List of publications

@article{2091,

title = {Physics design, construction and commissioning of the ICRH system for the stellarator Wendelstein 7-X},

author = {J. Ongena and D. Castano-Bardawil and K. Crombé and Y. O. Kazakov and B. Schweer and I. Stepanov and M. Van Schoor and M. Vervier and A. Krämer-Flecken and O. Neubauer and D. Nicolai and G. Satheeswaran and G. Offermanns and K. P. Hollfeld and A. Benndorf and A. Dinklage and D. Hartmann and J. P. Kallmeyer and R. C. Wolf and TEC},

url = {https://www.sciencedirect.com/science/article/pii/S0920379623002119},

doi = {https://doi.org/10.1016/j.fusengdes.2023.113627},

issn = {0920-3796},

year  = {2023},

date = {2023-07-01},

journal = {Fusion Engineering and Design},

volume = {192},

pages = {113627},

abstract = {The ICRH antenna for the stellarator Wendelstein 7-X (W7-X) aims at delivering RF power levels up to about 1.5 MW in the frequency range 25–38 MHz with pulse lengths up to 10 s. The antenna was constructed and tested in the institute IEK-4 of the Research Centre Jülich, and subsequently installed at W7-X. The paper will review the physics design, the construction and installation in W7-X, and the commissioning plans for the ICRH system in the coming months.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{2078,

title = {Identification of fast ion wall loads in Wendelstein 7-X from thermographic measurements},

author = {Mark J H Cornelissen and Samuel A Lazerson and Yu Gao and Josefine H E Proll and Paul McNeely and Norbert Rust and Dirk Hartmann and Marcin W Jakubowski and Adnan Ali and Fabio Pisano and Holger Niemann and Aleix Puig Sitjes and Ralf König and Robert C Wolf and W7-X Team},

url = {https://dx.doi.org/10.1088/1361-6587/aca0bf},

doi = {10.1088/1361-6587/aca0bf},

year  = {2022},

date = {2022-12-01},

journal = {Plasma Physics and Controlled Fusion},

volume = {64},

number = {12},

pages = {125015},

publisher = {IOP Publishing},

abstract = {Fast ion wall loads can result in excessively high heat fluxes to the plasma-facing components (PFCs). To allow for the development of mitigation strategies, and thereby protect the PFCs, the fast ion losses have to be predicted by faithful models. To ensure that fast ion models are an accurate representation of the real world, they need to be verified. The neutral-beam experiments performed in Wendelstein 7-X (W7-X) allow to investigate and verify models of the fast ion losses in the stellarator configuration. Infrared thermographic measurements were used to obtain the heat flux to both the baffle plates and the divertor. We found evidence of fast ion wall loads on the baffle plates, with loads between 100 kW m−2 and 1 MW m−2. The loads are attributed to fast ions which escape the main plasma via magnetic ripples. The fast ion wall loads on the baffle plates show up-down and toroidal asymmetry. The experimental results were compared to numerical simulations performed by the BEAMS3D and ASCOT codes. Qualitative agreement in up-down asymmetry is found, but the magnitude and toroidal asymmetry are not yet well predicted by the simulations. The asymmetries of the strike lines on the divertor suggest that fast ions also play a role here. Specifically, a second strike line emerged consistently in the high-iota configuration on the horizontal divertor. The shape and magnitude of the strike lines changed considerably during the neutral-beam injection (NBI) operation phase. Although no damage to steel components of W7-X was found, fast ion loads to the baffle plates could possibly limit the NBI operation in the upcoming campaigns of W7-X.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{2071,

title = {Simultaneous measurements of unstable and stable Alfvén eigenmodes in JET},

author = {R. A. Tinguely and J. Gonzalez-Martin and P. G. Puglia and N. Fil and S. Dowson and M. Porkolab and I. Kumar and M. Podestà and M. Baruzzo and A. Fasoli and Y. O. Kazakov and M. F. F. Nave and M. Nocente and J. Ongena and Ž. Štancar and JET Contributors},

url = {https://doi.org/10.1088/1741-4326/ac899e},

doi = {10.1088/1741-4326/ac899e},

year  = {2022},

date = {2022-11-01},

journal = {Nuclear Fusion},

volume = {62},

number = {11},

pages = {112008},

publisher = {IOP Publishing},

abstract = {In this paper, we report the novel experimental observation of both unstable and stable toroidicity-induced Alfvén eigenmodes (TAEs) measured simultaneously in a JET tokamak plasma. The three-ion-heating scheme (D-DNBI-3He) is employed to accelerate deuterons to MeV energies, thereby destabilizing TAEs with toroidal mode numbers n = 3–5, each decreasing in mode amplitude. At the same time, the Alfvén eigenmode active diagnostic resonantly excites a stable n = 6 TAE with total normalized damping rate −γ/ω 0 ≈ 1%–4%. Hybrid kinetic-MHD modeling with codes NOVA-K and MEGA both find eigenmodes with similar frequencies, mode structures, and radial locations as in experiment. NOVA-K demonstrates good agreement with the n = 3, 4, and 6 TAEs, matching the damping rate of the n = 6 mode within uncertainties and identifying radiative damping as the dominant contribution. Improved agreement is found with MEGA for all modes: the unstable n = 3–5 and stable n = 2, 6 modes, with the latter two stabilized by higher intrinsic damping and lower fast ion drive, respectively. While some discrepancies remain to be resolved, this unique validation effort gives us confidence in TAE stability predictions for future fusion devices.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{2072,

title = {Gyrokinetic study of transport suppression in JET plasmas with MeV-ions and toroidal Alfvén eigenmodes},

author = {S Mazzi and J Garcia and D Zarzoso and Y. O. Kazakov and J. Ongena and M Dreval and M Nocente and Ž Štancar and G Szepesi},

url = {https://doi.org/10.1088/1361-6587/ac91f3},

doi = {10.1088/1361-6587/ac91f3},

year  = {2022},

date = {2022-11-01},

journal = {Plasma Physics and Controlled Fusion},

volume = {64},

number = {11},

pages = {114001},

publisher = {IOP Publishing},

abstract = {The impact of fast ions, generated in the MeV-range through the efficient application of the three-ion scheme in JET plasmas, on the turbulence properties is presented through complex numerical simulations. The suppression of the ion-scale turbulent transport is studied by means of in-depth gyrokinetic numerical analyses. Such a suppression is demonstrated to be achieved in the presence of toroidal Alfvén eigenmodes (TAEs) destabilized by the highly energetic ions. Details on the TAE excitation are also provided with a multi-code analysis. The inherently nonlinear and multi-scale mechanism triggered by the fast ions, also involving the high-frequency modes and the large-scale zonal flows, is deeply analyzed. Such mechanism is thus demonstrated, with experimental validating studies, to be the main cause of turbulence suppression and improvement of ion thermal confinement. Additional simulations address the implications of reversed shear magnetic equilibrium on the turbulent transport.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{2067,

title = {Fusion product measurements by nuclear diagnostics in the Joint European Torus deuterium-tritium 2 campaign},

author = {M. Nocente and V. Kiptily and M. Tardocchi and P. J. Bonofiglo and T. Craciunescu and A. Dal Molin and E. De La Luna and J. Eriksson and J. Garcia and Z. Ghani and G. Gorini and L. Hägg and Y. O. Kazakov and E. Lerche and C. F. Maggi and P. Mantica and G. Marcer and M. Maslov and O. Putignano and D. Rigamonti and M. Salewski and S. Sharapov and P. Siren and Z. Stancar and A. Zohar and P. Beaumont and K. Crombé and G. Ericsson and M. Garcia-Munoz and D. Keeling and D. King and K. Kirov and M. F. F. Nave and J. Ongena and A. Patel and C. Perez Thun and JET Contributors},

year  = {2022},

date = {2022-09-01},

journal = {Review of Scientific Instruments},

volume = {93},

number = {9},

pages = {093520},

abstract = {A new deuterium–tritium experimental, DTE2, campaign has been conducted at the Joint European Torus (JET) between August 2021 and late December 2021. Motivated by significant enhancements in the past decade at JET, such as the ITER-like wall and enhanced auxiliary heating power, the campaign achieved a new fusion energy world record and performed a broad range of fundamental experiments to inform ITER physics scenarios and operations. New capabilities in the area of fusion product measurements by nuclear diagnostics were available as a result of a decade long enhancement program. These have been tested for the first time in DTE2 and a concise overview is provided here. Confined alpha particle measurements by gamma-ray spectroscopy were successfully demonstrated, albeit with limitations at neutron rates higher than some 1017 n/s. High resolution neutron spectroscopy measurements with the magnetic proton recoil instrument were complemented by novel data from a set of synthetic diamond detectors, which enabled studies of the supra-thermal contributions to the neutron emission. In the area of escaping fast ion diagnostics, a lost fast ion detector and a set of Faraday cups made it possible to determine information on the velocity space and poloidal distribution of the lost alpha particles for the first time. This extensive set of data provides unique information for fundamental physics studies and validation of the numerical models, which are key to inform the physics and scenarios of ITER.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{2068,

