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A merging preaccelerator for high current H{sup {minus}} ion beams

Journal Article · · Review of Scientific Instruments
DOI:https://doi.org/10.1063/1.1145449· OSTI ID:82224
; ; ; ;  [1]; ; ; ; ;  [2]
  1. Japan Atomic Energy Research Institute, Naka, Naka-machi, Naka-gun, Ibaraki-ken 311-01 (Japan)
  2. Lawrence Berkeley Laboratory, 1 Cyclotron Road, Berkeley, California 94720 (United States)
The high power ion beams used in the next generation thermonuclear fusion reactors require high current negative ion beams accelerated to high energy, with high efficiency. One way to meet these requirements is to merge multiple low current density H{sup {minus}} beamlets into a single high current beam. The feasibility of a high current merging preaccelerator was demonstrated in this experiment by merging 19 beamlets of H{sup {minus}} ions distributed over a circular area 80 mm in diameter from a Japan Atomic Energy Research Institute negative ion source. H{sup {minus}} ions were extracted at a current density exceeding 10 mA/cm{sup 2} at the ion source which operates at 0.13 Pa (1 mTorr), with a low arc power density (70 V{times}250 A). Spherically curved grids (with built-in magnetic electron suppression) were used in the preaccelerator to focus the extracted beamlets into a single 104 mA, 100 keV beam. The merged beam has a diameter of 23 mm and a converging angle of {plus_minus}30 mrad at the beam envelope. The rms emittance of the 104 mA merging beam was 1.00 {pi} mrad cm, which is a condition acceptable to the electrostatic quadropole accelerator for further acceleration. {copyright} {ital 1995} {ital American} {ital Institute} {ital of} {ital Physics}.
Research Organization:
Lawrence Berkeley National Laboratory
DOE Contract Number:
AC03-76SF00098
OSTI ID:
82224
Journal Information:
Review of Scientific Instruments, Journal Name: Review of Scientific Instruments Journal Issue: 7 Vol. 66; ISSN 0034-6748; ISSN RSINAK
Country of Publication:
United States
Language:
English