Experimental studies of implosion physics of indirect-drive inertial confinement fusion

In the research of laser indirect-drive inertial confinement fusion, the capsule is imploded symmetrically using radiative ablation. Then, the implosion kinetic energy is converted into the hotspot thermal energy in the deceleration phase so as to achieve the ignition condition and the resulting burn propagation. According to current knowledge, the most important factors that determine the implosion performance are the implosion symmetry, adiabatic factor, implosion velocity, and mix. The purpose of the experimental studies of the implosion physics is to develop the methods that can quantitatively characterize these factors, to investigate the scaling laws of these factors as the design parameters are changed, and to establish the ways to tune these factors. Considering the implosion symmetry, Bi sphere reemission experiments were carried out in order to characterize the incident flux asymmetry in the first 2 ns of the ignition pulse. With respect to the implosion velocity, the platform of homochromatic stream-line using spherical bent crystal was developed to measure the implosion velocity and the remaining mass. In the subject of mix, we performed implosion experiment using the capsule of doped inner layer, and ring-shaped images were obtained. Finally, comprehensive implosion experiments using DT gas were conducted on SGⅡ and SGⅢ prototype laser facilities. The correlations between neutron yield and initial target parameters were studied.