List of publications

@article{1755,

title = {Turbulent transport of MeV range cyclotron heated minorities as compared to alpha particles},

author = {Istvan Pusztai and George J Wilkie and Y. O. Kazakov and Tunde Fulop},

url = {http://stacks.iop.org/0741-3335/58/i=10/a=105001},

year  = {2016},

date = {2016-10-01},

journal = {Plasma Physics and Controlled Fusion},

volume = {58},

number = {10},

pages = {105001},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{1754,

title = {Modelling of the ICRF induced E x B convection in the scrape-off-layer of ASDEX Upgrade},

author = {W Zhang and Y Feng and J. -M. Noterdaeme and V Bobkov and L Colas and D Coster and T Lunt and R Bilato and J Jacquot and R Ochoukov and D. Van Eester and A. Krivska and P Jacquet and L Guimarais and ASDEX Upgrade Team},

url = {http://stacks.iop.org/0741-3335/58/i=9/a=095005},

year  = {2016},

date = {2016-09-01},

journal = {Plasma Physics and Controlled Fusion},

volume = {58},

number = {9},

pages = {095005},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{1835,

title = {Conceptual study of an ICRH traveling-wave antenna system for low-coupling conditions as expected in DEMO},

author = {R. Ragona and A. Messiaen},

url = {http://stacks.iop.org/0029-5515/56/i=7/a=076009},

year  = {2016},

date = {2016-07-01},

journal = {Nuclear Fusion},

volume = {56},

number = {7},

pages = {076009},

abstract = {For the central heating of a fusion reactor ion cyclotron radio frequency heating (ICRH) is the first choice method as it is able to couple RF power to the ions without density limit. The drawback of this heating method is the problem of excitation of the magneto-sonic wave through the plasma boundary layer from the antenna located along the wall, without exceeding its voltage standoff. The amount of coupling depends on the antenna excitation and the surface admittance at the antenna output due to the plasma profile. The paper deals with the optimization of the antenna excitation by the use of sections of traveling-wave antennas (TWAs) distributed all along the reactor wall between the blanket modules. They are mounted and fed in resonant ring system(s). First, the physics of the coupling of a strap array is studied by simple models and the coupling code ANTITER II. Then, after the study of the basic properties of a TWA section, its feeding problem is solved by hybrids driving them in resonant ring circuit(s). The complete modeling is obtained from the matrices of the TWA sections connected to one of the feeding hybrid(s). The solution is iterated with the coupling code to determine the loading for a reference low-coupling ITER plasma profile. The resulting wave pattern up to the plasma bulk is derived. The proposed system is totally load resilient and allows us to obtain a very selective exciting wave spectrum. A discussion of some practical implementation problems is added.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{1753,

title = {Robust analysis of trends in noisy tokamak confinement data using geodesic least squares regression},

author = {G. Verdoolaege and A Shabbir and G Hornung},

url = {http://aip.scitation.org/doi/abs/10.1063/1.4960069},

doi = {10.1063/1.4960069},

year  = {2016},

date = {2016-07-01},

journal = {Review of Scientific Instruments},

volume = {87},

number = {11},

pages = {11D422},

note = {Proceedings of the 20th Topical Conference on High-Temperature Plasma Diagnostics, Atlanta, Georgia, USA, June 2014.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{1742,

title = {A classification scheme for edge-localized modes based on their probability distributions},

author = {A Shabbir and G Hornung and G. Verdoolaege},

url = {http://aip.scitation.org/doi/abs/10.1063/1.4955479},

doi = {10.1063/1.4955479},

year  = {2016},

date = {2016-06-01},

journal = {Review of Scientific Instruments},

volume = {87},

number = {11},

pages = {11D404},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{1741,

title = {A First Approach Toward Bayesian Estimation of Turbulent Plasma Properties from Reflectometry},

author = {G Hornung and A Shabbir and G. Verdoolaege},

editor = {American Nuclear Society},

year  = {2016},

date = {2016-05-01},

journal = {Fusion Science and Technology},

volume = {69},

number = {3},

pages = {586-594},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{1739,

title = {Ion cyclotron wave coupling in the magnetized plasma edge of tokamaks: impact of a finite, inhomogeneous density inside the antenna box},

