2019
S A Bozhenkov; Y. O. Kazakov; O Ford; M Beurskens; J Baldzhun; H Damm; G Fuchert; A Langenberg; N Pablant; E Pasch; A Stechow; R C Wolf; W7-X Team
Plasma performance in high-density and high-confiement regimes in Wendelstein 7-X Proceedings Article
In: pp. O3.105, 2019.
@inproceedings{1915,
title = {Plasma performance in high-density and high-confiement regimes in Wendelstein 7-X},
author = {S A Bozhenkov and Y. O. Kazakov and O Ford and M Beurskens and J Baldzhun and H Damm and G Fuchert and A Langenberg and N Pablant and E Pasch and A Stechow and R C Wolf and W7-X Team},
year = {2019},
date = {2019-07-01},
journal = {Europhysics Conference Abstracts},
pages = {O3.105},
abstract = {46th EPS Conference on Plasma Physics, Milan (Italy), 08-12 July 2019},
keywords = {},
pubstate = {published},
tppubtype = {inproceedings}
}
K. Crombé; A Kostic; A Nikiforov; I. Shesterikov; M Usoltceva; H Faugel; H Fuenfgelder; S Heureaux; R Ochoukov; J. -M. Noterdaeme; IShTAR Team
Plasma operation and electric field measurements in IShTAR Proceedings Article
In: pp. P1.1014, 2019.
@inproceedings{1918,
title = {Plasma operation and electric field measurements in IShTAR},
author = {K. Crombé and A Kostic and A Nikiforov and I. Shesterikov and M Usoltceva and H Faugel and H Fuenfgelder and S Heureaux and R Ochoukov and J. -M. Noterdaeme and IShTAR Team},
year = {2019},
date = {2019-07-01},
journal = {Europhysics Conference Abstracts},
pages = {P1.1014},
abstract = {46th EPS Conference on Plasma Physics, Milan (Italy), 08-12 July 2019},
keywords = {},
pubstate = {published},
tppubtype = {inproceedings}
}
G L Falchetto; P Steand; R Coelho; D Coster; J Ferreira; T Jonsson; D Yadikin; R Dumont; B Faugeras; J Hollocombe; P Hyunh; J Joly; D. Kalupin; E. Lerche; J Morales; M Poradzinski; Sir P é; E Tholerus; D. Van Eester; J Varje; W Zwingmann; JET Contributors; EUROfusion-IM Team
Multi-machine analysis of EU experiments using the EUROfusion Integrated Modelling (EU-IM- framework) Proceedings Article
In: pp. P1.1081, 2019.
@inproceedings{1919,
title = {Multi-machine analysis of EU experiments using the EUROfusion Integrated Modelling (EU-IM- framework)},
author = {G L Falchetto and P Steand and R Coelho and D Coster and J Ferreira and T Jonsson and D Yadikin and R Dumont and B Faugeras and J Hollocombe and P Hyunh and J Joly and D. Kalupin and E. Lerche and J Morales and M Poradzinski and Sir P é and E Tholerus and D. Van Eester and J Varje and W Zwingmann and JET Contributors and EUROfusion-IM Team},
year = {2019},
date = {2019-07-01},
journal = {Europhysics Conference Abstracts},
pages = {P1.1081},
abstract = {46th EPS Conference on Plasma Physics, Milan (Italy), 08-12 July 2019},
keywords = {},
pubstate = {published},
tppubtype = {inproceedings}
}
A R Field; P Carvalho; L Garzotti; E. Lerche; C Maggi; F Rimini; C Roach; S Saarelma; M Sertoli; Jet Contributors
The effect of pacing pellets on ELMs, W impurity behaviour and pedestal charachteristics in high-power, JET-ILW H-mode plasmas Proceedings Article
In: pp. P5.1019, 2019.
@inproceedings{1924,
title = {The effect of pacing pellets on ELMs, W impurity behaviour and pedestal charachteristics in high-power, JET-ILW H-mode plasmas},
author = {A R Field and P Carvalho and L Garzotti and E. Lerche and C Maggi and F Rimini and C Roach and S Saarelma and M Sertoli and Jet Contributors},
year = {2019},
date = {2019-07-01},
journal = {Europhysics Conference Abstracts},
pages = {P5.1019},
abstract = {46th EPS Conference on Plasma Physics, Milan (Italy), 08-12 July 2019},
keywords = {},
pubstate = {published},
tppubtype = {inproceedings}
}
C Lau; R Barnett; N Bertelli; T Carter; K. Crombé; D Curreli; T DeHass; D L Green; C Migliore; J R Myra; S Tripathi; B. Van Compernolle; D. Van Eester; S Vincena; J Wright; X Yang
First experiments of the LAPD RF campaign Proceedings Article
In: pp. P4.1081, 2019.
@inproceedings{1923,
title = {First experiments of the LAPD RF campaign},
author = {C Lau and R Barnett and N Bertelli and T Carter and K. Crombé and D Curreli and T DeHass and D L Green and C Migliore and J R Myra and S Tripathi and B. Van Compernolle and D. Van Eester and S Vincena and J Wright and X Yang},
year = {2019},
date = {2019-07-01},
journal = {Europhysics Conference Abstracts},
pages = {P4.1081},
abstract = {46th EPS Conference on Plasma Physics, Milan (Italy), 08-12 July 2019},
keywords = {},
pubstate = {published},
tppubtype = {inproceedings}
}
M J Mantsinen; V Bobkov; D Gallart; A Kappatou; Y. O. Kazakov; M Weiland; JET Contributors; EUROfusion MST1 Team; ASDEX Upgrade Team
Modelling of three-ion ICRF schemes with PION Proceedings Article
In: pp. O5.102, 2019.
@inproceedings{1916,
title = {Modelling of three-ion ICRF schemes with PION},
author = {M J Mantsinen and V Bobkov and D Gallart and A Kappatou and Y. O. Kazakov and M Weiland and JET Contributors and EUROfusion MST1 Team and ASDEX Upgrade Team},
year = {2019},
date = {2019-07-01},
journal = {Europhysics Conference Abstracts},
pages = {O5.102},
abstract = {46th EPS Conference on Plasma Physics, Milan (Italy), 08-12 July 2019},
keywords = {},
pubstate = {published},
tppubtype = {inproceedings}
}
M Maslov; J Citrin; P Jacquet; Y. O. Kazakov; D L Keeling; D B King; E. Lerche; M Marin; J. Ongena; D. Van Eester; JET Contributors
High fusion power in tritium rich scenario in JET Proceedings Article
In: pp. O5.104, 2019.
@inproceedings{1917,
title = {High fusion power in tritium rich scenario in JET},
author = {M Maslov and J Citrin and P Jacquet and Y. O. Kazakov and D L Keeling and D B King and E. Lerche and M Marin and J. Ongena and D. Van Eester and JET Contributors},
year = {2019},
date = {2019-07-01},
journal = {Europhysics Conference Abstracts},
pages = {O5.104},
abstract = {46th EPS Conference on Plasma Physics, Milan (Italy), 08-12 July 2019},
keywords = {},
pubstate = {published},
tppubtype = {inproceedings}
}
M Nocente; N W Eidietis; L Giacomelli; G Gorini; Y. O. Kazakov; V Kiptily; A Lvovskiy; Paz C Soldan; D Rigamonti; M Salewski; M Tardocchi
MeV range particle physics studies in tokamak plasmas using gamma-ray spectroscopy Proceedings Article
In: 2019.
@inproceedings{1913,
title = {MeV range particle physics studies in tokamak plasmas using gamma-ray spectroscopy},
author = {M Nocente and N W Eidietis and L Giacomelli and G Gorini and Y. O. Kazakov and V Kiptily and A Lvovskiy and Paz C Soldan and D Rigamonti and M Salewski and M Tardocchi},
year = {2019},
date = {2019-07-01},
journal = {Europhysics Conference Abstracts},
number = {I1.103},
abstract = {46th EPS Conferene on Plasma Physics, Milan (Italy), 08-12 July 2019},
keywords = {},
pubstate = {published},
tppubtype = {inproceedings}
}
R K ö; M Krychowiak; M Jakubowski; Y Feng; O Schmitz; F Effenberg; F Reimold; S Brezinsek; M Otte; G Anda; T Barbui; C Biedermann; S Bozhenkov; P Drewelow; M Endler; D A Ennis; O Ford; G Fuchert; Y Gao; D Gradic; K C Hammond; Harris J M Hirsch; J Knauer; P Kornejew; G Kocsis; T Kremeyer; H Niemann; E Pasch; V Perseo; L Rudischhauser; G Schlisio; Puig A Sitjes; Sunn T Pedersen; F Pisano; T Szpesi; E Wang; T. Wauters; U Wenzel; V Winters; D Zhang; S Zoletnik; W7-X Team
Stable Completely Detached Plasma Operation in the First Island Divertor Experiment Campaign of Wendelstein 7-X Proceedings Article
In: pp. P2.1061, 2019.
@inproceedings{1920,
title = {Stable Completely Detached Plasma Operation in the First Island Divertor Experiment Campaign of Wendelstein 7-X},
author = {R K ö and M Krychowiak and M Jakubowski and Y Feng and O Schmitz and F Effenberg and F Reimold and S Brezinsek and M Otte and G Anda and T Barbui and C Biedermann and S Bozhenkov and P Drewelow and M Endler and D A Ennis and O Ford and G Fuchert and Y Gao and D Gradic and K C Hammond and Harris J M Hirsch and J Knauer and P Kornejew and G Kocsis and T Kremeyer and H Niemann and E Pasch and V Perseo and L Rudischhauser and G Schlisio and Puig A Sitjes and Sunn T Pedersen and F Pisano and T Szpesi and E Wang and T. Wauters and U Wenzel and V Winters and D Zhang and S Zoletnik and W7-X Team},
year = {2019},
date = {2019-07-01},
journal = {Europhysics Conference Abstracts},
pages = {P2.1061},
abstract = {46th EPS Conference on Plasma Physics, Milan (Italy), 08-12 July 2019},
keywords = {},
pubstate = {published},
tppubtype = {inproceedings}
}
E R Solano; P Carvalho; M Chernyshova; E Delabie; J C Hillesheim; C F Maggi; E Righi; G. Verdoolaege; JET Contributors
Revisiting H, D, T studies of L-H transition in JET Proceedings Article
In: pp. P5.1081, 2019.
@inproceedings{1925,
title = {Revisiting H, D, T studies of L-H transition in JET},
author = {E R Solano and P Carvalho and M Chernyshova and E Delabie and J C Hillesheim and C F Maggi and E Righi and G. Verdoolaege and JET Contributors},
year = {2019},
date = {2019-07-01},
journal = {Europhysics Conference Abstracts},
pages = {P5.1081},
abstract = {46th EPS Conference on Plasma Physics, Milan (Italy), 08-12 July 2019},
keywords = {},
pubstate = {published},
tppubtype = {inproceedings}
}
P Vallejos; T Jonsson; R. Ragona; T Hellsten; B Ljungberg; L Frassinetti
ICRF heating with poloidally phased antennas Proceedings Article
In: pp. P4.1077, 2019.
@inproceedings{1922,
title = {ICRF heating with poloidally phased antennas},
author = {P Vallejos and T Jonsson and R. Ragona and T Hellsten and B Ljungberg and L Frassinetti},
year = {2019},
date = {2019-07-01},
journal = {Europhysics Conference Abstracts},
pages = {P4.1077},
abstract = {46th EPS Conference on Plasma Physics, Milan (Italy), 08-12 July 2019},
keywords = {},
pubstate = {published},
tppubtype = {inproceedings}
}
T. Wauters; D Borodin; R Brakel; S Brezinsek; S Coda; A Dinklage; D Douai; A Hakola; E Joffrin; T Loarer; H Laqua; A. I. Lyssoivan; V Moiseenko; J. Ongena; D Ricci; V Rohde; ASDEX Upgrade Team; TVC Team; EUROfuions MST1 Team; JET Contributors; W7-X Team
Wall conditioning in fusion devices with superconducting coils Proceedings Article
In: pp. 12.102, 2019.
@inproceedings{1914,
title = {Wall conditioning in fusion devices with superconducting coils},
author = {T. Wauters and D Borodin and R Brakel and S Brezinsek and S Coda and A Dinklage and D Douai and A Hakola and E Joffrin and T Loarer and H Laqua and A. I. Lyssoivan and V Moiseenko and J. Ongena and D Ricci and V Rohde and ASDEX Upgrade Team and TVC Team and EUROfuions MST1 Team and JET Contributors and W7-X Team},
year = {2019},
date = {2019-07-01},
journal = {Europhysics Conference Abstracts},
pages = {12.102},
abstract = {46th EPS Conference on Plasma Physics, Milan (Italy), 08-12 July 2019},
keywords = {},
pubstate = {published},
tppubtype = {inproceedings}
}
A Kv á; V Bobkov; L Colas; P. Dumortier; F. Durodié; P Jacquet; C C Klepper; D Milanesio; G Urbanczyk
RF sheath modeling of experimentally observed plasma surface interactions with the JET ITER-Like Antenna Journal Article
In: Nuclear Materials and Energy, vol. 19, pp. 324 - 329, 2019, ISSN: 2352-1791.
