Biased-electrode operation of electron cyclotron resonance ion sources

In order to supplement our investigations on the biased electrode in electr on cyclotron resonance ion sources, we have carried out dedicated measureme nts with a special double structure (ring plus disk) electrode. This geomet ry allows to separate two mechanisms contributing to the "biased disk effec t": the creation of secondary electrons at the disk and the reflection of p lasma loss electrons by the potentials of the disk. At sufficiently high ri ng-electrode potentials the axial electron losses can be blocked completely . From the experimental results, it is suggested that electrostatic blockin g is the main contribution to the biased electrode effect. (C) 2001 America n Institute of Physics.