Dynamics of sawtooth phenomena in the Texas Experimental Tokamak

Thesis/Dissertation · Tue Jan 01 04:00:00 EST 1985

OSTI ID:5223729

Snipes, J A

To gain a better understanding of sawtooth phenomena, the sawtooth inversion radius, amplitude, and period and m = 1 frequency and growth rate were determined for scans of the toroidal field, plasma current, density, and background gas. Through a careful investigation of the amplitude and phase of m = 1 oscillations relative to sawteeth, a clearer understanding of the relationship between them was inferred. The sawtooth inversion radius was approximately a/q(a) within error and agreed with the q = 1 radius inferred from Thomson scattering profiles assuming q = 1 within the q = 1 radius. The sawtooth amplitude decreased with increasing toroidal field, but was nearly independent of changes in the plasma current. Both the sawtooth amplitude and period increased nearly linear with density for low and moderate densities, but plateaued at higher densities. Through studies of current ramping and different plateau currents, the sawtooth period was found to decrease with increasing plasma current. No dependence of the sawtooth period on toroidal field was observed. The growth rate of the precursor m = 1 oscillations varied by as much as a factor of three within the plateau of a given shot making any attempt at growth rate scaling impossible. The frequency of classic m = 1 oscillations increased linearly with the toroidal field and decreased with increasing mass of the background gas. Changes in the inversion radius and the temperature and density profiles resulted in nearly the same scaling of the electron diamagnetic drift frequency with toroidal field.

• Research Organization: Texas Univ., Austin (USA)
• OSTI ID: 5223729
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
700104* -- Fusion Energy-- Plasma Research-- Plasma Kinetics-Experimental-- (-1987)
AMPLITUDES
CHEMICAL ANALYSIS
CLOSED PLASMA DEVICES
CURRENTS
ELECTRIC CURRENTS
NONDESTRUCTIVE ANALYSIS
OSCILLATIONS
PLASMA DENSITY
TEXT DEVICES
THERMONUCLEAR DEVICES
TOKAMAK DEVICES
X-RAY EMISSION ANALYSIS