@article{1909,
title = {RF sheath modeling of experimentally observed plasma surface interactions with the JET ITER-Like Antenna},
author = {A Kv á and V Bobkov and L Colas and P. Dumortier and F. Durodié and P Jacquet and C C Klepper and D Milanesio and G Urbanczyk},
url = {http://www.sciencedirect.com/science/article/pii/S2352179118301741},
doi = {https://doi.org/10.1016/j.nme.2019.03.009},
issn = {2352-1791},
year = {2019},
date = {2019-05-01},
journal = {Nuclear Materials and Energy},
volume = {19},
pages = {324 - 329},
abstract = {Waves in the Ion Cyclotron Range of Frequencies (ICRF) enhance local Plasma-Surface Interactions (PSI) near the wave launchers and magnetically-connected objects via Radio-Frequency (RF) sheath rectification. ITER will use 20MW of ICRF power over long pulses, questioning the long-term impact of RF-enhanced localized erosion on the lifetime of its Beryllium (Be) wall. Recent dedicated ICRF-heated L-mode discharges documented this process on JET for different types of ICRF antennas. Using visible spectroscopy in JET ICRF-heated L-mode discharges, poloidally-localized regions of enhanced (by ∼2–4x) Be I and Be II light emission were observed on two outboard limiters magnetically connected to the bottom of the active ITER-Like Antenna (ILA). The observed RF-PSI induced by the ILA was qualitatively comparable to that induced by the JET standard, type-A2 antennas, for similar strap toroidal phasing and connection geometries. The Be II line emission was found more intense when powering the bottom half of the ILA rather than its top half. Conversely, more pronounced SOL density modifications were observed with only top array operation, on field lines connected to the top half of the ILA. So far the near-field modeling of the ILA with antenna code TOPICA (Torino Polytechnic Ion Cyclotron Antenna), using curved antenna model, was partially able to reproduce qualitatively the observed phenomena. A quantitative discrepancy persisted between the observed Be source amplification and the calculated, corresponding increases in E// field at the magnetically connected locations to the ILA when changing from only top to only bottom half antenna operation. This paper revisits these current drive phased and half-ILA powered cases using for the new simulations flat model of the ILA and more realistic antenna feeding to calculate the E// field maps with TOPICA code. Further, the Self-consistent Sheaths and Waves for Ion Cyclotron Heating Slow Wave (SSWICH-SW) code, which couples slow wave evanescence with DC Scrape-Off Layer (SOL) biasing, is used to estimate the poloidal distribution of rectified RF-sheath Direct Current (DC) potential VDC in the private SOL between the ILA poloidal limiters. The approach so far was limited to correlating the observed, enhanced emission regions at the remote limiters to the antenna near-electric fields, as calculated by TOPICA. The present approach includes also a model for the rectification of these near-fields in the private SOL of the ILA. With the improved approach, when comparing only top and only bottom half antenna feeding, we obtained good qualitative correlation between all experimental measurements and the calculated local variations in the E// field and VDC potential.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
K K Kirov; Yu. Baranov; I S Carvalho; C D Challis; J Eriksson; D Frigione; L Garzotti; J Graves; P Jacquet; D L Keeling; E. Lerche; P J Lomas; C Lowry; M Mantsinen; Rimini F and
Fast ion synergistic effects in JET high performance pulses Journal Article
In: Nuclear Fusion, vol. 59, no. 5, pp. 056005, 2019.
@article{1911,
title = {Fast ion synergistic effects in JET high performance pulses},
author = {K K Kirov and Yu. Baranov and I S Carvalho and C D Challis and J Eriksson and D Frigione and L Garzotti and J Graves and P Jacquet and D L Keeling and E. Lerche and P J Lomas and C Lowry and M Mantsinen and Rimini F and},
url = {https://doi.org/10.1088%2F1741-4326%2Fab02ae},
doi = {10.1088/1741-4326/ab02ae},
year = {2019},
date = {2019-05-01},
journal = {Nuclear Fusion},
volume = {59},
number = {5},
pages = {056005},
publisher = {IOP Publishing},
abstract = {Fast ion synergistic effects were studied by predictive modelling of JET best performing pulses for various levels of neutral beam injection (NBI) and radio frequency (RF) power. Calculated DD neutron yields were analysed with the intention of separating the impact of RF synergistic effects due to changes in fast ion (FI) distribution function (DF) from secondary effects accompanying the application of RF power, namely changes in T
e and T
i. A novel approach in analysing the efficiency of fast ions in fusion reactions based on evaluation of the cumulative reaction rates is outlined and used in the study. Conclusions on the impact of fast ion synergistic effects on fusion performance are based on comparisons of beam-target (BT) and thermal (Th) DD reaction rates. It was found that changes in auxiliary heating power, NBI and RF, by 4 MW will affect DD fusion performance and neutron rates significantly. Simulations of the best performing JET pulses show that for H minority RF heating scheme with available RF power the impact of RF synergistic effects is somewhat lesser than the secondary effects related to changes in T
e and T
i. In conditions of much higher RF power the modification in fast ion distribution function (FI DF) and the impact of the fast ions on BT DD fusion becomes significant. The impact of the RF and NBI power on the BT reactivities was found to be of similar order; however, the NBI power has greater impact on reaction rates due to its larger effect on fast ion density.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
e and T
i. A novel approach in analysing the efficiency of fast ions in fusion reactions based on evaluation of the cumulative reaction rates is outlined and used in the study. Conclusions on the impact of fast ion synergistic effects on fusion performance are based on comparisons of beam-target (BT) and thermal (Th) DD reaction rates. It was found that changes in auxiliary heating power, NBI and RF, by 4 MW will affect DD fusion performance and neutron rates significantly. Simulations of the best performing JET pulses show that for H minority RF heating scheme with available RF power the impact of RF synergistic effects is somewhat lesser than the secondary effects related to changes in T
e and T
i. In conditions of much higher RF power the modification in fast ion distribution function (FI DF) and the impact of the fast ions on BT DD fusion becomes significant. The impact of the RF and NBI power on the BT reactivities was found to be of similar order; however, the NBI power has greater impact on reaction rates due to its larger effect on fast ion density.
Sunwoo Moon; P Petersson; M Rubel; E Fortuna-Zalesna; A Widdowson; S. Jachmich; A Litnovsky; E Alves
First mirror test in JET for ITER: Complete overview after three ILW campaigns Journal Article
In: Nuclear Materials and Energy, vol. 19, pp. 59 - 66, 2019, ISSN: 2352-1791.
@article{1908,
title = {First mirror test in JET for ITER: Complete overview after three ILW campaigns},
author = {Sunwoo Moon and P Petersson and M Rubel and E Fortuna-Zalesna and A Widdowson and S. Jachmich and A Litnovsky and E Alves},
url = {http://www.sciencedirect.com/science/article/pii/S2352179118300814},
doi = {https://doi.org/10.1016/j.nme.2019.02.009},
issn = {2352-1791},
year = {2019},
date = {2019-05-01},
journal = {Nuclear Materials and Energy},
volume = {19},
pages = {59 - 66},
abstract = {The First Mirror Test for ITER has been carried out in JET with mirrors exposed during: (i) the third ILW campaign (ILW-3, 2015–2016, 23.33 h plasma) and (ii) all three campaigns, i.e. ILW-1 to ILW-3: 2011–2016, 63,52 h in total. All mirrors from main chamber wall show no significant changes of the total reflectivity from the initial value and the diffuse reflectivity does not exceed 3% in the spectral range above 500 nm. The modified layer on surface has very small amount of impurities such as D, Be, C, N, O and Ni. All mirrors from the divertor (inner, outer, base under the bulk W tile) lost reflectivity by 20–80% due to the beryllium-rich deposition also containing D, C, N, O, Ni and W. In the inner divertor N reaches 5 × 1017 cm−2, W is up to 4.3 × 1017 cm−2, while the content of Ni is the greatest in the outer divertor: 3.8 × 1017 cm−2. Oxygen-18 used as the tracer in experiments at the end of ILW-3 has been detected at the level of 1.1 × 1016 cm−2. The thickness of deposited layer is in the range of 90 nm to 900 nm. The layer growth rate in the base (2.7 pm s − 1) and inner divertor is proportional to the exposure time when a single campaign and all three are compared. In a few cases, on mirrors located at the cassette mouth, flaking of deposits and erosion occurred.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
G. Telesca; I Ivanova-Stanik; R Zagorski; S Brezinsek; P J Carvalho; A Czarnecka; C Giroud; A Huber; E. Lerche; S Wiesen
COREDIV numerical simulation of high neutron rate JET-ILW DD pulses in view of extension to JET-ILW DT experiments Journal Article
In: Nuclear Fusion, vol. 59, no. 5, pp. 056026, 2019.
@article{1912,
title = {COREDIV numerical simulation of high neutron rate JET-ILW DD pulses in view of extension to JET-ILW DT experiments},
author = {G. Telesca and I Ivanova-Stanik and R Zagorski and S Brezinsek and P J Carvalho and A Czarnecka and C Giroud and A Huber and E. Lerche and S Wiesen},
url = {https://doi.org/10.1088%2F1741-4326%2Fab0c47},
doi = {10.1088/1741-4326/ab0c47},
year = {2019},
date = {2019-05-01},
journal = {Nuclear Fusion},
volume = {59},
number = {5},
pages = {056026},
publisher = {IOP Publishing},
abstract = {Two high performance JET-ILW pulses, pertaining to the 2016 experimental campaign, have been numerically simulated with the self-consistent code COREDIV with the aim of predicting the ELM-averaged power load to the target when extrapolated to DT plasmas. The input power of about 33 MW as well as the total radiated power and the average density are similar in the two pulses, but for one of them the density is provided by combined low gas puff and pellet injection, characterized by low SOL density, for the other one by gas fuelling only, at higher SOL density. Considering the magnetic configuration of theses pulses and the presence of a significant amount of Ni (not included in the version of the code used for these simulations), a number of assumptions are made in order to reproduce numerically the main core and SOL experimental data. The extrapolation to DT plasmas at the original input power of 33 MW, and taking into account only the thermal component of the alpha-power, does not show any significant difference regarding the power to the target with respect to the DD case. In contrast, the simulations at auxiliary power 40 MW, both at the original I p = 3 MA and at I p = 4 MA, show that the power to the target for both pulses is possibly too high to be sustained for about 5 s by strike-point sweeping alone without any control by Ne seeding. Even though the target power load may decrease to about 13–15 MW with substantial Ne seeding for both pulses, as from numerical predictions, there are indications suggesting that the control of the power load may be more critical for the pulse with pellet injection, due to the reduced SOL radiation.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
W Zhang; R Bilato; T Lunt; A. Messiaen; R A Pitts; S Lisgo; X Bonnin; V Bobkov; D Coster; Y Feng; P Jacquet; J. -M. Noterdaeme
Scrape-off layer density tailoring with local gas puffing to maximize ICRF power coupling in ITER Journal Article
In: Nuclear Materials and Energy, vol. 19, pp. 364 - 371, 2019, ISSN: 2352-1791.
