100-MA LOW-EMITTANCE ION-SOURCE FOR ION-BEAM FUSION

A Penning-type ion source is described that meets the following requirements for ion-beam fusion: Pulsed capability, high currents of heavy ions, and low emittance. The source is a scaled version of a Zower-current ion source that produces 2 mA of singly charged xenon ions with a normalized emittance of 0.0015 mrad-cm. The scaled source, which utilizes permanent magnets and a filament cathode, was tested with both multiple-and single-aperture extraction. In the former case, pulsed xenon-ion currents of 100 mA at 2.5 keV were achieved at a current density of 15 mA/cm2; in the latter case, 30 mA at 4.5 mA/cm2 was extracted at 100 keV. The 30-mA case represents the first-gap conditions of a high gradient 1.5 MeV dc pre-accelerator. In all tests, the pulse length was ~ 1 msec with a repetition rate of 0.2 to 1.0 Hz. The experimental perveance data are in good agreement with the theoretical calculations. Copyright © 1979 by The Institute of Electrical and Electronics Engineers, Inc.