to the integro-differential character of the hot plasma wave equation. In this work a method is described that allows the integral in the hot-plasma wave equation to be rewritten as a set of differential operators by fitting a polynomial through the dielectric tensor components. This approach is applied to a one-dimensional simulation with typical profiles and plasma parameters for the JET fusion reactor. The accuracy and computational time are compared with an all-orders model and a truncated Finite Larmor Radius model. It is shown that the proposed method can be used to achieve accuracies previously only obtained with extremely heavy all-orders models like the two-dimensional AORSA code, but at significantly reduced computational costs. The MATLAB code that has been developed in this work is available under the GPLv3 licence.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
A. Kappatou; M. Weiland; R. Bilato; Y. O. Kazakov; R. Dux; V. Bobkov; T. Pütterich; R. M. McDermott
CXRS measurements of energetic helium ions in ASDEX Upgrade plasmas heated with a 3-ion ICRF scenario Journal Article
In: Nuclear Fusion, vol. 61, no. 3, pp. 036017, 2021.
@article{2003,
title = {CXRS measurements of energetic helium ions in ASDEX Upgrade plasmas heated with a 3-ion ICRF scenario},
author = {A. Kappatou and M. Weiland and R. Bilato and Y. O. Kazakov and R. Dux and V. Bobkov and T. Pütterich and R. M. McDermott},
url = {https://doi.org/10.1088/1741-4326/abca57},
doi = {10.1088/1741-4326/abca57},
year = {2021},
date = {2021-03-01},
journal = {Nuclear Fusion},
volume = {61},
number = {3},
pages = {036017},
publisher = {IOP Publishing},
abstract = {Fast ion physics is an active field of research in the fusion community, but most studies focus on deuterium fast ions. The generation and investigation of energetic helium in present devices, however, provide significantly more insight on how the fast alpha particles produced from fusion reactions, will behave in future reactor plasmas. Fast helium ion populations can be measured with charge exchange recombination spectroscopy (CXRS) in the wings of the helium spectral line (He II n = 4–3, 468.6 nm) providing information on their distribution function. CXRS measurements of energetic 3He ions, a first for ASDEX Upgrade, are presented. The 3He ions are accelerated to high energies by a three-ion cyclotron resonance frequency (ICRF) heating scenario in a mixed hydrogen–deuterium plasma. The spectral signature of the energetic helium ions in the charge exchange spectra is presented and compared with the theoretical predictions obtained with the TORIC-SSFPQL code. The magnitude of the predicted charge exchange spectral radiance, obtained via forward-modelling of the spectrum utilising TORIC-SSFPQL distribution functions, and the expected energies of the ions agree well with the measurement, confirming that the spectral feature is due to ICRF-accelerated 3He ions. Comparisons between the experimental measurement and the modelling reveal discrepancies that illuminate details of the velocity distribution function of these ions.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
M. Lennholm; R. McKean; R. Mooney; G. Tvalashvili; G. Artaserse; M. Baruzzo; E. Belonohy; G. Calabro; I. S. Carvalho; C. D. Challis; E. Luna; D. Frigione; L. Garzotti; R. B. Henriques; J. Hobirk; P. Jaquet; A. Kappatou; D. Keeling; D. King; P. T. Lang; E. Lerche; P. J. Lomas; C. Lowry; M. Maslov; S. Moradi; M. F. F. Nave; I. Nunes; C. Perez Thun; C. Reux; F. G. Rimini; A. C. C. Sips; C. Sozzi; M. Valovic; D. Van Eester; JET contributors
Statistical assessment of ELM triggering by pellets on JET Journal Article
In: Nuclear Fusion, vol. 61, no. 3, pp. 036035, 2021.
@article{2005,
title = {Statistical assessment of ELM triggering by pellets on JET},
author = {M. Lennholm and R. McKean and R. Mooney and G. Tvalashvili and G. Artaserse and M. Baruzzo and E. Belonohy and G. Calabro and I. S. Carvalho and C. D. Challis and E. Luna and D. Frigione and L. Garzotti and R. B. Henriques and J. Hobirk and P. Jaquet and A. Kappatou and D. Keeling and D. King and P. T. Lang and E. Lerche and P. J. Lomas and C. Lowry and M. Maslov and S. Moradi and M. F. F. Nave and I. Nunes and C. Perez Thun and C. Reux and F. G. Rimini and A. C. C. Sips and C. Sozzi and M. Valovic and D. Van Eester and JET contributors},
url = {https://doi.org/10.1088/1741-4326/abd861},
doi = {10.1088/1741-4326/abd861},
year = {2021},
date = {2021-03-01},
journal = {Nuclear Fusion},
volume = {61},
number = {3},
pages = {036035},
publisher = {IOP Publishing},
abstract = {This article investigates the triggering of ELMs on JET by injection of frozen pellets of isotopes of Hydrogen. A method is established to determine the probability that a specific pellet triggers a particular ELM. This method allows clear distinction between pellet-ELM pairs that are very likely to represent triggering events and pairs that are very unlikely to represent such an event. Based on this, the pellet parameters that are most likely to affect the ability of pellets to trigger ELMs have been investigated. It has been found that the injection location is very important, with injection from the vertical high field side showing a much higher triggering efficiency than low field side (LFS) injection. The dependence on parameters such as pellet speed and size and the time since the last ELM is also seen to be much stronger for LFS injection. Finally, the paper illustrates how improvements to the pellet injection system by streamlining the pellet flight lines and slightly increasing the pellet size has resulted in a significantly improved ability to deliver pellets to the plasma and trigger ELMs.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
R.Bisson; E.A.Hodille; J.Gaspar; D.Douai; T. Wauters; A.Gallo; J.Gunn; A.Hakola; T.Loarer; R.Nouailletas; J.Morales; B.Pégourié; C.Reux; R.Sabot; E.Tsitrone; S.Vartanian; E.Wang; N.Fedorczak; S.Brezinsek; team
Deuterium and helium outgassing following plasma discharges in WEST: Delayed D outgassing during D-to-He changeover experiments studied with threshold ionization mass spectrometry Journal Article
In: Nuclear Materials and Energy, vol. 26, no. 1, pp. 100885, 2021.
