Near-threshold electron injection in the laser-plasma wakefield accelerator leading to femtosecond bunches

Islam, M R and Brunetti, E and Shanks, R P and Ersfeld, B and Issac, R C and Cipiccia, S and Anania, M P and Welsh, G H and Wiggins, S M and Noble, A and Cairns, R A and Raj, G and Jaroszynski, D A (2015) Near-threshold electron injection in the laser-plasma wakefield accelerator leading to femtosecond bunches. New Journal of Physics, 17. 093033. ISSN 1367-2630 (https://doi.org/10.1088/1367-2630/17/9/093033)

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Abstract

The laser–plasma wakefield accelerator is a compact source of high brightness, ultra-short duration electron bunches. Self-injection occurs when electrons from the background plasma gain sufficient momentum at the back of the bubble-shaped accelerating structure to experience sustained acceleration. The shortest duration and highest brightness electron bunches result from self-injection close to the threshold for injection. Here we show that in this case injection is due to the localized charge density build-up in the sheath crossing region at the rear of the bubble, which has the effect of increasing the accelerating potential to above a critical value. Bunch duration is determined by the dwell time above this critical value, which explains why single or multiple ultra-short electron bunches with little dark current are formed in the first bubble. We confirm experimentally, using coherent optical transition radiation measurements, that single or multiple bunches with femtosecond duration and peak currents of several kiloAmpere, and femtosecond intervals between bunches, emerge from the accelerator.

ORCID iDs

Islam, M R, Brunetti, E ORCID logoORCID: https://orcid.org/0000-0001-8302-9762, Shanks, R P, Ersfeld, B ORCID logoORCID: https://orcid.org/0000-0001-5597-9429, Issac, R C, Cipiccia, S, Anania, M P, Welsh, G H ORCID logoORCID: https://orcid.org/0000-0001-7933-4190, Wiggins, S M ORCID logoORCID: https://orcid.org/0000-0001-7804-6146, Noble, A ORCID logoORCID: https://orcid.org/0000-0002-8181-7076, Cairns, R A, Raj, G and Jaroszynski, D A ORCID logoORCID: https://orcid.org/0000-0002-3006-5492;
  • Item type:Article
    ID code:54607
    Dates:
    Date
    Event
    17 September 2015
    Published
    24 August 2015
    Accepted
    Subjects:Science > Physics
    Department:Faculty of Science > Physics
    Depositing user: Pure Administrator
    Date deposited:19 Oct 2015 08:35
    Last modified:11 Nov 2024 11:12
    URI:https://strathprints.strath.ac.uk/id/eprint/54607
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