Abstract
Laser-driven plasma accelerators can generate accelerating gradients three orders of magnitude larger than radio-frequency accelerators and have achieved beam energies above 1 GeV in centimetre long stages. However, the pulse repetition rate and wall-plug efficiency of laser plasma accelerators is limited by the driving laser to less than approximately 1 Hz and 0.1% respectively. Here we investigate the prospects for exciting the plasma wave with trains of low-energy laser pulses rather than a single high-energy pulse. Resonantly exciting the wakefield in this way would enable the use of different technologies, such as fibre or thin-disc lasers, which are able to operate at multi-kilohertz pulse repetition rates and with wall-plug efficiencies two orders of magnitude higher than current laser systems. We outline the parameters of efficient, GeV-scale, 10 kHz plasma accelerators and show that they could drive compact x-ray sources with average photon fluxes comparable to those of third-generation light source but with significantly improved temporal resolution. Likewise free-electron laser (FEL) operation could be driven with comparable peak power but with significantly larger repetition rates than extant FELs.
Highlights
Many scientific fields use ultrafast pulses of radiation to probe dynamical processes
In this paper we investigate the prospects for multi-pulse laser wakefield acceleration (MP-laser wakefield accelerator (LWFA)), in which the wake is excited by a train of low-energy laser pulses rather than by a single high-energy pulse
In conclusion MP-LWFA offers a route for enabling plasma accelerators operating at multi-kHz pulse repetition rates to be driven by table-top laser systems with high wall-plug efficiency
Summary
Many scientific fields use ultrafast pulses of radiation to probe dynamical processes. Synchrotrons and the new generation of x-ray free-electron lasers (FELs), both of which are powered by energetic electron beams [1]. These facilities have played a pivotal role in driving progress in the physical, biological, and medical sciences, and this will continue to be the case. Their high cost and large scale—both primarily determined by that of the radio-frequency electron accelerators which drive them. Laser-accelerated electron beams have already been used to generate incoherent radiation with photon energies: up to about 100 eV in undulators [5]; in the 10 keV range by betatron motion within the plasma accelerator [6]; and beyond 100 keV by harmonicallyresonant betatron motion [7]
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