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Title: Negative hydrogen ion production mechanisms

Negative hydrogen/deuterium ions can be formed by processes occurring in the plasma volume and on surfaces facing the plasma. The principal mechanisms leading to the formation of these negative ions are dissociative electron attachment to ro-vibrationally excited hydrogen/deuterium molecules when the reaction takes place in the plasma volume, and the direct electron transfer from the low work function metal surface to the hydrogen/deuterium atoms when formation occurs on the surface. The existing theoretical models and reported experimental results on these two mechanisms are summarized. Performance of the negative hydrogen/deuterium ion sources that emerged from studies of these mechanisms is reviewed. Contemporary negative ion sources do not have negative ion production electrodes of original surface type sources but are operated with caesium with their structures nearly identical to volume production type sources. Reasons for enhanced negative ion current due to caesium addition to these sources are discussed.
Authors:
 [1] ;  [2]
  1. UPMC, LPP, Ecole Polytechnique, UMR CNRS 7648, Palaiseau (France)
  2. School of Science and Engineering, Doshisha University, Kyoto 610-0321 (Japan)
Publication Date:
OSTI Identifier:
22412798
Resource Type:
Journal Article
Resource Relation:
Journal Name: Applied physics reviews; Journal Volume: 2; Journal Issue: 2; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
74 ATOMIC AND MOLECULAR PHYSICS; ANIONS; ATOMS; CESIUM; CESIUM ADDITIONS; DEUTERIUM; DEUTERIUM IONS; ELECTRIC CURRENTS; ELECTRODES; ELECTRON ATTACHMENT; ELECTRON TRANSFER; HYDROGEN; HYDROGEN IONS; MOLECULES; PERFORMANCE; PLASMA; SURFACES; WORK FUNCTIONS