Non-Maxwellian electron distributions resulting from direct laser acceleration in near-critical plasmas

T. Toncian*, C. Wang, E. McCary, A. Meadows, A. V. Arefiev, J. Blakeney, K. Serratto, D. Kuk, C. Chester, R. Roycroft, L. Gao, H. Fu, X. Q. Yan, J. Schreiber, I. Pomerantz, A. Bernstein, H. Quevedo, G. Dyer, T. Ditmire, B. M. Hegelich

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

27 Scopus citations

Abstract

The irradiation of few-nm-thick targets by a finite-contrast high-intensity short-pulse laser results in a strong pre-expansion of these targets at the arrival time of the main pulse. The targets decompress to near and lower than critical densities with plasmas extending over few micrometers, i.e. multiple wavelengths. The interaction of the main pulse with such a highly localized but inhomogeneous target leads to the generation of a short channel and further self-focusing of the laser beam. Experiments at the Glass Hybrid OPCPA Scaled Test-bed (GHOST) laser system at University of Texas, Austin using such targets measured non-Maxwellian, peaked electron distribution with large bunch charge and high electron density in the laser propagation direction. These results are reproduced in 2D PIC simulations using the EPOCH code, identifying direct laser acceleration (DLA) [1] as the responsible mechanism. This is the first time that DLA has been observed to produce peaked spectra as opposed to broad, Maxwellian spectra observed in earlier experiments [2]. This high-density electrons have potential applications as injector beams for a further wakefield acceleration stage as well as for pump-probe applications.

Original languageEnglish
Pages (from-to)82-87
Number of pages6
JournalMatter and Radiation at Extremes
Volume1
Issue number1
DOIs
StatePublished - Jan 2016
Externally publishedYes

Funding

FundersFunder number
Air Force Office of Scientific ResearchFA9550-14-1-0045
Defense Advanced Research Projects Agency12-63-PULSE-FP014
National Nuclear Security AdministrationDE-NA0002008
Engineering and Physical Sciences Research CouncilEP/G054950/1, EP/G054940/1, EP/G055165/1, EP/G056803/1, EP/M022463/1

    Keywords

    • Direct laser acceleration
    • Electron acceleration
    • Near critical plasmas
    • PIC simulations

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