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RADIO FREQUENCY POWER IN PLASMAS: 15th Topical Conference on Radio Frequency Power in Plasmas Date: 19-21 May 2003 Location: Moran, Wyoming (USA) ISBN: 0-7354-0158-6 Editor(s): Cary B. Forest
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Waves and Instabilities in Dusty Plasmas

Robert L. Merlino

AIP Conf. Proc. 694, pp. 3-14; doi:http://dx.doi.org/10.1063/1.1637991 (12 pages)

Online Publication Date: 19 December 2003

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This review article is divided into five parts. The Introduction contains some examples of dusty plasmas in the Universe and in the laboratory. This is followed by a brief section describing the mechanisms by which dust particles acquire an electrical charge in plasmas. The next section provides theoretical background for understanding the effect of dust on waves and instabilities in dusty plasmas. A description of some of the experimental studies of waves in dusty plasmas is then given. A few concluding remarks are then made. © 2003 American Institute of Physics
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52.27.Lw Dusty or complex plasmas; plasma crystals
52.35.Fp Electrostatic waves and oscillations (e.g., ion-acoustic waves)
52.27.Gr Strongly-coupled plasmas

Electron Bernstein wave heating in fusion plasmas

H. P. Laqua, W7‐AS Team, and ECRH‐Group

AIP Conf. Proc. 694, pp. 15-23; doi:http://dx.doi.org/10.1063/1.1637992 (9 pages) | Cited 1 time

Online Publication Date: 19 December 2003

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Abstract Unavailable
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52.50.Sw Plasma heating by microwaves; ECR, LH, collisional heating
52.35.Fp Electrostatic waves and oscillations (e.g., ion-acoustic waves)
52.55.Wq Current drive; helicity injection

Lower Hybrid Current Drive: An Overview of Simulation Models, Benchmarking with Experiment, and Predictions for Future Devices

P. T. Bonoli, E. Barbato, R. W. Harvey, and F. Imbeaux

AIP Conf. Proc. 694, pp. 24-40; doi:http://dx.doi.org/10.1063/1.1637993 (17 pages) | Cited 4 times

Online Publication Date: 19 December 2003

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This paper reviews the status of lower hybrid current drive (LHCD) simulation and modeling. We first discuss modules used for wave propagation, absorption, and current drive with particular emphasis placed on comparing exact numerical solutions of the Fokker Planck equation in 2‐D with solution methods that employ 1‐D and adjoint approaches. We also survey model predictions for LHCD in past and present experiments showing detailed comparisons between simulated and observed current drive efficiencies and hard X‐ray profiles. Finally we discuss several model predictions for LH current profile control in proposed next step reactor options. © 2003 American Institute of Physics
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52.50.Sw Plasma heating by microwaves; ECR, LH, collisional heating
52.55.Wq Current drive; helicity injection
52.35.Hr Electromagnetic waves (e.g., electron-cyclotron, Whistler, Bernstein, upper hybrid, lower hybrid)
52.65.Ff Fokker-Planck and Vlasov equation

Bulk Plasma Rotation in the Presence of Waves in the Ion Cyclotron Range of Frequencies

L.‐G. Eriksson, J.‐M. Noterdaeme, S. Assas, C. Giroud, J. DeGrassie, T. Hellsten, T. Johnson, V. G. Kiptily, K. Kirov, M. Mantsinen, K.‐D. Zastrow, M. DeBaar, J. Brzozowski, R. Budny, R. Cesario, et al.

AIP Conf. Proc. 694, pp. 41-49; doi:http://dx.doi.org/10.1063/1.1637994 (9 pages)

Online Publication Date: 19 December 2003

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Experiments with directed ICRF waves have for the first time in JET demonstrated the influence of absorbed wave momentum on bulk plasma rotation. Resonating fast ions acted as an intermediary in this process and the experiments therefore provided evidence for the effect of fast ions on the plasma rotation. Results from these experiments are reviewed together with results from ICRF heated plasmas with symmetric spectra in JET and Tore Supra. The relevance of different theoretical models is briefly considered. © 2003 American Institute of Physics
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52.50.Qt Plasma heating by radio-frequency fields; ICR, ICP, helicons
52.55.Fa Tokamaks, spherical tokamaks
52.30.-q Plasma dynamics and flow