title = {A new dedicated signal processing system for gamma-ray spectrometers in high power deuterium–tritium plasma scenarios in tokamaks},

author = {G. Marcerer and E. Khilkevitch and A. Shevelev and G. Croci and A. Dal Molin and G. Gorini and G. Grosso and A. Muraro and M. Nocente and E. Perelli Cippo and O. Putignano and M. Rebai and D. Rigamonti and E. Luna and J. Garcia and Y. O. Kazakov and V. Kiptily and M. Maslov and M. F. F. Nave and J. Ongena and M. Tardocchi and JET Contributors},

year  = {2022},

date = {2022-09-01},

journal = {Review of Scientific Instruments},

volume = {93},

number = {9},

pages = {093525},

abstract = {The most performant deuterium–tritium (DT) plasma discharges realized by the Joint European Torus (JET) tokamak in the recent DT campaign have produced neutron yields on the order of 1018 n/s. At such high neutron yields, gamma-ray spectroscopy measurements with scintillators are challenging as events from the neutron-induced background often dominate over the signal, leading to a significant fraction of pileup events and instability of the photodetector gain along with the consequent degradation of the reconstructed spectrum. Here, we describe the solutions adopted for the tangential lanthanum bromide spectrometer installed at JET. A data acquisition system with free streaming mode digitization capabilities for the entire duration of the discharge has been used to solve dead-time related issues and a data reconstruction code with pileup recovery and photodetector gain drift restoration has been implemented for off-line analysis of the data. This work focuses on the acquired data storage and parsing, with a detailed explanation of the pileup recovery and gain drift restoration algorithms.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{2058,

title = {A novel measurement of marginal Alfvén eigenmode stability during high power auxiliary heating in JET},

author = {R. A. Tinguely and N. Fil and P. G. Puglia and S. Dowson and M. Porkolab and V. Guillemot and M. Podesta and M. Baruzzo and R. Dumont and A. Fasoli and M. Fitzgerald and Y. O. Kazakov and M. F. F. Nave and M. Nocente and J. Ongena and S. E. Sharapov and Ž. Štancar and JET Contributors},

url = {https://doi.org/10.1088/1741-4326/ac3c84},

doi = {10.1088/1741-4326/ac3c84},

year  = {2022},

date = {2022-07-01},

journal = {Nuclear Fusion},

volume = {62},

number = {7},

pages = {076001},

publisher = {IOP Publishing},

abstract = {The interaction of Alfvén eigenmodes (AEs) and energetic particles is one of many important factors determining the success of future tokamaks. In JET, eight in-vessel antennas were installed to actively probe stable AEs with frequencies ranging 25–250 kHz and toroidal mode numbers |n| < 20. During the 2019–2020 deuterium campaign, almost 7500 resonances and their frequencies f 0, net damping rates γ < 0, and toroidal mode numbers were measured in almost 800 plasma discharges. From a statistical analysis of this database, continuum and radiative damping are inferred to increase with edge safety factor, edge magnetic shear, and when including non-ideal effects. Both stable AE observations and their associated damping rates are found to decrease with |n|. Active antenna excitation is also found to be ineffective in H-mode as opposed to L-mode; this is likely due to the increased edge density gradient's effect on accessibility and ELM-related noise's impact on mode identification. A novel measurement is reported of a marginally stable, edge-localized ellipticity-induced AE probed by the antennas during high-power auxiliary heating (ion cyclotron resonance heating and neutral beam injection) up to 25 MW. NOVA-K kinetic-MHD simulations show good agreement with experimental measurements of f 0, γ, and n, indicating the dominance of continuum and electron Landau damping in this case. Similar experimental and computational studies are planned for the recent hydrogen and ongoing tritium campaigns, in preparation for the upcoming DT campaign.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{2062,

title = {Status and future development of Heating and Current Drive for the EU DEMO},

author = {M. Q. Tran and P. Agostinetti and G. Aiello and K. Avramidis and B. Baiocchi and M. Barbisan and V. Bobkov and S. Briefi and A. Bruschi and R. Chavan and I. Chelis and Ch. Day and R. Delogu and B. Ell and F. Fanale and A. Fassina and U. Fantz and H. Faugel and L. Figini and D. Fiorucci and R. Friedl and Th. Franke and G. Gantenbein and S. Garavaglia and G. Granucci and S. Hanke and J. -P. Hogge and C. Hopf and A. Kostic and S. Illy and Z. Ioannidis and J. Jelonnek and J. Jin and G. Latsas and F. Louche and V. Maquet and R. Maggiora and A. Messiaen and D. Milanesio and A. Mimo and A. Moro and R. Ochoukov and J. Ongena and I. G. Pagonakis and D. Peponis and A. Pimazzoni and R. Ragona and N. Rispoli and T. Ruess and T. Rzesnicki and T. Scherer and P. Spaeh and G. Starnella and D. Strauss and M. Thumm and W. Tierens and I. Tigelis and C. Tsironis and M. Usoltceva and D. Van Eester and F. Veronese and P. Vincenzi and F. Wagner and C. Wu and F. Zeus and W. Zhang},

url = {https://www.sciencedirect.com/science/article/pii/S0920379622001557},

doi = {https://doi.org/10.1016/j.fusengdes.2022.113159},

issn = {0920-3796},

year  = {2022},

date = {2022-07-01},

journal = {Fusion Engineering and Design},

volume = {180},

pages = {113159},

abstract = {The European DEMO is a pulsed device with pulse length of 2 hours. The functions devoted to the heating and current drive system are: plasma breakdown, plasma ramp-up to the flat-top where fusion reactions occur, the control of the plasma during the flat-top phase, and finally the plasma ramp-down. The EU-DEMO project was in a Pre-Concept Design Phase during 2014-2020, meaning that in some cases, the design values of the device and the precise requirements from the physics point of view were not yet frozen. A total of 130 MW was considered for the all phases of the plasma: in the flat top, 30 MW is required for neoclassical tearing modes (NTM) control, 30 MW for burn control, and 70 MW for the control of thermal instability (TI), without any specific functions requested from each system, Electron Cyclotron (EC), Ion Cyclotron (IC), or Neutral Beam (NB) Injection. At the beginning of 2020, a strategic decision was taken, to consider EC as the baseline for the next phase (in 2021 and beyond). R&D on IC and NB will be risk mitigation measures. In parallel with progresses in Physics modelling, a decision point on the heating strategy will be taken by 2024. This paper describes the status of the R&D development during the period 2014-2020. It assumes that the 3 systems EC, IC and NB will be needed. For integration studies, they are assumed to be implemented at a power level of at least 50 MW. This paper describes in detail the status reached by the EC, IC and NB at the end of 2020. It will be used in the future for further development of the baseline heating method EC, and serves as starting point to further develop IC and NB in areas needed for these systems to be considered for DEMO.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{2054,

title = {Excitation of Alfvén eigenmodes by fusion-born alpha-particles in D-3 He plasmas on JET},

author = {V G Kiptily and Y. O. Kazakov and M Nocente and J. Ongena and F Belli and M Dreval and T Craciunescu and J Eriksson and M Fitzgerald and L Giacomelli and V Goloborodko and M V Iliasova and E M Khilkevitch and D Rigamonti and A Sahlberg and M Salewski and A E Shevelev and J Garcia and H J C Oliver and S E Sharapov and Z Stancar and H Weisen},

