Analysis of Hot-Electron Preheat of High-Performing OMEGA Cryogenic Implosions *

Fast electrons generated in the coronal plasma by laser–plasma instabilities can preheat cryogenic DT fuel, thereby raising its adiabat and lowering final compression. One-dimensional LILAC simulations of high-performing OMEGA cryogenic implosions show the conditions at quarter critical to be above the threshold for two-plasmon–decay (TPD) instability. Significant amount of w/2 signal, characteristic of TPD decay, is also measured. We use methods developed from dedicated preheat measurement experiments to infer fast-electron preheat and quantify resulting performance degradation for some high-performing OMEGA cryogenic implosions. We also show that replacing CD ablator with silicate plastic CHSi can alleviate hot-electron preheat. This material is based upon work supported by the Department of Energy National Nuclear Security Administration under Award Number DE-NA0003856.

A. R. Christopherson et al., “Direct Measurements of DT Fuel Preheat from Hot Electrons in Direct-Drive Inertial Confinement Fusion,” to be published in Physical Review Letters.