@article{1910,
title = {Scrape-off layer density tailoring with local gas puffing to maximize ICRF power coupling in ITER},
author = {W Zhang and R Bilato and T Lunt and A. Messiaen and R A Pitts and S Lisgo and X Bonnin and V Bobkov and D Coster and Y Feng and P Jacquet and J. -M. Noterdaeme},
url = {http://www.sciencedirect.com/science/article/pii/S2352179118301236},
doi = {https://doi.org/10.1016/j.nme.2018.12.025},
issn = {2352-1791},
year = {2019},
date = {2019-05-01},
journal = {Nuclear Materials and Energy},
volume = {19},
pages = {364 - 371},
abstract = {The coupling of ion cyclotron range of frequencies (ICRF) power to the plasma depends critically on the scrape-off layer (SOL) density since the fast wave is evanescent below the cut-off density. The ICRF power coupling can be improved by increasing the SOL density locally in front of the antenna by means of local gas puffing/fueling. To understand the influence of local gas puffing on the SOL and ICRF coupling and to find the optimized gas valve positions to maximize ICRF coupling in ITER, the 3D SOL code EMC3-EIRENE is used to calculate the SOL density, and the ICRF antenna codes ANTITER and FELICE are then used to calculate the coupling resistances. Purely deuterium plasma is simulated and the total gas puff rate for all studied cases is 4.5e22 el/s. The divertor gas puffing case is considered as the reference case. The density and temperature profiles in the reference case are well fitted to the standard ITER profiles (both for the low and medium density) with proper transport parameter profiles. The gas source is then switched to other local positions of the main chamber while all other simulation parameters are kept the same. The simulation results indicate that midplane gas puffing increases the antenna coupling resistance most significantly (by 150%-200%) for both ICRF antennas. This increase is at the same level as long as the gas valve is located toroidally close to the antenna, no matter if the gas valve is right to or left to the antenna. Outer top gas puffing increases the coupling resistance less significantly (by 100%–150%) for the antenna with good magnetic field line connections to the gas valve, but the increase is at a much smaller level (by ∼30%–60%) for the other antenna with only partial field line connections to the valve. The simulations thus confirm for ITER a behavior similar as seen experimentally in current devices and strongly suggest that ITER should modify the existing main chamber injection configuration to bring one of the four planned injection points closer to the antennas.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
A. Messiaen; R. Ragona
In: Plasma Physics and Controlled Fusion, vol. 61, no. 4, pp. 044004, 2019.
@article{1907,
title = {Modeling in front of a plasma profile of a set of traveling wave antenna sections in view of the ion cyclotron range of frequencies heating of the fusion reactor},
author = {A. Messiaen and R. Ragona},
url = {https://doi.org/10.1088%2F1361-6587%2Faaf8bd},
doi = {10.1088/1361-6587/aaf8bd},
year = {2019},
date = {2019-04-01},
journal = {Plasma Physics and Controlled Fusion},
volume = {61},
number = {4},
pages = {044004},
publisher = {IOP Publishing},
abstract = {An upgraded version of the fast semi-analytical code ANTITER-II is used to model the traveling wave antenna (TWA) sections of any arbitrary number of radiating straps facing a low coupling plasma profile with their feeding system. The code computes the Y, Z and S matrices of the antenna array from which the performances of the TWA sections and of their feeding system are deduced as a function of the geometrical parameters of the TWA. The model incorporates the feeding of each section by a resonant ring circuit that re-circulates its output power. The cases of straps grounded at one of their ends (L grounding) or in their center (T grounding) are also compared. This model is extended to a number n
B of TWA sections of n
str straps with arbitrary positions in the y, z plane (i.e. machine wall). The full matrices of the resulting array of n
str
n
B straps are derived and connected to the resonant ring circuits feeding each TWA sections to incorporate the feeding in the model. Examples of toroidal and/or poloidal set of sections with T or L grounding and symmetric or asymmetric k
// spectra are analyzed. First conclusions for the design of a set of TWA sections for the reactor are already drawn.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
B of TWA sections of n
str straps with arbitrary positions in the y, z plane (i.e. machine wall). The full matrices of the resulting array of n
str
n
B straps are derived and connected to the resonant ring circuits feeding each TWA sections to incorporate the feeding in the model. Examples of toroidal and/or poloidal set of sections with T or L grounding and symmetric or asymmetric k
// spectra are analyzed. First conclusions for the design of a set of TWA sections for the reactor are already drawn.
Y Sun; R Sabot; S Heuraux; X Garbet; S Hacquin; G Hornung; G. Verdoolaege
Experimental trends of reflectometry frequency spectra emerging from a systematic analysis of the Tore Supra database Proceedings Article
In: Physic of Plasmas, pp. 032307, 2019.
@inproceedings{1906,
title = {Experimental trends of reflectometry frequency spectra emerging from a systematic analysis of the Tore Supra database},
author = {Y Sun and R Sabot and S Heuraux and X Garbet and S Hacquin and G Hornung and G. Verdoolaege},
year = {2019},
date = {2019-03-01},
booktitle = {Physic of Plasmas},
volume = {26},
pages = {032307},
keywords = {},
pubstate = {published},
tppubtype = {inproceedings}
}
V Bobkov; D Aguiam; R Bilato; S Brezinsek; L Colas; A Czarnecka; P. Dumortier; R Dux; H Faugel; H F ü; Ph. Jacquet; A Kallenbach; A. Krivska; C C Klepper; E. Lerche; Y Lin; D Milanesio; R Maggiora; I Monakhov; R Neu; J. -M. Noterdaeme; R Ochoukov; Th. P ü; M Reinke; W Tierens; A Tuccilo; O Tudisco; D. Van Eester; J Wright; S Wukitch; W Zhang
Impact of ICRF on the scrape-off layer and on plasma wall interactions: From present experiments to fusion reactor Journal Article
In: Nuclear Materials and Energy, vol. 18, pp. 131 - 140, 2019, ISSN: 2352-1791.
@article{1904,
title = {Impact of ICRF on the scrape-off layer and on plasma wall interactions: From present experiments to fusion reactor},
author = {V Bobkov and D Aguiam and R Bilato and S Brezinsek and L Colas and A Czarnecka and P. Dumortier and R Dux and H Faugel and H F ü and Ph. Jacquet and A Kallenbach and A. Krivska and C C Klepper and E. Lerche and Y Lin and D Milanesio and R Maggiora and I Monakhov and R Neu and J. -M. Noterdaeme and R Ochoukov and Th. P ü and M Reinke and W Tierens and A Tuccilo and O Tudisco and D. Van Eester and J Wright and S Wukitch and W Zhang},
url = {http://www.sciencedirect.com/science/article/pii/S2352179118301091},
doi = {https://doi.org/10.1016/j.nme.2018.11.017},
issn = {2352-1791},
year = {2019},
date = {2019-01-01},
journal = {Nuclear Materials and Energy},
volume = {18},
pages = {131 - 140},
abstract = {Recent achievements in studies of the effects of ICRF (Ion Cyclotron Range of Frequencies) power on the SOL (Scrape-Off Layer) and PWI (Plasma Wall Interactions) in ASDEX Upgrade (AUG), Alcator C-Mod, and JET-ILW are reviewed. Capabilities to diagnose and model the effect of DC biasing and associated impurity production at active antennas and on magnetic field connections to antennas are described. The experiments show that ICRF near-fields can lead not only to E × B convection, but also to modifications of the SOL density, which for Alcator C-Mod are limited to a narrow region near antenna. On the other hand, the SOL density distribution along with impurity sources can be tailored using local gas injection in AUG and JET-ILW with a positive effect on reduction of impurity sources. The technique of RF image current cancellation at antenna limiters was successfully applied in AUG using the 3-strap AUG antenna and extended to the 4-strap Alcator C-Mod field-aligned antenna. Multiple observations confirmed the reduction of the impact of ICRF on the SOL and on total impurity production when the ratio of the power of the central straps to the total antenna power is in the range 0.6 < Pcen/Ptotal< 0.8. Near-field calculations indicate that this fairly robust technique can be applied to the ITER ICRF antenna, enabling the mode of operation with reduced PWI. On the contrary, for the A2 antenna in JET-ILW the technique is hindered by RF sheaths excited at the antenna septum. Thus, in order to reduce the effect of ICRF power on PWI in a future fusion reactor, the antenna design has to be optimized along with design of plasma-facing components.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
A. Goriaev; T. Wauters; R Brakel; H Grote; M Gruca; O Volzke; S Brezinsek; A Dinklage; M Kubkowska; U Neuner
Development of glow discharge and electron cyclotron resonance heating conditioning on W7-X Journal Article
In: Nuclear Materials and Energy, vol. 18, pp. 227 - 232, 2019, ISSN: 2352-1791.
@article{1905,
title = {Development of glow discharge and electron cyclotron resonance heating conditioning on W7-X},
author = {A. Goriaev and T. Wauters and R Brakel and H Grote and M Gruca and O Volzke and S Brezinsek and A Dinklage and M Kubkowska and U Neuner},
url = {http://www.sciencedirect.com/science/article/pii/S2352179118302059},
doi = {https://doi.org/10.1016/j.nme.2018.12.010},
issn = {2352-1791},
year = {2019},
date = {2019-01-01},
journal = {Nuclear Materials and Energy},
volume = {18},
pages = {227 - 232},
abstract = {For successful operation of Wendelstein 7-X (W7-X) control of plasma impurity content and fuel recycling is required. This can be achieved by using wall conditioning methods. During the first divertor operation campaign (OP1.2a) of W7-X glow discharge conditioning (GDC), weekly in hydrogen and daily in helium for impurity and hydrogen removal respectively, was used in the absence of the magnetic field. He electron cyclotron resonance heating (ECRH) discharges were applied for density control in hydrogen plasmas during experimental days. The optimization of GDC and He ECRH wall conditioning on W7-X are presented. Solutions for glow discharge ignition problems are examined. The suitable He – GDC parameters, i.e. anode current and neutral gas pressure, are defined to keep the balance between maximum possible hydrogen removal rate and minimum plasma – facing component (PFC) erosion. Sequences of short He – ECRH pulses, so-called pulse trains, has been successfully implemented. The effect of pulse train main parameter variation such as gas prefill, input power, pulse length, duty cycle is described. The efficiency of single He recovery discharges and pulse trains are compared. The results of this work show significant improvement of wall cleaning efficiency.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
A Huber; S Brezinsek; A Kirschner; Str P ö; G Sergienko; V Huber; I Borodkina; D Douai; S. Jachmich; C Linsmeier; B Lomanowski; G F Matthews; P Mertens
Determination of tungsten sources in the JET-ILW divertor by spectroscopic imaging in the presence of a strong plasma continuum Journal Article
In: Nuclear Materials and Energy, vol. 18, pp. 118 - 124, 2019, ISSN: 2352-1791.
@article{1903,
title = {Determination of tungsten sources in the JET-ILW divertor by spectroscopic imaging in the presence of a strong plasma continuum},
author = {A Huber and S Brezinsek and A Kirschner and Str P ö and G Sergienko and V Huber and I Borodkina and D Douai and S. Jachmich and C Linsmeier and B Lomanowski and G F Matthews and P Mertens},
url = {http://www.sciencedirect.com/science/article/pii/S2352179118301406},
doi = {https://doi.org/10.1016/j.nme.2018.12.009},
issn = {2352-1791},
year = {2019},
date = {2019-01-01},
journal = {Nuclear Materials and Energy},
volume = {18},
pages = {118 - 124},
abstract = {The identification of the sources of atomic tungsten and the measurement of their radiation distribution in front of all plasma-facing components has been performed in JET with the help of two digital cameras with the same two-dimensional view, equipped with interference filters of different bandwidths centred on the W I (400.88 nm) emission line. A new algorithm for the subtraction of the continuum radiation was successfully developed and is now used to evaluate the W erosion even in the inner divertor region where the strong recombination emission is dominating over the tungsten emission. Analysis of W sputtering and W redistribution in the divertor by video imaging spectroscopy with high spatial resolution for three different magnetic configurations was performed. A strong variation of the emission of the neutral tungsten in toroidal direction and corresponding W erosion has been observed. It correlates strongly with the wetted area with a maximal W erosion at the edge of the divertor tile.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
T S Pedersen; R K ö; M Krychowiak; M Jakubowski; J Baldzuhn; S Bozhenkov; G Fuchert; A Langenberg; H.Niemann; D Zhang; K Rahbarnia; H -S Bosch; Y. O. Kazakov; S Brezinsek; Y Gao; N Pablant; W7-X Team
First results from divertor operation in Wendelstein 7-X Journal Article
In: Plasma Physics and Controlled Fusion, vol. 61, no. 1, pp. 014035, 2019.
