Enhanced Laser Coupling and Spatially Structured Electron Bunches from Multi-GeV Laser Wakefield Accelerators

Self-waveguided laser wakefield acceleration (LWFA) has enabled repeatable, compact 10 GeV electron accelerators capable of producing nanocoulombs of charge above 1 GeV in a single 30cm stage. In this technique, plasma waveguides generated over extended gas jets via optical field ionization (OFI) are necessary for maintaining a relativistic interaction over many Rayleigh lengths. This talk presents results from experiments at L-ALEPH in which the tunable optical properties of these waveguides were employed to improve accelerator stability and customize the spatial mode of resulting electron bunches. Specifically, the use of funnel-mouthed waveguides generated with custom UMD diffractive optics enabled enhanced electron repeatability and charge with reduced sensitivity to laser misalignment. Furthermore, we show experimental demonstrations of electron bunches with novel transverse spatial structures resulting directly from the modal properties of plasma waveguides . Finally, this presentation highlights our development of modular supersonic gas jets for longitudinal waveguide tailoring and scaling beyond one meter.