High-repetition CO laser for collective Thomson scattering diagnostic of particles in burning plasmas

Kondoh, Takashi; Hayashi, Toshimitsu; Kawano, Yasunori; Kusama, Yoshinori; Sugie, Tatsuo; Miura, Yukitoshi; Koseki, Ryoji*; Kawahara, Yoshihiro*

A collective Thomson scattering (CTS) technique based on a pulsed CO laser is being developed in order to establish a diagnostic method of confined -particles in burning plasmas. In International Thermonuclear Experimental Reactor (ITER), measurement of velocity and spatial distributions of confined -particles requires temporal resolution of 0.1 s and spatial resolution of a/10, where a is plasma minor radius. A new laser system (Energy 10J, repetition 10Hz) has been developed based on a commercially available laser (Shibuya Kogyo Co., Ltd, SEL4000) to meet the requirement of temporal resolution of ITER and to improve a signal-to-noise ratio. The laser has unstable resonator with a cavity length of 4 m and discharge electrodes with heat exchanger of laser gas for high-repetition operation. Proof-of-principle test of the CTS technique will be performed with the new laser system on JT-60U (JAEA Tokamak 60 - Upgrade). This work was supported by Grant-in-Aid for Scientific Research on Priority Areas "Advanced Diagnostics for Burning Plasmas" from Ministry of Education, Culture, Sports, Science and Technology, No.16082210.