Vol.28 No.4(4) [2006]

Initial Plasma Production by Induction Electric Field on QUEST Tokamak



Induction electric field by center solenoid coil plays a roll to produce initial plasma. According to Townsend avalanche theory, minimum electric field for plasma breakdown depends on neutral gas pressure and connection length. On QUEST spherical tokamak, a connection length is evaluated as 966m on null point neighborhood with coil current ratio IPF26/ICS=0.1, and induction electric field considering eddy current of vacuum vessel is evaluated as about 0.1V/m on null point neighborhood. With Townsend avalanche theory, there values manage to produce initial plasma on QUEST.