Laser wakefield accelerators: status and future

Summary form only given, as follows. Laser wakefield accelerators rely on the excitation of large amplitude electrostatic waves by an intense laser propagating through a plasma. These electrostatic plasma waves are characterized by field strengths that range in the 100 GV/m and that propagate with a phase velocity near the speed of light. Such large fields make it possible to accelerate electrons to relativistic energies in mm to cm scale lengths and hence the development of compact high energy accelerators that are several orders of magnitude shorter than conventional accelerators. Current designs for such a device consist of a source of electrons (injector), an accelerating structure (plasma channel)and a short-pulse multi-terawatt laser system as the power source. The source of electrons can either be from an external injector or from the self-trapping of background plasma electrons. Methods for controlled injection of self-trapped electrons have been developed theoretically and are being pursued experimentally. The accelerating structure must be able to guide the laser beam and overcome its natural diffraction and support the large plasma wakes. Plasma channels have been produced in the lab and used to guide high intensity laser pulses (> IO1* W/cm2) over distances on the order of tens of Rayleigh lengths. Laser-plasma accelerated electrons in excess of 100 MeV have been observed. The fundamentals of laser wakefield excitation and the current experimental progress will be discussed including progress on developing a 1 -GeV laser driven accelerator. Applications such as production of radioisotopes, intense coherent infrared radiation and femtosecond x-ray pulses will be covered.