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Title: Measurement of heat load density profile on acceleration grid in MeV-class negative ion accelerator

To understand the physics of the negative ion extraction/acceleration, the heat load density profile on the acceleration grid has been firstly measured in the ITER prototype accelerator where the negative ions are accelerated to 1 MeV with five acceleration stages. In order to clarify the profile, the peripheries around the apertures on the acceleration grid were separated into thermally insulated 34 blocks with thermocouples. The spatial resolution is as low as 3 mm and small enough to measure the tail of the beam profile with a beam diameter of ∼16 mm. It was found that there were two peaks of heat load density around the aperture. These two peaks were also clarified to be caused by the intercepted negative ions and secondary electrons from detailed investigation by changing the beam optics and gas density profile. This is the first experimental result, which is useful to understand the trajectories of these particles.
Authors:
; ; ; ; ; ; ; ; ;  [1] ;  [2]
  1. Japan Atomic Energy Agency, 801-1 Mukoyama, Naka 311-0193 (Japan)
  2. Naruto University of Education, 748 Nakashima, Takashima, Naruto-cho, Naruto-shi, Tokushima 772-8502 (Japan)
Publication Date:
OSTI Identifier:
22482957
Resource Type:
Journal Article
Resource Relation:
Journal Name: Review of Scientific Instruments; Journal Volume: 87; 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:
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY; ACCELERATION; ACCELERATORS; ANIONS; APERTURES; DENSITY; GRIDS; HEATING LOAD; ITER TOKAMAK; MEV RANGE; SPATIAL RESOLUTION