author = {L Lu and K. Crombé and D. Van Eester},

url = {http://stacks.iop.org/0741-3335/58/i=5/a=055001},

year  = {2016},

date = {2016-05-01},

journal = {Plasma Physics and Controlled Fusion},

volume = {58},

number = {5},

pages = {055001},

abstract = {Most present ion cyclotron resonant frequency (ICRF) heating codes and antenna codes assume the antenna sitting in a vacuum region and consider the fast wave only, which implicitly performs an abrupt density transition from vacuum to above lower hybrid (LH) resonance. The impact of the appearance of the LH resonance is entirely overlooked in their simulations. We studied the impact of densities that decay continuously inside the antenna box on near field patterns and power coupling. A new full wave code based on the COMSOL Finite Element Solver has been developed to investigate this topic. It is shown that: up to the memory limits of the adopted workstation, the local RF field pattern in low-density regions below the LH resonance changes with the grid size. Interestingly and importantly, however, the total coupled toroidal spectrum is almost independent on the mesh size and is weakly affected by the presence of the density profile inside the antenna box in dipole toroidal strap phasing. This suggests one can drop out this density for coupling studies to speed up the computation. Simulation also shows that varying the density gradient in the fast wave evanescence region has no significant effect on wave coupling.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{1738,

title = {Parameter study of ICRH wave propagation in IShTAR},

author = {K. Crombé and D. Van Eester},

doi = {10.1017/S0022377816000234},

year  = {2016},

date = {2016-04-01},

journal = {Journal of Plasma Physics},

volume = {82},

number = {2},

pages = {905820203},

publisher = {Cambridge University Press},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{1736,

title = {Maximization of ICRF power by SOL density tailoring with local gas injection},

author = {P Jacquet and E. Lerche and D. Van Eester},

url = {http://stacks.iop.org/0029-5515/56/i=4/a=046001},

year  = {2016},

date = {2016-04-01},

journal = {Nuclear Fusion},

volume = {56},

number = {4},

pages = {046001},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{1737,

title = {Comparison of H-mode plasmas in JET-ILW and JET-C with and without nitrogen seeding},

author = {A E Jaervinen and C Giroud and M Groth and P Belo and S Brezinsek and M Beurskens and G Corrigan and S Devaux and P Drewelow and D Harting and A Huber and S. Jachmich and K Lawson and B Lipschultz and G Maddison and C Maggi and C Marchetto and S Marsen and G F Matthews and A G Meigs and D Moulton and B Sieglin and M F Stamp and S Wiesen and JET Contributors},

url = {http://stacks.iop.org/0029-5515/56/i=4/a=046012},

year  = {2016},

date = {2016-04-01},

journal = {Nuclear Fusion},

volume = {56},

number = {4},

pages = {046012},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{1735,

title = {Optimization of ICRH for core impurity control in JET-ILW},

author = {E. Lerche and D. Van Eester},

url = {http://stacks.iop.org/0029-5515/56/i=3/a=036022},

year  = {2016},

date = {2016-03-01},

journal = {Nuclear Fusion},

volume = {56},

number = {3},

pages = {036022},

abstract = {Ion cyclotron resonance frequency (ICRF) heating has been an essential component in the development of high power H-mode scenarios in the Jet European Torus ITER-like wall (JET-ILW). The ICRF performance was improved by enhancing the antenna-plasma coupling with dedicated main chamber gas injection, including the preliminary minimization of RF-induced plasma-wall interactions, while the RF heating scenarios where optimized for core impurity screening in terms of the ion cyclotron resonance position and the minority hydrogen concentration. The impact of ICRF heating on core impurity content in a variety of 2.5 MA JET-ILW H-mode plasmas will be presented, and the steps that were taken for optimizing ICRF heating in these experiments will be reviewed.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{1734,

title = {Characterisation of the deuterium recycling at the W divertor target plates in JET during steady-state plasma conditions and ELMs},

author = {S Brezinsek and S Wiesen and D Harting and C Guillemaut and A J Webster and K Heinola and A G Meigs and M Rack and Y Gao and G Sergienko and V Philipps and M F Stamp and S. Jachmich and JET Contributors},

url = {http://stacks.iop.org/1402-4896/2016/i=T167/a=014076},

year  = {2016},

date = {2016-02-01},

journal = {Physica Scripta},

volume = {2016},

number = {T167},

pages = {014076},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{1733,

title = {Advances in understanding and utilising ELM control in JET},

author = {I T Chapman and E Luna and P T Lang and Y Liang and B Alper and P Denner and D Frigione and L Garzotti and C J Ham and G T A Huijsmans and S. Jachmich and G Kocsis and M Lennholm and I Lupelli and F G Rimini and A C C Sips and JET Contributors},

url = {http://stacks.iop.org/0741-3335/58/i=1/a=014017},

year  = {2016},

date = {2016-01-01},

journal = {Plasma Physics and Controlled Fusion},

volume = {58},

number = {1},

pages = {014017},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{1732,

title = {Real-time control of ELM and sawtooth frequencies: similarities and differences},

author = {M Lennholm and D Frigione and J P Graves and P S Beaumont and T Blackman and I S Carvalho and I Chapman and R Dumont and R Felton and L Garzotti and M Goniche and A Goodyear and D Grist and S. Jachmich and T Johnson and P Lang and E. Lerche and E Luna and I Monakhov and R Mooney and J Morris and M F F Nave and M Reich and F Rimini and G Sips and H Sheikh and C Sozzi and M Tsalas and JET Contributors},

