Improvements of data quality of the LHD Thomson scattering diagnostics in high-temperature plasma experiments

National Institute for Fusion Science, 322-6 Oroshi-cho, Toki 509-5292, Japan
Review of Scientific Instruments (Impact Factor: 1.58). 11/2010; 81(10):10D522 - 10D522-3. DOI: 10.1063/1.3483189
Source: IEEE Xplore

ABSTRACT In Large Helical Device (LHD) experiments, an electron temperature (Te) more than 15 keV has been observed by the yttrium-aluminum-garnet (YAG) laser Thomson scattering diagnostic. Since the LHD Thomson scattering system has been optimized for the temperature region, 50 eV ≤Te≤10 keV , the data quality becomes worse in the higher Te region exceeding 10 keV. In order to accurately determine Te in the LHD high- Te experiments, we tried to increase the laser pulse energy by simultaneously firing three lasers. The technique enables us to decrease the uncertainties in the measured Te . Another signal accumulation method was also tested. In addition, we estimated the influence of high-energy electrons on Te obtained by the LHD Thomson scattering system.

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