url = {https://doi.org/10.1088/1361-6587/ac5d9e},

doi = {10.1088/1361-6587/ac5d9e},

year  = {2022},

date = {2022-06-01},

journal = {Plasma Physics and Controlled Fusion},

volume = {64},

number = {6},

pages = {064001},

publisher = {IOP Publishing},

abstract = {Alfvén eigenmode (AE) instabilities driven by alpha-particles have been observed in D-3He fusion experiments on the Joint European Torus (JET) with the ITER-like wall. For the efficient generation of fusion alpha-particles from D-3He fusion reaction, the three-ion radio frequency scenario was used to accelerate the neutral beam injection 100 keV deuterons to higher energies in the core of mixed D-3He plasmas at high concentrations of 3He. A large variety of fast-ion driven magnetohydrodynamic modes were observed, including the elliptical Alfvén eigenmodes (EAEs) with mode numbers n = −1 and axisymmetric modes with n = 0 in the frequency range of EAEs. The simultaneous observation of these modes indicates the presence of rather strong alpha-particle population in the plasma with a `bump-on-tail' shaped velocity distribution. Linear stability analysis and Fokker–Planck calculations support the observations. Experimental evidence of the AEs excitation by fusion-born alpha-particles in the D-3He plasma is provided by neutron and gamma-ray diagnostics as well as fast-ion loss measurements. We discuss an experimental proposal for the planned full-scale D-T plasma experiments on JET based on the physics insights gained from these experiments.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{2055,

title = {Enhanced performance in fusion plasmas through turbulence suppression by megaelectronvolt ions},

author = {S. Mazzi and J. Garcia and D. Zarzoso and Y. O. Kazakov and J. Ongena and M. Dreval and M. Nocente and Z. Stancar and G. Szepesi and J. Eriksson and A. Sahlberg and S. Benkadda and JET Contributors},

year  = {2022},

date = {2022-06-01},

journal = {Nature Physics},

volume = {18},

pages = {776-788},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{2047,

title = {Alfvén cascade eigenmodes above the TAE-frequency and localization of Alfvén modes in D–3 He plasmas on JET},

author = {M. Dreval and S. E. Sharapov and Y. O. Kazakov and J. Ongena and M. Nocente and R. Calado and R. Coelho and J. Ferreira and A. Figueiredo and M. Fitzgerald and J. Garcia and C. Giroud and N. C. Hawkes and V. G. Kiptily and F. Nabais and M. F. F. Nave and H. Weisen and T. Craciunescu and M. Salewski and Ž. Štancar and JET Contributors},

url = {https://doi.org/10.1088/1741-4326/ac45a4},

doi = {10.1088/1741-4326/ac45a4},

year  = {2022},

date = {2022-05-01},

journal = {Nuclear Fusion},

volume = {62},

number = {5},

pages = {056001},

publisher = {IOP Publishing},

abstract = {Various types of Alfvén eigenmodes (AEs) have been destabilized by fast ions over a broad frequency range from ∼80 kHz to ∼700 kHz in a series of JET experiments in mixed D–3He plasmas heated with the three-ion ICRF scenario (2020 Nocente et al Nucl. Fusion 60 124006). In this paper, we identify the radial localization of AEs using an X-mode reflectometer, a multiline interferometer and soft x-ray diagnostics. The analysis is focused on the most representative example of these measurements in JET pulse #95691, where two different types of Alfvén cascade (AC) eigenmodes were observed. These modes originate from the presence of a local minimum of the safety factor q min. In addition to ACs with frequencies below the frequency of toroidal Alfvén eigenmodes (TAEs), ACs with frequencies above the TAE frequency were destabilized by energetic ions. Both low- (f ≈ 80–180 kHz) and high-frequency (f ≈ 330–450 kHz) ACs were localized in the central regions of the plasma. The characteristics of the high-frequency ACs are investigated in detail numerically using HELENA, CSCAS and MISHKA codes. The resonant conditions for the mode excitation are found to be determined by passing ions of rather high energy of several hundred keV and similar to those established in JT-60U with negative-ion-based NBI (2005 Takechi et al Phys. Plasmas 12 082509). The computed radial mode structure is found to be consistent with the experimental measurements. In contrast to low-frequency ACs observed most often, the frequency of the high-frequency ACs decreases with time as the value of q min decreases. This feature is in a qualitative agreement with the analytical model of the high-frequency ACs in Breizman et al (2003 Phys. Plasmas 10 3649). The high-frequency AC could be highly relevant for future ITER and fusion reactor plasmas dominated by ∼MeV energetic ions, including a significant population of passing fast ions.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{2039,

title = {Status of the WEST travelling wave array antenna design and results from the high power mock-up},

author = {R. Ragona and F. Durodie and A. Messiaen and J. Ongena and M. Van Schoor and S. Agzaf and T. Batal and J. -M. Bernard and X. Courtois and J. -M. Delaplanche and R. Dumont and F. Durand and F. Faisse and M. Firdaouss and L. Gargiulo and P. Garibaldi and J. Hillairet and T. Hoang and G. Lombard and P. Mollard and Z. Chen and Y. Song and H. Xu and Q. Yang and C. Yu},

url = {https://doi.org/10.1088/1741-4326/ac4467},

doi = {10.1088/1741-4326/ac4467},

year  = {2022},

date = {2022-02-01},

journal = {Nuclear Fusion},

volume = {62},

number = {2},

pages = {026046},

publisher = {IOP Publishing},

abstract = {This paper presents the current status of the WEST TWA antenna, its mock-up and a possible extrapolation to DEMO. The updated WEST TWA design has a reduced antenna length and features feeding and mechanical support from a single vessel port. A mock-up of the WEST TWA antenna was designed in 2019, manufactured during 2020 and installed in the TITAN test facility at the beginning of 2021. The results of the mock-up at low and high power, its diagnostic system and the prospects are explained. Extensions towards a TWA antenna for WEST and a possible TWA system for the future DEMO tokamak reactor are briefly discussed.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{2037,

title = {Plasma-surface interaction in the stellarator W7-X: conclusions drawn from operation with graphite plasma-facing components},

author = {S. BrezƖnsek and C. P. Dhard and M. Jakubowski and R. König and S. Masuzaki and M. Mayer and D. Naujoks and J. Romazanov and K. Schmid and O. Schmitz and D. Zhao and M. Balden and R. Brakel and B. Butterschoen and T. Dittmar and P. Drews and F. Effenberg and S. Elgeti and O. Ford and E. Fortuna-Zalesna and G. Fuchert and Y. Gao and A. Goriaev and A. Hakola and T. Kremeyer and M. Krychowiak and Y. Liang and Ch. Linsmeier and R. Lunsford and G. Motojima and R. Neu and O. Neubauer and J. Oelmann and P. Petersson and M. Rasinski and M. Rubel and S. Sereda and G. Sergienko and T. Sunn Pedersen and T. Vuoriheimo and E. Wang and T. Wauters and V. Winters and M. Zhao and R. Yi and W7-X Team},

url = {https://doi.org/10.1088/1741-4326/ac3508},

doi = {10.1088/1741-4326/ac3508},

year  = {2022},

date = {2022-01-01},

journal = {Nuclear Fusion},

volume = {62},

number = {1},

pages = {016006},

publisher = {IOP Publishing},

abstract = {W7-X completed its plasma operation in hydrogen with island divertor and inertially cooled test divertor unit (TDU) made of graphite. A substantial set of plasma-facing components (PFCs), including in particular marker target elements, were extracted from the W7-X vessel and analysed post-mortem. The analysis provided key information about underlying plasma–surface interactions (PSI) processes, namely erosion, transport, and deposition as well as fuel retention in the graphite components. The net carbon (C) erosion and deposition distribution on the horizontal target (HT) and vertical target (VT) plates were quantified and related to the plasma time in standard divertor configuration with edge transform ι = 5/5, the dominant magnetic configuration of the two operational phases (OP) with TDU. The operation resulted in integrated high net C erosion rate of 2.8 mg s−1 in OP1.2B over 4809 plasma seconds. Boronisations reduced the net erosion on the HT by about a factor 5.4 with respect to OP1.2A owing to the suppression of oxygen (O). In the case of the VT, high peak net C erosion of 11 μm at the strike line was measured during OP1.2B which converts to 2.5 nm s−1 or 1.4 mg s−1 when related to the exposed area of the target plate and the operational time in standard divertor configuration. PSI modelling with ERO2.0 and WallDYN-3D is applied in an interpretative manner and reproduces the net C erosion and deposition pattern at the target plates determined by different post-mortem analysis techniques. This includes also the 13C tracer deposition from the last experiment of OP1.2B with local 13CH4 injection through a magnetic island in one half module. The experimental findings are used to predict the C erosion, transport, and deposition in the next campaigns aiming in long-pulse operation up to 1800 s and utilising the actively cooled carbon-fibre composite (CFC) divertor currently being installed. The CFC divertor has the same geometrical design as the TDU and extrapolation depends mainly on the applied plasma boundary. Extrapolation from campaign averaged information obtained in OP1.2B reveals a net erosion of 7.6 g per 1800 s for a typical W7-X attached divertor plasma in hydrogen.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{2032,