url = {http://stacks.iop.org/0029-5515/56/i=1/a=016008},

year  = {2016},

date = {2016-01-01},

journal = {Nuclear Fusion},

volume = {56},

number = {1},

pages = {016008},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{1710,

title = {Status of the benchmark activity of ICRF full-wave codes within EUROfusion WPCD and beyond},

author = {R Bilato and N Bertelli and M Brambilla and R Dumont and E F Jaeger and T Johnson and E. Lerche and O Sauter and D. Van Eester and L Villard},

url = {http://dx.doi.org/10.1063/1.4936499},

doi = {10.1063/1.4936499},

issn = {0094-243X},

year  = {2015},

date = {2015-12-10},

journal = {AIP Conference Proceedings},

volume = {1689},

number = {1},

pages = {060001+},

abstract = {As follow-up of the benchmark activity of ICRF full-wave codes within the EUROfusion Code Development for Integrated Modelling project (WPCD), a simple-to-complex approach has been devised for verification of the European ICRF codes, imported in the European-Integrated Modelling infrastructure, which represents a unique environment for input-data sharing and result analysis. This benchmark activity has been recently extended to non-European codes, in particular the ICRF full-wave AORSA code. Here we discussed the results of this benchmark.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{1699,

title = {Progress in controlling ICRF-edge interactions in ASDEX upgrade},

author = {V. Vl Bobkov and Ph Jacquet and R Ochoukov and W Zhang and R Bilato and F Braun and D Carralero and L Colas and A Czarnecka and R Dux and H Faugel and H Fünfgelder and J Jacquot and A. Křivská and T Lunt and D Milanesio and R Maggiora and O Meyer and I Monakhov and J. -M. Noterdaeme and S Potzel and Th and I. Stepanov and ASDEX Upgrade Team},

url = {http://dx.doi.org/10.1063/1.4936469},

doi = {10.1063/1.4936469},

issn = {0094-243X},

year  = {2015},

date = {2015-12-10},

journal = {AIP Conference Proceedings},

volume = {1689},

number = {1},

pages = {030004+},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{1713,

title = {Heating performances of a IC in-blanket ring array},

author = {G. Bosia and R. Ragona},

url = {http://dx.doi.org/10.1063/1.4936508},

doi = {10.1063/1.4936508},

issn = {0094-243X},

year  = {2015},

date = {2015-12-10},

journal = {AIP Conference Proceedings},

volume = {1689},

number = {1},

pages = {070001+},

abstract = {An important limiting factor to the use of ICRF as candidate heating method in a commercial reactor is due to the evanescence of the fast wave in vacuum and in most of the SOL layer, imposing proximity of the launching structure to the plasma boundary and causing, at the highest power level, high RF standing and DC rectified voltages at the plasma periphery, with frequent voltage breakdowns and enhanced local wall loading. In a previous work [1] the concept for an Ion Cyclotron Heating & Current Drive array (and using a different wave guide technology, a Lower Hybrid array) based on the use of periodic ring structure, integrated in the reactor blanket first wall and operating at high input power and low power density, was introduced. Based on the above concept, the heating performance of such array operating on a commercial fusion reactor is estimated.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{1708,

title = {Radio-frequency sheath voltages and slow wave electric field spatial structure},

author = {Laurent Colas and Ling-Feng Lu and A. Křivská and Jonathan Jacquot},

url = {http://dx.doi.org/10.1063/1.4936497},

doi = {10.1063/1.4936497},

issn = {0094-243X},

year  = {2015},

date = {2015-12-10},

journal = {AIP Conference Proceedings},

volume = {1689},

number = {1},

pages = {050009+},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{1700,

title = {Studies of RF sheaths and diagnostics on IShTAR},

author = {K. Crombé and S Devaux and R D'Inca and E Faudot and H Faugel and H Fünfgelder and S Heuraux and J Jacquot and F. Louche and J Moritz and R Ochoukov and M. Tripsky and D. Van Eester and T. Wauters and J. -M. Noterdaeme},

url = {http://dx.doi.org/10.1063/1.4936471},

doi = {10.1063/1.4936471},

issn = {0094-243X},

year  = {2015},

date = {2015-12-10},

journal = {AIP Conference Proceedings},

volume = {1689},

number = {1},

pages = {030006+},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{1709,

title = {First experimental results on the IShTAR testbed},

author = {R D'Inca and J Jacquot and R Ochoukov and I Morgal and K. Crombé and F. Louche and D. Van Eester and S Heuraux and S Devaux and J Moritz and E Faudot and H Fünfgelder and H Faugel and J. -M. Noterdaeme},

