Design of a 50 TW / 20 J Chirped-Pulse Amplification Laser for High-Energy-Density Plasma Physics Experiments at the Nevada Terawatt Facility of the University of Nevada

摘要

We have developed a conceptual design for a 50 TW / 20 J short-pulse laser for performing high-energy-density plasma physics experiments at the Nevada Terawatt Facility of the University of Nevada, Reno. The purpose of the laser is to develop proton and x-ray radiography techniques, to use these techniques to study z-pinch plasmas, and to study deposition of intense laser energy into both magnetized and unmagnetized plasmas. Our design uses a commercial diode-pumped Nd:glass oscillator to generate 3-nJ, 200-fs mode-locked pulses at 1059 nm. An all-reflective grating stretcher increases pulse duration to 1.1 ns. A two-stage chirped-pulse optical parametric amplifier (OPCPA) using BBO crystals boosts pulse energy to 12 mJ, with gain saturation increasing pulse duration and bandwidth to ～1.9 ns and ～14 nm (FWHM), respectively. A chain using mixed silicate-phosphate Nd:glass increases pulse energy to 85 J while narrowing bandwidth to 7.4 nm (FWHM). A beam splitter directs 50 J to the laser target chamber to generate plasma. The remaining energy is directed to a roof-mirror pulse compressor that uses two 21 cm x 42 cm gold gratings to recompress pulses to ～350 fs. A 30-cm-focal-length off-axis parabolic reflector (OAP) focuses ～20 J onto target, producing an irradiance of 10~(19) W/cm~2 in a 10-μm-diameter spot. This paper describes planned plasma experiments, system performance requirements, the laser design, and the target area design.