EVIDENCE OF LOW-FREQUENCY OSCILLATIONS IN HEAVY-ION PLASMAS HEATED BYELECTRON-CYCLOTRON-RESONANCE

Time-resolved experiments (bremsstrahlung, diamagnetism, electron, and ion end-loss currents) have been carried out at the Electron Cyclotro n Resonance Ion Source Quadrumafios [A. Girard, et al., Rev. Sci. Inst rum. 65, 1714 (1994)] continuously operated with heavy neutral gases. All the diagnostics reveal oscillations (on the time scale of about 1 a) which could be characterized by variations of the hot electron perp endicular temperature. The onset of this low-frequency periodic regime with increasing heating powers and/or decreasing gas injection pressu res is shown to Limit the highly charged ion currents available. The a ddition of a lighter gas, e.g., He into Kr, delays the appearance of t he periodic regime and enables one to extract higher currents. (C) 199 6 American Institute of Physics.