An Optical design and accuracy estimation for a JT-60SA edge Thomson scattering diagnostic

Tojo, Hiroshi; Hatae, Takaki; Hamano, Takashi; Sakuma, Takeshi; Itami, Kiyoshi

For collection optics for the edge measurements in a JT-60SA Thomson scattering diagnostic, a compact Petzval-like lens system with smaller lenses (200 mm in diameter) is designed so that the stop position is the middle area of the system, which is effective to miniaturize the lens size. Use of two flat mirrors placed in the middle area enables preventing interferences with the space limit. Generally, the angle () between the scattering plane determined from the collection optics position and the laser polarization angle should be equal to 90. Otherwise the measured intensity of scattered light decays with . We optimized the angle so that enough intensity is provided for both collection optics positions for the edge and core measurements. It was found that the minimum error in was given at a condition with for edge optics ( for core optics).