Plasma electron acceleration driven by a long-wave-infrared laser

Abstract: Laser-driven plasma accelerators provide tabletop sources of relativistic electron bunches and femtosecond x-ray pulses, but usually require petawatt-class solid-state-laser pulses of wavelength λL ~ 1 μm. Longer-λL lasers can potentially accelerate higher-quality bunches, since they require less power to drive larger wakes in less dense plasma. Here, we report on a self-injecting plasma accelerator driven by a long-wave-infrared laser: a chirped-pulse-amplified CO2 laser (λL ≈ 10 μm). Through optical scattering experiments, we observed wakes that 4-ps CO2 pulses with < 1/2 terawatt (TW) peak power drove in hydrogen plasma of electron density down to 4 × 10^17 cm^−3 (1/100 atmospheric density) via a self-modulation (SM) instability. Shorter, more powerful CO2 pulses drove wakes in plasma down to 3 × 10^16 cm^−3 that captured and accelerated plasma electrons to relativistic energy. Collimated quasi-monoenergetic features in the electron output marked the onset of a transition from SM to bubble-regime acceleration, portending future higher-quality accelerators driven by yet shorter, more powerful pulses.

Recommended citation: Rafal Zgadzaj, James Welch, Yuxuan Cao, Ligia D. Amorim, Aiqi Cheng, Apurva Gaikwad, Pietro Iapozzutto, Prabhat Kumar, Vladimir N. Litvinenko, Irina Petrushina, Roman Samulyak, Navid Vafaei-Najafabadi, Chan Joshi, Chaojie Zhang, Marcus Babzien, Mikhail Fedurin, Rotem Kupfer, Karl Kusche, Mark A. Palmer, Igor V. Pogorelsky, Mikhail N. Polyanskiy, Christina Swinson, Mike C. Downer, "Plasma electron acceleration driven by a long-wave-infrared laser," Nat. Commun. 15, 4395 (2024).
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