Multi-GeV Electron Bunches from an All-Optical Laser Wakefield Accelerator
B. Miao, J. E. Shrock, Linus Feder, R. Hollinger, John H. Morrison, R. Nedbailo, A. Picksley, Huanyu Song, Shoujun Wang, J. J. Rocca, H. M. Milchberg
Abstract
We present the first demonstration of multi-GeV laser wakefield acceleration in a fully optically formed plasma waveguide, with an acceleration gradient as high as 25 GeV=m. The guide was formed via selfwaveguiding of <15 J, 45 fs (< 300 TW) pulses over 20 cm in a low-density hydrogen gas jet, with accelerated electron bunches driven up to 5 GeV in quasimonoenergetic peaks of relative energy width as narrow as 15%, with divergence down to 1 mrad and charge up to tens of picocoulombs. Energy gain is inversely correlated with on-axis waveguide density in the range N e0 1.3-3.2 10 17 cm -3 . We find that shot-to-shot stability of bunch spectra and charge are strongly dependent on the pointing of the injected laser pulse and gas jet uniformity. We also observe evidence of pump depletion-induced dephasing, a consequence of the long optical guiding distance.