Plasma Current Sustainment in Low-Q Discharges by Lower Hybrid Waves in the Petula-B Tokamak

摘要

Plasma currents up to 200 kA have been sustained in the iron core transformer Petula-B tokamak by lower hybrid waves at 1.25 GHz. This proved to be feasible even at q(a) approximately 2. For a mean density sub(e) = 1. x 10 exp 13 cm exp -3 , 100 kW of RF power is sufficient to drive 150 kAmps without the help of ohmic current. This efficiency has a 1/nsub(e) dependence up to nsub(e) approximately equal 2 x 10 exp 13 cm exp -3 . The RF current, as inferred from the loop voltage drop, versus power dependence shows a saturation which can be explained by strong magnetic coupling to the primary winding and by the inclusion of the plasma resistivity decrease during the RF current drive. (ERA citation 10:029458)