Compact tunable Compton x-ray source from laser-plasma accelerator and plasma mirror
Abstract
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 (a0 ∼ 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 × 10−12) exceeds that of any previous LPA-based quasi-monoenergetic Compton source. Particle-in-cell simulations agree well with the measurements.
Document Details
- Document Type
- Pub Defense Publication
- Publication Date
- Feb 01, 2015
- Source ID
- 10.1063/1.4907655
Entities
People
- Alexey V Arefiev
- G. Shvets
- Hai-En Tsai
- Joseph M. Shaw
- M. C. Downer
- Rafal Zgadzaj
- Vladimir Khudik
- Watson Henderson
- Xi Zhang
- Xiaoming Wang
- Zhengyan Li
Organizations
- Air Force Office of Scientific Research
- National Science Foundation
- United States Department of Energy
- University of Texas at Austin