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Title: Note: Multi-pass Thomson scattering measurement on the TST-2 spherical tokamak

In multi-pass Thomson scattering (TS) scheme, a laser pulse makes multiple round trips through the plasma, and the effective laser energy is enhanced, and we can increase the signal-to-noise ratio as a result. We have developed a coaxial optical cavity in which a laser pulse is confined, and we performed TS measurements using the coaxial cavity in tokamak plasmas for the first time. In the optical cavity, the laser energy attenuation was approximately 30% in each round trip, and we achieved a photon number gain of about 3 compared with that obtained in the first round trip. In addition, the temperature measurement accuracy was improved by accumulating the first three round trip waveforms.
Authors:
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  1. The University of Tokyo, Kashiwa 277-8561 (Japan)
  2. Kyushu University, Kasuga 816-8580 (Japan)
  3. National Institute for Fusion Science, Toki 509-5292 (Japan)
Publication Date:
OSTI Identifier:
22254864
Resource Type:
Journal Article
Resource Relation:
Journal Name: Review of Scientific Instruments; Journal Volume: 85; Journal Issue: 5; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; 46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY; ACCURACY; CAVITY RESONATORS; LASERS; PLASMA; PULSES; SIGNAL-TO-NOISE RATIO; SPHERICAL CONFIGURATION; TEMPERATURE MEASUREMENT; THOMSON SCATTERING; TOKAMAK DEVICES