Propagation of the end-face electrodes potential in the plasma volume of rf discharge

The problems of the creating a stationary electric field in a magnetized plasma of rf discharge are investigated. Helmholtz coils create a magnetic field in a cylindrical vacuum chamber with a diameter of 85.6 cm and a length of 220 cm. Radio-frequency discharge is generated at a frequency of about 5 MHz. Radio-frequency power absorbed by the plasma is in the range of 0.5–1.5 kW. Negatively charged electrodes are placed on the end-face of the chamber. We study three cathode configurations with diameters from 55 to 295 mm. Argon is used as the working gas. Radial profiles of plasma potential, electron density and electron temperature are obtained. The dependence of plasma potential in the discharge center on the voltage of end-face electrodes is studied. (paper)