Axisymmetric instability in a noncircular tokamak: experiment and theory

Technical Report · Sat Sep 01 04:00:00 EDT 1979

DOI:https://doi.org/10.2172/5863123· OSTI ID:5863123

Lipschultz, B; Prager, S C; Todd, A M.M.; Delucia, J

The stability of dee, inverse-dee and square cross section plasmas to axisymmetric modes has been investigated experimentally in Tokapole II, a tokamak with a four-null poloidal divertor. Experimental results are closely compared with predictions of two numerical stability codes -- the PEST code (ideal MHD, linear stability) adapted to tokapole geometry and a code which follows the nonlinear evolution of shapes similar to tokapole equilibria. Experimentally, the square is vertically stable and both dee's unstable to a vertical nonrigid axisymmetric shift. The central magnetic axis displacement grows exponentially with a growth time approximately 10/sup 3/ poloidal Alfven times plasma time. Proper initial positioning of the plasma on the midplane allows passive feedback to nonlinearly restore vertical motion to a small stable oscillation. Experimental poloidal flux plots are produced directly from internal magnetic probe measurements.

• Research Organization: Wisconsin Univ., Madison (USA)
• DOE Contract Number: EY-76-S-02-2387
• OSTI ID: 5863123
• Report Number(s): COO-2387-116
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
700107* -- Fusion Energy-- Plasma Research-- Instabilities
700202 -- Fusion Power Plant Technology-- Magnet Coils & Fields
CLOSED PLASMA DEVICES
COMPUTER CALCULATIONS
COMPUTER CODES
DIVERTORS
INSTABILITY
INTERNAL RING DEVICES
MAGNETIC FIELD CONFIGURATIONS
PLASMA INSTABILITY
POLOIDAL DIVERTORS
THERMONUCLEAR DEVICES
TOKAMAK DEVICES
TOKAPOLE DEVICES