Shock Ignition Simulations and Experiments in ignition-scale plasma conditions

Shock ignition (SI) is a promising route to direct drive ignition. As the implosion velocity is reduced below the self-ignition threshold, ignition is instead initiated by a strong shock. Consequently, SI has potential advantages over other laser fusion schemes; the laser energy requirements for ignition appear to be well within those possible on NIF and, as the implosion velocity can be lower, the susceptibility to fluid instabilities (Rayleigh-Taylor) is reduced. Finally, because more fuel mass can be imploded for a given driver energy, there is the potential for high gain at modest laser energies.

However as shock ignition requires increased laser intensity at the end of the drive pulse, laser plasma interaction instabilities (LPI) increasingly dominate the absorption of laser light and can create significant populations of hot-electrons. Depending on their energy spectrum, these hot-electrons may enhance the ignitor shock.

This talk will discuss the first experiments – performed on Omega 60 – to combine the laser intensity required for shock ignition (~1e16W/cm²) with NIF-like plasma conditions. We describe the novel targetry used to achieve these plasma conditions and the experimental results.