@article{2002,
title = {Deuterium and helium outgassing following plasma discharges in WEST: Delayed D outgassing during D-to-He changeover experiments studied with threshold ionization mass spectrometry},
author = {R.Bisson and E.A.Hodille and J.Gaspar and D.Douai and T. Wauters and A.Gallo and J.Gunn and A.Hakola and T.Loarer and R.Nouailletas and J.Morales and B.Pégourié and C.Reux and R.Sabot and E.Tsitrone and S.Vartanian and E.Wang and N.Fedorczak and S.Brezinsek and team},
year = {2021},
date = {2021-03-01},
journal = {Nuclear Materials and Energy},
volume = {26},
number = {1},
pages = {100885},
abstract = {Threshold ionization mass spectrometry (TIMS) is one of two methods envisioned in ITER to quantify the helium (He) fusion product in the exhaust pumping lines during plasma discharges. We present the first demonstration of another potential application of TIMS in a tokamak environment, namely, the analysis of deuterium (D) and He outgassing following a plasma discharge i.e. during the post-discharge. This method has been tested with sub-second temporal resolution in WEST during its first He plasma discharges in the so-called He changeover experimental campaign. The calibration method of TIMS using a D plasma discharge is presented while the uncertainties related to TIMS during rapid pressure variations, i.e. upon plasma breakdown and plasma termination, are discussed. The first results obtained with TIMS during consecutive D and He plasma discharges in the full tungsten (W) tokamak WEST are reported. It is found that the time evolutions for He and D outgassing in the post-discharge are markedly different. On one hand, He outgassing is instantaneous and decays within 60 s until the He signal gets below detection level. On the other hand, D outgassing can reach a maximum up to several tens of seconds after the termination of the plasma and this outgassing can last for about 10 min. These striking differences should be related to different retention and outgassing from WEST plasma facing components, presently constituted of actively-cooled ITER-like W units and inertially cooled W-coated graphite. Potential mechanisms at the origin of the different outgassing behavior for D and He in W plasma facing components are discussed in light of a systematic analysis of the He and D gas balance and a macroscopic rate equation modeling of the D outgassing from the divertor strike points.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
A. Sahlberg; J. Eriksson; S. Conroy; G. Ericsson; M. Nocente; Y. O. Kazakov; JET Contributors
Spatially resolved measurements of RF accelerated deuterons at JET Journal Article
In: Nuclear Fusion, vol. 61, no. 3, pp. 036025, 2021.
@article{2004,
title = {Spatially resolved measurements of RF accelerated deuterons at JET},
author = {A. Sahlberg and J. Eriksson and S. Conroy and G. Ericsson and M. Nocente and Y. O. Kazakov and JET Contributors},
url = {https://doi.org/10.1088/1741-4326/abd7b6},
doi = {10.1088/1741-4326/abd7b6},
year = {2021},
date = {2021-03-01},
journal = {Nuclear Fusion},
volume = {61},
number = {3},
pages = {036025},
publisher = {IOP Publishing},
abstract = {An understanding of fast (supra-thermal) ion behavior is of great importance in tokamak physics and is a subject studied from both theoretical and experimental perspectives. This paper investigates the spatial energy and density distributions of RF accelerated deuterons using the neutron camera at the tokamak JET. Using the 19 liquid scintillator detectors available in the neutron camera system, we obtain spatial information that cannot be accessed with a single sightline. We present a spectroscopic analysis method in which a spatially resolved model of the fast ion distribution is fitted to the pulse height spectra from all 19 detectors simultaneously. The fast ion distribution is parameterized in such a way that the density, energy, and pitch-angle parts are uncoupled. The energy part is composed of a Maxwellian distribution, characterized by an `RF tail temperature,' and the spatial dependence is modeled as a two-dimensional Gaussian distribution on the poloidal plane of the tokamak. From this parameterized model, we can calculate the spectrum of fusion born neutrons originating from reactions involving RF accelerated deuterons, and by fitting this model to the measured neutron camera pulse height spectra, we obtain an estimate of the spatially resolved distribution of the fast deuterons. The method has been applied to three JET pulses using different RF heating schemes and is shown to identify several features of the fast ion distribution produced in the various scenarios. Hence, this method is able to provide quantitative information about the fast ion distribution resulting from different heating schemes, and can also be useful, e.g., to validate simulation results from RF modeling codes.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
A. Goriaev; T. Wauters; S. Möller; R. Brakel; S. Brezinsek; J. Buermans; K. Crombé; A. Dinklage; R. Habrichs; D. Höschen; M. Krause; Yu. Kovtun; D. Lopez-Rodriguez; F. Louche; S. Moon; D. Nicolai; J. Thomas; R. Ragona; M. Rubel; T. Rüttgers; P. Petersson; P. Brunsell; Ch. Linsmeier; M. Van Schoor
The upgraded TOMAS device: A toroidal plasma facility for wall conditioning, plasma production, and plasma–surface interaction studies Journal Article
In: Review of Scientific Instruments, vol. 92, no. 2, pp. 023506, 2021.
@article{1999,
title = {The upgraded TOMAS device: A toroidal plasma facility for wall conditioning, plasma production, and plasma–surface interaction studies},
author = {A. Goriaev and T. Wauters and S. Möller and R. Brakel and S. Brezinsek and J. Buermans and K. Crombé and A. Dinklage and R. Habrichs and D. Höschen and M. Krause and Yu. Kovtun and D. Lopez-Rodriguez and F. Louche and S. Moon and D. Nicolai and J. Thomas and R. Ragona and M. Rubel and T. Rüttgers and P. Petersson and P. Brunsell and Ch. Linsmeier and M. Van Schoor},
year = {2021},
date = {2021-02-01},
journal = {Review of Scientific Instruments},
volume = {92},
number = {2},
pages = {023506},
abstract = {The Toroidal Magnetized System device has been significantly upgraded to enable development of various wall conditioning techniques, including methods based on ion and electron cyclotron (IC/EC) range of frequency plasmas, and to complement plasma–wall interaction research in tokamaks and stellarators. The toroidal magnetic field generated by 16 coils can reach its maximum of 125 mT on the toroidal axis. The EC system is operated at 2.45 GHz with up to 6 kW forward power. The IC system can couple up to 6 kW in the frequency range of 10 MHz–50 MHz. The direct current glow discharge system is based on a graphite anode with a maximum voltage of 1.5 kV and a current of 6 A. A load-lock system with a vertical manipulator allows exposure of material samples. A number of diagnostics have been installed: single- and triple-pin Langmuir probes for radial plasma profiles, a time-of-flight neutral particle analyzer capable of detecting neutrals in the energy range of 10 eV–1000 eV, and a quadrupole mass spectrometer and video systems for plasma imaging. The majority of systems and diagnostics are controlled by the Siemens SIMATIC S7 system, which also provides safety interlocks.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Y. O. Kazakov; J. Ongena; J. C. Wright; S. J. Wukitch; V. Bobkov; J. Garcia; V. G. Kiptily; M. J. Mantsinen; M. Nocente; M. Schneider; H. Weisen; Y. Barakov; M. Baruzzo; R. Bilato; A. Chomiczewska; R. Coelho; T. Craciunescu; K. Crombé; M. Dreval; E. Dumont; P. Dumortier; F. Durodié; J. Eriksson; M. Fitzgerald; J. Galdon-Quiroga; D. Gallart; M. Garcia-Munoz; L. Giacomelli; C. Giroud; J. Gonzalez Martin; A. Hakola; P. Jacquet; T. Johnson; A. Kappatou; D. Keeling; D. King; K. K. Kirov; P. U. Lamalle; M. Lennholm; E. Lerche; M. Maslov; S. Mazzi; S. Menmuir; I. Monakhov; F. Nabais; M. F. F. Nave; R. Ochoukov; A. R. Polevoi; S. D. Pinches; U. Plank; D. Rigamonti; M. Salewski; P. A. Schneider; S. E. Sharapov; Z. Stancar; A. Thorman; D. Valcarcel; D. Van Eester; M. Van Schoor; J. Varje; M. Weiland; N. Wendler; JET Contributors; ASDEX Upgrade Team; EUROfusion MST1 Team; Alcator C-Mod Team
Physics and applications of three-ion ICRF scenarios for fusion research Journal Article
In: Physics of Plasmas, vol. 28, no. 2, pp. 020501, 2021.