Study of Ion Cyclotron Range of Frequencies Mode Conversion in the Alcator C‐Mod Tokamak

Y. Lin, S. J. Wukitch, P. T. Bonoli, A. Mazurenko, E. Nelson‐Melby, M. Porkolab, J. C. Wright, I. H. Hutchinson, E. S. Marmar, D. Mossessian, S. Wolfe, C. K. Phillips, G. Schilling, and P. Phillips

AIP Conf. Proc. 694, pp. 50-57; doi:http://dx.doi.org/10.1063/1.1637995 (8 pages)

Online Publication Date: 19 December 2003

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ICRF mode conversion (MC) in H(3He, D) and D(H) plasmas have been studied in detail in Alcator C‐Mod. In H(3He, D) plasma, the mode converted ion cyclotron wave (MC ICW) was observed in tokamak plasmas for the first time using a phase contrast imaging system. The MC ICW was observed in the low field side of the ion‐ion hybrid layer, and generally had a wavelength in‐between the fast wave and the MC ion Bernstein wave (IBW). Localized mode conversion electron heating (MCEH) has been clearly observed for the first time in D(H) plasmas with moderate hydrogen concentration in Alcator C‐Mod. Both on‐ and off‐axis (high field side) MCEH have been studied. The MCEH profile was obtained from a break in slope analysis of Te signals in the presence of rf shut‐off. The experimental profiles were qualitatively in agreement with the predictions of the two‐dimensional full‐wave poloidal mode code TORIC. The electron heating contributions from MC ICW and MC IBW are examined from the TORIC simulations. © 2003 American Institute of Physics
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52.50.Qt Plasma heating by radio-frequency fields; ICR, ICP, helicons
52.55.Fa Tokamaks, spherical tokamaks
52.35.Mw Nonlinear phenomena: waves, wave propagation, and other interactions (including parametric effects, mode coupling, ponderomotive effects, etc.)

The Analysis of ICRF Heating Experiment in View of the Confinement of High‐energy Particles in LHD

K. Saito, R. Kumazawa, T. Mutoh, T. Seki, T. Watari, F. Shimpo, G. Nomura, A. Kato, M. Yokota, M. Isobe, T. Ozaki, M. Osakabe, M. Sasao, T. Saida, T. Yamamoto, et al.

AIP Conf. Proc. 694, pp. 58-65; doi:http://dx.doi.org/10.1063/1.1637996 (8 pages) | Cited 1 time

Online Publication Date: 19 December 2003

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The confinement of high‐energy particles produced by ICRF heating was studied in LHD experimentally setting magnetic axis at 3.6m and 3.75m in two methods. It was concluded that the confinement of high‐energy particles with Rax=3.6 m was better than that with Rax=3.75m. Based on this result the long pulse experiments were conducted in the magnetic configuration of Rax=3.6m. The plasma was sustained for 150sec. The total input power reached 71MJ though the pulse length was limited by the collapse of plasma due to density increase. The second harmonic experiment was done also with Rax=3.6m. The stored energy increased and the particles with the high‐energy were observed. © 2003 American Institute of Physics
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52.50.Qt Plasma heating by radio-frequency fields; ICR, ICP, helicons
52.55.Jd Magnetic mirrors, gas dynamic traps
52.70.-m Plasma diagnostic techniques and instrumentation

Recent 3He Radio Frequency Heating Experiments On JET

D. Van Eester, F. Imbeaux, P. Mantica, M. Mantsinen, M. de Baar, P. de Vries, L.‐G. Eriksson, R. Felton, A. Figueiredo, J. Harling, E. Joffrin, K. Lawson, H. Leggate, X. Litaudon, V. Kiptily, et al.

