Modification of sawteeth by second harmonic electron-cyclotron heating in a tokamak

Journal Article · Wed Feb 01 04:00:00 EST 1989 · Phys Fluids B; (United States)

DOI:https://doi.org/10.1063/1.859154· OSTI ID:6823486

Snider, R T; Content, D; James, R; Lohr, J; Mahdavi, M A; Prater, R; Stallard, B

Electron-cyclotron heating, using second harmonic waves launched from the low field side, has a strong effect on sawteeth in the DIII-D tokamak (Plasma Physics and Controlled Nuclear Fusion Research, 1986 (IAEA, Vienna, 1987), Vol. I, p. 159). There are two distinct methods and mechanisms for sawtooth period extension. In the first case a factor of 6 increase in sawtooth period, compared to that during Ohmic heating, occurs with electron-cyclotron heating (ECH) localized near the q = 1 surface. The sawtooth period increases faster than linearly with increasing ECH power. Qualitatively, there is agreement with sawtooth suppression models, although details of the accompanying m/n = 1/1 oscillation appear inconsistent. The second case is a technique for complete sawtooth suppression in which impurities and off-axis heating broaden the current profile and drive q/sub 0/>1. It appears that the temperature and the current and q profiles inside q = 1 are determined by the magnetohydrodynamic activity, which is modified by ECH, and not by the ECH power deposition directly.

• Research Organization: General Atomics, San Diego, California 92138-5608
• OSTI ID: 6823486
• Journal Information: Phys Fluids B; (United States), Journal Name: Phys Fluids B; (United States) Vol. 1:2; ISSN PFBPE
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
700101* -- Fusion Energy-- Plasma Research-- Confinement
Heating
& Production
700108 -- Fusion Energy-- Plasma Research-- Wave Phenomena
CLOSED PLASMA DEVICES
ECR HEATING
ELECTRON TEMPERATURE
HARMONICS
HEATING
HIGH-FREQUENCY HEATING
MODIFICATIONS
OSCILLATION MODES
OSCILLATIONS
PLASMA
PLASMA DISRUPTION
PLASMA HEATING
THERMONUCLEAR DEVICES
TOKAMAK DEVICES