The stray laser light simulation of the beam dump for Thomson scattering systems in HL-2M tokamak

Two compact beam dumps are needed to install in-vessel in the low field side (LFS) and the divertor region for Thomson scattering (TS) systems of HL-2M tokamak. An upgraded chevron-like beam dump with two dome layers will be installed on the TS systems. According to the ray-tracing simulation results, the upgraded mechanical structure could efficiently reduce stray light level emitting from the beam dump. Half divergence angle of stray laser light from the beam dump would reduce to 23 degrees, with the double dome-like covering over to the chevron beam dump. The upgraded beam dump is able to satisfy both the demands of Thomson scattering systems in the x-point region and the main plasma region. (author)