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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)

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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