title = {Plasma-wall interaction studies in W7-X: main results from the recent divertor operations},

author = {C P Dhard and S Brezinsek and M Mayer and D Naujoks and S Masuzaki and D Zhao and R Yi and J Oelmann and K Schmid and J Romazanov and C Pardanaud and M Kandler and A K Kharwandikar and G Schlisio and O Volzke and H Grote and Y Gao and L Rudischhauser and A. Goriaev and T. Wauters and A Kirschner and S Sereda and E Wang and M Rasinski and T Dittmar and G Motojima and D Hwangbo and S Kajita and M Balden and V V Burwitz and R Neu and Ch Linsmeier and W7-X Team},

url = {https://doi.org/10.1088/1402-4896/ac35c0},

doi = {10.1088/1402-4896/ac35c0},

year  = {2021},

date = {2021-12-01},

journal = {Physica Scripta},

volume = {96},

number = {12},

pages = {124059},

publisher = {IOP Publishing},

abstract = {Wendelstein 7-X (W7-X) is an optimized stellarator with a 3-dimensional five-fold modular geometry. The plasma-wall-interaction (PWI) investigations in the complex 3D geometry of W7-X were carried out by in situ spectroscopic observations, exhaust gas analysis and post-mortem measurements on a large number of plasma-facing components extracted after campaigns. The investigations showed that the divertor strike line areas on the divertor targets appeared to be the major source of carbon impurities. After multistep erosion and deposition events, carbon was found to be deposited largely at the first wall components, with thick deposits of >1 μm on some baffle tiles, moderate deposits on toroidal closure tiles and thin deposits at the heat shield tiles and the outer wall panels. Some amount of the eroded carbon was pumped out via the vacuum pumps as volatile hydrocarbons and carbon oxides (CO, CO2) formed due to the chemical processes. Boron was introduced by three boronizations and one boron powder injection experiment. Thin boron-dominated layers were found on the inner heat shield and the outer wall panels, some boron was also found at the test divertor unit and in redeposited layers together with carbon. Local erosion/deposition and global migration processes were studied using field-line transport simulations, analytical estimations, 3D-WallDYN and ERO2.0 modeling in standard magnetic field configuration.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{2027,

title = {First experiments on plasma production using field-aligned ICRF fast wave antennas in the large helical device},

author = {S. Kamio and V. E. Moiseenko and Yu. V. Kovtun and H. Kasahara and K. Saito and R. Seki and M. Kanda and G. Nomura and T. Seki and Y. Takemura and T. Wauters and R. Brakel and A. Dinklage and D. Hartmann and H. Laqua and T. Stange and A. Alonso and S. Lazerson and R. Ragona and J. Ongena and H. Thomsen and G. Fuchert and I. E. Garkusha},

url = {https://doi.org/10.1088/1741-4326/ac277b},

doi = {10.1088/1741-4326/ac277b},

year  = {2021},

date = {2021-11-01},

journal = {Nuclear Fusion},

volume = {61},

number = {11},

pages = {114004},

publisher = {IOP Publishing},

abstract = {The results of the first experimental series to produce a plasma using the ion cyclotron range of frequency (ICRF) in the large helical device (LHD) within the minority scenario developed at Uragan-2M (U-2M) are presented. The motivation of this study is to provide plasma creation in conditions when an electron cyclotron resonance heating start-up is not possible, and in this way widen the operational frame of helical machines. The major constraint of the experiments is the low RF power to reduce the possibility of arcing. No dangerous voltage increase at the radio-frequency (RF) system elements and no arcing has been detected. As a result, a low plasma density is obtained and the antenna-plasma coupling is not optimal. However, such plasmas are sufficient to be used as targets for further neutral beam injection (NBI) heating. This will open possibilities to explore new regimes of operation at LHD and Wendelstein 7-X (W7-X) stellarator. The successful RF plasma production in LHD in this experimental series stimulates the planning of further studies of ICRF plasma production aimed at increasing plasma density and temperature within the ICRF minority scenario as well as investigating the plasma prolongation by NBI heating.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{2028,

title = {Evidence for Alfvén eigenmodes driven by alpha particles in D-3He fusion experiments on JET},

author = {V. G. Kiptily and M. Fitzgerald and Y. O. Kazakov and J. Ongena and M. Nocente and S. E. Sharapov and M. Dreval and Ž. Štancar and T. Craciunescu and J. Garcia and L. Giacomelli and V. Goloborodko and H. J. C. Oliver and H. Weisen and JET Contributors},

url = {https://doi.org/10.1088/1741-4326/ac26a2},

doi = {10.1088/1741-4326/ac26a2},

year  = {2021},

date = {2021-11-01},

journal = {Nuclear Fusion},

volume = {61},

number = {11},

pages = {114006},

publisher = {IOP Publishing},

abstract = {Alfvén eigenmodes (AEs) driven by energetic alpha particles can lead to enhanced fast ion transport and losses, thereby degrading the plasma performance in ITER and future magnetic confinement fusion reactors. Unexpectedly, AEs with negative toroidal mode numbers, which are currently not considered for ITER, were observed in dedicated experiments with fusion-born alpha particles on the tokamak Joint European Torus (JET). The paper provides evidence for a complex interplay between fast ions, monster sawtooth crashes and AEs. Our results highlight the need for an improved description of the synergies between different fast ion phenomena in future burning plasmas.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{2029,

title = {Fast ion transport by sawtooth instability in the presence of ICRF–NBI synergy in JET plasmas},

author = {A. A. Teplukhina and M. Podesta and F. M. Poli and G. Szepesi and Y. O. Kazakov and P. J. Bonofiglo and M. Gorelenkova and M. Nocente and J. Ongena and Z. Stancar and JET Contributors},

url = {https://doi.org/10.1088/1741-4326/ac2524},

doi = {10.1088/1741-4326/ac2524},

year  = {2021},

date = {2021-11-01},

journal = {Nuclear Fusion},

volume = {61},

number = {11},

pages = {116056},

publisher = {IOP Publishing},

abstract = {JET experiments have shown that the three-ion scenarios using waves in the ion cyclotron range of frequencies (ICRF) is an efficient way to build fast ion population through beam ion acceleration by radio frequency (RF) waves. Such a heating scheme is applied to plasmas with at least two thermal ion species. Analysis of mixed discharges with complex heating schemes requires a workflow that allows to model thermal and fast ion transport consistently. This paper is dedicated to modelling of a mixed plasma discharge with significant fraction of fast ions and contributes to development of fast ion transport models. For interpretive analysis with the TRANSP code a JET hydrogen–deuterium plasma discharge with neutral beam injection (NBI) and ICRF heating has been chosen. The task is complicated by NBI–ICRF synergy and plasma magnetohydrodynamic activity, like sawtooth crashes. D beam ions accelerated by RF waves form a high energy tail in fast ion distribution. Significant difference between the neutron rate computed by TRANSP and measured one is observed if the same diffusivity for electrons and ions is assumed. Sensitivity studies show that uncertainties in input plasma parameters and thermal ion transport models are crucial for modelling mixed plasma discharges and increased D transport is required to reach the plasma composition consistent with diagnostic measurements at the plasma edge. Fast ion redistribution by a sawtooth instability is characterised by non-resonant transport due to reconnection of magnetic field lines and resonant transport caused by resonance interaction between the instability and fast ions. With ORBIT simulations it has been shown that resonant interaction strongly affects fast ions of high energies, like beam ions accelerated by RF waves and fusion products. For the considered case, fast ion profiles simulated by ORBIT remain peaked after the sawtooth crashes.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{2021,

title = {Characterization of injection and confinement improvement through impurity induced profile modifications on the Wendelstein 7-X stellarator},

author = {R. Lunsford and C. Killer and A. Nagy and D. A. Gates and T. Klinger and A. Dinklage and G. Satheeswaran and G. Kocsis and S. A. Lazerson and F. Nespoli and N. A. Pablant and A. Stechow and A. Alonso and T. Andreeva and M. Beurskens and C. Biedermann and S. Brezinsek and K. J. Brunner and B. Buttenschön and D. Carralero and G. Cseh and P. Drewelon F. Effebverg and T. Estrada O. P. Ford and O. Gruklke and U. Hergenhahn and U. Höefel and H. Knauer and M. Krause and M. Krychowiak and S. Kwak and A. Langenberg and U. Neuner and D. Nicolai and A. Pavone and A. Puig Sitjes and K. Rahbarnia and J. Schilling and J. Svensson and T. Szepesi and H. Thomsen and T. Wauters and T. Windisch and V. Winters and D. Zhang and L. Zsuga and W7-X Team},