@article{2000,
title = {Physics and applications of three-ion ICRF scenarios for fusion research},
author = {Y. O. Kazakov and J. Ongena and J. C. Wright and S. J. Wukitch and V. Bobkov and J. Garcia and V. G. Kiptily and M. J. Mantsinen and M. Nocente and M. Schneider and H. Weisen and Y. Barakov and M. Baruzzo and R. Bilato and A. Chomiczewska and R. Coelho and T. Craciunescu and K. Crombé and M. Dreval and E. Dumont and P. Dumortier and F. Durodié and J. Eriksson and M. Fitzgerald and J. Galdon-Quiroga and D. Gallart and M. Garcia-Munoz and L. Giacomelli and C. Giroud and J. Gonzalez Martin and A. Hakola and P. Jacquet and T. Johnson and A. Kappatou and D. Keeling and D. King and K. K. Kirov and P. U. Lamalle and M. Lennholm and E. Lerche and M. Maslov and S. Mazzi and S. Menmuir and I. Monakhov and F. Nabais and M. F. F. Nave and R. Ochoukov and A. R. Polevoi and S. D. Pinches and U. Plank and D. Rigamonti and M. Salewski and P. A. Schneider and S. E. Sharapov and Z. Stancar and A. Thorman and D. Valcarcel and D. Van Eester and M. Van Schoor and J. Varje and M. Weiland and N. Wendler and JET Contributors and ASDEX Upgrade Team and EUROfusion MST1 Team and Alcator C-Mod Team},
year = {2021},
date = {2021-02-01},
journal = {Physics of Plasmas},
volume = {28},
number = {2},
pages = {020501},
abstract = {This paper summarizes the physical principles behind the novel three-ion scenarios using radio frequency waves in the ion cyclotron range of frequencies (ICRF). We discuss how to transform mode conversion electron heating into a new flexible ICRF technique for ion cyclotron heating and fast-ion generation in multi-ion species plasmas. The theoretical section provides practical recipes for selecting the plasma composition to realize three-ion ICRF scenarios, including two equivalent possibilities for the choice of resonant absorbers that have been identified. The theoretical findings have been convincingly confirmed by the proof-of-principle experiments in mixed H–D plasmas on the Alcator C-Mod and JET tokamaks, using thermal 3He and fast D ions from neutral beam injection as resonant absorbers. Since 2018, significant progress has been made on the ASDEX Upgrade and JET tokamaks in H–4He and H–D plasmas, guided by the ITER needs. Furthermore, the scenario was also successfully applied in JET D–3He plasmas as a technique to generate fusion-born alpha particles and study effects of fast ions on plasma confinement under ITER-relevant plasma heating conditions. Tuned for the central deposition of ICRF power in a small region in the plasma core of large devices such as JET, three-ion ICRF scenarios are efficient in generating large populations of passing fast ions and modifying the q-profile. Recent experimental and modeling developments have expanded the use of three-ion scenarios from dedicated ICRF studies to a flexible tool with a broad range of different applications in fusion research.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
R. Casagrande; H. Faugel; F. Fischer; H. Fuenfgelder; F. Riedl; G. Siegl; P. Bettini; J. -M. Noterdaeme; K. Combé
Development of an experimental facility for the study of microparticle initiated radio frequency vacuum breakdown Journal Article
In: Review of Scientific Instruments, vol. 92, no. 1, pp. 013508, 2021.
@article{1998,
title = {Development of an experimental facility for the study of microparticle initiated radio frequency vacuum breakdown},
author = {R. Casagrande and H. Faugel and F. Fischer and H. Fuenfgelder and F. Riedl and G. Siegl and P. Bettini and J. -M. Noterdaeme and K. Combé},
year = {2021},
date = {2021-01-01},
journal = {Review of Scientific Instruments},
volume = {92},
number = {1},
pages = {013508},
abstract = {An ongoing objective in the ion cyclotron range of frequencies (ICRF) systems is the improvement of power coupling to the plasma. During the last decade, this goal has been mainly pursued through the study of the coupling resistance, either by optimizing the antenna layout or by tailoring the scrape-off layer profile with gas puffing. Another approach is to increase the voltage handling capability of the ICRF system, limited by breakdown in the launchers or in the transmission lines. This paper describes the design of the ICRF Breakdown EXperiment (IBEX), a device to investigate fundamental aspects of radio frequency arcs under ICRF-relevant conditions. IBEX can achieve a peak voltage of 48 kV at 54 MHz with a 5 kW input power.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
2020
E. Lerche; M Lennholm; I S Carvalho; P Jacquet; M Mantsinen; P. Dumortier; D. Van Eester; J P Graves; P Card; Noble C and
Sawtooth control with modulated ICRH in JET-ILW H-mode plasmas Journal Article
In: Nuclear Fusion, vol. 60, no. 12, pp. 126037, 2020.
