Demonstration of CO2-Laser-Driven Laser-Wakefield Acceleration at Brookhaven's Accelerator Test Facility

The advent of multi-TW CPA CO2 lasers[1] is opening mid-IR wavelengths for laser wakefield accelerators, favoring low plasma densities ne[2], and large accelerating structures enabling precise external lepton injection and optical and electron probing of wake density and field structure. We report (experiment AE95 BNL/ATF) the demonstration of electron acceleration, in the self-modulated regime, using the ATF CO2 mid-IR laser (2ps, 5J, w0\textasciitilde 30$\mu $m). Electron self-injection and acceleration was observed in a 2mm long H2 gas jet (\textasciitilde 1e17 \textless ne\textless 1e18cm-3) with bunch charge exceeding 10pc and energies exceeding 10MeV. The results agree well with 3D PIC simulations. [1] M. N. Polyanskiy et al., OSA Continuum 3, 459-472 (2020) [2] I. Pogorelsky et al, Plasma Phys. Control. Fusion 56, 084017 (2014)