Properties of field emission from high voltage RF antenna

A high voltage (up to 80 kV for 20 ms and 110 kV for 10 ms) resonant RF probe operating at 52 MHz is used to study the influence of surface effects and plasma on the operation of high voltage ion cyclotron RF antennas for nuclear fusion devices with magnetic confinement. From the measured DC charging characteristic of the blocking capacitor, the field emission currents are derived. The measurements are performed both with and without plasma at He pressure p <= 0.1 Pa, lower than the threshold pressure for ignition of a high voltage RF glow discharge in the system. Effects of conditioning and presence of plasma on the field emission properties (effective emission area A RF and amplification factor beta(RF)) are studied. (c) 2005 Elsevier B.V. All rights reserved.