year  = {2021},

date = {2021-08-01},

journal = {Physics of Plasmas},

volume = {28},

number = {8},

pages = {082506},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{2006,

title = {Ion cyclotron resonance heating fast and slow wave excitation and power deposition in edge plasmas with application to ITER},

author = {A. Messiaen and V. Maquet and J. Ongena},

url = {https://doi.org/10.1088/1361-6587/abdf2b},

doi = {10.1088/1361-6587/abdf2b},

year  = {2021},

date = {2021-04-01},

journal = {Plasma Physics and Controlled Fusion},

volume = {63},

number = {4},

pages = {045021},

publisher = {IOP Publishing},

abstract = {The antenna power coupling to the plasma centre and its possible deleterious coupling to the plasma edge are key parameters in an ion cyclotron resonance heating system. The influence on these parameters by the confluence between the slow and the fast magnetosonic waves is studied for the case of large machines. Until now, the modelling of the scrape off layer region has been calculated by ANTITER II, which contains only the fast wave description and where the confluence with the slow wave (S wave) is approximated by the Alfvén resonance. In the present study, a complete modelling of the slow and fast waves is made by ANTITER IV. The modelling by the two codes is compared and shows the important role of the Alfvén and the lower hybrid resonances for the excitation of large fields and associated power deposition at the edge of the plasma even far from the antenna location. The ANTITER IV modelling is thereafter applied to the case of the ITER antenna with a reference density profile and heating parameters. A comparative study is made for the edge power deposition and the excitation of large fields for different toroidal phasing cases of the antenna. This study also takes into account the tilting of the antenna array with respect to the total magnetic field in front of the antenna. If the Faraday screen is field-aligned, the excitation of the S wave occurs at the wave confluence; however, in the case of non-alignment the antenna directly excites the S wave. This effect is studied and quantified. All edge effects, even the direct excitation of S waves, can be strongly reduced by tailoring the current distribution in the straps of the antenna array. Resulting cases for the minimisation of edge power deposition in ITER and the reactor are studied.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{2000,

title = {Physics and applications of three-ion ICRF scenarios for fusion research},

author = {Y. O. Kazakov and J. Ongena and J. C. Wright and S. J. Wukitch and V. Bobkov and J. Garcia and V. G. Kiptily and M. J. Mantsinen and M. Nocente and M. Schneider and H. Weisen and Y. Barakov and M. Baruzzo and R. Bilato and A. Chomiczewska and R. Coelho and T. Craciunescu and K. Crombé and M. Dreval and E. Dumont and P. Dumortier and F. Durodié and J. Eriksson and M. Fitzgerald and J. Galdon-Quiroga and D. Gallart and M. Garcia-Munoz and L. Giacomelli and C. Giroud and J. Gonzalez Martin and A. Hakola and P. Jacquet and T. Johnson and A. Kappatou and D. Keeling and D. King and K. K. Kirov and P. U. Lamalle and M. Lennholm and E. Lerche and M. Maslov and S. Mazzi and S. Menmuir and I. Monakhov and F. Nabais and M. F. F. Nave and R. Ochoukov and A. R. Polevoi and S. D. Pinches and U. Plank and D. Rigamonti and M. Salewski and P. A. Schneider and S. E. Sharapov and Z. Stancar and A. Thorman and D. Valcarcel and D. Van Eester and M. Van Schoor and J. Varje and M. Weiland and N. Wendler and JET Contributors and ASDEX Upgrade Team and EUROfusion MST1 Team and Alcator C-Mod Team},

year  = {2021},

date = {2021-02-01},

journal = {Physics of Plasmas},

volume = {28},

number = {2},

pages = {020501},

abstract = {This paper summarizes the physical principles behind the novel three-ion scenarios using radio frequency waves in the ion cyclotron range of frequencies (ICRF). We discuss how to transform mode conversion electron heating into a new flexible ICRF technique for ion cyclotron heating and fast-ion generation in multi-ion species plasmas. The theoretical section provides practical recipes for selecting the plasma composition to realize three-ion ICRF scenarios, including two equivalent possibilities for the choice of resonant absorbers that have been identified. The theoretical findings have been convincingly confirmed by the proof-of-principle experiments in mixed H–D plasmas on the Alcator C-Mod and JET tokamaks, using thermal 3He and fast D ions from neutral beam injection as resonant absorbers. Since 2018, significant progress has been made on the ASDEX Upgrade and JET tokamaks in H–4He and H–D plasmas, guided by the ITER needs. Furthermore, the scenario was also successfully applied in JET D–3He plasmas as a technique to generate fusion-born alpha particles and study effects of fast ions on plasma confinement under ITER-relevant plasma heating conditions. Tuned for the central deposition of ICRF power in a small region in the plasma core of large devices such as JET, three-ion ICRF scenarios are efficient in generating large populations of passing fast ions and modifying the q-profile. Recent experimental and modeling developments have expanded the use of three-ion scenarios from dedicated ICRF studies to a flexible tool with a broad range of different applications in fusion research.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{1994,

title = {Generation and observation of fast deuterium ions and fusion-born alpha particles in JET D - 3He plasmas with the 3-ion radio-frequency heating scenario},

author = {M Nocente and Y. O. Kazakov and J Garcia and V G Kiptily and J. Ongena and M Dreval and M Fitzgerald and S E Sharapov and Z Stancar and H Weisen and Y Baranov and A Bierwage and T Craciunescu and Dal A Molin and E Luna and R Dumont and P. Dumortier and J Eriksson and L Giacomelli and C Giroud and V Goloborodko and G Gorini and E Khilkevitch and K K Kirov and M Iliasova and P Jacquet and P Lauber and E. Lerche and M J Mantsinen and A Mariani and S Mazzi and F Nabais and M F F Nave and J Oliver and E Panontin and D Rigamonti and A Sahlberg and M Salewski and A Shevelev and K Shinohara and P Siren and S Sumida and M Tardocchi and D. Van Eester and J Varje and A Zohar and JET Contributors},

url = {https://doi.org/10.1088%2F1741-4326%2Fabb95d},

doi = {10.1088/1741-4326/abb95d},

year  = {2020},

date = {2020-12-01},

journal = {Nuclear Fusion},

volume = {60},

number = {12},

pages = {124006},

publisher = {IOP Publishing},

abstract = {Dedicated experiments to generate energetic D ions and fusion-born alpha particles were performed at the Joint European Torus (JET) with the ITER-like wall (ILW). Using the 3-ion radio frequency (RF) heating scenario, deuterium ions from neutral beam injection (NBI) were accelerated in the core of mixed plasmas to higher energies with ion cyclotron resonance frequency (ICRF) waves, in turn leading to a core-localized source of alpha particles. The fast-ion distribution of RF-accelerated D-NBI ions was controlled by varying the ICRF and NBI power ( 4–6 MW, 3–20 MW), resulting in rather high D-D neutron (≈ 1 × 1016 s−1) and alpha rates (≈ 2 × 1016 s−1) at moderate input heating power. Theory and TRANSP analysis shows that large populations of co-passing MeV-range D ions were generated using the 3-ion ICRF scenario. This important result is corroborated by several experimental observations, in particular gamma-ray measurements. The developed experimental scenario at JET provides unique conditions for probing several aspects of future burning plasmas, such as the contribution from MeV range ions to global confinement, but without introducing tritium. Dominant fast-ion core electron heating with and a rich variety of fast-ion driven Alfvén eigenmodes (AEs) were observed in these plasmas. The observed AE activities do not have a detrimental effect on the thermal confinement and, in some cases, may be driven by the fusion born alpha particles. A strong continuous increase in neutron rate was observed during long-period sawteeth (1 s), accompanied by the observation of reversed shear AEs, which implies that a non monotonic q profile was systematically developed in these plasmas, sustained by the large fast-ion populations generated by the 3-ion ICRF scenario.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{1991,

title = {Excitation of elliptical and toroidal Alfvén eigenmodes by 3He-ions of the MeV-energy range in hydrogen-rich JET plasmas},

author = {V G Kiptily and Y. O. Kazakov and M Fitzgerald and M Nocente and M Iliasova and E Khilkevich and M J Mantsinen and M F F Nave and J. Ongena and S E Sharapov and A E Shevelev and Ž Š and G Szepesi and D M A Taylor and Yu. V. Yakovenko and},

