Conceptual design of the collection optics for the edge Thomson scattering system in ITER

Yatsuka, Eiichi; Hatae, Takaki; Suito, Satoshi*; Aida, Yoshiyuki*; Kusama, Yoshinori

The difficulty in the edge Thomson scattering (TS) diagnostic in ITER is caused by the neutron and -ray irradiation. The vacuum window shall not directly face to a plasma. The TS light is relayed through the relaying optics with labyrinth, and collected to the optical fiber bundles. The total transmissivity of the TS light from a plasma to the optical fiber is approximately 30%. An electron density of 2 is enough to measure electron temperature and electron density within a 10% and 5% margin of error, respectively, with 5 mm of the spatial resolution. The super-Gaussian beam is the ideal laser profile for the laser injection optics to avoid the break-down of filling gas at the calibration of the spectral transmissivity.