@article{1901,
title = {First results from divertor operation in Wendelstein 7-X},
author = {T S Pedersen and R K ö and M Krychowiak and M Jakubowski and J Baldzuhn and S Bozhenkov and G Fuchert and A Langenberg and H.Niemann and D Zhang and K Rahbarnia and H -S Bosch and Y. O. Kazakov and S Brezinsek and Y Gao and N Pablant and W7-X Team},
url = {http://stacks.iop.org/0741-3335/61/i=1/a=014035},
year = {2019},
date = {2019-01-01},
journal = {Plasma Physics and Controlled Fusion},
volume = {61},
number = {1},
pages = {014035},
abstract = {Wendelstein 7-X is a highly optimized stellarator that went into operation in 2015. With a 30 cubic meter volume, a superconducting coil system operating at 2.5 T, and steady-state heating capability of eventually up to 10 MW, it was built to demonstrate the benefits of optimized stellarators at parameters approaching those of a fusion power plant. We report here on the first results with the test divertor installed, during the second operation phase, which was performed in the second half of 2017. Operation with a divertor, and the addition of several new fueling systems, allowed higher density operation in hydrogen as well as helium. The effects that higher density operation had on both divertor operation and global confinement will be described. In particular, at high densities detachment was observed, and the highest fusion triple product for a stellarator was achieved.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
R C Wolf; S Bozhenkov; A Dinklage; G Fuchert; Y. O. Kazakov; H P Laqua; S Marsen; N B Marushchenko; T Stange; M Zanini; I Abramovic; A Alonso; J Baldzuhn; M Beurskens; C D Beidler; H Braune; K J Brunner; N Chaudhary; H Damm; P Drewelow; G Gantenbein; Yu Gao; J Geiger; M Hirsch; U H ö; M Jakubowski; J Jelonnek; T Jensen; W Kasparek; J Knauer; S B Korsholm; A Langenberg; C Lechte; F Leipold; Trimino H Mora; U Neuner; S K Nielsen; D Moseev; H Oosterbeek; N Pablant; E Pasch; B Plaum; Sunn T Pedersen; Puig A Sitjes; K Rahbarnia; J Rasmussen; M Salewski; J Schilling; E Scott; M Stejner; H Thomsen; M Thumm; Y Turkin; F Wilde; Wendelstein 7-X Team
Electron-cyclotron-resonance heating in Wendelstein 7-X: A versatile heating and current-drive method and a tool for in-depth physics studies Journal Article
In: Plasma Physics and Controlled Fusion, vol. 61, no. 1, pp. 014037, 2019.
@article{1902,
title = {Electron-cyclotron-resonance heating in Wendelstein 7-X: A versatile heating and current-drive method and a tool for in-depth physics studies},
author = {R C Wolf and S Bozhenkov and A Dinklage and G Fuchert and Y. O. Kazakov and H P Laqua and S Marsen and N B Marushchenko and T Stange and M Zanini and I Abramovic and A Alonso and J Baldzuhn and M Beurskens and C D Beidler and H Braune and K J Brunner and N Chaudhary and H Damm and P Drewelow and G Gantenbein and Yu Gao and J Geiger and M Hirsch and U H ö and M Jakubowski and J Jelonnek and T Jensen and W Kasparek and J Knauer and S B Korsholm and A Langenberg and C Lechte and F Leipold and Trimino H Mora and U Neuner and S K Nielsen and D Moseev and H Oosterbeek and N Pablant and E Pasch and B Plaum and Sunn T Pedersen and Puig A Sitjes and K Rahbarnia and J Rasmussen and M Salewski and J Schilling and E Scott and M Stejner and H Thomsen and M Thumm and Y Turkin and F Wilde and Wendelstein 7-X Team},
url = {http://stacks.iop.org/0741-3335/61/i=1/a=014037},
year = {2019},
date = {2019-01-01},
journal = {Plasma Physics and Controlled Fusion},
volume = {61},
number = {1},
pages = {014037},
abstract = {For stellarators, which need no or only small amounts of current drive, electron-cyclotron-resonance heating (ECRH) is a promising heating method even for the envisaged application in a fusion power plant. Wendelstein 7-X (W7-X) is equipped with a steady-state capable ECRH system, operating at 140 GHz, which corresponds to the 2nd cyclotron harmonic of the electrons at a magnetic field of 2.5 T. Ten gyrotrons are operational and already delivered 7 MW to W7-X plasmas. Combined with pellet injection, the highest triple product (0.68 × 10 20 keV m −3 s), observed up to now in stellarators, was achieved (Sunn Pedersen et al 2018 Plasma Phys. Control. Fusion 61 014035). For the first time, W7-X plasmas were sustained by 2nd harmonic O-mode heating, approaching the collisionality regime for which W7-X was optimized. Power deposition scans did not show any indication of electron temperature profile resilience. In low-density, low-power plasmas a compensation of the bootstrap current with electron-cyclotron current drive (ECCD) was demonstrated. Sufficiently strong ECCD close to the plasma centre produced periodic internal plasma-crash events, which coincide with the appearance of low order rationals of the rotational transform.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
2018
G P Glazunov; D I Baron; V E Moiseenko; M N Bondarenko; A L Konotopskiy; A V Lozin; A. I. Lyssoivan; T. Wauters; I E Garkusha
Characterization of wall conditions in Uragan-2M stellarator using stainless steel thermal desorption probe Journal Article
In: Fusion Engineering and Design, vol. 137, pp. 196 - 201, 2018, ISSN: 0920-3796.
@article{1898,
title = {Characterization of wall conditions in Uragan-2M stellarator using stainless steel thermal desorption probe},
author = {G P Glazunov and D I Baron and V E Moiseenko and M N Bondarenko and A L Konotopskiy and A V Lozin and A. I. Lyssoivan and T. Wauters and I E Garkusha},
url = {http://www.sciencedirect.com/science/article/pii/S0920379618306355},
doi = {https://doi.org/10.1016/j.fusengdes.2018.09.010},
issn = {0920-3796},
year = {2018},
date = {2018-12-01},
journal = {Fusion Engineering and Design},
volume = {137},
pages = {196 - 201},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
R. Ragona
A New ICRF Antenna for Future Reactors: The Travelling Wave Array Antenna PhD Thesis
University of Ghent, 2018.
@phdthesis{1900,
title = {A New ICRF Antenna for Future Reactors: The Travelling Wave Array Antenna},
author = {R. Ragona},
year = {2018},
date = {2018-12-01},
school = {University of Ghent},
keywords = {},
pubstate = {published},
tppubtype = {phdthesis}
}
T. Wauters; A. Goriaev; A Alonso; J Baldzuhn; R Brakel; S Brezinsek; A Dinklage; H Grote; J Fellinger; O P Ford; R K ö; H Laqua; D Matveev; T Stange; Van L ó
Wall conditioning throughout the first carbon divertor campaign on Wendelstein 7-X Journal Article
In: Nuclear Materials and Energy, vol. 17, pp. 235 - 241, 2018, ISSN: 2352-1791.
@article{1899,
title = {Wall conditioning throughout the first carbon divertor campaign on Wendelstein 7-X},
author = {T. Wauters and A. Goriaev and A Alonso and J Baldzuhn and R Brakel and S Brezinsek and A Dinklage and H Grote and J Fellinger and O P Ford and R K ö and H Laqua and D Matveev and T Stange and Van L ó},
url = {http://www.sciencedirect.com/science/article/pii/S2352179118300966},
doi = {https://doi.org/10.1016/j.nme.2018.11.004},
issn = {2352-1791},
year = {2018},
date = {2018-12-01},
journal = {Nuclear Materials and Energy},
volume = {17},
pages = {235 - 241},
abstract = {Controlling the recycling of hydrogen and the release of impurities from the plasma facing components proved to be essential and challenging throughout the first divertor campaign on W7-X. This paper discusses the conditioning requirements throughout the first divertor campaign on Wendelstein 7-X. Baking at 150 $,^circ$C and glow discharge conditioning (GDC) in H2 is performed after the initial pump down of the vacuum vessel. Experimental programs in hydrogen are interlaced with He discharges to desaturate the wall from hydrogen, recover good recycling conditions and hence establish plasma density control. Optimized He ECRH wall conditioning procedures consisted of sequences of short discharges with fixed duty cycle. He-GDC remained however needed before each experimental day to fully offset the hydrogen inventory build-up. A significant increase in the divertor temperature is observed throughout an operational day, enhancing outgassing of CO and H2O. Preliminary recombination-diffusion modelling of hydrogen outgassing suggests enhanced diffusion to deeper surface layers with increasing wall temperature, which results in better wall pumping. This indicates that the experienced plasma performance degradation throughout an operational day results from increased impurity outgassing at higher wall temperature rather than hydrogen saturation of the wall.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
W Zhang; T Franke; J. -M. Noterdaeme; D. Van Eester
EMC3-EIRENE modeling of edge plasma to improve the ICRF coupling with local gas puffing in DEMO Journal Article
In: Nuclear Fusion, vol. 58, no. 12, pp. 126005, 2018.
@article{1897,
title = {EMC3-EIRENE modeling of edge plasma to improve the ICRF coupling with local gas puffing in DEMO},
author = {W Zhang and T Franke and J. -M. Noterdaeme and D. Van Eester},
url = {http://stacks.iop.org/0029-5515/58/i=12/a=126005},
year = {2018},
date = {2018-12-01},
journal = {Nuclear Fusion},
volume = {58},
number = {12},
pages = {126005},
abstract = {We report the first 3D EMC3-EIRENE simulations of scrape-off layer (SOL) plasma in DEMO. EMC3-EIRENE is a 3D edge plasma fluid and neutral particle transport code. Effects of local gas puffing on the SOL density and ion cyclotron range of frequencies (ICRF) power coupling have been studied. A pure deuterium plasma is simulated and the puffing/fueling gas is deuterium gas. The gas puffing cases investigated include divertor, top, midplane and antenna gas puffing. The ICRF antenna is distributed through 360$,^circ$ toroidally, and poloidally located in the outer top of the vessel. The results show that toroidally distributed but poloidally localized antenna gas puffing increases the density in front of the antenna most significantly, while top or midplane gas puffing increases this antenna density to a moderate level. Influences of gas puff rate and particle transport parameters on the SOL density are investigated. The parameter scans indicate that the shift of the fast wave cut-off density position to the antenna depends almost linearly on the total gas puff rate. To achieve a significant antenna density increase, the antenna gas puff rate should be at the level of 1.8 × 10 23 el s −1 (i.e. 1.0 × 10 22 el s −1 per tokamak segment). As the total gas puff rate increases to 4.0 × 10 23 el s −1 , the evanescent layer of the fast wave (with ##IMG## [http://ej.iop.org/images/0029-5515/58/12/126005/nfaaddaeieqn001.gif] = 2 m −1 ) almost vanishes. Moreover, it is found that antenna gas puffing reduces the local power flux to the main chamber wall near the gas valve due to a local decrease of the SOL temperature.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
S A Bozhenkov; Y. O. Kazakov; J Baldzhun; H P Laqua; J A Alonso; M N A Beurskens; C Brandt; K J Brunner; H Damm; G Fuchert; M Hirsch; U H ö; M W Jakubowski; J Knauer; G Kocsis; R K ö; A Langenberg; S Lazeson; N B Marushchenko; K J McCarthy; E Pasch; N Pablant; Panadero N Alvarez; K Rahbarnia; J Shmitt; H Thomsen; Y Turkin; F Warmer; G Wurden; D zhang; T S Pedersen; R C Wolf; W7-X Team
High Density and High Performance Operation with Pellet Injection in W7-X Proceedings Article
In: Proceedings Fusion Energy 2018, pp. EX/P8-8, 2018.
@inproceedings{1889,
title = {High Density and High Performance Operation with Pellet Injection in W7-X},
author = {S A Bozhenkov and Y. O. Kazakov and J Baldzhun and H P Laqua and J A Alonso and M N A Beurskens and C Brandt and K J Brunner and H Damm and G Fuchert and M Hirsch and U H ö and M W Jakubowski and J Knauer and G Kocsis and R K ö and A Langenberg and S Lazeson and N B Marushchenko and K J McCarthy and E Pasch and N Pablant and Panadero N Alvarez and K Rahbarnia and J Shmitt and H Thomsen and Y Turkin and F Warmer and G Wurden and D zhang and T S Pedersen and R C Wolf and W7-X Team},
year = {2018},
date = {2018-10-01},
booktitle = {Proceedings Fusion Energy 2018},
volume = {IAEA-CN-258},
pages = {EX/P8-8},
keywords = {},
pubstate = {published},
tppubtype = {inproceedings}
}
R Brakel; A Dinklage; J Fellinger; G Fuchert; H Grote; R K ö; H Laqua; T Stange; O Volzke; G Schlisio; U Wenzel; D Zhang; A. Goriaev; T. Wauters; S Brezinsek; V E Moiseenko; A A Belitskii; W7-X Team
Strategy and Optimisation of Wall Conditioning at the Wendelstein 7-X Stellarator Proceedings Article
In: Proceedings Fusion Energy 2018, pp. EX/P8-17, 2018.
