Modelling Ion Cyclotron Resonance Heating and Fast Wave Current Drive in Tokamaks PDF Download

Author: Abdul Hannan
Publisher:
ISBN: 9789175016924
Category :
Languages : en
Pages : 0

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Author:
Publisher:
ISBN: 9789175016924
Category :
Languages : en
Pages : 53

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Author: Thomas Donavon Shepard
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ISBN:
Category :
Languages : en
Pages : 207

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Author: Thomas Donavon Shepard
Publisher:
ISBN:
Category :
Languages : en
Pages : 207

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Author: Brian David McVey
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ISBN:
Category : Tokamaks
Languages : en
Pages : 332

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Author: Tak Kuen Mau
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ISBN:
Category : High temperature plasmas
Languages : en
Pages : 318

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Author: Thomas Krücken
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Category :
Languages : de
Pages : 26

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Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 8

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In spherical tokamaks (ST), the magnetic field strength varies over a wide range across the plasma, and at high betas it deviates significantly from the 1/R dependence of conventional tokamaks. This, together with the high density expected in ST, poses challenging problems for RF heating and current drive. In this paper, the authors investigate the various possible applications of fast waves (FW) in ST. The adjoint technique of calculating current drive is implemented in the raytracing code CURRAY. The applicability of high harmonic and subharmonic FW to steady state ST is considered. They find that high harmonic FW tends to be totally absorbed before reaching the core and may be considered a candidate for off axis current drive while the subharmonic FW tends to be absorbed mainly in the core region and may be considered for central current drive. A difficult problem is the maintenance of current at the startup stage. In the bootstrap ramp-up scenario, the current ramp-up is mainly provided by the bootstrap current. Under this condition, the role of rf becomes mainly the sustainment of plasma through electron heating. Using a slab full-wave code SEMAL, the authors find that the ion-ion-hybrid mode conversion scheme is a promising candidate. The effect of possible existence of edge Alfven resonance and high harmonic cyclotron resonance is investigated and regimes of minimization of edge heating identified.

Author: Thomas Johnson
Publisher:
ISBN: 9789172837805
Category :
Languages : en
Pages : 61

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Author:
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ISBN:
Category :
Languages : en
Pages : 13

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Results from tokamak experiments on direct electron interaction with the compressional Alfven wave ({open_quote}fast wave{close_quote}) are reviewed. Experiments aimed at electron heating as well as those in which fast wave electron current drive was investigated are discussed. A distinction is drawn between experiments employing the lower hybrid range of frequencies, where both the lower hybrid wave ({open_quote}slow wave{close_quote}) and the fast wave can propagate in much of the plasma, and those experiments using the fast wave in the range of moderate to high ion cyclotron harmonics, where only the fast wave can penetrate to the plasma core. Most of the early tokamak experiments were in the lower hybrid frequency regime, and the observed electron interaction appeared to be very similar to that obtained with the slow wave at the same frequency. In particular, electron interaction with the fast wave was observed only below a density limit nearly the same as the well known slow wave density limit. In the more recent lower frequency fast wave experiments, electron interaction (heating and current drive) is observed at the center of the discharge, where slow waves are not present.