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Title: Development of the gas puff charge exchange recombination spectroscopy (GP-CXRS) technique for ion measurements in the plasma edge

A novel charge-exchange recombination spectroscopy (CXRS) diagnostic method is presented, which uses a simple thermal gas puff for its donor neutral source, instead of the typical high-energy neutral beam. This diagnostic, named gas puff CXRS (GP-CXRS), is used to measure ion density, velocity, and temperature in the tokamak edge/pedestal region with excellent signal-background ratios, and has a number of advantages to conventional beam-based CXRS systems. Here we develop the physics basis for GP-CXRS, including the neutral transport, the charge-exchange process at low energies, and effects of energy-dependent rate coefficients on the measurements. The GP-CXRS hardware setup is described on two separate tokamaks, Alcator C-Mod and ASDEX Upgrade. Measured spectra and profiles are also presented. Profile comparisons of GP-CXRS and a beam based CXRS system show good agreement. Emphasis is given throughout to describing guiding principles for users interested in applying the GP-CXRS diagnostic technique.
Authors:
; ;  [1] ; ; ;  [2] ; ;
  1. MIT Plasma Science and Fusion Center, Cambridge, Massachusetts 02139 (United States)
  2. Max-Planck-Institut für Plasmaphysik, EURATOM Association, Boltzmannstrasse 2, D-85748 Garching (Germany)
Publication Date:
OSTI Identifier:
22220346
Resource Type:
Journal Article
Resource Relation:
Journal Name: Review of Scientific Instruments; Journal Volume: 84; Journal Issue: 9; Other Information: (c) 2013 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; 70 PLASMA PHYSICS AND FUSION TECHNOLOGY; ALCATOR DEVICE; ASDEX TOKAMAK; BOUNDARY LAYERS; CHARGE EXCHANGE; DIAGNOSTIC TECHNIQUES; ELECTRON TEMPERATURE; ENERGY DEPENDENCE; ION DENSITY; ION TEMPERATURE; IONS; PLASMA DENSITY; PLASMA DIAGNOSTICS; RECOMBINATION; SIGNALS; SPECTRA; SPECTROSCOPY; TEMPERATURE MEASUREMENT