Plasma diagnostics at electron cyclotron resonance ion sources by injection of laser ablated fluxes of metal atoms

Abstract

Short pulses of neutral particles generated by laser ablation of metal targets have been injected into the Frankfurt 14 GHz electron cyclotron resonance (ECR) ion source. Rise/fall times of pulses of highly charged ions of Cd and Mg were registered as a function of microwave power and gas pressure. From a comparison of the measured data to numerical simulations, values of the electron density and the temperature in the ECR plasma were estimated to be about 0.75×10 12 cm −3 and a few keV. The effective electron temperature increases with increasing microwave power and decreases with increasing gas pressure. The electron density is only a weak function of the microwave power, but increases significantly with the gas pressure. In the Ar/O 2 gas-mixing mode of operation, an improved confinement of lowly charged ions was observed.