Producing shock-ignition-like pressures by indirect drive

The shock ignition scheme is an alternative Inertial Confinement Fusion ignition scheme that offers higher gains and a robustness to hydrodynamic instabilities. A desirable aspect of shock ignition is that the required intensities are achievable on existing facilities. Conventional approaches to shock ignition have only considered the use of direct laser drive. This is in part due to concerns that achieving the rapid rise in drive pressure needed in the final pressure spike may not be feasible using the indirect drive approach. The primary advantage of being able to utilise a hohlraum drive for a shock ignition experiment is that experiments could be carried out at existing, or soon to be completed, Mega-Joule scale facilities. Furthermore, this could be done without the need for any major modification to the facility architecture, such as would be required for direct drive experiments. One and two-dimensional radiation hydrodynamic simulations have been performed using the codes HYADES and h2d. The simulations investigated the level of x-ray fluxes that could produce shock ignition scale pressures as well as the laser powers that would be required to generate those pressures in a NIF scale-1 hohlraum. The second aspect of this work was to investigate the x-ray flux rise times that would be necessary to create a large enough shock ignition spike pressure (200-300 Mbar). It was found that pressures of 230 Mbar could be achieved through indirect drive using a laser source with a peak power of 400 TW. In addition, the rate of pressure increase in the final pressure spike is similar to the expected requirements for directly-driven shock ignition.