@article{1995,
title = {Sawtooth control with modulated ICRH in JET-ILW H-mode plasmas},
author = {E. Lerche and M Lennholm and I S Carvalho and P Jacquet and M Mantsinen and P. Dumortier and D. Van Eester and J P Graves and P Card and Noble C and},
url = {https://doi.org/10.1088%2F1741-4326%2Fabb424},
doi = {10.1088/1741-4326/abb424},
year = {2020},
date = {2020-12-01},
journal = {Nuclear Fusion},
volume = {60},
number = {12},
pages = {126037},
publisher = {IOP Publishing},
abstract = {Sawtooth pacing with modulated ion-cyclotron resonance heating (ICRH) has been demonstrated to be very efficient in JET-ILW L-mode plasmas (Lerche et al 2017 Nucl. Fusion 57 036027, Lennholm et al 2017 Fusion Eng. Des. 123 535–40), where the main heat source in the plasma centre is provided by the RF accelerated minority ions. In H-mode plasmas with substantial neutral beam injection power, this technique is more challenging since the fast beam particles have a stabilizing effect on the sawteeth, making it more difficult to trigger a sawtooth crash by removing the additional fast particle sources induced by ICRH inside the q = 1 surface. New results from JET-ILW experiments, showing that this technique can also be used in high power H-modes with considerable success will be presented, with focus on the sawtooth triggering efficiency at different pacing frequencies and plasma parameters, both during the flat-top phase of the discharges and during the H-mode exit and plasma termination.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
M Nocente; Y. O. Kazakov; J Garcia; V G Kiptily; J. Ongena; M Dreval; M Fitzgerald; S E Sharapov; Z Stancar; H Weisen; Y Baranov; A Bierwage; T Craciunescu; Dal A Molin; E Luna; R Dumont; P. Dumortier; J Eriksson; L Giacomelli; C Giroud; V Goloborodko; G Gorini; E Khilkevitch; K K Kirov; M Iliasova; P Jacquet; P Lauber; E. Lerche; M J Mantsinen; A Mariani; S Mazzi; F Nabais; M F F Nave; J Oliver; E Panontin; D Rigamonti; A Sahlberg; M Salewski; A Shevelev; K Shinohara; P Siren; S Sumida; M Tardocchi; D. Van Eester; J Varje; A Zohar; JET Contributors
In: Nuclear Fusion, vol. 60, no. 12, pp. 124006, 2020.
@article{1994,
title = {Generation and observation of fast deuterium ions and fusion-born alpha particles in JET D - 3He plasmas with the 3-ion radio-frequency heating scenario},
author = {M Nocente and Y. O. Kazakov and J Garcia and V G Kiptily and J. Ongena and M Dreval and M Fitzgerald and S E Sharapov and Z Stancar and H Weisen and Y Baranov and A Bierwage and T Craciunescu and Dal A Molin and E Luna and R Dumont and P. Dumortier and J Eriksson and L Giacomelli and C Giroud and V Goloborodko and G Gorini and E Khilkevitch and K K Kirov and M Iliasova and P Jacquet and P Lauber and E. Lerche and M J Mantsinen and A Mariani and S Mazzi and F Nabais and M F F Nave and J Oliver and E Panontin and D Rigamonti and A Sahlberg and M Salewski and A Shevelev and K Shinohara and P Siren and S Sumida and M Tardocchi and D. Van Eester and J Varje and A Zohar and JET Contributors},
url = {https://doi.org/10.1088%2F1741-4326%2Fabb95d},
doi = {10.1088/1741-4326/abb95d},
year = {2020},
date = {2020-12-01},
journal = {Nuclear Fusion},
volume = {60},
number = {12},
pages = {124006},
publisher = {IOP Publishing},
abstract = {Dedicated experiments to generate energetic D ions and fusion-born alpha particles were performed at the Joint European Torus (JET) with the ITER-like wall (ILW). Using the 3-ion radio frequency (RF) heating scenario, deuterium ions from neutral beam injection (NBI) were accelerated in the core of mixed plasmas to higher energies with ion cyclotron resonance frequency (ICRF) waves, in turn leading to a core-localized source of alpha particles. The fast-ion distribution of RF-accelerated D-NBI ions was controlled by varying the ICRF and NBI power ( 4–6 MW, 3–20 MW), resulting in rather high D-D neutron (≈ 1 × 1016 s−1) and alpha rates (≈ 2 × 1016 s−1) at moderate input heating power. Theory and TRANSP analysis shows that large populations of co-passing MeV-range D ions were generated using the 3-ion ICRF scenario. This important result is corroborated by several experimental observations, in particular gamma-ray measurements. The developed experimental scenario at JET provides unique conditions for probing several aspects of future burning plasmas, such as the contribution from MeV range ions to global confinement, but without introducing tritium. Dominant fast-ion core electron heating with and a rich variety of fast-ion driven Alfvén eigenmodes (AEs) were observed in these plasmas. The observed AE activities do not have a detrimental effect on the thermal confinement and, in some cases, may be driven by the fusion born alpha particles. A strong continuous increase in neutron rate was observed during long-period sawteeth (1 s), accompanied by the observation of reversed shear AEs, which implies that a non monotonic q profile was systematically developed in these plasmas, sustained by the large fast-ion populations generated by the 3-ion ICRF scenario.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
R Ochoukov; R Bilato; V Bobkov; S C Chapman; R Dendy; M Dreval; H Faugel; A Kappatou; Y. O. Kazakov; M Mantsinen; K G McClements; D Moseev; S K Nielsen; J. -M. Noterdaeme; M Salewski; P Schneider; M Weiland
In: Nuclear Fusion, vol. 60, no. 12, pp. 126043, 2020.
