Ion acceleration by an ultrashort laser pulse interacting with a near-critical-density gas jet
Abstract
We demonstrate laser-driven Helium ion acceleration with cut-off energies above 25 MeV and peaked ion number above 108 /MeV for 22(2) MeV projectiles from near-critical density gas jet targets. We employed shock gas jet nozzles at the high-repetition-rate (HRR) VEGA-2 laser system with 3 J in pulses of 30 fs focused down to intensities in the range between 9×1019 W/cm2 and 1.2×1020 W/cm2. We demonstrate acceleration spectra with minor shot-to-shot changes for small variations in the target gas density profile. Difference in gas profiles arise due to nozzles being exposed to a experimental environment, partially ablating and melting.
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