url = {https://doi.org/10.1088%2F1741-4326%2Fab79cb},

doi = {10.1088/1741-4326/ab79cb},

year  = {2020},

date = {2020-11-01},

journal = {Nuclear Fusion},

volume = {60},

number = {11},

pages = {112003},

publisher = {IOP Publishing},

abstract = {Elliptical (EAE) and toroidal Alfvén eigenmode (TAE) instabilities have been observed in hydrogen-rich JET discharges of the D-(3He)-H ion cyclotron resonance heating (ICRH) scenario, which is characterized by strong absorption of radio frequency waves at very low concentrations of the resonant 3He-ions. In the experiments, core localized TAEs with a frequency f TAE ≈ 280 kHz with mode numbers n= 3, 4, 5 and 6 were detected. Following the phase with TAE excitation, EAE modes at higher frequencies f EAE ≈ 550–580 kHz with mode numbers n = 1, 3, 5 were seen. These high frequency modes indicate that a MeV range population of trapped energetic ions was present in the plasma. The experimental evidence of existence of the MeV-energy 3He-ions able to excite the AEs is provided by neutron and gamma-ray diagnostics as well as fast ion loss measurements. The ICRH modelling code calculations confirm the acceleration of 3He-ions to MeV energies. The magnetohydrodynamic (MHD) analysis results are consistent with the experimental data showing that the MeV 3He ions satisfy to resonant conditions interacting with TAE and EAE modes. This experiment demonstrates the efficient plasma heating mimicking the conditions representative for the ITER plasmas and contribute to the understanding of fast-ion interaction with MHD wave modes.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{1992,

title = {Plasma heating and generation of energetic D ions with the 3-ion ICRF +NBI scenario in mixed H-D plasmas at JET-ILW},

author = {Y. O. Kazakov and M Nocente and M J Mantsinen and J. Ongena and Y Baranov and T Craciunescu and M Dreval and R Dumont and J Eriksson and J Garcia and L Giacomelli and V G Kiptily and K K Kirov and L Meneses and F Nabais and M F F Nave and M Salewski and S E Sharapov and Ž Š and J Varje and Weisen H and},

url = {https://doi.org/10.1088%2F1741-4326%2Fab9256},

doi = {10.1088/1741-4326/ab9256},

year  = {2020},

date = {2020-11-01},

journal = {Nuclear Fusion},

volume = {60},

number = {11},

pages = {112013},

publisher = {IOP Publishing},

abstract = {Dedicated experiments were conducted in mixed H-D plasmas in JET to demonstrate the efficiency of the 3-ion ICRF scenario for plasma heating, relying on injected fast NBI ions as the resonant ion component. Strong core localization of the RF power deposition in the close vicinity of the ion-ion hybrid layer was achieved, resulting in an efficient plasma heating, generation of energetic D ions, strong enhancement of the neutron rate and observation of Alfvénic modes. A consistent physical picture that emerged from a range of fast-ion measurements at JET, including neutron and gamma-ray measurements, a high-energy neutral particle analyzer and MHD mode localization analysis, is presented. The possibility to moderate the fast-ion energies with the ratio P 

ICRF/P 

NBI and the choice of the NBI injectors is demonstrated. An outlook of possible applications of the 3-ion scenarios, including a recent example of its use in mixed D-3He plasmas in JET and promising scenarios for D-T plasmas, are presented.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{1990,

title = {First experiments on ICRF discharge generation by a W7-X-like antenna in the Uragan-2M stellarator},

author = {V E Moiseenko and Yu. V Kovtun and T. Wauters and A. Goriaev and A. I. Lyssoivan and A V Lozin and R O Pavlichenko and A N Shapoval and S M Maznichenko and V B Korovin and E D Kramskoy and M M Kozulya and N V Zamanov and Y V Siusko and Yu. A Krasiuk and V S Romanov and A Alonso and R Brakel and A Dinklage and D Hartmann and Y. O. Kazakov and H Laqua and J. Ongena and T Stange},

year  = {2020},

date = {2020-10-01},

journal = {Journal of Plasma Physics},

volume = {86},

number = {5},

pages = {905860517},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{1971,

title = {ICRH options for JET-ILW DTE2 operation},

author = {E. Lerche and D. Van Eester and P Jacquet and F Casson and Y Baranov and P. Dumortier and D Gallart and J Graves and P Huynh and T Johnson and Y. O. Kazakov and V Kiptily and K Kirov and M Machielsen and M Mantsinen and I Monakhov and J. Ongena and JET Contributors},

year  = {2020},

date = {2020-09-01},

journal = {AIP Conference proceedings},

volume = {2254},

number = {1},

pages = {030007},

abstract = {Ion cyclotron resonance heating (ICRH) plays an important role in high performance JET-ILW plasma discharges, both for keeping the heavy impurities away from the plasma centre as for increasing the core ion temperature to boost fusion performance. While the former is needed in all high-performance discharges for steady state operation, the latter will be particularly important in the next-coming JET Deuterium-Tritium campaign (DTE2). Currently, the workhorse for impurity control in high power D plasmas is fundamental H minority ICRH (with simultaneous ω=2ωc harmonic D heating), which leads to localized core electron heating that induces turbulence (flatter density profiles) as well as peaked electron temperatures. For fusion power enhancement, dominant bulk ion heating and RF acceleration of the NBI ions to appropriate energies would be preferable and theoretical predictions suggest that ion heating is also effective for core impurity screening. In this paper, we discuss the basic modeling results of different ICRF scenarios available for the DTE2 campaign in JET-ILW, highlighting their main properties in terms of the RF absorption of the various species, their slowing-down properties and their impact on high-Z impurity transport. Correctly modeling the wave absorption, slowing-down and collisional energy redistribution of the simultaneously RF-heated species in a DT plasma mix with important neutral-beam injection (NBI) is numerically challenging and is outside the scope of this paper. The simplified calculations presented here are rather intended to give the reader an overview of the ICRH options for JET-DTE2 with references to the state-of-the-art ICRH modeling given throughout the paper.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{1973,

title = {Synergistic ICRH and NBI heating for fast ion generation and maximising fusion rate in mixed plasmas at JET},

author = {K K Kirov and Y. O. Kazakov and M Nocente and J. Ongena and Y Baranov and F Casson and J Eriksson and L Giacomelli and C Hellesen and V Kiptily and R Bilato and K. Crombé and R Dumont and P Jacquet and T Johnson and E Lerch and M Mantsinen and D. Van Eester and J Varje and H Weisen and JET Contributors},

year  = {2020},

date = {2020-09-01},

journal = {AIP Conference proceedings},

volume = {2254},

number = {1},

pages = {030011},

abstract = {The studies of recent JET experiments in H/D≈0.85/0.15 plasma (2.9T/2MA) in which neutron rate was enhanced by applying 2.5MW of ICRH using D-(DNBI)-H three-ion scheme are reported. An extensive analysis of this novel heating scenario has been carried out by means of integrated TRANSP/TORIC modelling, and a comprehensive validation of the computed Fast Ion Distribution Function (FI DF) with a range of fast ion diagnostics available at JET is presented. The predicted acceleration of D Neutral Beam Injection (NBI) ions beyond their injection energies and the associated changes in FI DF by RF waves are found to be in good agreement with measured neutron yield and TOFOR neutron spectrometer measurements, as well as with multi-channel neutron camera observations and neutral particle analyser diagnostic. An outlook of the possible applications of the developed technique for future DTE2 studies on JET has been highlighted. Controlled acceleration of TNBI ions in D-rich and DNBI ions in T-rich plasmas to optimal energies can be applied to maximise BT fusion rates and contribute to the success of future DT experiments at JET and ITER as illustrated in this study.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{1975,

title = {Measurements of the scattering matrix of the W7-X prototype ICRH antenna and capacitor units},

author = {I. Stepanov and V Borsuk and K. Crombé and Casta D n and G Offermanns and J. Ongena and B Schweer and M. Vervier},

year  = {2020},

date = {2020-09-01},

journal = {AIP Conference proceedings},

volume = {2254},

number = {1},

pages = {040003},

abstract = {Low-power measurements of the W7-X prototype ICRH antenna and variable capacitor units have been performed at FZJ Jülich. The antenna scattering matrices, with and without the carbon limiter tiles, have been de-embedded from network analyzer measurements using custom-built RF adapters. The results have been compared to the matrices calculated with CST Microwave Studio 2017 using a model based on the original CAD files. A very good agreement is seen, since a) the difference in magnitude is less than 0.02 in the whole frequency range, and ~ 0.015 or less in the range of interest (between 20 and 40 MHz) and b) the difference in phase is less than 5◦ in the whole frequency range, and ~ 2◦ or less between 20 and 40 MHz. 

