Bright X-ray radiation from plasma bubbles in an evolving laser wakefield accelerator

Bloom, M. S. and Streeter, M. J. V. and Kneip, S. and Bendoyro, R. A. and Cheklov, O. and Cole, J. M. and Doepp, A. and Hooker, C. J. and Holloway, J. and Jiang, J. and Lopes, N. C. and Nakamura, H. and Norreys, P. A. and Rajeev, P. P. and Symes, D. R. and Schreiber, J. and Wood, J. C. and Wing, M. and Najmudin, Z. and Mangles, S. P. D. (2017) Bright X-ray radiation from plasma bubbles in an evolving laser wakefield accelerator. arXiv.org.

Abstract

We show that the properties of the electron beam and bright X-rays produced by a laser wakefield accelerator can be predicted if the distance over which the laser self-focuses and compresses prior to self-injection is taken into account. A model based on oscillations of the beam inside a plasma bubble shows that performance is optimised when the plasma length is matched to the laser depletion length. With a 200~TW laser pulse this results in an X-ray beam with median photon energy of 20 keV, $> 10^{9}$ photons per shot and a peak brightness of $4 \times 10^{23}$ photons s$^{-1}$ mrad$^{-2}$ mm$^{-2}$ (0.1 % BW)$^{-1}$.