Spatial charge effects in retarding field analyzer ion measurements in a cathodic vacuum arc

D. GRONDONA; H. KELLY; A. MÁRQUEZ

APPLIED PHYSICS LETTERS

AIP

Año: 2001 vol. 79 p. 317 - 319

0003-6951

The ion energy distribution generated in a pulsed vacuum arc operated with a Ti cathode and N22 filling gas is reported. A retarding field analyzer system is employed, for which the usual derivation of the ion energy spectrum has been modified to take into account spatial charge effects in the grid-collector region of the analyzer. It allows one to interpret the decrease in the collector current at collector bias voltages unusually low ~even negatives! observed in this experiment, as well as in others. It is found that spatial charge effects are more marked when the arc operates with gas filling because of the creation ~by charge-exchange processes! of low energy gaseous ions which are easily stopped by the potential hump created by the positive charge in the grid-collector region of the analyzer.~even negatives! observed in this experiment, as well as in others. It is found that spatial charge effects are more marked when the arc operates with gas filling because of the creation ~by charge-exchange processes! of low energy gaseous ions which are easily stopped by the potential hump created by the positive charge in the grid-collector region of the analyzer.~by charge-exchange processes! of low energy gaseous ions which are easily stopped by the potential hump created by the positive charge in the grid-collector region of the analyzer.