A pathway towards burning plasmas through low-convergence-ratio direct drive ICF implosions

The 1D radiation hydrodynamics code Hyades was used to simulate direct-drive implosions in the low-convergence-ratio regime, which restricts hydrodynamic instability growth through limits on implosion velocity and in-flight aspect ratio and parametric instability growth through limits on incident intensity. The simulations demonstrated potential gains of 0.2 on LMJ-scale (0.8 MJ) systems and 0.8 on NIF-scale (1.7 MJ) systems, and a reactor-level gain of 50 for an 8.5 MJ implosion. Further simulations for the lower-energy systems demonstrated a major increase in yield with the deposition of electron energy into the hotspot through auxiliary heating. Results included yield amplification (compared to the case of no auxiliary heating) of up to 80 times (for a capsule requiring 100 kJ of laser compression), and break-even for 1.1 MJ of total energy input (including an estimated 370 kJ of short-pulse laser energy to produce electron beams for the auxiliary heating).