@inproceedings{1891,
title = {Strategy and Optimisation of Wall Conditioning at the Wendelstein 7-X Stellarator},
author = {R Brakel and A Dinklage and J Fellinger and G Fuchert and H Grote and R K ö and H Laqua and T Stange and O Volzke and G Schlisio and U Wenzel and D Zhang and A. Goriaev and T. Wauters and S Brezinsek and V E Moiseenko and A A Belitskii and W7-X Team},
year = {2018},
date = {2018-10-01},
booktitle = {Proceedings Fusion Energy 2018},
volume = {IAEA-CN-258},
pages = {EX/P8-17},
abstract = {Wall conditioning is of utmost importance on the path to high density, steady state operation at the superconducting Wendelstein 7-X stellarator. Major issues are to achieve low outgassing from the first wall and a low level of plasma impurities, which are prerequisite to achieve controllable high density plasmas. In addition to the traditional tools of baking and glow discharge conditioning alternate microwave based methods which are applicable with the permanently activated magnetic field are systematically developed and optimized. These use ECRH-pulse trains or single longer ECRH-discharges at moderate plasma density to desaturate the wall from the fueling gas. Additionally, the first boronisation significantly extended the operation space up to densities beyond 1020 m-3 by significant reduction of oxygen and carbon impurities.},
keywords = {},
pubstate = {published},
tppubtype = {inproceedings}
}
S Brezinsek; D Borodin; A Huber; A Baron-Wiechec; I Borodkina; I Coffey; Ch. Guillemaut; K Heinola; M Imrisek; S. Jachmich; E Pawelec; A Kirschner; S Krat; G Sergienko; G F Matthews; M Mayer; A G Meigs; S Wiesen; A Widdowson; JET contributors
Erosion, Screening, and Migration of Tungsten in the JET Divertor Proceedings Article
In: Proceedings Fusion Energy 2018, pp. EX/9-4, 2018.
@inproceedings{1883,
title = {Erosion, Screening, and Migration of Tungsten in the JET Divertor},
author = {S Brezinsek and D Borodin and A Huber and A Baron-Wiechec and I Borodkina and I Coffey and Ch. Guillemaut and K Heinola and M Imrisek and S. Jachmich and E Pawelec and A Kirschner and S Krat and G Sergienko and G F Matthews and M Mayer and A G Meigs and S Wiesen and A Widdowson and JET contributors},
year = {2018},
date = {2018-10-01},
booktitle = {Proceedings Fusion Energy 2018},
volume = {IAEA-CN-258},
pages = {EX/9-4},
keywords = {},
pubstate = {published},
tppubtype = {inproceedings}
}
F J Casson; H Patten; C Bourdelle; S Breton; J Citrin; F Koechl; C Angioni; Y Baranov; R Bilato; E A Belli; C D Challis; G Corrigan; A Czarnecka; O Ficker; L Garzotti; M Goniche; J P Graves; T Johnson; K Kirov; P Knight; E. Lerche; M Mantsinen; J Mylnar; M Sertoli; M Valisa; JET Contributors
Predictive Multi-Channel Flux-Driven Modelling to Optimise ICRH Tungsten Control in JET Proceedings Article
In: Proceedings Fusion Energy 2018, pp. TH/3-2, 2018.
@inproceedings{1894,
title = {Predictive Multi-Channel Flux-Driven Modelling to Optimise ICRH Tungsten Control in JET},
author = {F J Casson and H Patten and C Bourdelle and S Breton and J Citrin and F Koechl and C Angioni and Y Baranov and R Bilato and E A Belli and C D Challis and G Corrigan and A Czarnecka and O Ficker and L Garzotti and M Goniche and J P Graves and T Johnson and K Kirov and P Knight and E. Lerche and M Mantsinen and J Mylnar and M Sertoli and M Valisa and JET Contributors},
year = {2018},
date = {2018-10-01},
booktitle = {Proceedings Fusion Energy 2018},
volume = {IAEA-CN-258},
pages = {TH/3-2},
abstract = {The evolution of the JET high performance hybrid scenario, including central accumulation of the tungsten (W) impurity, is reproduced with predictive multi-channel integrated modelling over multiple confinement times using first-principle based models. 8 transport channels ( T i , T e , j , nD , n Be , n N i , nW , ω ) are modelled predictively, with self-consistent sources, radiation and magnetic equilibrium, yielding a system with multiple non-linearities which can produce a radiative temperature collapse after several confinement times. W is transported inward by neoclassical convection driven by the main ion density gradients and enhanced by poloidal asymmetries due to centrifugal acceleration. The slow evolution of the bulk density profile sets the timescale for W accumulation. Prediction of this phenomenon requires a turbulent transport model capable of accurately predicting particle and momentum transport (QuaLiKiz) and a neoclassical transport model including the effects of poloidal asymmetries (NEO) coupled to an integrated plasma simulator (JINTRAC). The modelling capability is applied to optimise the available actuators to prevent W accumulation, and to extrapolate in power and pulse length. Central NBI heating is preferred for high performance, but comes at the price of central deposition of particles and torque which pose the risk of W accumulation. The primary mechanisms for ICRH to control W in JET are via its impact on the bulk profiles and turbulent diffusion. High power ICRH near the axis can sensitively mitigate against W accumulation, and ion heating (He-3 minority) is predicted to provide more resilience to W accumulation than electron heating (H minority) in the JET hybrid. Extrapolation to DT plasmas finds 15MW of fusion power and improved confinement compared to DD, due to reduced ion-electron energy exchange, and increased Ti/Te stabilisation of ITG instabilities. The turbulence reduction in DT increases density peaking and accelerates the arrival of W on axis; this may be mitigated by reducing the penetration of the beam particle source with an increased pedestal density.},
keywords = {},
pubstate = {published},
tppubtype = {inproceedings}
}
G Fuchert; J Brunner; K Rahbarnia; T Stange; D Zhang; J Baldzuhn; S A Bozhenkov; C D Beidler; S Brezinsek; R Burhenn; H Damm; A Dinklage; M Hirsch; Y. O. Kazakov; J Knauer; Y Feng; A Langenberg; H P Laqua; S Lazerson; N Pablant; E Pasch; Sunn T Pedersen; E Scott; F Warmer; V Winters; R C Wolf; W7-X Team
Increasing the Density in W7-X: Benefits and Limitations Proceedings Article
In: Proceedings Fusion Energy 2018, pp. EX/3-5, 2018.
@inproceedings{1881,
title = {Increasing the Density in W7-X: Benefits and Limitations},
author = {G Fuchert and J Brunner and K Rahbarnia and T Stange and D Zhang and J Baldzuhn and S A Bozhenkov and C D Beidler and S Brezinsek and R Burhenn and H Damm and A Dinklage and M Hirsch and Y. O. Kazakov and J Knauer and Y Feng and A Langenberg and H P Laqua and S Lazerson and N Pablant and E Pasch and Sunn T Pedersen and E Scott and F Warmer and V Winters and R C Wolf and W7-X Team},
year = {2018},
date = {2018-10-01},
booktitle = {Proceedings Fusion Energy 2018},
volume = {IAEA-CN-258},
pages = {EX/3-5},
abstract = {In stellarators, increasing the density is beneficial for the energy confinement. While there is probably not one single reason for this observation, it is still very robust across different devices. This is, for example, reflected in the empirical energy confinement time scaling for stellarators, ISS04. In order to study whether this is also true for Wendelstein 7-X, the energy confinement time scaling for the first divertor experiments is analyzed and compared to ISS04. When the density is increased too much, however, radiative collapses are frequently observed. Existing analytical models for the critical density are revisited to assess whether they can predict the accessible density range. Furthermore, since close to the collapse the radiation losses increase substantially, the impact of the global energy confinement is investigated. It is found that energy confinement starts to become affected as soon as the radiation losses reach 50 % of the heating power. In the second half of the first divertor campaign, boronization has been applied to W7-X for the first time. This broadened the operational window, allowing for operation at higher density and, hence, higher stored energy.},
keywords = {},
pubstate = {published},
tppubtype = {inproceedings}
}
D Gallart; M J Mantsinen; C Challis; D Frigione; J Graves; E Belonohy; F Casson; A Czarnecka; J Eriksson; J Garcia; M Goniche; C Hellesen; J Hobirk; P Jaquet; E Joffrin; N Krawczyk; D King; M Lennholm; E. Lerche; E Pawelec; X S á; M Sertoli; G Sips; E Solano; M Tsalas; P Vallejos; M Valisa; JET Contributors
Modelling of JET hybrid plasmas with emphasis on performance of combined ICRF and NBI heating Journal Article
In: Nuclear Fusion, vol. 58, no. 10, pp. 106037, 2018.
@article{1872,
title = {Modelling of JET hybrid plasmas with emphasis on performance of combined ICRF and NBI heating},
author = {D Gallart and M J Mantsinen and C Challis and D Frigione and J Graves and E Belonohy and F Casson and A Czarnecka and J Eriksson and J Garcia and M Goniche and C Hellesen and J Hobirk and P Jaquet and E Joffrin and N Krawczyk and D King and M Lennholm and E. Lerche and E Pawelec and X S á and M Sertoli and G Sips and E Solano and M Tsalas and P Vallejos and M Valisa and JET Contributors},
url = {http://stacks.iop.org/0029-5515/58/i=10/a=106037},
year = {2018},
date = {2018-10-01},
journal = {Nuclear Fusion},
volume = {58},
number = {10},
pages = {106037},
abstract = {During the 2015–2016 JET campaigns, many efforts have been devoted to the exploration of high-performance plasma scenarios envisaged for DT operation in JET. In this paper, we review various key recent hybrid discharges and model the combined ICRF+NBI heating. These deuterium discharges with deuterium beams had the ICRF antenna frequency tuned to match the cyclotron frequency of minority H at the centre of the tokamak coinciding with the second harmonic cyclotron resonance of D. The modelling takes into account the synergy between ICRF and NBI heating through the second harmonic cyclotron resonance of D beam ions, allowing us to assess its impact on the neutron rate R NT . For discharges carried out with a fixed ICRF antenna frequency and changing toroidal magnetic field to vary the resonance position, we evaluate the influence of the resonance position on the heating performance and central impurity control. The H concentration is varied between discharges in order to test its role in the heating performance. It is found that discharges with a resonance beyond ∼0.15 m from the magnetic axis R 0 suffer from MHD activity and impurity accumulation in these plasma conditions. According to our modelling, the ICRF enhancement of R NT increases with the ICRF power absorbed by deuterons as the H concentration decreases. We find that in the recent hybrid discharges, this ICRF enhancement varies due to a variation of H concentration and is in the range of 10%–25%. The modelling of a recent record high-performance hybrid discharge shows that ICRF fusion yield enhancement of ∼30% and ∼15% respectively can be achieved in the ramp-up phase and during the main heating phase. We extrapolate the results to DT and find that the best performing hybrid discharges correspond to an equivalent fusion power of ∼7.0 MW in DT. Finally, an optimization analysis of the bulk ion heating for the DT scenario reveals around 15%–20% larger bulk ion heating for the 3 He minority scenario as compared to the H minority scenario.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
L/ Garzotti; C Challis; R Dumont; D Frigione; J Graves; E. Lerche; J Mailloux; M Mantsinen; F Rimini; F Casson; A Czarnecka; J Eriksson; R Felton; L Frassinetti; D Gallart; J Garcia; G Giroud; E offrin; H -T Kim; N Krawczyk; M Lennholm; P Lomas; C Lowry; L Meneses; I Nunes; M Romanelli; S Sharapov; S Silburn; A Sips; E Stefanikova; M Taslas; Valovic M a; JET Contributors
Scenario Development for DT Operation at JET Proceedings Article
In: Proceedings Fusion Energy 2018, pp. 684, 2018.
@inproceedings{1880,
title = {Scenario Development for DT Operation at JET},
author = {L/ Garzotti and C Challis and R Dumont and D Frigione and J Graves and E. Lerche and J Mailloux and M Mantsinen and F Rimini and F Casson and A Czarnecka and J Eriksson and R Felton and L Frassinetti and D Gallart and J Garcia and G Giroud and E offrin and H -T Kim and N Krawczyk and M Lennholm and P Lomas and C Lowry and L Meneses and I Nunes and M Romanelli and S Sharapov and S Silburn and A Sips and E Stefanikova and M Taslas and Valovic M a and JET Contributors},
year = {2018},
date = {2018-10-01},
booktitle = {Proceedings Fusion Energy 2018},
volume = {IAEA-CN-258},
pages = {684},
abstract = {The JET exploitation plan foresees D-T operations in 2020 (DTE2). With respect to the first D-T campaign in 1997 (DTE1), when JET was equipped with a carbon wall, the experiments will be conducted in presence of a beryllium-tungsten ITER-like wall (ILW) and will benefit from an extended and improved set of diagnostics and higher additional heating power (34 MW NBI + 8 MW ICRH). Among the challenges presented by operations with the new wall, there are a general deterioration of the pedestal confinement, the risk of heavy impurity accumulation in the core, which, if not controlled, can cause the radiative collapse of the discharge, and the requirement to protect the divertor from excessive heat loads, which may damage it permanently. Therefore, an intense activity of scenario development has been undertaken at JET during the last three years to overcome these difficulties and prepare the plasmas needed to demonstrate stationary high fusion performance and clear alpha particle effects. The paper describes the status and main achievements of this scenario development activity, both from an operational and plasma physics point of view.},
keywords = {},
pubstate = {published},
tppubtype = {inproceedings}
}
A Huber; D Kinna; V Huber; G Arnoux; G Sergienko; I Balboa; C Balorin; P Carman; P Carvalho; S Collins; N Conway; P McCullen; A Drenik; S. Jachmich; M Jouve; Ch. Linsmeier; B Lomanowski; P J Lomas; C G Lowry; C F Maggi; G F Matthews; A Meigs; Ph. Mertens; I Nunes; M Price; P Puglia; V Riccardo; F G Rimini; A Widdowson; K -D Zastrow; JET contributors
Real-time protection of the JET ITER-like wall based on near infrared imaging diagnostic systems Journal Article
In: Nuclear Fusion, vol. 58, no. 10, pp. 106021, 2018.