@article{1997,
title = {High frequency Alfvén eigenmodes detected with ion-cyclotron-emission diagnostics during NBI and ICRF heated plasmas on the ASDEX Upgrade tokamak},
author = {R Ochoukov and R Bilato and V Bobkov and S C Chapman and R Dendy and M Dreval and H Faugel and A Kappatou and Y. O. Kazakov and M Mantsinen and K G McClements and D Moseev and S K Nielsen and J. -M. Noterdaeme and M Salewski and P Schneider and M Weiland},
url = {https://doi.org/10.1088%2F1741-4326%2Fabb79f},
doi = {10.1088/1741-4326/abb79f},
year = {2020},
date = {2020-12-01},
journal = {Nuclear Fusion},
volume = {60},
number = {12},
pages = {126043},
publisher = {IOP Publishing},
abstract = {The paper presents the first reported observation of high frequency Alfvén eigenmode excitation on the ASDEX Upgrade tokamak. The mode is driven in a novel way using radio frequency (RF) wave acceleration of either beam-injected deuterium ions or thermal He-3 minority ions in a three-ion heating scenario. In the case of beam ion acceleration, the instability only appears during deuteron acceleration at the third beam ion cyclotron harmonic (wave frequency ω = 3ΩD where ΩD is the deuterium cyclotron frequency), as the mode is not detected during the more commonly used second harmonic/minority heating scenario or in the absence of beam-injected ions. The mode frequency is around 0.6–0.7ΩD, where ΩD is evaluated in the low-field side plasma edge, and tracks the magnetic field B and the edge plasma electron density ne via the Alfvénic relation ω ∼ B ne −1/2. The mode does not appear as a single frequency wave but as a bundle of closely spaced (in frequency) sub-modes. When the parallel beam ion velocity component is increased, the sub-mode frequency spacing is observed to decrease, possibly due to a change in the eigenmode structure. Under certain conditions, typically in discharges with a relatively low plasma current, IP < 0.7 MA, the mode appears to be driven directly by sub-Alfvénic deuterium beam ions. Absolute measurements of the mode amplitude show that at least 1% of the beam-injected power is transferred non-collisionally to the instability. While this is too low for practical alpha-channeling applications, discharges are planned with the aim of increasing the level of power transferred non-collisionally between fast ions and the instability.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
G Urbanczyk; X J Zhang; L Zhang; L Colas; R Dumont; W Tierens; E. Lerche; D. Van Eester; S Heuraux; X D Yang; C M Qin; A Ekedahl; Y P Zhao; A Grosjean; B Zhang; N Fedorczak; J C Xu; Y Peysson; F Ding; J G Li; K Wang
Metallic impurity content behavior during ICRH-heated L-mode discharges in EAST Journal Article
In: Nuclear Fusion, vol. 60, no. 12, pp. 126003, 2020.
@article{1993,
title = {Metallic impurity content behavior during ICRH-heated L-mode discharges in EAST},
author = {G Urbanczyk and X J Zhang and L Zhang and L Colas and R Dumont and W Tierens and E. Lerche and D. Van Eester and S Heuraux and X D Yang and C M Qin and A Ekedahl and Y P Zhao and A Grosjean and B Zhang and N Fedorczak and J C Xu and Y Peysson and F Ding and J G Li and K Wang},
url = {https://doi.org/10.1088%2F1741-4326%2Fabae82},
doi = {10.1088/1741-4326/abae82},
year = {2020},
date = {2020-12-01},
journal = {Nuclear Fusion},
volume = {60},
number = {12},
pages = {126003},
publisher = {IOP Publishing},
abstract = {This study uses the diversity of materials at known locations in the experimental advanced superconducting tokamak to extract, local information on which plasma-surface interaction processes are dominant during ion cyclotron resonance heating (ICRH) (near vs far field effects). Metallic impurity content is indicated by the intensity of impurity line emissions observed with a fast-time-response extreme ultraviolet spectrometer, normalized to line-averaged plasma density, i.e. I
imp/n
e. Parametric dependencies are explored over scans of ICRH and LH (lower hybrid) power and for different toroidal phasings between straps, strap power balance, and magnetic configurations. This diversity of behavior is interpreted as the signature of different physical processes. Before 2017, as only the upper divertor region contained tungsten (W), the W content in the core used to increase a lot when moving from lower to upper single null configurations, and was correlated with the total injected power rather than the ICRH power. Molybdenum, covering the part of the inner wall facing one ion cyclotron range of frequencies (ICRF) antenna appear sensitive to this antenna power and phasing benchmarked by modeling suggesting a probable interaction due to residual ICRF waves crossing the plasma. Materials close and magnetically-connected to an active antenna show better correlation with ICRF antenna electrical tuning than those which are far away, or not connected. This is particularly the case with W since 2018, because the limiter tiles of the LH launchers were changed from graphite to tungsten. In these latter conditions, it is shown that W sources at the mid-plane (equatorial plane) contribute to a significant fraction of the core contamination by tungsten (25% in ohmic regime, and more during ICRH).},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
imp/n
e. Parametric dependencies are explored over scans of ICRH and LH (lower hybrid) power and for different toroidal phasings between straps, strap power balance, and magnetic configurations. This diversity of behavior is interpreted as the signature of different physical processes. Before 2017, as only the upper divertor region contained tungsten (W), the W content in the core used to increase a lot when moving from lower to upper single null configurations, and was correlated with the total injected power rather than the ICRH power. Molybdenum, covering the part of the inner wall facing one ion cyclotron range of frequencies (ICRF) antenna appear sensitive to this antenna power and phasing benchmarked by modeling suggesting a probable interaction due to residual ICRF waves crossing the plasma. Materials close and magnetically-connected to an active antenna show better correlation with ICRF antenna electrical tuning than those which are far away, or not connected. This is particularly the case with W since 2018, because the limiter tiles of the LH launchers were changed from graphite to tungsten. In these latter conditions, it is shown that W sources at the mid-plane (equatorial plane) contribute to a significant fraction of the core contamination by tungsten (25% in ohmic regime, and more during ICRH).
V. Maquet; A. Messiaen
Optimized phasing conditions to avoid edge mode excitation by ICRH antennas Journal Article
In: Journal of Plasma Physics, vol. 86, no. 6, pp. 855860601, 2020.
