Intensity distribution measurement and analysis of microwave beam for ECRH system in the HL-2A tokamak

The intensity distribution, measured by IR camera at three different positions along the propagation routine, is used to calculate the first and second order moments of the radiation patterns and to retrieve the phase information, and then the propagation direction of the microwave along the waveguide can be determined. The alignment of two ECRH subsystems has been analyzed by using this method and the results show that the power distribution of two subsystems is Gaussian, the tilt angle of No.3 transmission line (7m) is about 0.05 degree and No.4 (6m) is about 0.14 degree. (authors)