GeV electron bunches in low-density plasma channels by all-optical density transition injection

ORAL

Abstract

Hydrodynamic [1,2] and conditioned hydrodynamic [3,4] optical-field-ionised plasma channels are promising candidates to support low-density, high repetition-rate multi-GeV laser wakefield accelerator (LWFA) stages. They are generated by focusing an ultrashort pulse into neutral gas, forming a hot column of plasma via optical field ionization, which expands hydrodynamically to form a plasma channel. An advantage of optically generated channels is the potential to sculpt the plasma density along the LWFA stage, for example to promote injection. Here we explore the use of a density down-ramp generated between neutral gas immediately prior to the channel and the channel itself to trap electrons. We present results of a recent experiment at the Gemini TA3 laser (RAL) in which ~ 1 GeV bunches, with percent-level energy spread, were generated by sub-100 TW laser pulses. The effect of the longitudinal and transverse position of the drive pulse focus on the generated electron bunches was investigated. These results, and particle-in-cell simulations, demonstrate that the channel entrance down-ramp is responsible for electron injection.



[1] Shalloo, RJ, et al, (2018). PRE, 97(5)

[2] Shalloo, RJ, et al, (2019). PRAB, 22(4)

[3] Picksley, A, et al, (2020). PRE, 102(5)

[4] Feder, L, et al, (2020). PRR, 2(4)

*This work was supported by the UK Science and Technology Facilities Council (STFC UK) [grant numbers ST/P002048/1, ST/R505006/1, ST/S505833/1]; the Engineering and Physical Sciences Research Council [EP/V006797/1]. This material is based upon work supported by the Air Force Office of Scientific Research under award number FA9550-18-1-7005.

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Presenters

  • Alexander Picksley

    • Lawrence Berkeley National Labortory
    • John Adams Institute for Accelerator Science and Department Physics, University of Oxford
    • Lawrence Berkeley National Laboratory

Authors

  • Alexander Picksley

    • Lawrence Berkeley National Labortory
    • John Adams Institute for Accelerator Science and Department Physics, University of Oxford
    • Lawrence Berkeley National Laboratory

  • James Chappell

    • John Adams Institute for Accelerator Science and Department Physics, University of Oxford

  • Emily Archer

    • John Adams Institute for Accelerator Science and Department Physics, University of Oxford

  • Nicolas Bourgeois

    • Central Laser Facility, Rutherford Appleton Laboratory

  • James Cowley

    • John Adams Institute for Accelerator Science and Department Physics, University of Oxford

  • Linus Feder

    • John Adams Institute for Accelerator Science and Department Physics, University of Oxford

  • Oscar Jakobsson

    • John Adams Institute for Accelerator Science and Department Physics, University of Oxford

  • Aimee J Ross

    • John Adams Institute for Accelerator Science and Department Physics, University of Oxford

  • Wei-Ting (Warren) Wang

    • John Adams Institute for Accelerator Science and Department Physics, University of Oxford

  • Roman Walczak

    • University of Oxford
    • John Adams Institute for Accelerator Science and Department Physics, University of Oxford

  • Simon M Hooker

    • University of Oxford
    • John Adams Institute for Accelerator Science and Department Physics, University of Oxford