Single-Shot Multi-keV X-Ray Absorption Spectroscopy Using an Ultrashort Laser-Wakefield Accelerator Source

B. Kettle, E. Gerstmayr, M. J. V. Streeter, F. Albert, R. A. Baggott, N. Bourgeois, J. M. Cole, S. Dann, K. Falk, I. Gallardo González, A. E. Hussein, N. Lemos, N. C. Lopes, O. Lundh, Y. Ma, S. J. Rose, C. Spindloe, D. R. Symes, M. Šmíd, A. G. R. Thomas, R. Watt, and S. P. D. Mangles

Phys. Rev. Lett. 123, 254801 – Published 17 December 2019

Abstract

Single-shot absorption measurements have been performed using the multi-keV x rays generated by a laser-wakefield accelerator. A 200 TW laser was used to drive a laser-wakefield accelerator in a mode which produced broadband electron beams with a maximum energy above 1 GeV and a broad divergence of $\approx 15 mrad$ FWHM. Betatron oscillations of these electrons generated $1.2 \pm 0.2 \times 10^{6} photons / eV$ in the 5 keV region, with a signal-to-noise ratio of approximately $300 ∶ 1$ . This was sufficient to allow high-resolution x-ray absorption near-edge structure measurements at the $K$ edge of a titanium sample in a single shot. We demonstrate that this source is capable of single-shot, simultaneous measurements of both the electron and ion distributions in matter heated to eV temperatures by comparison with density functional theory simulations. The unique combination of a high-flux, large bandwidth, few femtosecond duration x-ray pulse synchronized to a high-power laser will enable key advances in the study of ultrafast energetic processes such as electron-ion equilibration.

Received 24 July 2019
Revised 16 October 2019

DOI:https://doi.org/10.1103/PhysRevLett.123.254801

Physics Subject Headings (PhySH)

High-energy-density plasmas Laboratory studies of space & astrophysical plasmas Laser wakefield acceleration

Strongly-coupled plasmas Warm-dense matter

X-ray absorption fine structure spectroscopy X-ray absorption near-edge spectroscopy X-ray absorption spectroscopy

Accelerators & BeamsPlasma Physics

Authors & Affiliations

B. Kettle ^1,*, E. Gerstmayr ¹, M. J. V. Streeter^2,†, F. Albert³, R. A. Baggott ¹, N. Bourgeois⁴, J. M. Cole¹, S. Dann ^2,‡, K. Falk^5,6,10, I. Gallardo González ⁷, A. E. Hussein ⁸, N. Lemos³, N. C. Lopes⁹, O. Lundh⁷, Y. Ma^2,§, S. J. Rose ¹, C. Spindloe⁴, D. R. Symes⁴, M. Šmíd⁵, A. G. R. Thomas ^8,2, R. Watt¹, and S. P. D. Mangles ¹

¹The John Adams Institute for Accelerator Science, Imperial College London, London, SW7 2AZ, United Kingdom
²Physics Department, Lancaster University, Lancaster LA1 4YB, United Kingdom
³Lawrence Livermore National Laboratory (LLNL), Livermore, California 94550, USA
⁴Central Laser Facility, STFC Rutherford Appleton Laboratory, Didcot OX11 0QX, United Kingdom
⁵Helmholtz-Zentrum Dresden-Rossendorf, Bautzner Landstrasse 400, 01328 Dresden, Germany
⁶Institute of Physics of the ASCR, Na Slovance 1999/2, 182 21 Prague, Czech Republic
⁷Department of Physics, Lund University, P.O. Box 118, S-22100, Lund, Sweden
⁸Center for Ultrafast Optical Science, University of Michigan, Ann Arbor, Michigan 48109-2099, USA
⁹GoLP/Instituto de Plasmas e Fusão Nuclear, Instituto Superior Técnico, U.L., Lisboa 1049-001, Portugal
¹⁰Technische Universität Dresden, 01062, Dresden, Germany

^*b.kettle@imperial.ac.uk
^†Present address: The John Adams Institute for Accelerator Science, Imperial College London, London, SW7 2AZ, United Kingdom.
^‡Present address: Central Laser Facility, STFC Rutherford Appleton Laboratory, Didcot OX11 0QX, United Kingdom.
^§Present address: Center for Ultrafast Optical Science, University of Michigan, Ann Arbor, Michigan 48109-2099, USA.