@article{1996,
title = {Optimized phasing conditions to avoid edge mode excitation by ICRH antennas},
author = {V. Maquet and A. Messiaen},
url = {https://doi.org/10.1088%2F1741-4326%2Fabae82},
doi = {10.1088/1741-4326/abae82},
year = {2020},
date = {2020-12-01},
journal = {Journal of Plasma Physics},
volume = {86},
number = {6},
pages = {855860601},
publisher = {IOP Publishing},
abstract = {This study uses the diversity of materials at known locations in the experimental advanced superconducting tokamak to extract, local information on which plasma-surface interaction processes are dominant during ion cyclotron resonance heating (ICRH) (near vs far field effects). Metallic impurity content is indicated by the intensity of impurity line emissions observed with a fast-time-response extreme ultraviolet spectrometer, normalized to line-averaged plasma density, i.e. I
imp/n
e. Parametric dependencies are explored over scans of ICRH and LH (lower hybrid) power and for different toroidal phasings between straps, strap power balance, and magnetic configurations. This diversity of behavior is interpreted as the signature of different physical processes. Before 2017, as only the upper divertor region contained tungsten (W), the W content in the core used to increase a lot when moving from lower to upper single null configurations, and was correlated with the total injected power rather than the ICRH power. Molybdenum, covering the part of the inner wall facing one ion cyclotron range of frequencies (ICRF) antenna appear sensitive to this antenna power and phasing benchmarked by modeling suggesting a probable interaction due to residual ICRF waves crossing the plasma. Materials close and magnetically-connected to an active antenna show better correlation with ICRF antenna electrical tuning than those which are far away, or not connected. This is particularly the case with W since 2018, because the limiter tiles of the LH launchers were changed from graphite to tungsten. In these latter conditions, it is shown that W sources at the mid-plane (equatorial plane) contribute to a significant fraction of the core contamination by tungsten (25% in ohmic regime, and more during ICRH).},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
imp/n
e. Parametric dependencies are explored over scans of ICRH and LH (lower hybrid) power and for different toroidal phasings between straps, strap power balance, and magnetic configurations. This diversity of behavior is interpreted as the signature of different physical processes. Before 2017, as only the upper divertor region contained tungsten (W), the W content in the core used to increase a lot when moving from lower to upper single null configurations, and was correlated with the total injected power rather than the ICRH power. Molybdenum, covering the part of the inner wall facing one ion cyclotron range of frequencies (ICRF) antenna appear sensitive to this antenna power and phasing benchmarked by modeling suggesting a probable interaction due to residual ICRF waves crossing the plasma. Materials close and magnetically-connected to an active antenna show better correlation with ICRF antenna electrical tuning than those which are far away, or not connected. This is particularly the case with W since 2018, because the limiter tiles of the LH launchers were changed from graphite to tungsten. In these latter conditions, it is shown that W sources at the mid-plane (equatorial plane) contribute to a significant fraction of the core contamination by tungsten (25% in ohmic regime, and more during ICRH).
Y. O. Kazakov; M Nocente; M J Mantsinen; J. Ongena; Y Baranov; T Craciunescu; M Dreval; R Dumont; J Eriksson; J Garcia; L Giacomelli; V G Kiptily; K K Kirov; L Meneses; F Nabais; M F F Nave; M Salewski; S E Sharapov; Ž Š; J Varje; Weisen H and
Plasma heating and generation of energetic D ions with the 3-ion ICRF +NBI scenario in mixed H-D plasmas at JET-ILW Journal Article
In: Nuclear Fusion, vol. 60, no. 11, pp. 112013, 2020.
@article{1992,
title = {Plasma heating and generation of energetic D ions with the 3-ion ICRF +NBI scenario in mixed H-D plasmas at JET-ILW},
author = {Y. O. Kazakov and M Nocente and M J Mantsinen and J. Ongena and Y Baranov and T Craciunescu and M Dreval and R Dumont and J Eriksson and J Garcia and L Giacomelli and V G Kiptily and K K Kirov and L Meneses and F Nabais and M F F Nave and M Salewski and S E Sharapov and Ž Š and J Varje and Weisen H and},
url = {https://doi.org/10.1088%2F1741-4326%2Fab9256},
doi = {10.1088/1741-4326/ab9256},
year = {2020},
date = {2020-11-01},
journal = {Nuclear Fusion},
volume = {60},
number = {11},
pages = {112013},
publisher = {IOP Publishing},
abstract = {Dedicated experiments were conducted in mixed H-D plasmas in JET to demonstrate the efficiency of the 3-ion ICRF scenario for plasma heating, relying on injected fast NBI ions as the resonant ion component. Strong core localization of the RF power deposition in the close vicinity of the ion-ion hybrid layer was achieved, resulting in an efficient plasma heating, generation of energetic D ions, strong enhancement of the neutron rate and observation of Alfvénic modes. A consistent physical picture that emerged from a range of fast-ion measurements at JET, including neutron and gamma-ray measurements, a high-energy neutral particle analyzer and MHD mode localization analysis, is presented. The possibility to moderate the fast-ion energies with the ratio P
ICRF/P
NBI and the choice of the NBI injectors is demonstrated. An outlook of possible applications of the 3-ion scenarios, including a recent example of its use in mixed D-3He plasmas in JET and promising scenarios for D-T plasmas, are presented.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
ICRF/P
NBI and the choice of the NBI injectors is demonstrated. An outlook of possible applications of the 3-ion scenarios, including a recent example of its use in mixed D-3He plasmas in JET and promising scenarios for D-T plasmas, are presented.
V G Kiptily; Y. O. Kazakov; M Fitzgerald; M Nocente; M Iliasova; E Khilkevich; M J Mantsinen; M F F Nave; J. Ongena; S E Sharapov; A E Shevelev; Ž Š; G Szepesi; D M A Taylor; Yu. V. Yakovenko and
Excitation of elliptical and toroidal Alfvén eigenmodes by 3He-ions of the MeV-energy range in hydrogen-rich JET plasmas Journal Article
In: Nuclear Fusion, vol. 60, no. 11, pp. 112003, 2020.
