RF generated voltage on the Faraday screen of an ICRF antenna and its effect on the Phaedrus-T edge plasma

摘要

Work done on the Phaedrus-T tokamak is summarized regarding RF voltages induced on the sides of slotted side Faraday screens (FSs). Direct in-air measurements show voltages induced on slotted side FSs, while theory and computer simulations suggest that these voltages are induced by radial currents on antenna feeds. Triple probe measurements in the edge region of the Phaedrus-T tokamak suggest that the induced voltages modify edge plasma parameters and increase sheath potentials, which increase sputtering of the FS material and result in an increase of the impurity content of the plasma. These effects of the induced voltages can be eliminated by using insulating plates as FS side limiters.