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Title: Laser photodetachment diagnostics of a 1/3-size negative hydrogen ion source for NBI

To investigate the flows of charged particles in front of the plasma grid (PG) in a negative hydrogen ion source, the information of the local densities of electrons and negative hydrogen ions (H-) are necessary. For this purpose, the laser photodetachment is applied for pure hydrogen plasmas and Cs-seeded plasma in a 1/3-size negative hydrogen ion source in NIFS-NBI test stand. The H- density obtained by photodetachment is calibrated by the results from cavity ring-down (CRD). The pressure dependence and PG bias dependence of the local H- density are presented and discussed. The results show that H- density increases significantly by seeding Cs into the plasma. In Cs-seeded plasma, relativity exists between the H- ion density and plasma potential.
Authors:
 [1] ; ; ; ; ; ; ; ;  [2]
  1. The Graduate University for Advanced Studies, Oroshi, Toki, Gifu 509-5292 (Japan)
  2. National Institutes for Fusion Science, 322-6 Oroshi, Toki, Gifu 509-5292 Japan (Japan)
Publication Date:
OSTI Identifier:
22391436
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; CESIUM; ELECTRONS; HYDROGEN; HYDROGEN IONS 1 MINUS; ION DENSITY; PLASMA; PLASMA DIAGNOSTICS; PLASMA PRESSURE; PLASMA PRODUCTION; PRESSURE DEPENDENCE; US NATIONAL IGNITION FACILITY