High Quality Electron Beams from Laser Accelerators

Twenty five years ago, laser driven accelerators were proposed as an alternative to conventional accelerator systems.[1] The appeal was and is the large accelerating gradients (up to hundreds of GV/m) that can allow the development of compact devices capable of producing multi-GeV electron beams. Until recently, all experiments produced large gradients but beams with 100 {\%} energy spread and only a small amount of electrons at high energy. This has recently changed. At the multi-beam L'OASIS facility at LBNL we have produced beams with narrow energy spread using a channel guided laser accelerator.[2] At Rutherford Appleton Laboratories (UK)[3] and at the Ecole Polytechnique (France),[4] beams with narrow energy spread were produced by using laser beams with relatively large focal spots. These results demonstrate that laser-plasma based accelerator can produce high quality electron beams. A review of the L'OASIS experiments will be presented as well as our plans and activities for producing a GeV-class electron beam. \newline \newline [1] T. Tajima and J.M. Dawson, Phys. Rev. Lett. \textbf{43}, 267-270 (1979). \newline [2] C.G.R. Geddes et al., Nature \textbf{431}, 538- 541(2004). \newline [3] S.P.D. Mangles et al., Nature \textbf{431}, 535 --538 (2004). \newline [4] J. Faure et al., Nature \textbf{431, }541-544 (2004).