Angular distribution of the hohlraum radiation temperature in indirect drive fusion

Hohlraum radiation flux is the source of the capsule implosion in the indirect drive fusion, which strongly affects the capsule compression properties. It is very important to study the angular distribution of the hohlraum radiation temperature in order to understand the radiation properties inside the hohlraum. In this work, the angular distribution of the hohlraum radiation temperature is studied through theoretical analysis and multi-group radiation transfer simulations with LARED. It is found that the angular distribution of the radiation temperature is mainly determined by the ratio of the radiation flux between the hot spot and non-spot region, the ratio of the hot spot area in the detected line of sight, and the component of the volume emission. The theoretical analysis agrees very well with the LARED simulation in the two dimensional laser cone case. It is found that the two dimensional LARED simulation can be effectively used to study the angular distribution of the radiation temperature in the SGIII-P hohlraum experiments with three dimensional laser spot structures. An improved method is proposed to measure the angular distribution of the radiation temperature with more significant variation of the radiation temperature.