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Title: Compact tunable Compton x-ray source from laser-plasma accelerator and plasma mirror

We present an in-depth experimental-computational study of the parameters necessary to optimize a tunable, quasi-monoenergetic, efficient, low-background Compton backscattering (CBS) x-ray source that is based on the self-aligned combination of a laser-plasma accelerator (LPA) and a plasma mirror (PM). The main findings are (1) an LPA driven in the blowout regime by 30 TW, 30 fs laser pulses produce not only a high-quality, tunable, quasi-monoenergetic electron beam, but also a high-quality, relativistically intense (a{sub 0} ∼ 1) spent drive pulse that remains stable in profile and intensity over the LPA tuning range. (2) A thin plastic film near the gas jet exit retro-reflects the spent drive pulse efficiently into oncoming electrons to produce CBS x-rays without detectable bremsstrahlung background. Meanwhile, anomalous far-field divergence of the retro-reflected light demonstrates relativistic “denting” of the PM. Exploiting these optimized LPA and PM conditions, we demonstrate quasi-monoenergetic (50% FWHM energy spread), tunable (75–200 KeV) CBS x-rays, characteristics previously achieved only on more powerful laser systems by CBS of a split-off, counter-propagating pulse. Moreover, laser-to-x-ray photon conversion efficiency (∼6 × 10{sup −12}) exceeds that of any previous LPA-based quasi-monoenergetic Compton source. Particle-in-cell simulations agree well with the measurements.
Authors:
; ; ; ; ; ;  [1] ;  [2] ; ; ;  [1] ;  [3]
  1. Department of Physics, The University of Texas at Austin, Austin, Texas 78712-1081 (United States)
  2. Institute for Fusion Studies, The University of Texas at Austin, Austin, Texas 78712 (United States)
  3. (United States)
Publication Date:
OSTI Identifier:
22408136
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physics of Plasmas; Journal Volume: 22; Journal Issue: 2; Other Information: (c) 2015 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; BACKSCATTERING; BLOWOUTS; BREMSSTRAHLUNG; COMPTON EFFECT; COMPUTERIZED SIMULATION; ELECTRON BEAMS; LASER-PRODUCED PLASMA; MIRRORS; PHOTONS; PLASMA GUNS; PLASTICS; PULSES; RELATIVISTIC RANGE; THIN FILMS; VISIBLE RADIATION; X RADIATION; X-RAY SOURCES