Magnetic and material limiter discharges in Tokapole II

Technical Report · Fri Jan 01 04:00:00 EST 1988

OSTI ID:7044160

Moyer, R A

Disruptive instabilities have been studied in Tokapole II, a small poloidal divertor tokamak, in magnetic and material limiter configurations. In the magnetic limiter configuration, the divertor separatrix defines the tokamak current channel boundary. Limiters or neutralizer plates are not used to remove plasma in the scrape-off region. The relatively hot, dense plasma in the scrape-off region carries 5--20% of the current. In the material limiter configuration, limiter plates are inserted to the separatrix to remove plasma and current in the scrape-off region. The plates vary the tokamak current channel boundary condition in a controlled manner, and provide a benchmark for comparison with other tokamaks. Internal and external disruptions have been studied, and several unique features in the magnetic limiter configuration have been identified. The magnitic limiter configuration enables routine passing of the stability barriers at q(a) = 2 and q(a) = 1, where q(a) is the the edge safety factor, without a close fitting wall, external windings, or detailed profile control techniques. Passing the q(a) = 1 barrier permits operation in the q < 1 regime where total reconnection of the sawtooth does not occur. Discharges with q < 1 are also obtained in the material limiter configuration, suggesting that partial reconnection is characteristic of the sawteeth, and not the magnetic limiter configuration. The magnetic limiter configuration suppresses current termination in a major disruption. Current termination occurs in material limiter discharges due to enhanced interaction with the inboard limiter following the post-disruptive shift in major radius.

• Research Organization: Wisconsin Univ., Madison (USA). Plasma Physics Research
• DOE Contract Number: FG02-86ER53227
• OSTI ID: 7044160
• Report Number(s): DOE/ER/53227-123; ON: DE88011867
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
700101* -- Fusion Energy-- Plasma Research-- Confinement
Heating
&amp; Production
700102 -- Fusion Energy-- Plasma Research-- Diagnostics
700107 -- Fusion Energy-- Plasma Research-- Instabilities
BENCHMARKS
BOUNDARY LAYERS
CLOSED PLASMA DEVICES
CURRENT DENSITY
DIVERTORS
ELECTRON TEMPERATURE
EQUILIBRIUM PLASMA
INSTABILITY
INTERNAL RING DEVICES
ION TEMPERATURE
LAYERS
LIMITERS
MAGNETIC FIELD CONFIGURATIONS
PLASMA
PLASMA DENSITY
PLASMA DIAGNOSTICS
PLASMA DISRUPTION
PLASMA INSTABILITY
PLASMA SCRAPE-OFF LAYER
POLOIDAL FIELD DIVERTORS
THERMONUCLEAR DEVICES
TOKAMAK DEVICES
TOKAPOLE DEVICES