Radiation Trapping and Hot-Spot Energy Balance in High-Z Pusher Implosions

Single-,[1] double-,[2] and triple-shell[3] inertial confinement fusion target designs offer an alternative (to cryogenic layer implosions) pathway to ignition. They use a high-Z layer (metal pusher) on the inside of the innermost shell that effectively traps the radiation from the hot spot and lowers the temperature required to achieve ignition conditions. It also improves the hot-spot compression because of the increase in the shell density. In this talk, we use the radiation-hydrodynamic code LILAC to analyze energy balance between the compression work and thermal-conduction and radiation losses in the DT hot spot of CH single-shell implosions with a high-Z inner layer. The code employs a straight line (Sn) model to accurately treat the radiation transport in both the optically thin hot spot and the optically thick high-Z layer around it. The studies will be used to design a low convergence ratio, high-adiabat implosion to experimentally study the hot-spot radiation trapping on the OMEGA Laser System. This material is based upon work supported by the Department of Energy National Nuclear Security Administration under Award Number DE-NA0003856.

[1] E. L. Dewald et al., Phys. Plasmas 15, 072706 (2008).

[2] D. S. Montgomery et al., Phys. Plasmas 25, 092706 (2018).

[3] K. Molvig et al., Phys. Rev. Lett. 116, 255003 (2016).