MeV electron acceleration at 1 kHz using mJ-scale few-cycle laser pulses*

We demonstrate acceleration of quasi monoenergetic electron bunches to MeV-scale energies at 1 kHz repetition rate using laser pulses with ~7fs duration and ~2.2mJ energy focused on a near-critical density gas target. Our previous experiments using 30fs laser pulses showed that using a near-critical density gas jet lowers the critical power for relativistic self-focusing sufficiently to enable MeV-scale electron acceleration using a high repetition rate laser system with mJ-scale pulse energy [1]. However, those electron bunches, accelerated in the self-modulated wakefield regime, had a large energy spread and divergence angle.

Here, we show that using ~7fs duration pulses, generated through a hollow core fiber as the drive pulse, we can accelerate few-MeV quasi monoenergetic electron bunches with a low divergence angle from various dense gas target mixtures. We present results using a range of gas target species, densities and gas flow regimes.



1. F. Salehi et al., Opt. Lett. 42, 215 (2017)