Abstract

The Nova laser amplifier system at Lawrence Livermore National Laboratory was designed to deliver 80-120 kJ of 1.05-μm laser radiation in 1.0-3.0-ns pulse-to-frequency conversion crystals, The crystals (type II /type II KDP) convert this efficiently to give 50-80 kJ of second harmonic or 40-70 kJ of third harmonic light, which is focused onto fusion targets in a target chamber.¹ Single-beam and full-system trials done shortly after completion of the facility demonstrated that the laser amplifier and harmonic conversion systems could easily meet these operating goals.² We are presently prevented from routinely operating at these levels because of the threat of damage to the glass in the output amplifier stages. The laser glass in the amplifiers and the BK-7 optical glass in other components contain a few particles per liter of small metallic platinum inclusions, which cause damage to the glass at fluences exceeding 2.0 J/cm².³ This has caused us to limit energy routinely available from Nova to 50-60 kJ at 1.05 /μm, which yields 20-25 kJ of the third harmonic on-target.

© 1988 Optical Society of America