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Title: Negative Ion Beam Extraction and Emittance

The use of magnetic fields to both aid the production of negative ions and suppress the co-extracted electrons causes the emittance and hence the divergence of the negative ion beam to increase significantly due to the plasma non-uniformity from jxB drift. This drift distorts the beam-plasma meniscus and experimental results of the beam emittance are presented, which show that non-uniformity causes the square of the emittance to be proportional to the 2/3 power of the extracted current density. This can cause the divergence of the negative ion beam to be significantly larger than its positive ion counterpart. By comparing results from positive and negative ion beam emittances from the same source, it is also possible to draw conclusions about their vulnerability to magnetic effects. Finally emittances of caesiated and un-caesiated negative ion beams are compared to show how the surface and volume modes of production interact.
Authors:
 [1]
  1. Marcham Scientific Ltd, Hungerford RG17 0LH (United Kingdom)
Publication Date:
OSTI Identifier:
21032657
Resource Type:
Journal Article
Resource Relation:
Journal Name: AIP Conference Proceedings; Journal Volume: 925; Journal Issue: 1; Conference: 11. international symposium on the production and neutralization of negative ions and beams, Santa Fe, NM (United States), 13-15 Sep 2006; Other Information: DOI: 10.1063/1.2773664; (c) 2007 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; ANIONS; BEAM EMITTANCE; BEAM EXTRACTION; BEAM-PLASMA SYSTEMS; CATIONS; CURRENT DENSITY; ELECTRONS; ION BEAMS; MAGNETIC FIELDS; PARTICLE BEAMS; PLASMA