AIP Conf. Proc. 694, pp. 66-73; doi:http://dx.doi.org/10.1063/1.1637997 (8 pages) | Cited 2 times

Online Publication Date: 19 December 2003

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Various ITER relevant experiments using 3He in a majority D plasma were performed in the recent JET campaigns. Two types can be distinguished: dedicated studies of the various RF heating scenarios which rely on the presence of 3He, and physics studies using RF heating as a working tool to provide a tunable heat source. As the success of a number of these experiments depended on the capability to keep the 3He concentration fixed, real time control of the 3He concentration was developed and used. This paper presents a brief overview of the results obtained, zooms in on some of the more interesting recent findings and discusses some of the theoretical background. © 2003 American Institute of Physics
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52.50.Qt Plasma heating by radio-frequency fields; ICR, ICP, helicons
52.55.Fa Tokamaks, spherical tokamaks
52.35.Mw Nonlinear phenomena: waves, wave propagation, and other interactions (including parametric effects, mode coupling, ponderomotive effects, etc.)

Local Improvement Confinement in the Ion Bernstein (IBW) Experiment on FTU (Frascati Tokamak Upgrade)

R. Cesario, A. Cardinali, C. Castaldo, M. Marinucci, G. Ravera, S. Bernabei, E. Giovannozzi, M. Leigheb, F. Paoletti, V. Pericoli‐Ridolfini, F. Zonca, G. Apruzzese, R. De Angelis, E. Giovannozzi, L. Gabellieri, et al.

AIP Conf. Proc. 694, pp. 74-81; doi:http://dx.doi.org/10.1063/1.1637998 (8 pages)

Online Publication Date: 19 December 2003

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New experiments with the ion Bernstein waves (IBW) has been performed on FTU both in Hydrogen (H) and Deuterium (D) majority plasmas, at higher radio‐frequency power level, plasma density, current, lower effective ion charge than in previous campaign of 1999. Also in these conditions, no role is played by non‐linear edge physics, which prevented, instead, the RF penetration in the plasma bulk of DIII‐D. With resonant toroidal magnetic field (≈8T), improved confinement occurs inside a radial region of 1/3 of the minor radius operating in H‐plasma, and 2/3 of the minor radius operating in D‐majority plasma. Such behavior is consistent with the model of turbulence suppression by locally‐induced‐IBW‐sheared flow expected to occur close the resonant layer. The FTU results provide support for active control of the pressure profile by IBW which is of relevance for advanced tokamaks . © 2003 American Institute of Physics
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52.55.Fa Tokamaks, spherical tokamaks
52.50.Qt Plasma heating by radio-frequency fields; ICR, ICP, helicons
52.35.Hr Electromagnetic waves (e.g., electron-cyclotron, Whistler, Bernstein, upper hybrid, lower hybrid)

Properties of segmented Ion Cyclotron antennas

G. Bosia and S. Bremond

AIP Conf. Proc. 694, pp. 82-85; doi:http://dx.doi.org/10.1063/1.1637999 (4 pages) | Cited 1 time

Online Publication Date: 19 December 2003

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A possible issue for Ion Cyclotron Heating and Current Drive systems in next step fusion devices is related to the high electric field at which these systems are planned to operate, which may limit the power transfer efficiency to the plasma core. This paper addresses the problem of maintaining a high power handling in an IC launcher at high power density, with some suggestion for a solution. © 2003 American Institute of Physics
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52.50.Qt Plasma heating by radio-frequency fields; ICR, ICP, helicons
52.55.Wq Current drive; helicity injection
52.40.Fd Plasma interactions with antennas; plasma-filled waveguides

Interaction of Neutral Beam (NB) Injected Fast Ions With Ion Cyclotron Resonance Frequency (ICRF) Waves

M. Choi, V. S. Chan, S. C. Chiu, Y. A. Omelchenko, Y. Sentoku, and H. E. St. John

AIP Conf. Proc. 694, pp. 86-89; doi:http://dx.doi.org/10.1063/1.1638000 (4 pages) | Cited 3 times