url = {http://dx.doi.org/10.1063/1.4936498},

doi = {10.1063/1.4936498},

issn = {0094-243X},

year  = {2015},

date = {2015-12-10},

journal = {AIP Conference Proceedings},

volume = {1689},

number = {1},

pages = {050010+},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{1714,

title = {Calibrations and verifications performed in view of the ILA reinstatement at JET},

author = {P. Dumortier and F. Durodié and W Helou and I Monakhov and C Noble and E Wooldridge and T Blackman and M Graham and contributors},

url = {http://dx.doi.org/10.1063/1.4936510},

doi = {10.1063/1.4936510},

issn = {0094-243X},

year  = {2015},

date = {2015-12-10},

journal = {AIP Conference Proceedings},

volume = {1689},

number = {1},

pages = {070003+},

abstract = {The calibrations and verifications that are performed in preparation of the ITER-Like antenna (ILA) reinstatement at JET are reviewed. A brief reminder of the ILA system layout is given. The different calibration methods and results are then discussed. They encompass the calibrations of the directional couplers present in the system, the determination of the relation between the capacitor position readings and the capacitance value, the voltage probes calibration inside the antenna housing, the RF cables characterization and the acquisition electronics circuit 

calibration. Earlier experience with the ILA has shown that accurate calibrations are essential for the control of the full ILA close-packed antenna array, its protection through the S-Matrix Arc Detection and the new second stage matching algorithm to be implemented. Finally the voltage stand-off of the capacitors is checked and the phase range achievable with the system is verified. The system layout is modified as to allow dipole operation over the whole operating frequency range when operating with the 3dB combiner-splitters.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{1719,

title = {Circuit model of the ITER-like antenna for JET and simulation of its control algorithms},

author = {F. Durodié and P. Dumortier and Walid Helou and A. Křivská and E. Lerche and JET Contributors},

url = {http://dx.doi.org/10.1063/1.4936520},

doi = {10.1063/1.4936520},

issn = {0094-243X},

year  = {2015},

date = {2015-12-10},

journal = {AIP Conference Proceedings},

volume = {1689},

number = {1},

pages = {070013+},

abstract = {The ITER-like Antenna (ILA) for JET [1] is a 2 toroidal by 2 poloidal array of Resonant Double Loops (RDL) featuring in-vessel matching capacitors feeding RF current straps in conjugate-T manner, a low impedance quarter-wave impedance transformer, a service stub allowing hydraulic actuator and water cooling services to reach the aforementioned capacitors and a 2nd stage phase-shifter-stub matching circuit allowing to correct/choose the conjugate-T working impedance. Toroidally adjacent RDLs are fed from a 3dB hybrid splitter. It has been operated at 33, 42 and 47MHz on plasma (2008-2009) while it presently estimated frequency range is from 29 to 49MHz. 

At the time of the design (2001-2004) as well as the experiments the circuit models of the ILA were quite basic. The ILA front face and strap array Topica model was relatively crude and failed to correctly represent the poloidal central septum, Faraday Screen attachment as well as the segmented antenna central septum limiter. The ILA matching capacitors, T-junction, Vacuum Transmission Line (VTL) and Service Stubs were represented by lumped circuit elements and simple transmission line models. 

The assessment of the ILA results carried out to decide on the repair of the ILA identified that achieving routine full array operation requires a better understanding of the RF circuit, a feedback control algorithm for the 2nd stage matching as well as tighter calibrations of RF measurements. 

The paper presents the progress in modelling of the ILA comprising a more detailed Topica model of the front face for various plasma Scrape Off Layer profiles, a comprehensive HFSS model of the matching capacitors including internal bellows and electrode cylinders, 3D-EM models of the VTL including vacuum ceramic window, Service stub, a transmission line model of the 2nd stage matching circuit and main transmission lines including the 3dB hybrid splitters. 

A time evolving simulation using the improved circuit model allowed to design and simulate the effectiveness of a feedback control algorithm for the 2nd stage matching and demonstrates the simultaneous matching and control of the 4 RDLs: 11 feedback loops control 21 actuators (8 capacitors, 4 phase shifters and 4 stubs for the 2nd stage matching, 4 main phase shifters controlling of the toroidal phasing and the electronically controlled phase between RF sources feeding top and bottom parts of the array and determines the poloidal phasing of the array which is solved explicitly at each time step) on (simulated) ELMy plasmas.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{1706,

title = {Wave induced density modification in RF sheaths and close to wave launchers},

author = {D. Van Eester and K. Crombé and Ling-Feng Lu},

url = {http://dx.doi.org/10.1063/1.4936493},

doi = {10.1063/1.4936493},

issn = {0094-243X},

year  = {2015},

date = {2015-12-10},

journal = {AIP Conference Proceedings},

volume = {1689},

number = {1},

pages = {050005+},

abstract = {With the return to full metal walls - a necessary step towards viable fusion machines - and due to the high power densities of current-day ICRH (Ion Cyclotron Resonance Heating) or RF 

