David BRADLEY (NIF, Lawrence Livermore National Laboratory, USA)
“Hyper-Laser force implodes a tiny artificial sun.”
|Title:||Advances in X-ray Diagnostic Capabilities at the National Ignition Facility|
|Author:||David Bradley, et al.|
|Affiliation:||National Ignition Facility, Laurence Livermore National Laborator|
X-ray self-emission from the implosion of a DT-filled, W-doped diamond capsule at the National ignition facility. The bright features are believed to be from plasma jets generated by the tube used to fill the capsule. The total duration of the movie is approx. 500 ps
|Experiments at the National Ignition Facility utilize a comprehensive suite of x-ray, optical and nuclear diagnostics to diagnose indirectly-driven implosions. The x-ray based instruments play the dominant role in characterizing the performance of the hohlraum and capsule using fast gated and streaked self-emission imaging, radiography and spectroscopy. Key measurements include the illumination pattern and symmetry of the drive, the velocity imparted to the capsule, the shape of the hot-spot and cold fuel layer during the hydro assembly of the fuel and the temperature of the hot spot.
The fast timescales and the harsh environment of these hohlraums and implosions impose tight constraints on the performance of these instruments, both in terms of temporal and spatial resolution, background rejection and their survivability. Several existing diagnostics have undergone upgrades to significantly improve their performance. An overview of the diagnostic capability at the NIF will be presented, and the design and improved performance of new and upgraded diagnostics will be discussed.
*Work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under contract DE-AC52-07NA27344.
|Biographical Sketch:||David Bradley received his B.Sc. (1980) and PhD (1985) from Imperial College, London. From 1987-88 he was a researcher at the Lawrence Berkeley National Laboratory, working on time-resolved x-ray spectroscopy, and from 1988 to 1998 he was employed at the University of Rochester Laboratory for Laser Energetics, where he worked on the OMEGA laser facility, developing a range of high-speed time-resolved x-ray diagnostics and techniques for direct-drive laser fusion experiments. In 1998 he moved to Lawrence Livermore National Laboratory, where he has worked on a number of projects in support of the high-energy density science and inertial confinement fusion programs at the laboratory. He is currently the Group leader of the X-ray Diagnostics and Measurement Science group, and the lead scientist for diagnostics on the National Ignition Facility. In 2009 Dr. Bradley was elected a Fellow of the American Physical Society for “the development and use of high speed optical and X-ray instrumentation to discover new phenomena in high-energy density plasmas.”|