Online Publication Date: 19 December 2003

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Existing tokamaks such as DIII‐D and future experiments like ITER employ both NB injection (NBI) and ion‐cyclotron resonance heating (ICRH) for auxiliary heating and current drive. The presence of energetic particles produced by NBI can result in absorption of the Ion cyclotron radio frequency (ICRF) power. ICRF can also interact with the energetic beam ions to alter the characteristics of NBI momentum deposition and resultant impact on current drive and plasma rotation. To study the synergism between NBI and ICRF, a simple physical model for the slowing‐down of NB injected fast ions is implemented in a Monte‐Carlo rf orbit code. This paper presents the first results. The velocity space distributions of energetic ions generated by ICRF and NBI are calculated and compared. The change in mechanical momentum of the beam and an estimate of its impact on the NB‐driven current are presented and compared with ONETWO simulation results. © 2003 American Institute of Physics
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52.50.Qt Plasma heating by radio-frequency fields; ICR, ICP, helicons
52.40.Mj Particle beam interactions in plasmas
52.55.Fa Tokamaks, spherical tokamaks

RF‐Sheath Assessment of ICRF Antenna Geometry for Long Pulses

L. Colas, S. Heuraux, and S. Bremond

AIP Conf. Proc. 694, pp. 90-93; doi:http://dx.doi.org/10.1063/1.1638001 (4 pages)

Online Publication Date: 19 December 2003

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Monitoring powered Ion Cyclotron Resonance Frequency (ICRF) antennas in magnetic fusion devices has revealed localized modifications of the plasma edge in the antenna shadow, most of them probably related to an enhanced polarization of the Scrape‐Off Layer (SOL) through Radio‐Frequency (RF) sheath rectification. Although tolerable on present short RF pulses, sheaths should be minimized, as they may hinder proper operation of steady‐state antennas and other subsystems connected magnetically to them, such as lower hybrid grills. As a first step towards mitigating RF sheaths in the design of future antennas, the present paper analyses the spatial structure of sheath potential maps in their vicinity, in relation with the 3D topology of RF near fields and the geometry of antenna front faces. Various combinations of poloidal radiating straps are first considered, and results are confronted to those inferred from transmission line theory. The dependence of sheath potentials on RF voltages or RF currents is studied. The role of RF near‐field symmetries along tilted field lines is stressed to interpret such effects as that of strap phasing. A generalization of the “dipole effect” is proposed. With similar arguments, the behavior of Faraday screen corners, where hot spots concentrate on Tore Supra (TS), is then studied. The merits of aligning the antenna structure with the tilted magnetic field are thus discussed. The effect of switching from TS (high RF voltage near corners) to ITER‐like electrical configurations of the straps (high voltage near equatorial plane) is also analyzed. © 2003 American Institute of Physics
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52.50.Qt Plasma heating by radio-frequency fields; ICR, ICP, helicons
52.40.Fd Plasma interactions with antennas; plasma-filled waveguides
52.40.Kh Plasma sheaths
52.65.-y Plasma simulation

ELM Resilient External Matching System for the ICRF System of ITER: 2. Design of the Components and Implementation

P. Dumortier, F. Durodié, A. Messiaen, and S. Brons

AIP Conf. Proc. 694, pp. 94-97; doi:http://dx.doi.org/10.1063/1.1638002 (4 pages) | Cited 2 times

Online Publication Date: 19 December 2003

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This paper summarizes the design and implementation of an ICRF system for ITER capable of radiating 20 MW and matched to the power source outside the machine vacuum. The key points are the absence of in‐vessel remotely operated parts, the ELM resilient conjugate‐T matching through conventional line stretchers, the possibility to modify the tuning layout without breaking the machine vacuum and the reduction of the number of matching circuits to four. © 2003 American Institute of Physics
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52.50.Qt Plasma heating by radio-frequency fields; ICR, ICP, helicons
52.40.Fd Plasma interactions with antennas; plasma-filled waveguides
52.55.Fa Tokamaks, spherical tokamaks

The ITER‐like ICRH Launcher Project For JET

F. Durodié, G. Agarici, G. Amarante, F. W. Baity, B. Beaumont, S. Brémond, P. Chappuis, C. Damiani, J. Fanthome, R. H. Goulding, J. Hosea, G. H. Jones, A. Kaye, P. U. Lamalle, G. D. Loesser, et al.

