Scrape-off layer current in diverted Tokamak

摘要

A negative current in the scrape-off region beyond the separatrix of a diverted Tokamak can improve its MHD stability. By utilizing a strong thermionic emitter a current of up to 25 of the plasma current can be driven in the scrape-off region. If the thermionic current is emitted at only one end of the open field lines, a current will flow in the absence of a potential bias. The heat to maintain the electron emission that drives the scrape-off current would be supplied by the plasma outflow and no additional power is needed