(radio frequency) 

antennas, there is ample renewed interest in exploring the reasons for wave-induced sputtering and formation of hot spots. Moreover, there is experimental evidence on various machines that RF 

waves influence the density profile close to the wave launchers so that waves indirectly influence their own coupling efficiency. The present study presents a return to first principles and describes the wave-particle interaction using a 2-time scale model involving the equation of motion, the continuity equation and the wave equation on each of the time scales. Through the changing density pattern, the fast time scale dynamics is affected by the slow time scale events. In turn, the slow time scale density and flows are modified by the presence of the RF 

waves through quasilinear terms. Although finite zero order flows are identified, the usual cold plasma dielectric tensor - ignoring such flows - is adopted as a first approximation to describe the wave response to the RF driver. The resulting set of equations is composed of linear and nonlinear equations and is tackled in 1D in the present paper. Whereas the former can be solved using standard numerical techniques, the latter require special handling. At the price of multiple iterations, a simple 'derivative switch-on' procedure allows to reformulate the nonlinear problem as a sequence of linear problems. Analytical expressions allow a first crude assessment - revealing that the ponderomotive potential plays a role similar to that of the electrostatic potential arising from charge separation - but numerical implementation is required to get a feeling of the full dynamics. A few tentative examples are provided to illustrate the phenomena involved.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{1711,

title = {Modelling of ICRF heating in DEMO with special emphasis on bulk ion heating},

author = {Dani Gallart and Mervi Mantsinen and Y. O. Kazakov},

url = {http://dx.doi.org/10.1063/1.4936502},

doi = {10.1063/1.4936502},

issn = {0094-243X},

year  = {2015},

date = {2015-12-10},

journal = {AIP Conference Proceedings},

volume = {1689},

number = {1},

pages = {060004+},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{1715,

title = {SIDON: A simulator of radio-frequency networks. Application to WEST ICRF launchers},

author = {Walid Helou and P. Dumortier and F. Durodié and Marc Goniche and Julien Hillairet and Patrick Mollard and Gilles Berger-By and Jean-Michel Bernard and Laurent Colas and Gilles Lombard and Riccardo Maggiora and Roland Magne and Daniele Milanesio and Didier Moreau},

url = {http://dx.doi.org/10.1063/1.4936511},

doi = {10.1063/1.4936511},

issn = {0094-243X},

year  = {2015},

date = {2015-12-10},

journal = {AIP Conference Proceedings},

volume = {1689},

number = {1},

pages = {070004+},

abstract = {SIDON (SImulator of raDiO-frequency Networks) is an in-house developed Radio-Frequency (RF) network solver that has been implemented to cross-validate the design of WEST ICRF launchers and simulate their impedance matching algorithm while considering all mutual couplings and asymmetries. In this paper, the authors illustrate the theory of SIDON as well as results of its calculations. The authors have built time-varying plasma scenarios (a sequence of launchers front-faces L-mode and H-mode Z-matrices), where at each time step (1 millisecond here), SIDON solves the RF network. At the same time, when activated, the impedance matching algorithm controls the matching elements (vacuum capacitors) and thus their corresponding S-matrices. Typically a 1-second pulse requires around 10 seconds of computational time on a desktop computer. These tasks can be hardly handled by commercial RF software. This innovative work allows identifying strategies for the launchers future operation while insuring the limitations on the currents, voltages and electric fields, matching and Load-Resilience, as well as the required straps voltage amplitude/phase balance. In this paper, a particular attention is paid to the simulation of the launchers behavior when arcs appear at several locations of their circuits using SIDON calculator. This latter work shall confirm or identify strategies for the arc detection using various RF electrical signals. One shall note that the use of such solvers in not limited to ICRF launchers simulations but can be employed, in principle, to any linear or linearized RF problem.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{1716,

title = {Ion cyclotron resonance heating systems upgrade toward high power and CW operations in WEST},

author = {Julien Hillairet and Patrick Mollard and Yanping Zhao and Jean-Michel Bernard and Yuntao Song and Arnaud Argouarch and Gilles Berger-By and Nicolas Charabot and Gen Chen and Zhaoxi Chen and Laurent Colas and Jean-Marc Delaplanche and P. Dumortier and F. Durodié and Annika Ekedahl and Nicolas Fedorczak and Fabien Ferlay and Marc Goniche and Jean-Claude Hatchressian and Walid Helou and Jonathan Jacquot and Emmanuel Joffrin and Xavier Litaudon and Gilles Lombard and Riccardo Maggiora and Roland Magne and Daniele Milanesio and Jean-Claude Patterlini and Marc Prou and Jean-Marc Verger and Robert Volpe and Karl Vulliez and Yongsheng Wang and Konstantin Winkler and Qingxi Yang and Shuai Yuan},

url = {http://dx.doi.org/10.1063/1.4936512},

doi = {10.1063/1.4936512},

issn = {0094-243X},

year  = {2015},

date = {2015-12-10},

journal = {AIP Conference Proceedings},

volume = {1689},

number = {1},

pages = {070005+},

abstract = {The design of the WEST (Tungsten-W Environment in Steady-state Tokamak) 

