Injection and Confinement of a Laser Pulse in an Optical Cavity for Multi-Pass Thomson Scattering Diagnostics in the TST-2 Spherical Tokamak Device
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概要
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A multi-pass Thomson scattering (TS) system based on confining laser pulses in an optical cavity was constructed for measuring very low-density plasma in the TST-2 spherical tokamak device. This paper describes the setup of the optical system, injection of the laser pulse into the cavity, and properties of the confined laser pulse. A combination of Pockels cell plus polarizer, which serves as an optical shutter, allows us to inject and then confine intense laser pulses in the cavity. A photodiode signal monitoring the very weak light leaking from the cavity mirrors demonstrated that the laser pulse makes many round trips, with a round-trip efficiency of approximately 0.73. The effective number of round trips (i.e., the signal enhancement factor) is approximately 3.7. For an injection efficiency of approximately 0.69, a cavity-confined laser pulse, applied to Thomson scattering, will yield a scattered signal that is five times larger than that from a single-pass laser pulse.
- 社団法人 プラズマ・核融合学会の論文
著者
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NARIHARA Kazumichi
National Insitute for Fusion Science
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YAMADA Ichihiro
National Insitute for Fusion Science
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YAMAGUCHI Takashi
The University of Tokyo, Tokyo 113-0033, Japan
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NAGASHIMA Yoshihiko
Kyushu University
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Ejiri Akira
The University Of Tokyo
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Hiratsuka Junichi
The University Of Tokyo
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Takase Yuichi
The University of Tokyo
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HASEGAWA Makoto
Kyushu University, 6-1 Kasuga-koen, Kasuga, Fukuoka 816-8580, Japan
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TOJO Hiroshi
Japan Atomic Energy Agency
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TOGASHI Hiro
The University of Tokyo
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TSUJII Naoto
The University of Tokyo
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NAKAMURA Keishun
The University of Tokyo
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