@article{1870,
title = {Real-time protection of the JET ITER-like wall based on near infrared imaging diagnostic systems},
author = {A Huber and D Kinna and V Huber and G Arnoux and G Sergienko and I Balboa and C Balorin and P Carman and P Carvalho and S Collins and N Conway and P McCullen and A Drenik and S. Jachmich and M Jouve and Ch. Linsmeier and B Lomanowski and P J Lomas and C G Lowry and C F Maggi and G F Matthews and A Meigs and Ph. Mertens and I Nunes and M Price and P Puglia and V Riccardo and F G Rimini and A Widdowson and K -D Zastrow and JET contributors},
url = {http://stacks.iop.org/0029-5515/58/i=10/a=106021},
year = {2018},
date = {2018-10-01},
journal = {Nuclear Fusion},
volume = {58},
number = {10},
pages = {106021},
abstract = {In JET with ITER-like wall (JET-ILW), the first wall was changed to metallic materials (tungsten and beryllium) [1] which require a reliable protection system to avoid damage of the plasma-facing components (PFCs) due to beryllium melting or cracking of tungsten owing to thermal fatigue. To address this issue, a protection system with real time control, based on imaging diagnostics, has been implemented on JET-ILW in 2011. This paper describes the design, implementation, and operation of the near infrared imaging diagnostic system of the JET-ILW plasma experiment and its integration into the existing JET-ILW protection architecture. The imaging system comprises eleven analogue CCD cameras which demonstrate a high robustness against changes of system parameters like the emissivity. The system covers about two thirds of the main chamber wall and almost half of the divertor. A real-time imaging processing unit is used to convert the raw data into surface temperatures taking into account the different emissivity for the various materials and correcting for artefacts resulting e.g. from neutron impact. Regions of interest (ROI) on the selected PFCs are analysed in real time and the maximum temperature measured for each ROI is sent to other real time systems to trigger an appropriate response of the plasma control system, depending on the location of a hot spot. A hot spot validation algorithm was successfully integrated into the real-time system and is now used to avoid false alarms caused by neutrons and dust. The design choices made for the video imaging system, the implications for the hardware components and the calibration procedure are discussed. It will be demonstrated that the video imaging protection system can work properly under harsh electromagnetic conditions as well as under neutron and gamma radiation. Examples will be shown of instances of hot spot detection that abort the plasma discharge. The limits of the protection system and the associated constraints on plasma operation are also presented. The real-time protection system has been operating routinely since 2011. During this period, less than 0.5% of the terminated discharges were aborted by a malfunction of the system. About 2%–3% of the discharges were terminated due to the detection of actual hot spots.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
D Iglesias; W Arter; I Balboa; P Bunting; C Challis; J W Coenen; Y Corre; S Esquembri; S. Jachmich; K Krieger; G F Matthews; R A Pitts; V Riccardo; M L Richiusa; M Porton; F Rimini; S Silburn; V Thompson; R Otin; D Valcarcel; L Vitton-Mea; Z Vizvary; J Williams; JET Contributors
Advances in Predictive Thermo-Mechanical Modelling for the JET Divertor Experimental Interpretation, Improved Protection, and Reliable Operation Proceedings Article
In: Proceedings Fusion Energy 2018, 2018.
@inproceedings{1879,
title = {Advances in Predictive Thermo-Mechanical Modelling for the JET Divertor Experimental Interpretation, Improved Protection, and Reliable Operation},
author = {D Iglesias and W Arter and I Balboa and P Bunting and C Challis and J W Coenen and Y Corre and S Esquembri and S. Jachmich and K Krieger and G F Matthews and R A Pitts and V Riccardo and M L Richiusa and M Porton and F Rimini and S Silburn and V Thompson and R Otin and D Valcarcel and L Vitton-Mea and Z Vizvary and J Williams and JET Contributors},
year = {2018},
date = {2018-10-01},
booktitle = {Proceedings Fusion Energy 2018},
volume = {IAEA-CN-258},
abstract = {The JET outboard divertor targets are the in-vessel components which receive the largest heat flux density. Surface delamination, radial cracks, and tie rod failures have been observed in the outboard tungsten-coated CFC tiles, while bulk tungsten special lamellas were intentionally melted in dedicated experiments. These different types of damage were not reproducible using existing models and tools. Several analysis and development activities have been completed during the last campaigns for improving the tools used for prediction of the plasma parallel heat flux density and the thermo- mechanical behaviour of the tiles. Experimental thermography measurements at different impinging angles, interpreted with new algorithms including a correction to the optical projection have led to a reduction of the peak parallel heat flux density of 1/3 compared to the previously estimated value. Integrity assessments are performed using the engineering footprint concept, which averages ELM and inter-ELM plasma load. Improvements on the ELM profiles result in a fall-off length for this engineering footprint of one order of magnitude larger than that inferred from the inter-ELM scaling laws. All these advances have been implemented in integrated analysis tools which can quickly predict the behaviour of the divertor tiles in an automated and power consistent manner. This development carried out at JET supports the experimental understanding, enhances the real-time protection systems, improves the evaluation of the operating instructions, and is also transferable to ITER.},
keywords = {},
pubstate = {published},
tppubtype = {inproceedings}
}
D Iglesias; P Bunting; J W Coenen; G F Matthews; R A Pitts; S Silburn; I Balboa; I Coffey; Y Corre; R Dejarnac; J Gaspar; E Gauthier; S. Jachmich; K Krieger; S Pamela; V Riccardo; M Stamp; JET contributors
An improved model for the accurate calculation of parallel heat fluxes at the JET bulk tungsten outer divertor Journal Article
In: Nuclear Fusion, vol. 58, no. 10, pp. 106034, 2018.
@article{1871,
title = {An improved model for the accurate calculation of parallel heat fluxes at the JET bulk tungsten outer divertor},
author = {D Iglesias and P Bunting and J W Coenen and G F Matthews and R A Pitts and S Silburn and I Balboa and I Coffey and Y Corre and R Dejarnac and J Gaspar and E Gauthier and S. Jachmich and K Krieger and S Pamela and V Riccardo and M Stamp and JET contributors},
url = {http://stacks.iop.org/0029-5515/58/i=10/a=106034},
year = {2018},
date = {2018-10-01},
journal = {Nuclear Fusion},
volume = {58},
number = {10},
pages = {106034},
abstract = {Parallel heat flux calculations at the JET divertor have been based on the assumption that all incoming heat is due to the projection of the heat flux parallel to the magnetic line, ##IMG## [http://ej.iop.org/images/0029-5515/58/10/106034/nfaad83eieqn001.gif] , plus a constant background. This simplification led to inconsistencies during the analysis of a series of dedicated tungsten melting experiments performed in 2013, for which infrared (IR) thermography surface measurements could not be recreated through simulations unless the parallel heat flux was reduced by 80% for L-mode and 60% for H-mode. We give an explanation for these differences using a new IR inverse analysis code, a set of geometrical corrections, and most importantly an additional term for the divertor heat flux accounting for non-parallel effects such as cross-field transport, recycled neutrals or charge exchange. This component has been evaluated comparing four different geometries with impinging angles varying from 2 to 90$,^circ$. Its magnitude corresponds to 1.2%–1.9% of ##IMG## [http://ej.iop.org/images/0029-5515/58/10/106034/nfaad83eieqn002.gif] , but because it is not affected by the magnetic projection, it accounts for up to 20%–30% of the tile surface heat flux. The geometrical corrections imply a further reduction of 24% of the measured heat flux. In addition, the application of the new inverse code increases the accuracy of the tile heat flux calculation, eliminating any previous discrepancy. The parallel heat flux computed with this new model is actually much lower than previously deduced by inverse analysis of IR temperatures—40% for L-mode and 50% for H-mode—while being independent of the geometry on which it is measured. This main result confirms the validity of the optical projection as long as a non-constant and non-parallel component is considered. For a given total heating power, the model predicts over 10% reduction of the maximum tile surface heat flux compared to strict optical modelling, as well as a 30% reduced sensitivity to manufacturing and assembling tolerances. These conclusions, along with the improvement in the predictability of the divertor thermal behaviour, are critical for JET future DT operations, and are also directly applicable to the design of the ITER divertor monoblocks.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Telesca G Ivanova-Stanik; R Zagorski; S Brezinsek; P J Carvalho; A Czarnecka; C Giroud; A Huber; E. Lerche; S Wiesen; JET Contributors
Numerical Simulation of High Neutron Rate JET-ILW DD Pulses in View of Extention to DT Experiments Proceedings Article
In: Proceedings Fusion Energy 2018, pp. P6-24, 2018.
@inproceedings{1896,
title = {Numerical Simulation of High Neutron Rate JET-ILW DD Pulses in View of Extention to DT Experiments},
author = {Telesca G Ivanova-Stanik and R Zagorski and S Brezinsek and P J Carvalho and A Czarnecka and C Giroud and A Huber and E. Lerche and S Wiesen and JET Contributors},
year = {2018},
date = {2018-10-01},
booktitle = {Proceedings Fusion Energy 2018},
volume = {IAEA-TH},
pages = {P6-24},
abstract = {Two high performance JET pulses, pertaining to the 2016 experimental campaign, have been numerically simulated with the self-consistent code COREDIV with the aim of predicting the power load to the target when extrapolated to DT plasmas. The input power as well as the total radiated power and the average density are similar in the two pulses, but for one of them the density is provided by combined low gas puff and pellet injection, characterized by low SOL density, for the other by gas fuelling only, at higher SOL density. Considering the magnetic configuration of theses pulses and the presence of a significant amount of Ni (that we have chosen not to be included in the actual version of the code), a number of assumptions are made in order to reproduce numerically the main core and SOL experimental data. The extrapolation to DT plasmas at the original input power of 33 MW, and taking into account only the thermal component of the alpha-power, doesn't show any significant difference regarding the power to the target with respect to the DD case. In contrast, the simulations at input power= 40 MW show that the power to the target for both pulses is possibly too high to be sustained for about 5 s by strike-point sweeping alone without any control by Ne seeding. Even though the target power load may decrease to about 13-15 MW with substantial Ne seeding for both pulses, as from numerical predictions, there are indications suggesting that the control of the power load may be more critical for the pulse with pellet injection.},
keywords = {},
pubstate = {published},
tppubtype = {inproceedings}
}
S. Jachmich; M Lehnen; P Drewelow; U Kruezi; I S Carvalho; M Imrisek; V Plyusnin; C Reux; JET Contributors
Minimising Power Load Asymmetries During Disruption Mitigation at JET Proceedings Article
In: Proceedings Fusion Energy 2018, pp. EX/P1-23, 2018.
