Precision of ion temperature and impurity fractional density measurement using the JET collective Thomson scattering diagnostic

F. Orsitto

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Abstract

In this work some calculations are reported about the possibility of a simultaneous determination of the temperatures and densities of several different plasma ions using the JET gyrotron collective scattering diagnostic. It should be possible to determine the ion temperatures with a 20% error and the ion densities with ∼50% error, because of the high S/N (signal-to-noise ratio) that can be obtained in this experiment. These figures are obtained assuming 400 kW of incident power, a short integration time (10 ms), the central frequencies and the bandwidths of a 14 channels filter bank of the detection system, and a global (ECE background+detection system) noise temperature of ∼600 eV. The results are obtained using a multiparameter fit of an "experimental spectrum" obtained averaging the calculated form factor in each channel of the filter bank and associating an error to this number calculated using the heterodyne S/N signal-to-noise ratio. The model function used in the fit is a known function of ion temperatures and densities. A deuterium plasma has been considered with hydrogen, carbon, and beryllium impurities. Teand neare assumed to be known from other diagnostics. These conclusions are confirmed using a Monte Carlo code, which takes into account the statistics of the scattered signal.
Original languageEnglish
Pages (from-to)4651 - 4652
Number of pages2
JournalReview of Scientific Instruments
Volume63
Issue number10
DOIs
Publication statusPublished - 1992
Externally publishedYes

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All Science Journal Classification (ASJC) codes

  • Instrumentation
  • Physics and Astronomy (miscellaneous)

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