Suppression of disruptive current termination in a poloidal divertor tokamak with a magnetic limiter

Technical Report · Wed Jan 01 00:00:00 EST 1986

OSTI ID:5919058

Moyer, R A; Osborne, T H; Dexter, R N; Prager, S C

The magnetic separatrix of a poloidal divertor tokamak (Tokapole II) has been used effectively as a magnetic limiter to suppress disruptive current termination. For magnetically limited discharges (without scrape-off plates) with an effective edge safety factor q(a) approx.3, major disruptions appear as repetitive (period approx.1 ms) giant crashes in soft x-ray signal levels in the discharge core with inversion radii near the q = 2 rational surface and with even m/odd n magnetic precursers. Temperature and density are pumped into the divertor scrape-off region, the current profile broadens and moves inward in major radius, but the discharge recovers, with soft x-ray signals ramping up to the next crash. The magnetic limiter has been replaced with a material limiter by inserting retractable limiter plates to the divertor separatrix. In this case, the discharge terminates abruptly when the inward shift in major radius following the first disruption carries the plasma into the inboard limiter plate. Various spectroscopic data indicate that the current quench arises from the plasma/limiter contact and not from changes in impurity levels prior to the disruption. 16 refs., 8 figs.

• Research Organization: Wisconsin Univ., Madison (USA). Dept. of Physics
• DOE Contract Number: AC02-76ET53051
• OSTI ID: 5919058
• Report Number(s): DOE/ET/53051-88; ON: DE86007796
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
TOKAPOLE DEVICES
PLASMA INSTABILITY
ELECTRIC DISCHARGES
LIMITERS
PLASMA SCRAPE-OFF LAYER
POLOIDAL FIELD DIVERTORS
SOFT X RADIATION
BOUNDARY LAYERS
CLOSED PLASMA DEVICES
DIVERTORS
ELECTROMAGNETIC RADIATION
INSTABILITY
INTERNAL RING DEVICES
IONIZING RADIATIONS
LAYERS
RADIATIONS
THERMONUCLEAR DEVICES
TOKAMAK DEVICES
X RADIATION
700202* - Fusion Power Plant Technology- Magnet Coils & Fields