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Stabilization of ideal modes by resistive walls in tokamaks with plasma rotation and its effect on the beta limit

Technical Report:

Abstract

It is shown that pressure-driven, ideal external modes in tokamaks can be fully stabilized by resistive walls when the plasma rotates at some fraction of the sound speed. For wall stabilized plasmas, there are two types of potentially unstable external modes: those which are nearly locked to the wall and those which rotate with the plasma. For the modes rotating with the plasma, the stabilizing effect of the wall increases when the wall is brought closer to the plasma, while, for the wall-locked modes, the stabilization improves with increasing wall distance. When the plasma rotates at some fraction of the sound speed, there is a window of stability to both the wall-locked and the rotating mode. This window closes when beta exceeds a new limit which can be significantly higher than the wall-at-infinity limit. The stabilization depends principally on the toroidal coupling to sound waves and is affected by ion Landau damping. Two dimensional stability calculations are presented to evaluate the gains in beta limit resulting from this wall stabilization for different equilibria and rotation speeds. In particular, results are shown for advanced tokamak configurations with bootstrap fractions of {approx_equal} 100%. (author) 14 figs., 25 refs.
Authors:
Ward, D J; Bondeson, A [1] 
  1. Ecole Polytechnique Federale, Lausanne (Switzerland). Centre de Recherche en Physique des Plasma (CRPP)
Publication Date:
Sep 01, 1994
Product Type:
Technical Report
Report Number:
LRP-502/94
Reference Number:
SCA: 700340; PA: AIX-26:009172; EDB-95:011472; SN: 95001302011
Resource Relation:
Other Information: PBD: Sep 1994
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; BETA RATIO; LIMITING VALUES; PLASMA INSTABILITY; FIRST WALL; TOKAMAK DEVICES; BOOTSTRAP CURRENT; LANDAU DAMPING; ROTATING PLASMA; SOUND WAVES; THEORETICAL DATA; 700340; PLASMA WAVES, OSCILLATIONS, AND INSTABILITIES
OSTI ID:
10103995
Research Organizations:
Ecole Polytechnique Federale, Lausanne (Switzerland). Centre de Recherche en Physique des Plasma (CRPP)
Country of Origin:
Switzerland
Language:
English
Other Identifying Numbers:
Other: ON: DE95611652; TRN: CH9400374009172
Availability:
OSTI; NTIS; INIS
Submitting Site:
CHN
Size:
[41] p.
Announcement Date:
Jun 30, 2005

Technical Report:

Citation Formats

Ward, D J, and Bondeson, A. Stabilization of ideal modes by resistive walls in tokamaks with plasma rotation and its effect on the beta limit. Switzerland: N. p., 1994. Web.
Ward, D J, & Bondeson, A. Stabilization of ideal modes by resistive walls in tokamaks with plasma rotation and its effect on the beta limit. Switzerland.
Ward, D J, and Bondeson, A. 1994. "Stabilization of ideal modes by resistive walls in tokamaks with plasma rotation and its effect on the beta limit." Switzerland.
@misc{etde_10103995,
title = {Stabilization of ideal modes by resistive walls in tokamaks with plasma rotation and its effect on the beta limit}
author = {Ward, D J, and Bondeson, A}
abstractNote = {It is shown that pressure-driven, ideal external modes in tokamaks can be fully stabilized by resistive walls when the plasma rotates at some fraction of the sound speed. For wall stabilized plasmas, there are two types of potentially unstable external modes: those which are nearly locked to the wall and those which rotate with the plasma. For the modes rotating with the plasma, the stabilizing effect of the wall increases when the wall is brought closer to the plasma, while, for the wall-locked modes, the stabilization improves with increasing wall distance. When the plasma rotates at some fraction of the sound speed, there is a window of stability to both the wall-locked and the rotating mode. This window closes when beta exceeds a new limit which can be significantly higher than the wall-at-infinity limit. The stabilization depends principally on the toroidal coupling to sound waves and is affected by ion Landau damping. Two dimensional stability calculations are presented to evaluate the gains in beta limit resulting from this wall stabilization for different equilibria and rotation speeds. In particular, results are shown for advanced tokamak configurations with bootstrap fractions of {approx_equal} 100%. (author) 14 figs., 25 refs.}
place = {Switzerland}
year = {1994}
month = {Sep}
}