Analysis of scattered light from multi-blade and V-grooved laser dumps in Thomson scattering diagnostic

Laser dump is an essential optical component in Thomson scattering diagnostic. Both multi-blade and V-grooved dumps can increase the ability of absorbing laser energy by using multiple surfaces to reduce the energy density on the wall surface. Still, the wall edges of the dump easily produce scattered light. The distribution and intensity of scattered light escaping from these two dumps, as well as the distribution and intensity of scattered light on the wall, are analyzed by the theory and simulation. In which an optical-mechanical simulation model of the laser dump was built. The results indicate that increasing the depth of the laser beam incident into the dump can decrease the distribution of escaping scattered light for these two dumps. When both the half-angle of V-groove and the incidence angle of beam on the entrance surface take a small amount, the V-grooved dump has an advantage of weaker escaping scattered light intensity, while there is a problem of heat accumulation at the bottom. For a fixed laser beam diameter, there is an optimal spacing for the dump to minimize the intensity of escaping scattered light. Additionally, the intensity of escaping scattered light is affected by the surface properties of dump, with low surface specular reflection resulting in low intensity.