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

M R Islam, E Brunetti, R P Shanks, B Ersfeld, R C Issac, S Cipiccia, M P Anania, G H Welsh, S M Wiggins, A Noble, R A Cairns, G Raj, D A Jaroszynski

Research output: Contribution to journalArticle

24 Citations (Scopus)

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.
LanguageEnglish
Article number093033
Number of pages12
JournalNew Journal of Physics
Volume17
DOIs
Publication statusPublished - 17 Sep 2015

Fingerprint

plasma accelerators
laser plasmas
injection
thresholds
bubbles
electrons
brightness
radiation measurement
dwell
dark current
optical transition
sheaths
accelerators
intervals
momentum

Keywords

  • laser plasma wakefield accelerator
  • electron bunches
  • ultra-short electron bunches
  • injection mechanisms

Cite this

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title = "Near-threshold electron injection in the laser-plasma wakefield accelerator leading to femtosecond bunches",
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.",
keywords = "laser plasma wakefield accelerator, electron bunches, ultra-short electron bunches , injection mechanisms",
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Near-threshold electron injection in the laser-plasma wakefield accelerator leading to femtosecond bunches. / Islam, M R; Brunetti, E; Shanks, R P; Ersfeld, B; Issac, R C; Cipiccia, S; Anania, M P; Welsh, G H; Wiggins, S M; Noble, A; Cairns, R A; Raj, G; Jaroszynski, D A.

In: New Journal of Physics, Vol. 17, 093033, 17.09.2015.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Near-threshold electron injection in the laser-plasma wakefield accelerator leading to femtosecond bunches

AU - Islam, M R

AU - Brunetti, E

AU - Shanks, R P

AU - Ersfeld, B

AU - Issac, R C

AU - Cipiccia, S

AU - Anania, M P

AU - Welsh, G H

AU - Wiggins, S M

AU - Noble, A

AU - Cairns, R A

AU - Raj, G

AU - Jaroszynski, D A

PY - 2015/9/17

Y1 - 2015/9/17

N2 - 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.

AB - 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.

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