Direct Drive Fusion Energy Shock Ignition Designs for Sub-MJ Lasers

Abstract

New approaches in target design have increased the possibility that useful fusion power can be generated with sub-MJ lasers. We have performed many 1D and 2D simulations that examine the characteristics of target designs for sub-MJ lasers. These designs use the recently-proposed shock-ignition target scheme, which utilizes a separate high-intensity pulse to induce ignition. A promising feature of these designs is their significantly higher gains at lower energies (one dimensional (1D) gain ˜ 100 at Elaser ˜ 250kJ) than can be expected for the conventional central ignition scheme. The results of these simulations are shown and we discuss the implications for target fabrication and laser design. Of particular interest are the constraints on the target and laser from asymmetries due to target imperfections and laser imprint.