Wednesday, April 09, 2008

Petawatt Power Peak Reached

The Texas Petawatt laser produced a petawatt of peak power on March 31, making it the highest powered laser in the world, said Todd Ditmire, a physicist at the University of Texas at Austin.

There has only been one petawatt laser in the US history, the Nova laser at Lawrence Livermore Laboratory (LLNL, operated by the University of California for the energy department). Nova, which took up a football field in space, is now defunct. In the past eight or so years, there has been a worldwide push to achieve petawatts (10 to the 15th power). Terawatts (10 to the 12th power) were produced by short pulse lasers in the late 1980s using chirped pulse amplification, the method Ditmire is using.

Other US petawatt projects include the OmegaEP laser at the University of Rochester, The Ohio State University petawatt, and the Z-Beamlet project at the Sandia National Labs Z-Petawatt Laser Facility. Projects are also underway in the UK, France, Germany, Japan, China, and other countries.

The challenge for researchers is to produce a lot of energy in a little time, and a petwatt can be the result if enough energy can be produced in a short enough pulse. The Hercules laser at the University of Michigan, for example, is only 0.3 petawatts, but it focuses to an incredibly tiny spot. For sheer power -- energy divided by pulse duration -- the Texas petawatt laser now leads the way in the US.

The laser produces a very short duration, very low-energy pulse, and this pulse is stretched in time to a very long pulse, is amplified to huge energy, then finally is compressed to a high-energy, super-short-duration pulse. One of the critical aspects of the system is the diffraction gratings used to compress the pulse; these were made by Jerry Britten's group at LLNL, and they are some of the most difficult-to-manufacture optics in the world.

Related Link: Texas High Intensity Laser


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