@inproceedings{1878,
title = {Minimising Power Load Asymmetries During Disruption Mitigation at JET},
author = {S. Jachmich and M Lehnen and P Drewelow and U Kruezi and I S Carvalho and M Imrisek and V Plyusnin and C Reux and JET Contributors},
year = {2018},
date = {2018-10-01},
booktitle = {Proceedings Fusion Energy 2018},
volume = {IAEA-CN-123/45},
pages = {EX/P1-23},
abstract = {The high thermal loads caused by a disruption of an ITER baseline scenario pulse with stored thermal energy of 350MJ and magnetic energy inside the vessel of 400 MJ pose a severe threat to the first wall components. Massive gas injection (MGI) into a disrupting plasma in JET has been shown to be capable of reducing the energy deposited onto the plasma facing components by increasing the radiation. However, the uneven distribution of the radiated power following a single local massive gas injection leads to highly localised radiation and hence to significant thermal loads due to the radiation ``flash''. In addition, the presence of the n=1 mode during the disruption produces toroidal and poloidal radiation asymmetries. In order to address this issue, JET has installed three MGI-valves. Single or a combination of two MGI-valves have been fired into a locked error field mode, whose toroidal O-point position was imposed by applying an external n=1 magnetic perturbation field. By measuring the radiated power at two separate toroidal locations and varying the toroidal phase of the perturbation field a toroidal peaking factor TPF, defined as the ratio of the maximum radiation to the average value, could be estimated. For a single injection TPFs in the range of 1.5 up to 1.8 have been found, depending on the type of impurity gas used. Optimising the time delay between two MGI-valves, which are toroidally at opposite locations, allowed a reduction of the TPF down to 1.2. This paper summarises the experimental findings of radiation asymmetries during mitigated disruptions caused by a seeded error field mode and compares the result with a heuristic model.},
keywords = {},
pubstate = {published},
tppubtype = {inproceedings}
}
A Kappatou; P Manas; C Angioni; E. Lerche; A C C Sips; T P ü; M Dunne; R Neu; C Giroud; H T Kim; F Ryter; P A Schneider; C Challis; J Hobirk; I Nunes; M Tsalas; R M McDermott; K Cave-Ayland; D F Valcarcel; S Potzel; R Dux; L Frassinetti; E Delabie; S Saarelma; S Menmuir; M Bernert; A Lebschy; E Viezzer; EUROfusion MST1 Team; ASDEX Upgrade Team; JET Contributors
Energy Confinement and Performance of Pure Helium Plasmas and Helium Seeded Deuterium Plasmas Proceedings Article
In: Proceedings Fusion Energy 2018, pp. EX/P8-1, 2018.
@inproceedings{1888,
title = {Energy Confinement and Performance of Pure Helium Plasmas and Helium Seeded Deuterium Plasmas},
author = {A Kappatou and P Manas and C Angioni and E. Lerche and A C C Sips and T P ü and M Dunne and R Neu and C Giroud and H T Kim and F Ryter and P A Schneider and C Challis and J Hobirk and I Nunes and M Tsalas and R M McDermott and K Cave-Ayland and D F Valcarcel and S Potzel and R Dux and L Frassinetti and E Delabie and S Saarelma and S Menmuir and M Bernert and A Lebschy and E Viezzer and EUROfusion MST1 Team and ASDEX Upgrade Team and JET Contributors},
year = {2018},
date = {2018-10-01},
booktitle = {Proceedings Fusion Energy 2018},
volume = {IAEA-CN-258},
pages = {EX/P8-1},
abstract = {The presence of fusion-produced helium is fundamentally connected to the performance of a fusion reactor. Not only will He ash dilute the fusion fuel if not removed promptly, but the presence of He in a D plasma is reported to negatively affect the plasma confinement. Furthermore, He plasmas are one of the options foreseen for the ITER non-nuclear phase, although, the energy confinement in such plasmas is consistently observed to be ∼30% lower than in D plasmas. These considerations strongly motivate the experimental characterization and theoretical understanding of the physics of He transport in tokamak plasmas, with He as main ion or impurity. The negative impact on the performance due to reactor relevant He concentrations in D plasmas is identified and compared in JET and ASDEX Upgrade (AUG) discharges. Moreover, the confinement of He plasmas in AUG is studied, experimentally identifying and theoretically explaining the plasma conditions where the confinement observed in He is the same as that in D plasmas.},
keywords = {},
pubstate = {published},
tppubtype = {inproceedings}
}
Y. O. Kazakov; J. Ongena; R Bilato; V Bobkov; J M Faustin; A Kappatou; V G Kiptily; E. Lerche; M Mansinen; M Nocente; M Schneider; D. Van Eester; M Weiland; H Weisen; Y Baranov; J Galdon-Quiroga; M Garcia-Munoz; J Gonzalez-Martin; K Kirov; J Bielecki; S A Bozhenkov; Cardinali A Castaldo; T Craciunescu; K. Crombé; A Czarnecka; R Dumont; P. Dumortier; F. Durodié; J Eriksson; R Felton; M Fitzgerald; D Gallart; L Giacomelli; C Giroud; M Goniche; J Graves; C Hellesen; P Jacquet; T Johnson; N Krawczyk; M Lennholm; T Loarer; S Menmuir; I Monakhov; F Nabais; M F F Nave; J. -M. Noterdaeme; R Ochoukov; H Patten; M Porkolab; P Schneinder; S E Sharapov; D Valcarcel; M. Van Schoor; J C Wright; S J Wukitch; JET Contributors; ASDEX Upgrade Team; EUROfusion MST1 Team
Recent Advances in ICRF heating of mixture plasmas: Survey of JET and AUG Experiments and Extrapolation to JET-DT and ITER Proceedings Article
In: Proceedings Fusion Energy 2018, pp. EX/8-1, 2018.
@inproceedings{1882,
title = {Recent Advances in ICRF heating of mixture plasmas: Survey of JET and AUG Experiments and Extrapolation to JET-DT and ITER},
author = {Y. O. Kazakov and J. Ongena and R Bilato and V Bobkov and J M Faustin and A Kappatou and V G Kiptily and E. Lerche and M Mansinen and M Nocente and M Schneider and D. Van Eester and M Weiland and H Weisen and Y Baranov and J Galdon-Quiroga and M Garcia-Munoz and J Gonzalez-Martin and K Kirov and J Bielecki and S A Bozhenkov and Cardinali A Castaldo and T Craciunescu and K. Crombé and A Czarnecka and R Dumont and P. Dumortier and F. Durodié and J Eriksson and R Felton and M Fitzgerald and D Gallart and L Giacomelli and C Giroud and M Goniche and J Graves and C Hellesen and P Jacquet and T Johnson and N Krawczyk and M Lennholm and T Loarer and S Menmuir and I Monakhov and F Nabais and M F F Nave and J. -M. Noterdaeme and R Ochoukov and H Patten and M Porkolab and P Schneinder and S E Sharapov and D Valcarcel and M. Van Schoor and J C Wright and S J Wukitch and JET Contributors and ASDEX Upgrade Team and EUROfusion MST1 Team},
year = {2018},
date = {2018-10-01},
booktitle = {Proceedings Fusion Energy 2018},
volume = {IAEA-CN-258},
pages = {EX/8-1},
abstract = {This contribution summarizes recent experimental developments of the novel three-ion species ICRH heating scheme on JET and AUG. We give an overview of experiments in which a small amount of 3He ions (~1% and below) were injected into H-D plasmas in order to absorb RF power and heat the plasma. In JET, effective plasma heating was observed both at extremely low 3He concentrations of ~0.1-0.2% and at higher concentrations of ~1-1.5%. Heating AUG plasmas with this ICRH scenario requires 3He ions to be less energetic than in JET, as otherwise they are not confined in the plasma. The combination of moderate 3He concentrations of ~1% and off-axis 3He resonance was successfully applied to reduce fast-ion energies and thus improve confinement of RF-heated ions in AUG. We also successfully demonstrated effective heating of H-D mixtures in JET by further ICRH acceleration of the injected D-NBI ions as resonant `third' species in the D-(DNBI)-H three-ion scenario. The heating scenario was tuned such that D-NBI ions with injection energy of 100 keV absorbed most of launched RF power and were accelerated with ICRH up to ~2 MeV. The established technique of accelerating NBI ions to higher energies with ICRH in mixture plasmas holds promises for generating alpha particles in D-3He plasmas and for maximizing the Q-value and D-T fusion reactivity.},
keywords = {},
pubstate = {published},
tppubtype = {inproceedings}
}
C C Klepper; M Goniche; S Vartanian; B Pegourie; E Delabie; D. Van Eester; E. Lerche; I Borodkina; D Douai; I Jedpu; U Kruezi; A Shaw; JET ICRF Groupe; JET KT5 Upgrade Team; JET Contributors
Subdivertor Fuel Isotopic Content Detection Limit for JET and Impact on the Control of ICRH for JET-ILW and JET-DT Operation Proceedings Article
In: Proceedings Fusion Energy 2018, pp. EX/P1-29, 2018.
@inproceedings{1886,
title = {Subdivertor Fuel Isotopic Content Detection Limit for JET and Impact on the Control of ICRH for JET-ILW and JET-DT Operation},
author = {C C Klepper and M Goniche and S Vartanian and B Pegourie and E Delabie and D. Van Eester and E. Lerche and I Borodkina and D Douai and I Jedpu and U Kruezi and A Shaw and JET ICRF Groupe and JET KT5 Upgrade Team and JET Contributors},
year = {2018},
date = {2018-10-01},
booktitle = {Proceedings Fusion Energy 2018},
volume = {IAEA-CN-258},
pages = {EX/P1-29},
abstract = {The ability to detect and control fuel isotopic content down to a 1% concentration level is greatly important for the upcoming JET DTE2 campaign, as well as its associated TT and DD phases. A reduction of H minority concentration even from 2% down to 1% is shown here to have significant impact on the effectiveness of ICRF core heating, while the ability to maintain T or D concentration at or below 1% is critical to limiting fusion neutron generation in the DD and TT phases, correspondingly. The subdivertor measurement of (global) isotopic concentration, based on Penning-activated optical spectroscopy can deliver minimally this 1% detection for DTE2 as long as light collection from the Penning emission can be optimized and gradual window transmission deterioration can be minimized. This is simulated with a statistical analysis developed to understand the uncertainty sources in the JET DTE1 data, as well as to guide the optimization of an upgraded, fuel-isotopic content (and helium-ash concentration) gas analysis system for the JET divertor in preparation for DTE2. While this random error can be reduced to allow measurement substantially below 1% concentration, analysis also shows a systematic error of up to 1% understood to be due to plasma-surface interactions in the Penning excitation , suggesting that 1% may still be the low-end limit for the subdivertor measurement, unless a Penning-source conditioning approach is also developed.},
keywords = {},
pubstate = {published},
tppubtype = {inproceedings}
}
A Kostic; R Dux; K. Crombé; A Nikiforov; R Ochoukov; I. Shesterikov; A H Martin; J. -M. Noterdaeme
Development of a spectroscopic diagnostic tool for electric field measurements in IShTAR (Ion cyclotron Sheath Tes Arrangement) Proceedings Article
In: Review of Scientific Instruments, pp. 10D115, 2018.
@inproceedings{1873,
title = {Development of a spectroscopic diagnostic tool for electric field measurements in IShTAR (Ion cyclotron Sheath Tes Arrangement)},
author = {A Kostic and R Dux and K. Crombé and A Nikiforov and R Ochoukov and I. Shesterikov and A H Martin and J. -M. Noterdaeme},
year = {2018},
date = {2018-10-01},
booktitle = {Review of Scientific Instruments},
volume = {89},
pages = {10D115},
abstract = {IShTAR, Ion cyclotron Sheath Test ARrangement, is a linear device dedicated to the investigation of the edge plasma–ICRF (Ion Cyclotron Range of Frequencies) antenna interactions in tokamak edge-like conditions and serves as a platform for a diagnostic development for measuring the electric fields in the vicinity of ICRF antennas. We present here our progress in the development of an optical emission spectroscopy method for measuring the electric fields which concentrates on the changes in the helium spectral line profiles introduced by the external electrical field, i.e., the Stark effect. To be able to fully control the operating parameters, at the first stage of the study, the measurements are conducted on a planar electrode installed in the centre of the plasma column in IShTAR's helicon plasma source. At the second stage, the measurements are performed in the vicinity of IShTAR's ICRF antenna.},
keywords = {},
pubstate = {published},
tppubtype = {inproceedings}
}
Sunwoo Moon; M Rubel; P Petersson; E Fortuna-Zalesna; A Widdowson; S. Jachmich; A Litnovsky; E Alves; JET Contributors
First Mirror Test in JET for ITER: Overview after three campaigns in JET with ITER-like wall Proceedings Article
In: Proceedings Fusion Energy 2018, pp. EX/P1-17, 2018.
@inproceedings{1884,
title = {First Mirror Test in JET for ITER: Overview after three campaigns in JET with ITER-like wall},
author = {Sunwoo Moon and M Rubel and P Petersson and E Fortuna-Zalesna and A Widdowson and S. Jachmich and A Litnovsky and E Alves and JET Contributors},
year = {2018},
date = {2018-10-01},
booktitle = {Proceedings Fusion Energy 2018},
volume = {IAEA-CN-258},
pages = {EX/P1-17},
keywords = {},
pubstate = {published},
tppubtype = {inproceedings}
}
J. -M. Noterdaeme; V Bobkov; Y. O. Kazakov; A Kostic; R Ochoukov; I. Shesterikov; W Tierens; M Usoltceva; W Zhang; D Aguiam; R Bilato; L Colas; K. Crombé; H Faugel; J Faustin; H Fuenfgelder; S Heuraux; A Kappatou; R Maggiora; M Mantsinen; A. Messiaen; D Milanesio; J. Ongena; R. Ragona; A Silva; Suarez G Lopez; D. Van Eester; M Weiland; ASDEX Upgrade Team; EUROfusion MST1 Team
Ion Cyclotron Range of Frequency Power, Progress in Operation and Understanding for Experiments with Metallic Walls Proceedings Article
In: Proceedings Fusion Energy 2018, pp. EX/P8-23, 2018.
