292 / 2023-04-25 17:21:01

Demonstration of direct-drive spherical implosion via shaped laser pulse loading

inertial confinement fusion,shaped laser pulse loading,shock interactions,VISAR,SOP

惯性约束聚变物理学 > 惯性约束聚变物理学-海报

The generation and propagation of shock waves are critical in the study of the compression process in inertial confinement fusion (ICF). In the double cone ignition (DCI) scheme, in order to achieve better compression and acceleration results, the laser pulse shape is theoretically designed by machine learning. The velocity interferometer system for any reflector (VISAR) and streaked optical pyrometer (SOP) systems are used to experimentally diagnose the shock velocities and material temperatures during compression and acceleration process. The 3-picket compressional front is separated out for shock-timing modulation experiments. A maximum shock velocity of 47 km/s by merging three shocks near the same spatial and temporal position within the planar targets is obtained. Accordingly, the optimized 3-picket pulse following a square main pulse is used to perform an implosion experiment on gold cone targets. The diagnostic results combined with the radiation-hydrodynamic simulation results show that the characteristic time for fuel jet from the gold cone is 5.0 ns, the temperature is 42 eV, and the average velocity is 182 km/s. During the total implosion process, the maximum IFAR of the shell target is 29.5, and the adiabat is 1.34, achieving the low-entropy implosion. These results will provide an important reference for laser pulse shape and standard target designs for further DCI campaigns.