GeV-scale electron acceleration in a gas-filled capillary discharge waveguide

We report experimental results on laser-driven electron acceleration with low divergence. The electron beam was generated by focussing 750 mJ, 42 fs laser pulses into a gas-filled capillary discharge waveguide at electron densities in the range between 1018 and 1019cm−3. Quasi-monoenergetic electron bunches with energies as high as 500 MeV have been detected, with features reaching up to 1 GeV, albeit with large shot-to-shot fluctuations. A more stable regime with higher bunch charge (20–45 pC) and less energy (200–300 MeV) could also be observed. The beam divergence and the pointing stability are around or below 1 mrad and 8 mrad, respectively. These findings are consistent with self-injection of electrons into a breaking plasma wave. 6 Author to whom any correspondence should be addressed. New Journal of Physics 9 (2007) 415 PII: S1367-2630(07)60033-