All-optical GeV electron bunch generation in a laser-plasma accelerator via truncated-channel injection

• Main Authors: Picksley, A, Chappell, J, Archer, E, Bourgeois, N, Cowley, J, Emerson, D. R, Feder, L, Gu, X. J, Jakobsson, O, Ross, A. J, Wang, W, Walczak, R, Hooker, S. M
• Format: Journal Article
• Language: English
• Published: 25.07.2023
• Subjects: Physics - Accelerator Physics; Physics - Plasma Physics
• DOI: 10.48550/arxiv.2307.13689

We describe a simple scheme, truncated-channel injection, to inject electrons directly into the wakefield driven by a drive pulse guided by an all-optical plasma channel. We use this approach to generate dark-current-free 1.2 GeV, 4.5 % relative energy spread electron bunches with 120 TW laser pulses guided in a 110-mm-long hydrodynamic optical-field-ionized (HOFI) plasma channel. Our experiments and particle-in-cell simulations show that high-quality electron bunches were only obtained when the drive pulse was closely aligned with the channel axis, and was focused close to the density down-ramp formed at the channel entrance. Start-to-end simulations of the channel formation, and electron injection and acceleration show that increasing the channel length to 410 mm would yield 3.65 GeV bunches, with a slice energy spread $\sim 5 \times 10^{-4}$.