Opportunities for Science from the Petawatt Laser


DURING the past 25 years, Lawrence Livermore has become a world-renowned research center for designing, building, and utilizing high-peak-power and high-energy lasers. Starting with the 100-million-watt, two-beam Janus laser in 1974, we designed and built a series of laser systems, each providing five to ten times more irradiance (power per unit area) than its predecessor.
Our series of increasingly more capable facilities now culminates in a revolutionary one-aperture laser, the Petawatt, with output power exceeding a quadrillion watts. Using the technique of chirped-pulse amplification, which enables us to produce very short (less than a trillionth of a second) energetic pulses on one arm of the ten-arm Nova laser, the Petawatt is able to exceed the total power of Nova by a factor of 10.
Even more impressive than its output power is the Petawatt's extraordinary brightness. Coupled with innovative focusing schemes, this brightness will enable the Petawatt to be focused to irradiances that produce an electric field exceeding by a factor of 100 the force that binds an electron to a proton in the hydrogen atom.
"Crossing the Petawatt Threshold," beginning on p. 4, describes the major technical and scientific advances that were required to make a petawatt laser a reality at Livermore. These advances in laser science and optical component fabrication have enabled revolutionary new concepts in laser science and machining as well as information display production technologies.
What's more, the enormous energy density of the Petawatt will push back the frontiers of knowledge about laser-matter interaction and expand our knowledge of matter under extreme conditions. For the first time in a laboratory setting, we will be exploring relativistic plasma physics and new sources of coherent and incoherent radiation at high photon energy.
Finally, the Petawatt will allow us to test a new pathway to laser fusion, called "fast ignition," that was developed at Lawrence Livermore early in this decade. As described in the article, the fast-ignition concept cleverly sidesteps the most difficult aspects of achieving fusion ignition with conventional inertial confinement fusion design.
The enormous opportunities created by the Petawatt will keep Lawrence Livermore in the forefront of high-power laser physics and high-energy-density physics for the foreseeable future.

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