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Title: Roles of a plasma grid in a negative hydrogen ion source

The plasma grid is electrically biased with respect to other parts of source chamber wall in both volume sources and sources seeded with alkali metals. The roles of the plasma grid in these two kinds of sources will be described. The main functions of the plasma grid in volume sources are: optimizing the extracted negative ion current, reducing the co-extracted electron current, controlling the axial plasma potential profile, recycling the hydrogen atoms to molecules, concentrating the negative ions near its surface and, when biased positive, depleting the electron population near its surface. These functions are maintained in the sources seeded with alkali metals. However an additional function appears in the Cs seeded sources, namely direct emission of negative ions under positive ion and neutral hydrogen bombardment.
Authors:
 [1] ;  [2] ;  [3] ;  [4]
  1. UPMC, LPP, Ecole Polytechnique, Palaiseau, UMR CNRS 7648 (France)
  2. R and D Promotion Organization, Doshisha University, Kamigyoku, Kyoto 602-8580 (Japan)
  3. School of Science and Engineering, Doshisha University, Kyotonabe, Kyoto 610-0321 (Japan)
  4. CCFE, Culham Science Center, Abingdon, Oxfordshire 0X14 3DB (United Kingdom)
Publication Date:
OSTI Identifier:
22391393
Resource Type:
Journal Article
Resource Relation:
Journal Name: AIP Conference Proceedings; Journal Volume: 1655; Journal Issue: 1; Conference: NIBS 2014: 4. International Symposium on Negative Ions, Beams and Sources, Garching (Germany), 6-10 Oct 2014; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; 07 ISOTOPES AND RADIATION SOURCES; ANIONS; ATOMS; CATIONS; ELECTRIC CURRENTS; ELECTRONS; HYDROGEN; HYDROGEN IONS; ION EMISSION; MOLECULES; OPTIMIZATION; PLASMA; PLASMA POTENTIAL; SURFACES