Development of CO laser interferometer/polarimeter system in JT-60SA

Sasao, Hajime; Kawano, Yasunori*; Arakawa, Hiroyuki; Sakuma, Takeshi; Imazawa, Ryota; Kubo, Hirotaka; Itami, Kiyoshi

Development of CO laser interferometer/polarimeter system for JT-60SA has progressed. The CO laser interferometer/polarimeter system consists of a two color heterodyne interferometer and a polarimeter based on dual PEMs. In JT-60SA, the laser interferometer/ polarimeter system is located in a diagnostic room apart from the tokamak hall, and the laser transmission length is about 200 m. Therefore, it is a key issue for the reliable measurement to transmit the laser light with high stability for the long distance. To realize the stable long-distance transmission, new technologies are developed including a laser spectral beam profile monitor for two color lasers and a laser axis stabilizing system. In addition, a new method for expansion of polarization angle is developed to improve measurement resolution of the polarimeter.