Abstract

Direct-drive laser fusion requires generation of densities of several 100 g/cm³ in fusion fuel capsules ablatively imploded by irradiation of intense laser light. Use of short-wavelength radiation ensures efficient laser-target coupling with negligible energy conversion to superthermal electrons. At intensities of ~5 × 10¹⁴ W/cm², ablation pressures in excess of 40 Mbars are generated with nanosecond 351-nm laser light, sufficient to drive effectively high-density implosions. For direct target illumination, the efficient overall energy coupling is balanced by the severe requirements on irradiation uniformity. From simple heuristic arguments, and detailed hydrodynamic code simulations, the overall energy deposition uniformity on the surface of the target must be ~1 % to ensure tolerable implosion symmetry.

© 1986 Optical Society of America