AIP Conf. Proc. 694, pp. 98-101; doi:http://dx.doi.org/10.1063/1.1638003 (4 pages)

Online Publication Date: 19 December 2003

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The paper reports on the status of the JET ITER‐Like ICRF Antenna project and highlights main challenges that have come up during its design phase. © 2003 American Institute of Physics
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52.50.Qt Plasma heating by radio-frequency fields; ICR, ICP, helicons
52.40.Fd Plasma interactions with antennas; plasma-filled waveguides
52.55.Fa Tokamaks, spherical tokamaks

Initial operation of the JET ITER‐like High‐Power Prototype ICRF Antenna

R. H. Goulding, F. W. Baity, F. Durodié, A. Fadnek, J. C. Hosea, G. H. Jones, G. D. Loesser, B. E. Nelson, D. A. Rasmussen, P. M. Ryan, D. O. Sparks, D. W. Swain, and R. Walton

AIP Conf. Proc. 694, pp. 102-105; doi:http://dx.doi.org/10.1063/1.1638004 (4 pages)

Online Publication Date: 19 December 2003

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Fabrication and assembly of a High Power Prototype (HPP) of the JET ITER‐like Ion Cyclotron Range of Frequencies (ICRF) launcher have been completed at Oak Ridge National Laboratory (ORNL), and high power tests have begun. The HPP consists of one quadrant of the full 7.5 MW antenna (1). The prototype is the product of a collaboration between ORNL, Princeton Plasma Physics Laboratory, and EFDA‐JET/UKAEA. Internal matching capacitors are utilized in a circuit that maintains a voltage standing wave ratio (VSWR) at the input < 1.5 over a factor of ten range in resistive loading. Short (.05 s) pulses have achieved > 45 kV peak voltage at the internal matching capacitors, which is greater than the original design voltage. High power pulses up to 2s have been run. Diagnostics include thermocouples, voltage probes at the capacitors and along the integral λ/4 matching transformer, and an optical temperature sensor for in‐situ measurements of capacitor temperatures. Low power measurements of electrical characteristics of the antenna have been made and compared with a 3‐D electromagnetic model. © 2003 American Institute of Physics
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52.50.Qt Plasma heating by radio-frequency fields; ICR, ICP, helicons
52.40.Fd Plasma interactions with antennas; plasma-filled waveguides
52.55.Fa Tokamaks, spherical tokamaks

Measurements and Calculations of Electrical Properties of ICRF Antennas

D. A. Hartmann, R. Bilato, D. Birus, M. Brambilla, F. Braun, J.‐M. Noterdaeme, and F. Wesner

AIP Conf. Proc. 694, pp. 106-109; doi:http://dx.doi.org/10.1063/1.1638005 (4 pages)

Online Publication Date: 19 December 2003

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The S‐matrix of mock‐up ICRF antennas and the ASDEX Upgrade antenna were measured and compared with the commercial code HFSS ™ , designed to calculate electromechanical properties of structures, and with FELICE, written to calculate the coupling of ICRH antennas to a warm plasma in slab geometry, but also usable for calculating antenna properties without plasma. Proper assessment of the boundary conditions led to excellent agreement between the measurements and the results of HFSS for a wide range of antennas. Good agreement between the measurements and the calculations with FELICE was found for those cases were the actual antenna geometries and those that could be implemented in FELICE were not too different. © 2003 American Institute of Physics
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52.50.Qt Plasma heating by radio-frequency fields; ICR, ICP, helicons
52.40.Fd Plasma interactions with antennas; plasma-filled waveguides
52.65.-y Plasma simulation

The Effect of Weak Single Pass Damping on the Coupled ICRH Power Spectrum

T. Hellsten and M. Laxåback

AIP Conf. Proc. 694, pp. 110-113; doi:http://dx.doi.org/10.1063/1.1638006 (4 pages)

Online Publication Date: 19 December 2003

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Consequences of coupling to eigenmodes during ICRH for weak single pass damping are discussed. A degradation of the central heating and an enhancement of parasitic absorption are found as the single pass absorption decreases. © 2003 American Institute of Physics
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52.50.Qt Plasma heating by radio-frequency fields; ICR, ICP, helicons
52.40.Fd Plasma interactions with antennas; plasma-filled waveguides
52.35.Mw Nonlinear phenomena: waves, wave propagation, and other interactions (including parametric effects, mode coupling, ponderomotive effects, etc.)

