Low Aspect Ratio Double Shell Targets for High Density and High Gain and a Comparison with Ultra Thin Shells

摘要

Double shell targets may have decisive advantages over single shells for achieving a number of goals in the laser fusion program. With 0.2 mu light, such designs achieve 500 to 1000 times liquid density at 2 kJ absorbed; 10 percent or more of breakeven at 15 kJ absorbed, and gains of 10 or more at 200 kJ absorbed. These targets are relatively insensitive to preheat, laser pulse shape, and hydrodynamic instability. A double shell in which the outer pusher is fuel may achieve a gain of 1000 for lasers in the 1 to 10 megajoule size. Ultra thin targets have only about a factor of two reduction in power shells with aspect ratios of 2 to 4 while requiring about the same input energy and achieving about the same gain. Their extreme sensitivity to preheat, symmetry, and hydrodynamic instability makes them unattractive for targets in advanced lasers systems. (ERA citation 03:056673)