Ion cyclotron resonance heating 

antennas is based on a previously tested conjugate-T Resonant Double Loops prototype equipped with internal vacuum matching capacitors. The design and construction of three new WEST ICRH antennas are being carried out in close collaboration with ASIPP, within the framework of the Associated Laboratory in the fusion field between IRFM and ASIPP. The coupling performance to the plasma and the load-tolerance have been improved, while adding Continuous Wave operation capability by introducing water cooling in the entire antenna. On the generator side, the operation class of the high power tetrodes is changed from AB to B in order to allow high power operation (up to 3 MW per antenna) under higher VSWR (up to 2:1). Reliability of the generators is also improved by increasing the cavity breakdown voltage. The control and data acquisition 

system is also upgraded in order to resolve and react on fast events, such as ELMs. A new optical arc detection system comes in reinforcement of the Vr/Vf and SHAD systems.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{1707,

title = {Full wave propagation modelling in view to integrated ICRH wave coupling/RF sheaths modelling},

author = {Jonathan Jacquot and Volodymyr Bobkov and Laurent Colas and Stéphane Heuraux and A. Křivská and Lingfeng Lu and J. -M. Noterdaeme and team and team},

url = {http://dx.doi.org/10.1063/1.4936496},

doi = {10.1063/1.4936496},

issn = {0094-243X},

year  = {2015},

date = {2015-12-10},

journal = {AIP Conference Proceedings},

volume = {1689},

number = {1},

pages = {050008+},

abstract = {RF 

sheaths 

rectification can be the reason for operational limits for Ion Cyclotron Range of Frequencies (ICRF) heating systems via impurity production or excessive heat loads. To simulate this process in realistic geometry, the Self-consistent Sheaths and Waves for Ion Cyclotron Heating (SSWICH) code is a minimal set of coupled equations that computes self-consistently wave propagation and DC plasma biasing. The present version of its wave propagation module only deals with the Slow Wave assumed to be the source of RF 

sheath oscillations. However the ICRF power coupling to the plasma is due to the fast wave (FW). This paper proposes to replace this one wave equation module by a full wave module in either 2D or 3D as a first step towards integrated modelling of RF 

sheaths and wave coupling. Since the FW is propagative in the main plasma, Perfectly Matched Layers (PMLs) adapted for plasmas were implemented at the inner side of the simulation domain to absorb outgoing waves and tested numerically with tilted B 

0 in Cartesian geometry, by either rotating the cold magnetized plasma 

dielectric tensors in 2D or rotating the coordinate vector basis in 3D. The PML was further formulated in cylindrical coordinates to account for for the toroidal curvature of the plasma. 

Toroidal curvature itself does not seem to change much the coupling. A detailed 3D geometrical description of Tore Supra and ASDEX Upgrade (AUG) antennas was included in the coupling code. The full antenna structure was introduced, since its toroidal symmetry with respect to the septum plane is broken (FS bars, toroidal phasing, non-symmetrical structure). Reliable convergence has been obtained with the density profile up to the leading edge of antenna limiters. Parallel electric field maps have been obtained as an input for the present version of SSWICH.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{1702,

title = {Fast ion generation and bulk plasma heating with three-ion ICRF scenarios},

author = {Y. O. Kazakov and D. Van Eester and R Dumont and J. Ongena and E. Lerche and A. Messiaen},

url = {http://dx.doi.org/10.1063/1.4936473},

doi = {10.1063/1.4936473},

issn = {0094-243X},

year  = {2015},

date = {2015-12-10},

journal = {AIP Conference Proceedings},

volume = {1689},

number = {1},

pages = {030008+},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{1704,

title = {Estimation of sheath potentials in front of ASDEX upgrade ICRF antenna with SSWICH asymptotic code},

author = {A. Křivská and V Bobkov and L Colas and J Jacquot and D Milanesio and Ochoukov and team},

url = {http://dx.doi.org/10.1063/1.4936490},

doi = {10.1063/1.4936490},

issn = {0094-243X},

year  = {2015},

date = {2015-12-10},

journal = {AIP Conference Proceedings},

volume = {1689},

number = {1},

pages = {050002+},

abstract = {Multi-megawatt Ion Cyclotron Range of Frequencies (ICRF) heating became problematic in ASDEX Upgrade (AUG) tokamak after coating of ICRF antenna 

limiters and other plasma facing components by tungsten. Strong impurity influx was indeed produced at levels of injected power markedly lower than in the previous experiments. It is assumed that the impurity production is mainly driven by parallel component of Radio-Frequency (RF) antenna electric near-field E// that is rectified in sheaths. In this contribution we estimate poloidal distribution of sheath 

