Energy Scaling of Laser Direct-Drive Implosion Performance on OMEGA

The best implosions at the Omega Laser Facility have achieved ~20% of the Lawson product needed to ignite. As these experiments are limited to 30 kJ of laser energy, the capabilities of future laser-direct-drive (LDD) systems is a strong function of fusion performance versus driver energy, as well as any mechanisms that depend on scale. Prominent examples include cross-beam energy transfer, two-plasmon decay, and stimulated Raman scattering. To assess the behavior of LDD systems versus laser energy and target size, we have performed experiments where total energy (and capsule radius) is reduced a factor of ~2 (1.25). We find that fusion yield and areal density increase quickly with laser energy and target size, and much faster than 1D theory would typically expect. We discuss these observations, and show they are consistent with 2D simulations assuming the main flaws in the laser and target are ~ fixed in physical dimensions. For context, we will also consider several extrapolations of LDD under a variety of scenarios. This material is based upon work supported by the Department of Energy National Nuclear Security Administration under Awards No. DE-NA0004414 and No. DE-NA0003856, the University of Rochester, and the New York State Energy Research and Development Authority.