The Radial Mode Transition of Excited Fast Alfvén Waves in the Mirror Plasmas

H. Higaki, M. Ichimura, Y. Yamaguchi, S. Kakimoto, K. Horinouchi, K. Ide, H. Utsumi, D. Inoue, H. Hojo, and K. Yatsu

AIP Conf. Proc. 694, pp. 114-117; doi:http://dx.doi.org/10.1063/1.1638007 (4 pages) | Cited 1 time

Online Publication Date: 19 December 2003

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For producing a high density and high energy plasma in the GAMMA10 tandem mirror, the high harmonics ICRF waves were employed. The axial wave number of excited fast Alfvén waves with the frequency of 41.5 MHz was measured for the wide range of plasma parameters with magnetic probes. It was found that the plasma density increased clearly by applying the high harmonics ICRF (f = 41.5MHz) and the radial mode transition of excited fast Alfvén wave was observed at nl ∼ 5 × 10 13 cm −2. © 2003 American Institute of Physics
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52.50.Qt Plasma heating by radio-frequency fields; ICR, ICP, helicons
52.35.Bj Magnetohydrodynamic waves (e.g., Alfven waves)
28.52.Av Theory, design, and computerized simulation
52.55.-s Magnetic confinement and equilibrium

Radio‐frequency matching studies for the JET ITER‐Like ICRF system

P. U. Lamalle, F. Durodié, R. H. Goulding, I. Monakhov, M. Nightingale, A. Walden, P. Wouters, and EFDA JET Workprogramme Contributors

AIP Conf. Proc. 694, pp. 118-121; doi:http://dx.doi.org/10.1063/1.1638008 (4 pages)

Online Publication Date: 19 December 2003

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The transmisssion and matching system of the JET ITER‐Like ICRF antenna includes specific design features, contributing to tolerance of the generators to large (dominantly) resistive increases in loading, and to be tested on JET in ITER‐relevant ELMy H mode conditions for the first time. Beside the “conjugate‐T” circuit, internally matching the launcher to a very low reference impedance, an original adjustable wideband transformer has been designed for compatibility with various ancillary functions. Optional 3dB splitters provide futher generator isolation. The paper discusses design choices leading to the final layout and briefly presents the simulated performance of the system. © 2003 American Institute of Physics
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52.50.Qt Plasma heating by radio-frequency fields; ICR, ICP, helicons
52.40.Fd Plasma interactions with antennas; plasma-filled waveguides
52.55.Fa Tokamaks, spherical tokamaks
28.52.Lf Components and instrumentation

Three‐dimensional electromagnetic modelling of the JET ITER‐Like ICRF antenna

P. U. Lamalle, F. Durodié, A. Whitehurst, R. H. Goulding, P. M. Ryan, and EFDA JET Workprogramme Contributors

AIP Conf. Proc. 694, pp. 122-125; doi:http://dx.doi.org/10.1063/1.1638009 (4 pages)

Online Publication Date: 19 December 2003

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During its design phase, the JET ITER‐Like ICRF antenna array has been modeled in great detail with the 3D electromagnetic software CST MICROWAVE STUDIO®. The resulting rf field and current density patterns have guided the optimization of the antenna feeder shapes, leading overall to a strong reduction (∼25%) of the maximum electric field, and to a factor‐of‐three reduction of the inhomogeneity of rf current at the matching capacitors. The computed frequency response of the array is now used in matching studies and development of a control algorithm. Comparison with the experimental frequency response of the High Power antenna Prototype developed by ORNL and PPPL shows fair agreement. © 2003 American Institute of Physics
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52.50.Qt Plasma heating by radio-frequency fields; ICR, ICP, helicons
52.40.Fd Plasma interactions with antennas; plasma-filled waveguides
84.40.Ba Antennas: theory, components and accessories

Self‐Consistent Modelling of Polychromatic ICRH in Tokamaks

M. Laxåback, T. Johnson, T. Hellsten, and M. Mantsinen

AIP Conf. Proc. 694, pp. 126-129; doi:http://dx.doi.org/10.1063/1.1638010 (4 pages)