Direct Current (DC) potential in front of the ICRF antenna and simulate its relative variations over the parametric scans performed during experiments, trying to reproduce some of the experimental observations. In addition, relative comparison between two types of AUG ICRF antenna configurations, used for experiments in 2014, has been performed. For this purpose we use the Torino Polytechnic Ion Cyclotron Antenna (TOPICA) code and asymptotic version of the Self-consistent Sheaths and Waves for Ion Cyclotron Heating (SSWICH) code. Further, we investigate correlation between amplitudes of the calculated oscillating sheath voltages and the E// fields computed at the lateral side of the antenna box, in relation with a heuristic antenna design strategy at IPP Garching to mitigate RF sheaths.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{1701,

title = {Status of the ITER ion cyclotron heating and current drive system},

author = {P. U. Lamalle and B Beaumont and F Kazarian and T Gassmann and G Agarici and Alonzo T Montemayor and R Bamber and J M Bernard and D Boilson and A Cadinot and F Calarco and L Colas and X Courtois and C Deibele and F. Durodié and J Fano and E Fredd and R Goulding and N Greenough and J Hillairet and J Jacquinot and A S Kaye and M Kočan and H Labidi and D Leichtle and A Loarte and M McCarthy and A. Messiaen and L Meunier and A Mukherjee and C Oberlin-Harris and A M Patel and B Peters and K Rajnish and D Rasmussen and R Sanabria and R Sartori and R Singh and D Swain and R G Trivedi and A Turner},

url = {http://dx.doi.org/10.1063/1.4936472},

doi = {10.1063/1.4936472},

issn = {0094-243X},

year  = {2015},

date = {2015-12-10},

journal = {AIP Conference Proceedings},

volume = {1689},

number = {1},

pages = {030007+},

abstract = {The paper reports on latest developments for the ITER Ion Cyclotron Heating and Current Drive system: imminent acceptance tests of a prototype power supply at full power; successful factory acceptance of candidate RF 

amplifier tubes which will be tested on dedicated facilities; further design integration and experimental validation of transmission line components under 6MW hour-long pulses. The antenna Faraday shield thermal design has been validated above requirements by cyclic high heat flux tests. R&D on ceramic brazing is under way for the RF vacuum windows. The antenna port plug RF design is stable but major evolution of the mechanical design is in preparation to achieve compliance with the load specification, warrant manufacturability and incorporate late interface change requests. The antenna power coupling capability predictions have been strengthened by showing that, if the plasma scrape-off layer turns out to be steep and the edge density low, the reference burning plasma can realistically be displaced to improve the coupling.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{1698,

title = {ICRH for core impurity mitigation in JET-ILW},

author = {E. Lerche and M Goniche and P Jacquet and D. Van Eester and V Bobkov and L Colas and I Monakhov and F Rimini and A Czarnecka and K. Crombé and R Dumont and J Hobirk and Y. O. Kazakov and M L Mayoral and L Meneses and J Mlynar and C Noble and I Nunes and J. Ongena and V Petrzilka and M Reich and M Santala and A Shaw and M Tsalas and Contributors},

url = {http://dx.doi.org/10.1063/1.4936467},

doi = {10.1063/1.4936467},

issn = {0094-243X},

year  = {2015},

date = {2015-12-10},

journal = {AIP Conference Proceedings},

volume = {1689},

number = {1},

pages = {030002+},

abstract = {Ion cyclotron resonance frequency (ICRF) heating has been an essential component in the development of high power H-mode scenarios in JET-ILW. The steps that were taken for the successful use of ICRF heating in terms of enhancing the power capabilities and optimizing the heating performance in view of core impurity mitigation in these experiments will be reviewed.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{1703,

title = {N=2 ICRH of H majority plasmas in JET-ILW},

author = {E. Lerche and D. Van Eester and Y. O. Kazakov and P Jacquet and I Monakhov and M Goniche and L Colas and F Rimini and K. Crombé and R Dumont and V Kiptily and M Santala and contributors},

url = {http://dx.doi.org/10.1063/1.4936486},

doi = {10.1063/1.4936486},

issn = {0094-243X},

year  = {2015},

date = {2015-12-10},

journal = {AIP Conference Proceedings},

volume = {1689},

number = {1},

pages = {040003+},

abstract = {Heating single ion species plasmas with ICRF is a challenging task: Fundamental ion cyclotron heating (w = wci) suffers from the adverse polarization of the RF electric fields near the majority cyclotron resonance while second harmonic heating (w = 2wci) typically requires pre-heating of the plasma ions to become efficient. Recently},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{1720,

