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 producesnot 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 to 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 ~6e12 exceeds that of any previous LPA-based quasi-monoenergetic Compton source. Particle-in-cell simulations agree well with the measurements.
Cite
@article{arxiv.1411.2134,
title = {Compact tunable Compton x-ray source from laser-plasma accelerator and plasma mirror},
author = {Hai-En Tsai and Xiaoming Wang and Joseph Shaw and Zhengyan Li and Alexey V. Arefiev and Xi Zhang and Rafal Zgadzaj and Watson Henderson and V. Khudik and G. Shvets and M. C. Downer},
journal= {arXiv preprint arXiv:1411.2134},
year = {2015}
}
Comments
10 pages, 7 figures