Inertial confinement fusion experiments with OMEGA-A 30-kJ, 60-beam UV laser

摘要

The Laboratory for Laser Energetics (LLE) experimental program supports the US inertial confinement fusion (ICF) effort by investigating the requirements for attaining ignition using direct drive targets. The primary tool for this research is OMEGA, a 60-beam, 351-nm, Nd:glass laser with an on-target energy capability in excess of 30 kJ. The laser is designed to ultimately achieve an irradiation uniformity of ~ 1 on direct-drive capsules with shaped laser pulses (dynamic range > 400:1). In addition, OMEGA provides unique capabilities for irradiating indirect-drive targets. This paper reports on a number of recent laser enhancements, including a new design for distributed phase plates (DPPs), two-dimensional smoothing by spectral dispersion (2-D SSD), distributed polarization rotators (DPRs) and laser pulse shaping. A variety of spherical-implosion, planar-target, and indirect-drive experiments attest to the versatility of the OMEGA laser. A key result is the highest thermonuclear yield (10~(14) neutrons) and yield efficiency (1 of scientific breakeven) ever attained in laser fusion experiments.