Online Publication Date: 19 December 2003

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Polychromatic, multi‐frequency, ion cyclotron resonance heating provide a useful tool for the optimization of plasma performance in fusion devices by tailoring the fast ion distribution function. Not only can the radial profile of the fast ion distributions be modified, but also the fast energy content, the power partition on resonant species and the bulk plasma ion‐ and electron heating rates. This work describes finite orbit effects of polychromatic ICRH which are demonstrated using the SELFO code. © 2003 American Institute of Physics
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52.50.Qt Plasma heating by radio-frequency fields; ICR, ICP, helicons
52.55.Fa Tokamaks, spherical tokamaks
52.65.Pp Monte Carlo methods

Effect of ICRF Mode Conversion at the Ion‐Ion Hybrid Resonance on Plasma Confinement in JET

A. Lyssoivan, M. J. Mantsinen, D. Van Eester, R. Koch, A. Salmi, J.‐M. Noterdaeme, I. Monakhov, and JET EFDA Contributors

AIP Conf. Proc. 694, pp. 130-133; doi:http://dx.doi.org/10.1063/1.1638011 (4 pages)

Online Publication Date: 19 December 2003

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The objective of the present study is to find out the range of the IIHR layer radial position within which the plasma confinement in conventional L‐mode regime may be improved. The recent ICRF‐MC heating experiments on JET (RF power dominated D(3He)‐discharges, PRF/(Ptot‐PRF)≈2.0) were analyzed. The RF power coupled into plasma in the ICRF‐MC scenario improved confinement properties of discharges with respect to the (OH+NBI)‐phase at the central locations of IIHR (∣rii/apl∣ < 0.3) with the best result (up to ∼60% improved confinement) closer to axis and at dipole antenna phasing. A shift of IIHR towards the plasma edge (∣rii/apl∣ > 0.4) resulted in degradation of confinement. An analysis of plasma confinement based on plasma diamagnetic and thermal energy content, and results of modeling of the absorbed power at ICRF‐MC are discussed. © 2003 American Institute of Physics
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52.50.Qt Plasma heating by radio-frequency fields; ICR, ICP, helicons
52.55.Fa Tokamaks, spherical tokamaks
52.55.Dy General theory and basic studies of plasma lifetime, particle and heat loss, energy balance, field structure, etc.

Efficient Self Consistent 3D/1D Analysis of ICRF Antennas

R. Maggiora, G. Vecchi, V. Lancellotti, and V. Kyrytsya

AIP Conf. Proc. 694, pp. 134-137; doi:http://dx.doi.org/10.1063/1.1638012 (4 pages) | Cited 1 time

Online Publication Date: 19 December 2003

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An innovative tool has been realized for the 3D/1D simulation of Ion Cyclotron Radio Frequency (ICRF), i.e. accounting for antennas in a realistic 3D geometry and with an accurate 1D plasma model. The approach to the problem is based on an integral‐equation formulation for the self‐consistent evaluation of the current distribution on the conductors. The environment has been subdivided in two coupled region: the plasma region and the vacuum region. The two problems are linked by means of a magnetic current (electric field) distribution on the aperture between the two regions. In the vacuum region all the calculations are executed in the spatial domain while in the plasma region an extraction in the spectral domain and an analytical evaluation of some integrals are employed that permit to significantly reduce the integration support and to obtain a high numerical efficiency leading to the practical possibility of using a large number of sub‐domain basis functions on each solid conductor of the system. The plasma enters the formalism of the plasma region via a surface impedance matrix; for this reason any plasma model can be used; at present the FELICE code has been adopted, that affords density and temperature profiles, and FLR effects. The source term directly models the TEM mode of the coax feeding the antenna and the current in the coax is determined self‐consistently, giving the input impedance/admittance of the antenna itself. Calculation of field distributions (both magnetic and electric), useful for sheath considerations, is included. This tool has been implemented in a suite, called TOPICA, that is modular and applicable to ICRF antenna structures of arbitrary shape. This new simulation tool can assist during the detailed design phase and for this reason can be considered a “Virtual Prototyping Laboratory” (VPL). The TOPICA suite has been tested against assessed codes and against measurements and data of mock‐ups and existing antennas. The VPL is being used in the design of various ICRF antennas and also for the performance prediction of the ALCATOR C‐MOD D antenna. © 2003 American Institute of Physics
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52.50.Qt Plasma heating by radio-frequency fields; ICR, ICP, helicons
52.40.Fd Plasma interactions with antennas; plasma-filled waveguides
52.70.-m Plasma diagnostic techniques and instrumentation

