Page 392 - High Power Laser Handbook

360 So l i d - S t at e La s e r s The National Ignition Facility Laser 361

• Discovery of, theoretical description of, and development of
countermeasures for optical damage due to transverse Brill-
ouin scattering in large-aperture fused-silica optics
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• Neutron yield greater than 10 in 1986 17
• First petawatt laser (1.3 PW in 500-fs pulse) in 1996 18
• First x-ray laser (213 Å) in 1985 19
• Compression of an ICF target by a factor of 35 (linear
dimension), which was close to that needed for gain, in 1987 20
A number of lasers at other facilities throughout the world have
also made important contributions to ICF research and have helped
lay the foundation for the NIF design and specifications. Omega, at
the University of Rochester’s Laboratory for Laser Energetics, was
commissioned in 1995. This 60-beam Nd:glass laser is capable of
delivering as much as 30 kJ at up to 60 TW at 351 nm. Omega was the
world’s highest-energy laser from 1999, when Nova was decommis-
sioned, until 2005, when the first eight beams of NIF demonstrated
output approximately double Omega’s. Omega’s record of 10 neu-
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trons in a single shot, set in 1999, still stands, as does its record for
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3
compressed fuel density (100 g/cm ), set in 2008. Since 1999, much
of the experimental science preparatory to the ignition campaign has
been developed and prototyped on Omega. In 2008, the Omega EP
(extended performance) laser system became operational. This addi-
tion to Omega consists of four beamlines that are near-clones of NIF
beams, a new target chamber, and a vacuum pulse-compression
chamber for achieving petawatt pulses at ~1 ps. In addition to basic
science experiments, the goal of this combined facility will be to carry
out fully integrated cryogenic fast-ignition experiments. 23
Gekko XII, a 12-beam, Nd:glass laser at Osaka University’s Insti-
tute of Laser Engineering, was completed in 1983. It delivered as
much as 10 kJ in 1 to 2-ns pulses and was initially used to study
direct-drive implosion symmetry and exploding-pusher target yields.
In 1996–1997, Gekko was upgraded by the addition of a 400-J, ~100-fs
short-pulse beam and has been used for experiments in fast-ignition
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physics. In 2002, it demonstrated a factor of 10 yield increase by
using its original 12 beams to achieve capsule compression and then
heating with its petawatt beam. Gekko is currently being upgraded
with the addition of a 10-kJ, 10-ps beamline.
Phebus, a two-beam laser capable of 20-kJ IR, 5-kJ ultraviolet
(UV) in 1-ns pulses, is part of the Laboratoire pour l’Utilisation des
Lasers Intenses (LULI) at the École Polytechnique (Palaiseau, France).
It has been a European center for research into high-energy density
physics and has been responsible for important advances in plasma
diagnostics and understanding of the initiation and growth of optical
damage.