Experimental and theoretical investigation of a finite-. beta. modified drift wave

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

OSTI ID:5815117

Fredrickson, E D

The saturated state of a low frequency, coherent, m = 2, global mode has been studied in the Encore tokamak using probe techniques. The mode is found to have large fluctuations in density, electron temperature, space potential and magnetic field. The equilibrium plasma characteristics were also determined with probe measurements. Magnetic probes were used to determine the radial profile of the poloidal magnetic field, from which the rotational transform and current density profiles could be deduced. A Langmuir probe was used to measure radial profiles of the density, electron temperature and space potential. By comparing the experimental measurements with the predictions of a computer code, the mode was identified as a finite ..beta../sub T/ modified drift wave. The code is based on a linear, two-fluid theory of the coupling of drift and shear-Alfven modes. Of the two shear-Alfven solutions and the drift branch solution, it was found that the drift wave solution best fit the observed frequency of the mode and the relative amplitudes of the density, space potential and magnetic fluctuations. The identification of the mode as a finite ..beta../sub T/ modified drift wave means that the mode is more closely related to the higher frequency, turbulent fluctuations observed on larger machines, rather than the lower frequency, coherent Mirnov oscillations.

• OSTI ID: 5815117
• Resource Relation: Other Information: Thesis (Ph. D.)
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
TOKAMAK DEVICES
DRIFT INSTABILITY
PLASMA DIAGNOSTICS
ALFVEN WAVES
CLOSED PLASMA DEVICES
HYDROMAGNETIC WAVES
INSTABILITY
PLASMA INSTABILITY
PLASMA MICROINSTABILITIES
THERMONUCLEAR DEVICES
700107* - Fusion Energy- Plasma Research- Instabilities
700108 - Fusion Energy- Plasma Research- Wave Phenomena