The S-parameters of the tuning capacitors have also been measured, to determine the relationship between the internal DC capacitance CDC of each unit, and the actual ''equivalent'' capacitance Ceq seen by the antenna at the ports. It is seen that the latter, 36-475 pF, is substantially different from the nominal DC range, which is 15-200 pF. Nonetheless this is not expected to pose a problem for antenna operation. 

The S-parameters of other key components of the ICRF system, such as the matching unit and line sections containing directional couplers, were also measured and, where applicable, compared to models or used to extract calibration data.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{1979,

title = {Analysis of metallic impurities during the application of three-ion ICRH scenario at JET-ILW},

author = {A Chomiczewska and N Krawczyk and Y. O. Kazakov and V Bobkov and Kowalska-Strz E e and E. Lerche and M J Mantsinen and J. Ongena and G Pucella and T P ü and D. Van Eester and JET Contributors},

year  = {2020},

date = {2020-09-01},

journal = {AIP Conference proceedings},

volume = {2254},

number = {1},

pages = {050005},

abstract = {The effect of the novel `three-ion' D-(3He)-H minority ICRH heating scheme on the behavior of the metallic impurities at JET-ILW is discussed. The reported experiment was performed in L-mode plasmas at a magnetic field BT = 3.2 T, plasma current Ip = 2 MA and central plasma densities ne(0) ≈ 4×1019 m-3. ICRH power was delivered with dipole or +π/2 antenna phasing at f ≈ 32.2-33MHz, placing the 3He cyclotron resonance at the plasma core. The edge isotopic ratio H/(H+D) was varied between 73 and 92%, and 3He concentration in the range of 0.1-1.5% to assess the sensitivity of the scheme to the detailed plasma composition. The results of our analysis show a linear increase of the plasma effective charge Zeff, radiated power Prad,bulk and content of metallic impurities with ICRF power. The observed scattering of the points reflects the difference in the plasma composition and ICRF antenna phasing. For discharges heated with similar ICRH power level ~4MW, our analysis indicates that for a large range of H/(H+D) the novel scenario effectively heats the plasma with reduced content of metallic impurities. The impurities are shown to be concentrated mainly around the mid- radius region of the plasma. We conclude this paper with a discussion of the effect of the long-period sawteeth on the observed dynamics of metallic impurities in the plasma core.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{1982,

title = {Effect of poloidal magnetic field and cross-coupling on a set of traveling wave antenna sections for the ICRH of fusion reactor plasmas},

author = {A. Messiaen and R. Ragona and R. Koch and V. Maquet and J. Ongena},

year  = {2020},

date = {2020-09-01},

journal = {AIP Conference proceedings},

volume = {2254},

number = {1},

pages = {060005},

abstract = {A set of Traveling Wave antenna (TWA) sections has been proposed for the ICRF heating of the reactor in view to decrease the antenna power density. The reduction of the antenna voltage and associate electric field and current is compensated by the number of radiating straps. An upgraded version of the fast semi-analytical code ANTITER-II is used to model a set of TWA sections of any arbitrary number of radiating straps facing a low coupling plasma profile with their feeding system. Now it incorporates the effect of the non-alignment of the antenna to the total steady magnetic field (toroidal + poloidal) in front of it. The model incorporates the feeding of each section by a resonant ring circuit that recirculates its output power. The cases of straps grounded at one of their ends (L grounding) or in their center (T grounding) are also compared. The model is applied to the proposed TWA section layout for the ICRF heating of DEMO. It is shown that the antenna tilting affects mostly the poloidal radiating spectrum seen by the plasma. This effect increases with the absolute value of the k// selected by the antenna system. The coupling reduction and the effect on the strap current and voltage distribution due to the tilting is compared with the ones resulting from the mutual coupling between the sections. The effects of the tilting for the expected qedge value of the reactor and of mutual coupling between toroidally spaced sections remain weak. The effect of coupling between poloidally superposed sections can become large.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{1984,

title = {The ICRH system for the stellarator Wendelstein 7-X},

author = {J. Ongena and A. Messiaen and Y. O. Kazakov and B Schweer and I. Stepanov and M. Vervier and K. Crombé and M. Van Schoor and V Borsuk and Casta D n and A Kraemer-Flecken and K P Hollfeld and G Offermanns and D A Hartmann and J P Kallmeyer and R C Wolf},

year  = {2020},

date = {2020-09-01},

journal = {AIP Conference proceedings},

volume = {2254},

number = {1},

pages = {070003},

abstract = {An important test for W7-X is to demonstrate confinement of fast trapped ions at volume averaged beta values up to 5%, corresponding to plasma densities above 1020 m-3. Energetic ions in W7-X with energies 50 < E < 100 keV mimic alphas in a reactor. To generate such a population is a challenging task in high-density plasmas but this can be efficiently realized with the H- (3He)-D three-ion heating ICRH scenario, foreseen for f ~ 25 MHz in W7-X. An ICRH system is prepared for W7-X, expected to deposit RF powers up to ~1.5 MW (depending on the coupling) at frequencies between 25-38 MHz in pulses up to 10s. A two-strap ICRH antenna for W7-X is under construction. Each strap of the antenna is on one side connected to a tuning capacitor 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 to check the main functional tests of the full ICRH antenna system.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{1985,

title = {Conceptual study of an ICRH traveling wave antenna (TWA) for T-15MD at 60 MHz},

author = {A V Melnikov and J. Ongena and A. Messiaen and R. Ragona and A V Sushkov and Y. O. Kazakov and D. Van Eester and Yu. N Dnestrovskii and P P Khvostenko and I N Roy},

year  = {2020},

date = {2020-09-01},

journal = {AIP Conference proceedings},

volume = {2254},

number = {1},

pages = {070007},

abstract = {This paper proposes a Traveling Wave Antenna for ICRH heating of T-15MD located below the equatorial plane of the tokamak for operation at 60MHz. Resonant ring feeding allows the recirculation of the RF power that is not radiated to the plasma and the termination of the TWA section in its iterative impedance. The paper describes the antenna design, the feeding ring tuning algorithm and expected performances of this antenna concept. The chosen geometry of the TWA sections is compatible with that of a future reactor and therefore this ICRH antenna system for T-15MD also represents a test bed for DEMO.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{1988,

title = {Progress on the design of a DEMO high power ICRH travelling wave antenna mock-up to be tested on WEST},

author = {R. Ragona and T Batal and J Hillairet and A. Messiaen and M Firdaouss and J -M Bernard and J. Ongena},

year  = {2020},

date = {2020-09-01},

journal = {AIP Conference proceedings},

volume = {2254},

number = {1},

pages = {070014},

abstract = {WEST represents the ideal device to test a reactor relevant TWA due to its long pulse capability and full metal wall configuration. Moreover, the already installed ICRF high power launchers will allow a direct comparison between a classical in-port antenna and the TWA. This paper reports the progress in the design of an actively cooled high power mock-up of the WEST TWA antenna that will be tested in the TITAN facility. The main objective of the test is to assess the voltage stand-off of the antenna at a power level relevant for future operation. In order to be installed and operated in WEST, the antenna design has to comply with the specific machine requirements, in particular active cooling, magnetic configuration and interface with existing auxiliary heating systems. Here several aspects are taken into account: toroidal magnetic field ripple, field line inter-connection and thermal loads on the antenna. An initial assessment of mechanical compatibility in case of VDE is performed. In conclusion, the next steps and implications of the project are outlined.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{1957,

title = {Wall conditioning in fusion devices with superconducting coils},

author = {T. Wauters and D Borodin and R Brakel and S Brezinsek and K J Brunner and J Buermans and S Coda and A Dinklage and D Douai and O Ford and G Fuchert and A. Goriaev and H Grote and A Hakola and E Joffrin and J Knauer and T Loarer and H Laqua and A. I. Lyssoivan and V Moiseenko and D Moseev and J. Ongena and K Rahbarnia and D Ricci and V Rohde and S Romanelli and S Sereda and T Stange and Tabar F L é and Lilla Van ó and O Volzke and E Wang and and and and},