Comparison of monochromatic and polychromatic ICRH on JET

M. J. Mantsinen, M. Laxåback, A. Salmi, V. Kiptily, D. Testa, Yu. Baranov, R. Barnsley, P. Beaumont, S. Conroy, P. de Vries, C. Giroud, C. Gowers, T. Hellsten, L. C. Ingesson, T. Johnson, et al.

AIP Conf. Proc. 694, pp. 138-141; doi:http://dx.doi.org/10.1063/1.1638013 (4 pages)

Online Publication Date: 19 December 2003

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Experiments have been carried out on the JET tokamak to investigate differences between multiple and single frequency ICRH operation with ICRH power in the range of 3 to 8 MW using H and 3He minority heating. High‐energy neutral particle analysis and gamma‐ray emission tomography are used to measure fast ions, including their radial localisation. For 3 MW of 3He minority heating, the fast 3He ion profile is broader according to the gamma emission data and the fast ion tail temperature Ttail and energy content Wfast are lower with polychromatic ICRH than monochromatic ICRH. Polychromatic ICRH has the advantage of producing smaller‐amplitude and shorter‐period sawteeth, consistent with a lower fast ion pressure inside q = 1, and higher Ti/Te ratios (i.e. similar Ti at lower Te). At high powers with resonances in the centre and/or on the low field side, the data indicates a larger fraction of trapped ions and a lower Ttail for polychromatic ICRH. Experimental results are compared with theoretical predictions. © 2003 American Institute of Physics
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52.50.Qt Plasma heating by radio-frequency fields; ICR, ICP, helicons
52.55.Fa Tokamaks, spherical tokamaks
28.52.Lf Components and instrumentation
52.70.La X-ray and γ-ray measurements

ELM Resilient External Matching System for the ICRF System of ITER: 1. Principle and Performances

A. Messiaen, P. Dumortier, and F. Durodié

AIP Conf. Proc. 694, pp. 142-145; doi:http://dx.doi.org/10.1063/1.1638014 (4 pages) | Cited 2 times

Online Publication Date: 19 December 2003

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The design of an ICRF antenna plug for ITER capable of radiating 20 MW and matched to the power source outside the machine vacuum is summarized in this paper and in a companion one. The present paper describes the general layout of the system and how the ELM resilience is obtained through a conjugate‐T external matching network that uses robust adjustable components only outside the vacuum vessel. © 2003 American Institute of Physics
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52.50.Qt Plasma heating by radio-frequency fields; ICR, ICP, helicons
52.40.Fd Plasma interactions with antennas; plasma-filled waveguides
52.55.Fa Tokamaks, spherical tokamaks
84.40.Ba Antennas: theory, components and accessories

Studies of JET ICRH Antenna Coupling During ELMs

I. Monakhov, T. Blackman, M.‐L. Mayoral, M. Nightingale, A. Walden, P. U. Lamalle, P. Wouters, and JET EFDA contributors

AIP Conf. Proc. 694, pp. 146-149; doi:http://dx.doi.org/10.1063/1.1638015 (4 pages) | Cited 1 time

Online Publication Date: 19 December 2003

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Details are provided of a new fast data acquisition system that records RF data for a complete four‐strap JET ICRH antenna array with sampling rates up to 250 kHz, triggered by the rapid increase in plasma Dα emission intensity during an ELM. The coupling properties are deduced from the transmission line voltage amplitude and phase measured using 80dB directional couplers installed close to the antenna. Resistive and reactive components of antenna loading perturbation are reported during different types of ELMs and discharge magnetic configurations. © 2003 American Institute of Physics
Show PACS
52.50.Qt Plasma heating by radio-frequency fields; ICR, ICP, helicons
52.40.Fd Plasma interactions with antennas; plasma-filled waveguides
84.40.Ba Antennas: theory, components and accessories
52.55.Fa Tokamaks, spherical tokamaks
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