Electron cyclotron resonance plasma excitation in a toroidal plasma

In this article, Electron Cyclotron Resonance (ECR) absorption, Upper-Hybrid Resonance (UHR) absorption and Electron Bernstein Wave (EBW) conversion are systematically confirmed in magnetically confined KT-5D plasma which is sole-excited by a magnetron source. A 2.45 GHz ECR system has been developed on the toroidal helimak KT-5D to produce and sustain a steady-state plasma. 0.98 kW electron cyclotron wave produced by the magnetron is injected into the vacuum chamber through rectangular waveguides with a power absorption efficiency of 40∼50%. A steady-state plasma is excited with a density of several 1016/m3 and electron temperature of up to 30 eV. The radial profile of plasma density shows that ECR absorption dominates the power deposition with a higher hydrogen pressure of at the order of 10-1 Pa, while UHR absorption dominates with a lower hydrogen pressure of at the order of 10-2 Pa. Plasma density in the discharge with a superimposed magnetic shear has demonstrated the wave conversion from ECR to EBW.