Ion source electrode biasing technique for microsecond beam pulse rise times
- Lawrence Berkeley National Laboratory, Berkeley, California94720 (United States)
Heavy ion fusion (HIF) induction accelerators require ion sources that can deliver intense heavy ion beams with low emittance. The typical pulse length is 20 {mu}s with a rise time less than 1 {mu}s and a repetition rate of 10 Hz. So far, the surface ionization sources have been used in most HIF induction linac designs. However, there are other ions of interest to HIF (e.g., Hg, Xe, Rb, Ar, and Ne) which cannot be produced by the surface ionization sources, but rather by volume ion sources. In this paper, we describe an experiment that uses a multicusp source with a magnetic filter to produce beam pulses that have a rise time in the order of 1 {mu}s. By applying a positive biasing pulse on the plasma electrode with respect to the source body, the positive plasma ions can be temporarily repelled from the neighborhood of the extraction aperture, leading to a suppression of the ion beam. As the bias is removed, positive ions flow to the extraction region, enabling a fast-rising beam pulse. The beam current pulses show that there are two distinct groups of ions. An initial fast current rise time ({lt}2{mu}s) corresponding to ions originating from within the magnetic filter region followed by a second group of ions with a longer rise time (10{endash}20 {mu}s) originating from the plasma bulk region. Proper positioning of the filament cathode and the magnetic filter field relative to the extraction aperture was found to be critical. {copyright} {ital 1998 American Institute of Physics.}
- OSTI ID:
- 615354
- Report Number(s):
- CONF-980145-; ISSN 0034-6748; TRN: 98:005585
- Journal Information:
- Review of Scientific Instruments, Vol. 69, Issue 2; Conference: 7. international conference on ion sources, Shirahama (Japan), 26-27 Jan 1998; Other Information: PBD: Feb 1998
- Country of Publication:
- United States
- Language:
- English
Similar Records
Ions Beams and Ferroelectric Plasma Sources
High current short pulse ion sources