@article{1991,
title = {Excitation of elliptical and toroidal Alfvén eigenmodes by 3He-ions of the MeV-energy range in hydrogen-rich JET plasmas},
author = {V G Kiptily and Y. O. Kazakov and M Fitzgerald and M Nocente and M Iliasova and E Khilkevich and M J Mantsinen and M F F Nave and J. Ongena and S E Sharapov and A E Shevelev and Ž Š and G Szepesi and D M A Taylor and Yu. V. Yakovenko and},
url = {https://doi.org/10.1088%2F1741-4326%2Fab79cb},
doi = {10.1088/1741-4326/ab79cb},
year = {2020},
date = {2020-11-01},
journal = {Nuclear Fusion},
volume = {60},
number = {11},
pages = {112003},
publisher = {IOP Publishing},
abstract = {Elliptical (EAE) and toroidal Alfvén eigenmode (TAE) instabilities have been observed in hydrogen-rich JET discharges of the D-(3He)-H ion cyclotron resonance heating (ICRH) scenario, which is characterized by strong absorption of radio frequency waves at very low concentrations of the resonant 3He-ions. In the experiments, core localized TAEs with a frequency f TAE ≈ 280 kHz with mode numbers n= 3, 4, 5 and 6 were detected. Following the phase with TAE excitation, EAE modes at higher frequencies f EAE ≈ 550–580 kHz with mode numbers n = 1, 3, 5 were seen. These high frequency modes indicate that a MeV range population of trapped energetic ions was present in the plasma. The experimental evidence of existence of the MeV-energy 3He-ions able to excite the AEs is provided by neutron and gamma-ray diagnostics as well as fast ion loss measurements. The ICRH modelling code calculations confirm the acceleration of 3He-ions to MeV energies. The magnetohydrodynamic (MHD) analysis results are consistent with the experimental data showing that the MeV 3He ions satisfy to resonant conditions interacting with TAE and EAE modes. This experiment demonstrates the efficient plasma heating mimicking the conditions representative for the ITER plasmas and contribute to the understanding of fast-ion interaction with MHD wave modes.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
V E Moiseenko; Yu. V Kovtun; T. Wauters; A. Goriaev; A. I. Lyssoivan; A V Lozin; R O Pavlichenko; A N Shapoval; S M Maznichenko; V B Korovin; E D Kramskoy; M M Kozulya; N V Zamanov; Y V Siusko; Yu. A Krasiuk; V S Romanov; A Alonso; R Brakel; A Dinklage; D Hartmann; Y. O. Kazakov; H Laqua; J. Ongena; T Stange
First experiments on ICRF discharge generation by a W7-X-like antenna in the Uragan-2M stellarator Journal Article
In: Journal of Plasma Physics, vol. 86, no. 5, pp. 905860517, 2020.
@article{1990,
title = {First experiments on ICRF discharge generation by a W7-X-like antenna in the Uragan-2M stellarator},
author = {V E Moiseenko and Yu. V Kovtun and T. Wauters and A. Goriaev and A. I. Lyssoivan and A V Lozin and R O Pavlichenko and A N Shapoval and S M Maznichenko and V B Korovin and E D Kramskoy and M M Kozulya and N V Zamanov and Y V Siusko and Yu. A Krasiuk and V S Romanov and A Alonso and R Brakel and A Dinklage and D Hartmann and Y. O. Kazakov and H Laqua and J. Ongena and T Stange},
year = {2020},
date = {2020-10-01},
journal = {Journal of Plasma Physics},
volume = {86},
number = {5},
pages = {905860517},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
T. Wauters; J Buermans; R Haelterman; V Moiseenko; D Ricci; T Verhaeghe; S Coda; D Douai; A Hakola; A. I. Lyssoivan; D. Van Eester
RF plasma simulations using the TOMATOR 1D code: a case study for TCV helium ECRH plasmas Journal Article
In: Plasma Physics and Controlled Fusion, vol. 62, no. 10, pp. 105010, 2020.
@article{1989,
title = {RF plasma simulations using the TOMATOR 1D code: a case study for TCV helium ECRH plasmas},
author = {T. Wauters and J Buermans and R Haelterman and V Moiseenko and D Ricci and T Verhaeghe and S Coda and D Douai and A Hakola and A. I. Lyssoivan and D. Van Eester},
url = {https://doi.org/10.1088%2F1361-6587%2Faba767},
doi = {10.1088/1361-6587/aba767},
year = {2020},
date = {2020-10-01},
journal = {Plasma Physics and Controlled Fusion},
volume = {62},
number = {10},
pages = {105010},
publisher = {IOP Publishing},
abstract = {The 1-dimensional reaction-diffusion-convection code TOMATOR-1D describes plasma production by RF waves inside a tokamak using the Braginskii continuity and heat balance equations. The model simulates self-consistent radial density and temperature profiles for magnetised plasma mixtures of hydrogen and helium. The model reproduces the density profiles of X2 electron cyclotron resonance heating (ECRH) plasmas on TCV and proposes a Bohm-like poloidal magnetic field dependent scaling for anomalous diffusion and a convection scaling that results from drifts in the toroidal magnetic field configuration. A relation is proposed between the anomalous diffusion and the outward convection in toroidal plasmas. It is found that the EC absorption efficiency decreases at higher power, which is understood from the acceleration of electrons beyond the optimal energy for the electron impact ionisation of helium. A dramatic increase of the absorption efficiency is seen at intermediate vertical magnetic field values of which results in the highest density plasmas. Losses along the field lines in the vertical direction become dominant at higher fields which effectively reduces the plasma density in these discharges. To arrive at predictive capabilities towards ECRH plasmas on JT-60SA and ITER, the proposed scalings, subsuming dependencies on the torus major radius and the toroidal field strength, need to be validated in a multi-machine study.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
V Bobkov; R Bilato; H Faugel; H F ü; Y. O. Kazakov; M Mantsinen; J. -M. Noterdaeme; R Ochoukov; Th. P ü; Suárez G L ó; W Tierens; W Zhang; ASDEX Upgrade; EUROfusion MST1 Team
Improved operating space of the ICRF system in ASDEX upgrade Journal Article
In: AIP Conference proceedings, vol. 2254, no. 1, pp. 040005, 2020.
@article{1977,
title = {Improved operating space of the ICRF system in ASDEX upgrade},
author = {V Bobkov and R Bilato and H Faugel and H F ü and Y. O. Kazakov and M Mantsinen and J. -M. Noterdaeme and R Ochoukov and Th. P ü and Suárez G L ó and W Tierens and W Zhang and ASDEX Upgrade and EUROfusion MST1 Team},
year = {2020},
date = {2020-09-01},
journal = {AIP Conference proceedings},
volume = {2254},
number = {1},
pages = {040005},
abstract = {Following the improvements of compatibility of ICRF system with the tungsten (W) wall in ASDEX Upgrade (AUG) by using the boron-coated limiters on the 2-strap ICRF antennas and the 3-strap antennas with the W-limiters, the ICRF operating space was further extended in 3 areas: power, phase control between the antennas and frequency range. The available ICRF power in AUG was increased by using an additional RF generator to feed the central straps of the 3- strap antennas which require a 1.5:1 or 2:1 power ratio between the central strap and the two outer straps (combined) to minimize the ICRF-specific W sources. This increases the total experimentally achievable launched ICRF power in the optimized configuration to ~ 5.7 MW. A new phase control system enabled phase-locked operation of all 4 AUG ICRF antennas. This allows a better control of the launched k|| spectrum which on its turn is modified when both neighboring antennas are active, as well as of the structure of the global RF field distribution within the AUG vessel. Measurements by the RF magnetic field (B-dot) probes show that the RF field distribution can indeed be significantly affected by the variation of the phasing between the ICRF antenna pairs. However, its effect on the core plasma and on the residual ICRF specific plasma-wall interactions is small, for the cases so far limited to the H-modes at medium plasma densities. The available frequency range was extended and now covers four discrete frequencies (f): 30.0, 36.5, 41.8 and 55.1 MHz. In addition to the standard hydrogen (H) minority in deuterium (D) on-axis heating scheme at the magnetic field (Bt) of 2.0, 2.5, 2.8 and 3.1 T, the RF frequency range allows the use of the 3-ion D-(3He)-H and 4He-(3He)-H heating schemes at Bt=2.5-3.1 T (f=30 MHz – off-axis and on-axis), on-axis 3ωc D heating at Bt=1.9 T (f=41.8 MHz) and at Bt=2.5 T (f=55.1 MHz) and 2ωc H heating at Bt=1.9T (f=55.1 MHz).},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
A Chomiczewska; N Krawczyk; Y. O. Kazakov; V Bobkov; Kowalska-Strz E e; E. Lerche; M J Mantsinen; J. Ongena; G Pucella; T P ü; D. Van Eester; JET Contributors
Analysis of metallic impurities during the application of three-ion ICRH scenario at JET-ILW Journal Article
In: AIP Conference proceedings, vol. 2254, no. 1, pp. 050005, 2020.
