RADIAL-DISTRIBUTION OF SPACE-CHARGE FORCE IN COMPENSATED POSITIVE-IONBEAMS

The space-charge compensated state of drifting de beams of He+ ions of 10 keV ion energy and 0.14 and 1.5 mA current was determined with an electron beam probe, a rf resonance probe, the analysis of residual ga s ion energies, and emittance measurement. The results are compatible with a basic model describing a two-dimensional multiplicity of possib le self-consistent radial density distributions of beam ions, residual gas ions, and compensating electrons. The effects of electron drainag e and beam current oscillations on space-charge compensation are point ed out. (C) 1998 American Institute of Physics.