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Title: Characterization of the fast electrons distribution produced in a high intensity laser target interaction

Experiments on the Titan laser (∼150 J, 0.7 ps, 2 × 10{sup 20} W cm{sup −2}) at the Lawrence Livermore National Laboratory were carried out in order to study the properties of fast electrons produced by high-intensity, short pulse laser interacting with matter under conditions relevant to Fast Ignition. Bremsstrahlung x-rays produced by these fast electrons were measured by a set of compact filter-stack based x-ray detectors placed at three angles with respect to the target. The measured bremsstrahlung signal allows a characterization of the fast electron beam spectrum, conversion efficiency of laser energy into fast electron kinetic energy and angular distribution. A Monte Carlo code Integrated Tiger Series was used to model the bremsstrahlung signal and infer a laser to fast electron conversion efficiency of 30%, an electron slope temperature of about 2.2 MeV, and a mean divergence angle of 39°. Simulations were also performed with the hybrid transport code ZUMA which includes fields in the target. In this case, a conversion efficiency of laser energy to fast electron energy of 34% and a slope temperature between 1.5 MeV and 4 MeV depending on the angle between the target normal direction and the measuring spectrometer are found. The observed temperature of the bremsstrahlung spectrum, and therefore the inferredmore » electron spectrum are found to be angle dependent.« less
Authors:
 [1] ;  [2] ; ; ;  [3] ;  [1]
  1. Department of Mechanical and Aerospace Engineering, University of California San Diego, La Jolla, California 92093 (United States)
  2. (United States)
  3. Lawrence Livermore National Laboratory, Livermore, California 94550 (United States)
Publication Date:
OSTI Identifier:
22252016
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physics of Plasmas; Journal Volume: 21; Journal Issue: 3; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; ANGULAR DISTRIBUTION; BREMSSTRAHLUNG; EFFICIENCY; ELECTRON BEAMS; ELECTRON SPECTRA; ELECTRONS; INTERACTIONS; KINETIC ENERGY; LASER TARGETS; MONTE CARLO METHOD; SIGNALS; SIMULATION; SPECTROMETERS; THERMONUCLEAR IGNITION; X RADIATION