url = {https://doi.org/10.1088%2F1361-6587%2Fab5ad0},

doi = {10.1088/1361-6587/ab5ad0},

year  = {2020},

date = {2020-03-01},

journal = {Plasma Physics and Controlled Fusion},

volume = {62},

number = {3},

pages = {034002},

publisher = {IOP Publishing},

abstract = {Wall conditioning is essential in tokamak and stellarator research to achieve plasma performance and reproducibility. This paper presents an overview of recent conditioning results, both from experiments in present devices and modelling, in view of devices with superconducting coils, with focus on W7-X, JT-60SA and ITER. In these devices, the coils stay energised throughout an experimental day or week which demands for new conditioning techniques that work in presence of the nominal field, in addition to the proven conditioning methods such as baking, glow discharge conditioning (GDC) and low-Z wall coating through GDC-plasma, which do not work under such condition. The discussed techniques are RF conditioning without plasma current, both in the ion cyclotron and electron cyclotron range of frequencies, and diverted conditioning plasmas with nested magnetic flux surfaces. Similarities and differences between tokamaks and stellarators are highlighted. Finally a conditional tritium recovery strategy for ITER is proposed based on Ion Cyclotron Wall Conditioning and L-mode plasma results from JET, equipped with an ITER-like wall (beryllium main chamber wall and tungsten divertor).},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{1953,

title = {A travelling wave array system as solution for the ion cyclotron resonance frequencies 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},

url = {https://doi.org/10.1088%2F1741-4326%2Fab504a},

doi = {10.1088/1741-4326/ab504a},

year  = {2020},

date = {2020-01-01},

journal = {Nuclear Fusion},

volume = {60},

number = {1},

pages = {016027},

publisher = {IOP Publishing},

abstract = {Travelling wave array (TWA) antennas distributed along the periphery of the tokamak are presently considered as an 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 eight straps shows that a power capability exceeding 50 MW 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 15 kV and maximum inter-strap voltage amplitude of 18 kV. The generators remain matched for all loading conditions: the system is totally load resilient. Following the recommendation of the work package heating and current drive Review Panel, a TWA ion cyclotron resonant heating (ICRH) system consisting of 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 50 MW on the ITER density profile, voltages up to 30 kV 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 an ICRH system for a DEMO reactor, a test on an existing medium size tokamak is under study.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{1935,

title = {Conceptual study of an ICRH system for T-15MD using traveling wave antenna (TWA) sections},

author = {J. Ongena and A. Messiaen and A V Melnikov and R. Ragona and Y. O. Kazakov and D. Van Eester and Yu. N Dnestrovskii and P P Khvostenko and I N Roy and A N Romannikov},

url = {http://www.sciencedirect.com/science/article/pii/S0920379619300882},

doi = {https://doi.org/10.1016/j.fusengdes.2019.01.080},

issn = {0920-3796},

year  = {2019},

date = {2019-09-01},

journal = {Fusion Engineering and Design},

volume = {146},

pages = {787-791},

abstract = {This paper describes a conceptual ICRH system for the tokamak T-15MД, in construction at the Nuclear Fusion Institute of the Kurchatov Research Centre for Atomic Energy in Moscow. The proposed system consists of a number of Travelling Wave Antenna sections, located below the equatorial plane of the tokamak. This antenna system, loaded by a simulated density profile provided by the T-15MД team, is modelled including its resonant ring feeding system. Resonant ring feeding allows the recirculation of the RF power that is not radiated to the plasma and the termination of the TWA section on its iterative impedance. The paper describes the antenna design, the feeding ring tuning algorithm and expected performances of this antenna concept. The chosen geometry of the TWA sections is compatible with that of a future reactor and therefore this ICRH antenna system for T-15MД represents also a test bed for DEMO.},

note = {SI:SOFT-30},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{1936,

title = {Traveling wave array for DEMO with proof of principle on WEST},

author = {R. Ragona and A. Messiaen and J M Bernard and E Delchambre and R Dumont and F. Durodié and J Hillairet and J. Ongena and D. Van Eester and M. Van Schoor},

url = {http://www.sciencedirect.com/science/article/pii/S0920379619301085},

doi = {https://doi.org/10.1016/j.fusengdes.2019.01.097},

issn = {0920-3796},

year  = {2019},

date = {2019-09-01},

journal = {Fusion Engineering and Design},

volume = {146},

pages = {854-857},

abstract = {To decrease the power density and associated high voltages, a distributed antenna system is proposed as ICRH system for the DEMO reactor. Among the different solutions, a layout made from a set of travelling wave array (TWA) sections is considered as the most promising. It optimizes coupling to the plasma, is load resilient and avoids large values for the VSWR in the feeding lines. The total radiated power scales as the number of independently fed sections such that high reliability can be expected. The TWA concept for ICRH is innovative and very different from the traditional IC antennas. A test on WEST would provide a proof of principle of the validity of the TWA approach together with a comparison with the existing WEST IC antennas. The chosen geometry of the TWA section is compatible with one unit of the complete set designed for a future reactor. The paper describes the progress made in the preparation of a test on WEST along with the extrapolation for a future reactor like DEMO. A comparative modeling with the present antennas is also discussed and a preliminary RAMI analysis is introduced showing the promising positive impact of the TWA design on the RAMI scores.},

note = {SI:SOFT-30},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{1937,

title = {Progress on an ion cyclotron range of frequency system for DEMO},

author = {J. -M. Noterdaeme and A. Messiaen and R. Ragona and W Zhang and A Bader and F. Durodié and U Fischer and T Franke and E Smigelskis and J. Ongena and M Q Tran and D. Van Eester and M. Van Schoor},

url = {http://www.sciencedirect.com/science/article/pii/S0920379619302443},

doi = {https://doi.org/10.1016/j.fusengdes.2019.02.067},

issn = {0920-3796},

year  = {2019},

date = {2019-09-01},

journal = {Fusion Engineering and Design},

volume = {146},

pages = {1321-1324},

abstract = {An Ion Cyclotron Range of Frequency (ICRF) system can provide power for a number of tasks, experimentally verified on present machines: heating and current drive, first wall conditioning, plasma startup, removing central impurities, controlling sawteeth and current ramp down assist. The system has a high plug-to-power efficiency and most of the components external to the machine are sturdy, with industrial steady state capability. Traditional ICRF antenna systems are often characterized by a high operating voltage and high power density. Low power density and low voltage however provides a bonus in terms of reliability. Therefore, travelling wave type antennas have been proposed (Ragona and Messiaen, 2016). They can be integrated in the blanket and use only a limited number of feeders. The effect on the tritium breeding ratio of such an antenna incorporated in the blanket, including the feeders, is small. The k// spectrum is peaked and the dominant k// value can be optimized for coupling and bulk absorption, while avoiding the generation of coaxial modes in the edge. The coupling can be further enhanced with gas puffing near the antenna. Assuming the ITER-2010-low density profile, 50 MW can be coupled with a voltage on the antenna components of about 15 kV.},

note = {SI:SOFT-30},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{1928,

title = {Performance of Wendelstein 7-X stellarator plasmas during the first divertor operation phase},

author = {R C Wolf and A Alonso and S Akaslompolo and J Baldzhun and M Beurskens and C D Beidler and C Biedermann and H -S Bosch and S Bozhenkov and R Brakel and H Braune and S Brezinsek and K -J Brunner and H Damm and A Dinklage and P Drewelow and F Effenberg and Y Feng and O Ford and G Fuchert and Y Gao and J Geiger and O Grulke and N Harder and D Hartmann and P Helander and B Heinemann and M Hirsch and U H ö and C Hopf and K Ida and M Isobe and M W Jakubowski and Y. O. Kazakov and C Killer and T Klinger and J Knauer and R K ö and M Krychowiak and A Langenberg and H P Laqua and S Lazerson and P McNeely and S Marsen and N Marushchenko and R Nocentini and K Ogawa and G Orozco and M Osakabe and M Otte and D Pablant and E Pasch and A Pavone and M Porkolab and Puig A Sitjes and K Rahbarnia and R Riedl and N Rust and E Scott and H Schilling and R Schroeder and T Stange and Von A Stechow and E Strumberger and Sunn T Pedersen and J Svensson and H Thomson and Y Turkin and L Vano and T. Wauters and G Wurden and M Yoshinuma and M Zanini and D Zhang and Wendelstein 7-X Team},

year  = {2019},

date = {2019-08-01},

journal = {Physics of Plasmas},

volume = {26},

pages = {082504},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@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}

}

@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}

}

@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}

}