INVESTIGATIONS OF THE NEW GIESSEN 10-GHZ ELECTRON-CYCLOTRON-RESONANCEION-SOURCE

A 10 GHz electron-cyclotron-resonance (ECR) ion source has been design ed and built to extend our studies of the collisions of highly charged ions with electrons. The magnetic system of the ion source consists o f three solenoid coils for the axial field component and a hexapole pe rmanent magnet for the radial field component. A 10 GHz microwave syst em supplies up to 2.5 kW of microwave power to the plasma. The ion sou rce can be operated at a high voltage potential of 20 kV and yields to tal ion currents of 0.2-2.5 mA. lon beams produced with argon, oxygen and xenon were analyzed by a dipole magnet. Substantial currents up to O7+,Ar11+ and Xe27+ were measured. Furthermore, newly recognized prop erties of the extracted ion beams were obtained from electron-impact i onization studies. A strong correlation between the electron-impact io nization cross section in the supplied microwave power level resulted in a significantly higher ionization cross section of the reaction O5 +e- --> O6+ +2e-. Multiply charged ions from ECR ion sources would ap pear to have a ''memory'' of the conditions of their production.