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

H. Togashi, A. Ejiri, J. Hiratsuka, K. Nakamura, Y. Takase, T. Yamaguchi, H. Furui, K. Imamura, T. Inada, H. Kakuda, A. Nakanishi, T. Oosako, T. Shinya, M. Sonehara, S. Tsuda, N. Tsujii, T. Wakatsuki, M. Hasegawa, Y. Nagashima, K. NariharaI. Yamada, H. Tojo

Research output: Contribution to journalArticlepeer-review

6 Citations (Scopus)


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.

Original languageEnglish
Article number056103
JournalReview of Scientific Instruments
Issue number5
Publication statusPublished - May 2014

All Science Journal Classification (ASJC) codes

  • Instrumentation


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