@article{1979,
title = {Analysis of metallic impurities during the application of three-ion ICRH scenario at JET-ILW},
author = {A Chomiczewska and N Krawczyk and Y. O. Kazakov and V Bobkov and Kowalska-Strz E e and E. Lerche and M J Mantsinen and J. Ongena and G Pucella and T P ü and D. Van Eester and JET Contributors},
year = {2020},
date = {2020-09-01},
journal = {AIP Conference proceedings},
volume = {2254},
number = {1},
pages = {050005},
abstract = {The effect of the novel `three-ion' D-(3He)-H minority ICRH heating scheme on the behavior of the metallic impurities at JET-ILW is discussed. The reported experiment was performed in L-mode plasmas at a magnetic field BT = 3.2 T, plasma current Ip = 2 MA and central plasma densities ne(0) ≈ 4×1019 m-3. ICRH power was delivered with dipole or +π/2 antenna phasing at f ≈ 32.2-33MHz, placing the 3He cyclotron resonance at the plasma core. The edge isotopic ratio H/(H+D) was varied between 73 and 92%, and 3He concentration in the range of 0.1-1.5% to assess the sensitivity of the scheme to the detailed plasma composition. The results of our analysis show a linear increase of the plasma effective charge Zeff, radiated power Prad,bulk and content of metallic impurities with ICRF power. The observed scattering of the points reflects the difference in the plasma composition and ICRF antenna phasing. For discharges heated with similar ICRH power level ~4MW, our analysis indicates that for a large range of H/(H+D) the novel scenario effectively heats the plasma with reduced content of metallic impurities. The impurities are shown to be concentrated mainly around the mid- radius region of the plasma. We conclude this paper with a discussion of the effect of the long-period sawteeth on the observed dynamics of metallic impurities in the plasma core.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
L Colas; G Urbanczyk; M Goniche; E. Lerche; J Hillairet; W Helou; G Lombard; P Mollard; V Bobkov; O Meyer; J Gunn; C Desgranges; V Basiuk; Pégouri B é; R Dumont; J F Artaud; C Bourdelle; N Fedorczak; F. Durodié; J -M Bernard; WEST Team
First application of Ion Cyclotron resonant frequency waves on WEST plasma scenarios Journal Article
In: AIP Conference proceedings, vol. 2254, no. 1, pp. 040004, 2020.
@article{1976,
title = {First application of Ion Cyclotron resonant frequency waves on WEST plasma scenarios},
author = {L Colas and G Urbanczyk and M Goniche and E. Lerche and J Hillairet and W Helou and G Lombard and P Mollard and V Bobkov and O Meyer and J Gunn and C Desgranges and V Basiuk and Pégouri B é and R Dumont and J F Artaud and C Bourdelle and N Fedorczak and F. Durodié and J -M Bernard and WEST Team},
year = {2020},
date = {2020-09-01},
journal = {AIP Conference proceedings},
volume = {2254},
number = {1},
pages = {040004},
abstract = {In 2018, Ion Cyclotron Resonant Frequency (ICRF) waves were for the first time applied to the WEST plasma scenarios. In ICRF-only plasmas at medium density, or on top of a low level of Lower Hybrid (LH) power, the coupled ICRF power increases the plasma energy content. However in discharges with large LH power at high core density, nearly all the applied ICRF power gets radiated, mainly in the plasma bulk. Both the energy content and conducted power decrease. Two peculiarities of WEST, that may combine, are presently invoked to explain this phenomenology:1) Fast ion ripple losses, evidenced between TF coils on the baffle, likely degrade the ICRF heating efficiency. 2) RF-enhanced W sources, evidenced on several Plasma-Facing Components (PFCs), likely over-contaminate the high-power plasmas.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
P. Dumortier; F. Durodié; F. Louche; M. Vervier; A Kv á; A. Messiaen; I. Stepanov
Further studies on the ITER ICRF antenna grounding Journal Article
In: AIP Conference proceedings, vol. 2254, no. 1, pp. 070013, 2020.
@article{1987,
title = {Further studies on the ITER ICRF antenna grounding},
author = {P. Dumortier and F. Durodié and F. Louche and M. Vervier and A Kv á and A. Messiaen and I. Stepanov},
year = {2020},
date = {2020-09-01},
journal = {AIP Conference proceedings},
volume = {2254},
number = {1},
pages = {070013},
abstract = {The ITER ICRF antenna is a port-plug antenna. There is a clearance gap surrounding the antenna between the antenna plug walls and the vacuum vessel, creating a cavity in which resonant modes can be excited. The frequency response of the antenna array is perturbed by the excitation of a TE0,1 (p=1) mode in the ITER frequency band (around 45MHz) in the clearance gap in absence of any additional grounding. Different grounding options have been proposed and both numerically studied and tested on a scaled low-power mock-up of the ITER antenna. These studies however did not take the Faraday screen into account. In view of the technical difficulties to implement the proposed grounding options the present contribution revisits the need for grounding based on new gap voltage measurements on a reduced- scale mock-up of the ITER ICRH antenna and numerical modeling, including the presence of the Faraday screen.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}