Study of first mirror exposure and protection in HL-2A tokamak

Glass and copper mirrors were exposed inside the HL-2A vacuum chamber. Arc discharge mark has been found on the glass mirror. The optical transmission character of test mirrors has been measured. The main components of the deposited materials on the first mirror are carbon and iron analyzed by AES. The Monte-Carlo method has been used to simulate the defending effect of the shield for test mirror. After a 2 years tokamak experiment, one can find that the reflectivity of copper mirror decline slower than that of glass mirror. The first mirror is polluted easier during glow discharge and wall processing than omhic discharge. Using buffer and shutter can play down the pollution, especially during the glow discharge and wall processing.