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Title: Dual-angle, self-calibrating Thomson scattering measurements in RFX-MOD

In the multipoint Thomson scattering (TS) system of the RFX-MOD experiment the signals from a few spatial positions can be observed simultaneously under two different scattering angles. In addition the detection system uses optical multiplexing by signal delays in fiber optic cables of different length so that the two sets of TS signals can be observed by the same polychromator. Owing to the dependence of the TS spectrum on the scattering angle, it was then possible to implement self-calibrating TS measurements in which the electron temperature T{sub e}, the electron density n{sub e} and the relative calibration coefficients of spectral channels sensitivity C{sub i} were simultaneously determined by a suitable analysis of the two sets of TS data collected at the two angles. The analysis has shown that, in spite of the small difference in the spectra obtained at the two angles, reliable values of the relative calibration coefficients can be determined by the analysis of good S/N dual‑angle spectra recorded in a few tens of plasma shots. This analysis suggests that in RFX-MOD the calibration of the entire set of TS polychromators by means of the similar, dual-laser (Nd:YAG/Nd:YLF) TS technique, should be feasible.
Authors:
 [1] ;  [2] ;  [3] ;  [1]
  1. Consorzio RFX, Corso Stati Uniti, 4, 35127 Padova (Italy)
  2. (Italy)
  3. Department of Industrial Engineering, Padova University, Via Gradenigo 6/a, 35131 Padova (Italy)
Publication Date:
OSTI Identifier:
22308611
Resource Type:
Journal Article
Resource Relation:
Journal Name: Review of Scientific Instruments; Journal Volume: 85; Journal Issue: 11; Other Information: (c) 2014 Euratom; 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; CALIBRATION; DETECTION; ELECTRON DENSITY; ELECTRON TEMPERATURE; NEODYMIUM LASERS; OPTICAL FIBERS; PLASMA; REVERSE-FIELD PINCH; SENSITIVITY; SIGNALS; SPECTRA; THOMSON SCATTERING