title = {Designing the IShTAR antenna: Physics and engineering aspects},

author = {F. Louche and J Jacquot and K. Crombé and D. Van Eester and R D'Inca and S Devaux and E Faudot and H Faugel and H Fünfgelder and S Heuraux and I Morgal and J Moritz and R Ochoukov and J. -M. Noterdaeme},

url = {http://dx.doi.org/10.1063/1.4936523},

doi = {10.1063/1.4936523},

issn = {0094-243X},

year  = {2015},

date = {2015-12-10},

journal = {AIP Conference Proceedings},

volume = {1689},

number = {1},

pages = {070016+},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{1705,

title = {Wave coupling in the magnetized plasma edge: Impact of a finite, inhomogeneous density inside the antenna box},

author = {L Lu and K. Crombé and D. Van Eester and L Colas and J Jacquot},

url = {http://dx.doi.org/10.1063/1.4936491},

doi = {10.1063/1.4936491},

issn = {0094-243X},

year  = {2015},

date = {2015-12-10},

journal = {AIP Conference Proceedings},

volume = {1689},

number = {1},

pages = {050003+},

abstract = {Most present Ion Cyclotron Resonant Frequency (ICRF) heating codes and antenna codes assume the antenna sitting in a vacuum region and consider the fast wave only, which implicitly performs an abrupt density transition from vacuum to above lower hybrid (LH) resonance. We studied the impact of densities that decay continuously inside the antenna box on near field patterns and power coupling. A new full wave code based on the COMSOL Finite Element Solver has been developed to investigate this topic. It is shown that: up to the memory limits of the adopted workstation, the local RF field pattern in low-density regions below the LH resonance changes with the grid size. Interestingly and importantly, however, the total coupled spectrum is independent to the mesh size and is weakly affected by the presence of the density profile inside the antenna box in dipole phasing. Thus one can drop out this density for coupling studies. Simulation also shows that varying the density gradient in the fast wave evanescence region has no significant effect on wave coupling.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{1717,

title = {Analysis of the phase control of the ITER ICRH antenna array. Influence on the load resilience and radiated power spectrum},

author = {A. Messiaen and D Swain and J. Ongena and M. Vervier},

url = {http://dx.doi.org/10.1063/1.4936518},

doi = {10.1063/1.4936518},

issn = {0094-243X},

year  = {2015},

date = {2015-12-10},

journal = {AIP Conference Proceedings},

volume = {1689},

number = {1},

pages = {070011},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{1712,

title = {Monte Carlo simulation of ICRF discharge initiation in ITER},

author = {M. Tripsky and T. Wauters and A. I. Lyssoivan and A. Křivská and F. Louche and M. Van Schoor and J. -M. Noterdaeme},

url = {http://dx.doi.org/10.1063/1.4936507},

doi = {10.1063/1.4936507},

issn = {0094-243X},

year  = {2015},

date = {2015-12-10},

journal = {AIP Conference Proceedings},

volume = {1689},

number = {1},

pages = {060009+},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{1718,

title = {Study of the choice of the decoupling layout for the ITER ICRH system},

author = {M. Vervier and A. Messiaen and J. Ongena and F. Durodié},

url = {http://dx.doi.org/10.1063/1.4936519},

doi = {10.1063/1.4936519},

issn = {0094-243X},

year  = {2015},

date = {2015-12-10},

journal = {AIP Conference Proceedings},

volume = {1689},

number = {1},

pages = {070012+},

abstract = {10 decouplers are used to neutralize the mutual coupling effects and to control the current amplitude of the 24 straps array of the ITER ICRH antenna in the case of current drive phasing. In the case of heating phasing only 4 decouplers are active and the array current control needs to act on the ratio between the power delivered by the 4 generators. This ratio is very sensitive to the precise adjustment of the antenna array phasing. The maximum total radiated power capability is then limited when the power of one generator reaches its maximum value. With the addition of four switches all 10 installed decouplers are made active and can act on all mutual coupling effects with equal source power from the 4 generators. With four more switches the current drive phasing could work with a reduced poloidal phasing resulting in a 35% increase of its coupling to the plasma.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{1730,

title = {A crude model to study radio frequency induced density modification close to launchers},

author = {D. Van Eester and K. Crombé},

url = {http://dx.doi.org/10.1063/1.4936979},

doi = {10.1063/1.4936979},

year  = {2015},

date = {2015-12-01},

journal = {Physics of Plasmas},

volume = {22},

number = {12},

pages = {122505},

keywords = {},

pubstate = {published},

tppubtype = {article}

}