Enabling high repetition rate laser wakefield acceleration at high- and low-plasma densities

I will present recent results from 2 sets of laser plasma acceleration experiments spanning 4 orders of magnitude in plasma density. In near critical density hydrogen plasmas using 5 fs, < 3mJ laser pulses , we have demonstrated acceleration of few pC monoenergetic electron bunches up to 15 MeV at 1 kHz, at a record low beam divergence <10 mrad [1]. Mitigation of carrier envelope phase slip is key to this result. At the other extreme of plasma density, we have demonstrated 2 techniques [2,3] for generation of metre-scale low density plasma waveguides up to several hundred Rayleigh ranges in length, with recent preliminary results showing guiding of up to several hundred terawatts. [1] Laser-accelerated, low divergence 15 MeV quasi-monoenergetic electron bunches at 1 kHz, F. Salehi, M. Le, L. Railing, and H. M. Milchberg, submitted for publication [2] Optical Guiding in Meter-Scale Plasma Waveguides, B. Miao, L. Feder, J. E. Shrock, A. Goffin, and H. M. Milchberg, PHYSICAL REVIEW LETTERS 125, 074801 (2020) [3] Self-waveguiding of relativistic laser pulses in neutral gas channels, L. Feder, B. Miao, J. E. Shrock, A. Goffin, and H. M. Milchberg, PHYSICAL REVIEW RESEARCH 2, 043173 (2020)