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(IFP/10) Update on Fast Ignition Experiments at Nova Petawatt

R. B. Stephens1), T. E. Cowan2)*, R. R. Freeman3), S. Hatchett2), M. H. Key2), J. A. Koch2), R. W. Lee2), A. MacKinnon2), D. Pennington2), R. Snavely2), M. Tabak2), and K. Yasuike2)
 
1) General Atomics, San Diego, California USA
2) Lawrence Livermore National Laboratory, Livermore, California USA
3) University of California, Davis, Livermore, California USA
* Present Address: General Atomics

Abstract.  The physics of fast ignition was studied on the PetaWatt laser facility at LLNL for $ \sim$ 3 years, to May 1999. The previous report to this conference described experiments that demonstrated the efficient transfer of laser energy to relativistic electrons that penetrated into the target and heated to temperatures $ \sim$ 1keV. Since then, we have looked at energy transfer and propagation in dense plasmas in considerably more detail. Measurements show that the relativistic electrons penetrate > 100$ \mu$m into a CH foil in a collimated beam with a complex annular structure. Production of an energetic (up to 55 MeV) proton beam was also discovered. The protons are tightly bunched (< 40oC spread) and are emitted normal to the back target surface, so can be accurately directed. This gives another promising possibility for delivery of the ignition pulse.

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IAEA 2001