Thermal Transfiguration Analysis for the Large Aperture Optical Element of Switchyard in ICF Driver Target Area

Abstract

Temperature gradient is one of the most important factors that cause large deformation of the large aperture optical element in an inertial confinement fusion (ICF) laser driver. In this study, we measured the ambient temperature around the laser switchyard and analyzed the temperature distribution and changing characteristics over time. The results indicated that variation trends of temperature inside the switchyard was almost the same, the temperature gradients of the uppermost part were higher than the bottom, and the temperatures in the centre were higher than both sides. Loading the temperature profile into the finite element model of the switchyard showed that the deformation of the optical element changed with time. The results indicate that temperature distribution has a great impact on the optical elements, and it attains the design objective of being smaller than 0.24urad and contents with the requirement of shooting practice when temperature difference is about 0.01°C or partial temperature difference inside the switchyard is about 0.1°C.