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Experimental studies of the rotational stability of the Phaedrus Tandem Mirror

Thesis/Dissertation ·
OSTI ID:7108757
It is demonstrated that the radial electric field in the Phaedrus Tandem Mirror can be altered using Plasma Potential Control rings (PPC rings) situated at each end of the device, and the azimuthal plasma rotational velocity may thus be varied. A simple calculation to model the change in central-cell potential due to a bias voltage applied to the PPC rings is presented. Low-frequency (w << w/sub ci/), low azimuthal mode number (m =-1 and m = -2) instabilities drive by E x B rotation were observed. The radial potential profile was experimentally variable using the same method for the case that Phaedrus was operated as an axisymmetric tandem mirror with MHD stability provided by the RF ponderomotive force. Instabilities having azimuthal m = -1, -2, and -3 (W << w/sub ci/), were observed to occur as E x B was increased. The destabilizing centrifugal force due to E x B rotation was compared to the destabilizing curvature force and RF ponderomotive force and found to account for the observed instabilities.
Research Organization:
Wisconsin Univ., Madison (USA)
OSTI ID:
7108757
Country of Publication:
United States
Language:
English