Electron-Cyclotron Resonance Heating of Alkali Plasmas

A method has been developed for heating the electrons in a thermally generated alkali plasma by the resonant absorption of electromagnetic waves at the electron-cyclotron frequency. The electron temperature was increased from 0.2 eV to ∼1.0 eV with the application of ∼1 W of power at a frequency of 10 kMHz. Excellent consistency has been found between diamagnetic measurements of plasma pressure, microwave determinations of plasma density, and double-probe determinations of temperature. The observed temperature increases were in quantitative agreement with computations which consider the heat loss by thermal conduction.