@inproceedings{1892,
title = {Ion Cyclotron Range of Frequency Power, Progress in Operation and Understanding for Experiments with Metallic Walls},
author = {J. -M. Noterdaeme and V Bobkov and Y. O. Kazakov and A Kostic and R Ochoukov and I. Shesterikov and W Tierens and M Usoltceva and W Zhang and D Aguiam and R Bilato and L Colas and K. Crombé and H Faugel and J Faustin and H Fuenfgelder and S Heuraux and A Kappatou and R Maggiora and M Mantsinen and A. Messiaen and D Milanesio and J. Ongena and R. Ragona and A Silva and Suarez G Lopez and D. Van Eester and M Weiland and ASDEX Upgrade Team and EUROfusion MST1 Team},
year = {2018},
date = {2018-10-01},
booktitle = {Proceedings Fusion Energy 2018},
volume = {IAEA-CN-258/350},
pages = {EX/P8-23},
abstract = {Significant progress in applying ICRF power to ASDEX Upgrade (AUG) through improved power coupling and reduced impurity production has been associated with progress in understanding and modelling. First, the coupling of the fast wave was improved using outer mid-plane gas injection. The local edge density increase in front of the antenna shifts the fast wave cut-off position closer to the antenna by ~2cm, a result confirmed with new density measurements in front of the antenna. The ICRF coupling increases by 120% (only 25% for top gas puffing). The increased density and resulting improved coupling. was also numerically modelled. Second, the new 3-strap antennas in AUG demonstrated clearly that a proper antenna design can successfully mitigate ICRF-specific tungsten (W) sputtering. The reduction of the W sputtering was achieved by minimizing the RF currents on the antenna surfaces exposed to the scrape-off-layer (SOL) plasma. The local RF currents, rectified DC currents and the W sputtering yield at the antenna side limiters experience a clear minimum close to a phasing between the central and the outer straps of 180$,^circ$ and a power balance ratio Pcen/Pout of ~ 2. At this optimum, the local source of sputtered W at the limiters is reduced by a factor between 1.5 and 6, depending on the location. The experiments and modelling confirm the hypothesis of sheath rectification as the source of the sputtered W. Furthermore, the new 3-ion ICRF heating scenario, which can produce very energetic particles, has been successfully reproduced in AUG. The progress in operation, in understanding and modelling is strongly supported by improved ICRF diagnostic coverage including density measurements directly in front of the antenna by reflectometry, advanced RF coupling characterization, measurements of antenna limiter currents, B-dot probes, Ion Cyclotron Emission (ICE) measurements and by dedicated tests on the experimental device IShTAR (Ion cyclotron Sheath Test ARrangement).},
keywords = {},
pubstate = {published},
tppubtype = {inproceedings}
}
J. Ongena; A. Messiaen; Y. O. Kazakov; B Schweer; I. Stepanov; M. Vervier; M Berte; K. Crombé; P Despontin; F. Durodié; G Jouniaux; A. Krivska; F. Louche; A. I. Lyssoivan; R Philips; M. Van Schoor; T. Wauters; V Borsuk; A Kraemer-Flecken; O Neubeaur; D Nicolai; G Satheeswaran; R Schick; D. Castano-Bardawil; K P Hollfeld; A Mauel; G Offermanns; S Bozhenkov; A Dinklage; J Faustin; D A Hartmann; J P Kallmeyer; H Laqua; R C Worlf; TEC Team; W7-X Team
Preparing the ICRH System for the Wendelsteind 7-X Stellarator Proceedings
vol. IAEA-CN-258, 2018.
@proceedings{1893,
title = {Preparing the ICRH System for the Wendelsteind 7-X Stellarator},
author = {J. Ongena and A. Messiaen and Y. O. Kazakov and B Schweer and I. Stepanov and M. Vervier and M Berte and K. Crombé and P Despontin and F. Durodié and G Jouniaux and A. Krivska and F. Louche and A. I. Lyssoivan and R Philips and M. Van Schoor and T. Wauters and V Borsuk and A Kraemer-Flecken and O Neubeaur and D Nicolai and G Satheeswaran and R Schick and D. Castano-Bardawil and K P Hollfeld and A Mauel and G Offermanns and S Bozhenkov and A Dinklage and J Faustin and D A Hartmann and J P Kallmeyer and H Laqua and R C Worlf and TEC Team and W7-X Team},
year = {2018},
date = {2018-10-01},
booktitle = {Proceedings Fusion Energy 2018},
volume = {IAEA-CN-258},
pages = {EX/P8-27},
abstract = {An important aim of W7-X is to demonstrate fast ion confinement at volume averaged beta values up to 5%, corresponding to plasma densities above 1020 m-3. To this end, an ICRH system is prepared for W7-X, with RF power up to ~1.5 MW (depending on the coupling) at frequencies between 25-38 MHz in pulses up to 10 s. Energetic ions in W7-X with energies 50 < E < 100 keV mimic alphas in a reactor. To generate such a population is challenging in high-density plasmas with traditional ICRH heating scenarios and different auxiliary heating methods. However, fast particles can be very efficiently using the H-(3He)-D three-ion heating ICRH scenario, foreseen for f ~ 25 MHz in W7-X. ICRH is an ideal heating method to deposit power in the plasma center at such high density as it is not hampered by a high-density cut-off, a fundamental property of the propagation of Fast Alfvén Waves in plasmas. A two-strap ICRH antenna is under construction for W7-X. Each strap is on one side connected to a tuning capacitor (15-200 pF) and grounded to the antenna box at the other end. A prematching has been implemented by connecting the RF transmission lines at an intermediate position on each strap. The main dimensions of straps and antenna box have been optimized to maximise the power delivered to the plasma, using the reference plasma density profile in front of the antenna, provided by the W7- X team. A dedicated test stand is under construction in IEK-4 / FZJ to perform main functional tests on the antenna.},
keywords = {},
pubstate = {published},
tppubtype = {proceedings}
}
J. Ongena
Fusion: A True Challenge For An Enormous Reward Journal Article
In: vol. 189, pp. 00015, 2018.
@article{1876,
title = {Fusion: A True Challenge For An Enormous Reward},
author = {J. Ongena},
year = {2018},
date = {2018-10-01},
booktitle = {EPJ Web of Conferences},
volume = {189},
pages = {00015},
abstract = {Nuclear physics shows that energy can be released from both fission of heavy nuclei and fusion of light nuclei. Steady progress shows that fusion — an important additional option for energy production in the future — promises to be a clean and safe solution for mankind's long-term energy needs with minimal environmental impact. A source of energy which would be inexhaustible, inherently safe and environmentally friendly, is this not a marvellous prospect? Nuclear fusion, a possible candidate for this role, has been the energy source of our Sun and the stars in the universe for billions of years. This process requires temperatures of tens of millions of degrees, so extremely high and foreign to our daily experience that it seems out of reach. Nevertheless, these extremely high temperatures are routinely realised in several laboratories all over the world, and since the early 1990s, tens of MW fusion power have been released from fusion reactions. We are witnessing the birth of a new technology destined to meet the gigantic future energy needs of mankind with minimal impact on the environment.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
R. Ragona; A. Messiaen; J. Ongena; D. Van Eester; M. Van Schoor; J -M Bernard; J Hillairet; J. -M. Noterdaeme; M Q Tran
A Travelling Wave Array System as Solution for the ICRF Heating of DEMO Proceedings Article
In: Proceedings Fusion Energy 2018, pp. FIP/P8-11, 2018.
@inproceedings{1890,
title = {A Travelling Wave Array System as Solution for the ICRF Heating of DEMO},
author = {R. Ragona and A. Messiaen and J. Ongena and D. Van Eester and M. Van Schoor and J -M Bernard and J Hillairet and J. -M. Noterdaeme and M Q Tran},
year = {2018},
date = {2018-10-01},
booktitle = {Proceedings Fusion Energy 2018},
volume = {IAEA-CN-258},
pages = {FIP/P8-11},
abstract = {Travelling Wave Array (TWA) antennas distributed along the periphery of the tokamak are presently considered as Ion Cyclotron Resonance Frequencies (ICRF) heating solution for the DEMO reactor. Compared to the conventional ICRF antenna systems currently in use or designed for future machines like ITER, the TWA consists of antenna sections integrated in the breeding blanket scattered around the machine, each one fed through a variable coupler in a resonant ring configuration. Previous modelling of an antenna system for DEMO with 16 quadruple TWA sections of 8 straps shows that a power capability exceeding 50MW can be obtained in the frequency band of interest using the reference low coupling plasma profile of ITER. The described system optimizes the coupling to the plasma by providing a large number of radiating elements, which results in enhanced antenna directivity hereby decreasing the antenna power density. This results in a maximum strap voltage amplitude of only 15kV and maximum inter-strap voltage amplitude of 18kV. The generators remain matched for all loading conditions: the system is totally load resilient. Following the recommendation of the WPHCD Review Panel, a TWA ICRH system consisting in fewer sections concentrated in front of the equatorial ports is analysed in this paper and compared to the previous design. Reducing the number of sections increases the power density and its associated voltages. To couple 50MW on the ITER density profile, voltages up to 30kV are now required. Some aspects like the coupling between sections and its repercussion on the feeding network are briefly discussed. To assess the feasibility of the TWA fed by a resonant ring as ICRH system for a DEMO reactor, a test on an existing medium-size-tokamak is under study.},
keywords = {},
pubstate = {published},
tppubtype = {inproceedings}
}
M Schneider; A Polevoi; S/H/ Kim; A Loarte; J -F Artaud; B Beaumont; R Bilato; D Boilson; D J Campbell; P. Dumortier; D Farina; L Figini; J Garcia; L Garzotti; YU. Gribov; N Hayashi; M Henderson; T Johnson; R R Khayrutdinov; A A Kavin; F K ö; T Kurki-Suonio; A Kuyanov; P. U. Lamalle; E. Lerche; T Luce; V E Lukash; A. Messiaen; S D Pinches; F Poli; K Sarkimaki; M Singh; A Snicker; D. Van Eester; I Voitsekhovitch
Modelling One-Third Field Operation in the ITER Pre-Fusion Power Operation Phase Proceedings Article
In: Proceedings Fusion Energy 2018, pp. TH/6-1, 2018.
@inproceedings{1895,
title = {Modelling One-Third Field Operation in the ITER Pre-Fusion Power Operation Phase},
author = {M Schneider and A Polevoi and S/H/ Kim and A Loarte and J -F Artaud and B Beaumont and R Bilato and D Boilson and D J Campbell and P. Dumortier and D Farina and L Figini and J Garcia and L Garzotti and YU. Gribov and N Hayashi and M Henderson and T Johnson and R R Khayrutdinov and A A Kavin and F K ö and T Kurki-Suonio and A Kuyanov and P. U. Lamalle and E. Lerche and T Luce and V E Lukash and A. Messiaen and S D Pinches and F Poli and K Sarkimaki and M Singh and A Snicker and D. Van Eester and I Voitsekhovitch},
year = {2018},
date = {2018-10-01},
booktitle = {Proceedings Fusion Energy 2018},
volume = {IAEA-CN-258},
pages = {TH/6-1},
abstract = {In the four-stage approach of the new ITER Research Plan, the first Pre-Fusion Power Operation (PFPO) phase will only have a limited power available from external Heating and Current Drive (H&CD) systems: 20 to 30 MW, provided by the Electron Cyclotron Resonance Heating system (ECRH). Accessing the H-mode confinement regime at such low auxiliary power requires operating at lower magnetic field, plasma current and density, i.e. 1.8 T and 5 MA for a density between 40% and 50% of the Greenwald density. H-mode plasmas at 5 MA / 1.8 T are also considered for the second PFPO phase when ITER will have its full installed H&CD capabilities, i.e. 20−30 MW of ECRH, 20 MW of Ion Cyclotron Resonance Heating (ICRH) and 33 MW of Neutral Beam Injection (NBI). The present paper describes the operational conditions of such scenarios in hydrogen and helium plasmas and the H&CD capabilities for these plasmas, to assess the viability of such scenarios and the issues that will be possible to address with them. The modelling results show that 5 MA / 1.8 T scenarios are viable and will allow the exploration of the H-mode physics and control issues foreseen in the ITER Research Programme in the PFPO phases.},
keywords = {},
pubstate = {published},
tppubtype = {inproceedings}
}