Editing Inertial confinement fusion (section)

===Shiva and Nova===
One of the earliest large scale attempts at an ICF driver design was the [[Shiva laser]], a 20-beam neodymium doped glass laser system at LLNL that started operation in 1978. Shiva was a "proof of concept" design intended to demonstrate compression of fusion fuel capsules to many times the liquid density of hydrogen. In this, Shiva succeeded, reaching 100 times the liquid density of deuterium. However, due to the laser's coupling with hot electrons, premature heating of the dense plasma was problematic and fusion yields were low. This failure to efficiently heat the compressed plasma pointed to the use of [[optical frequency multiplier]]s as a solution that would frequency triple the infrared light from the laser into the ultraviolet at 351&nbsp;nm. Schemes to efficiently triple the frequency of laser light discovered at the [[Laboratory for Laser Energetics]] in 1980 was experimented with in the 24 beam OMEGA laser and the [[NOVETTE laser]], which was followed by the [[Nova (laser)|Nova laser]] design with 10 times Shiva's energy, the first design with the specific goal of reaching ignition.

Nova also failed, this time due to severe variation in laser intensity in its beams (and differences in intensity between beams) caused by filamentation that resulted in large non-uniformity in irradiation smoothness at the target and asymmetric implosion. The techniques pioneered earlier could not address these new issues. This failure led to a much greater understanding of the process of implosion, and the way forward again seemed clear, namely to increase the uniformity of irradiation, reduce hot-spots in the laser beams through beam smoothing techniques to reduce Rayleigh–Taylor instabilities and increase laser energy on target by at least an order of magnitude. Funding was constrained in the 1980s.