skip to main content

SciTech ConnectSciTech Connect

Title: Effects of electron recirculation on a hard x-ray source observed during the interaction of a high intensity laser pulse with thin Au targets

The interaction of a high intensity laser pulse on the preplasma of a high-Z solid target produced by the pulse's pedestal generates high-energy electrons. These electrons subsequently penetrate inside the solid target and produce bremsstrahlung photons, generating an x-ray source which can be used for photonuclear studies or to radiograph high area density objects. The source characteristics are compared for targets with thin (20 μm) and thick (100 μm) Au foils on the Omega EP laser at Laboratory for Laser Energetics. Simulations using the particle-in-cell code CALDER show that for a 20 μm thickness Au target, electrons perform multiple round-trips in the target under the effect of the laser ponderomotive potential and the target electrostatic potential. These relativistic electrons have random transverse displacements, with respect to the target normal, attributed to electrostatic fluctuation fields. As a result, the x-ray spot size is increased by a factor 2 for thin target compared to thick targets, in agreement with experimental results. In addition, the computed doses agree with the measured ones provided that electron recirculation in the thin target is taken into account. A dose increase by a factor 1.7 is then computed by allowing for recirculation. In the 100 μm targetmore » case, on the other hand, this effect is found to be negligible.« less
Authors:
; ; ; ;  [1] ; ;  [2]
  1. CEA, DAM, DIF, F-91297 Arpajon (France)
  2. Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14623 (United States)
Publication Date:
OSTI Identifier:
22218366
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physics of Plasmas; Journal Volume: 20; Journal Issue: 12; Other Information: (c) 2013 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; 07 ISOTOPES AND RADIATION SOURCES; BEAM-PLASMA SYSTEMS; BREMSSTRAHLUNG; COMPARATIVE EVALUATIONS; ELECTRON BEAMS; ELECTRONS; FLUCTUATIONS; GOLD; HARD X RADIATION; LASER-PRODUCED PLASMA; LASERS; NONLINEAR PROBLEMS; PHOTONS; PLASMA DIAGNOSTICS; PLASMA PRODUCTION; PLASMA SIMULATION; PONDEROMOTIVE FORCE; X-RAY SOURCES