Laser wakefield dynamics and high gradient acceleration of short electron bunches in guiding structures

Complete text of publication follows. Nonlinear dynamics of high gradient accelerating plasma wakefields generated by a short intense laser pulse in guiding structures is analyzed on the base of elaborated spectroscopic diagnostics and full scale modeling. The results of last experiments on the plasma wave excitation over a length of up to 8 centimetres are demonstrated using laser guiding of intense laser pulses through hydrogen filled glass capillary. Analytical predictions of the laser frequency red shift due to the wakefield excited in the capillary waveguide are confirmed by self-consistent modelling results. The role of ionization blue shift and nonlinear laser pulse and wakefield dynamics on the spectrum modification is analyzed. The plasma waves are diagnosed by spectral analysis of the transmitted laser radiation. The dependence of the spectral red shift, as well as the laser spectra, measured as a functions of filling pressure, capillary tube length and incident laser energy, are in excellent agreement with simulation results. The longitudinal accelerating field inferred from the full scale modelling is in the range 1-10 GV/m. High gradient acceleration of electrons by plasma wake waves generated in plasma by short intense laser pulses is analyzed. The influence of the loading effect and initial emittance on the quality of accelerated electron bunches is studied. Analytical predictions confirmed by the fully self-consistent 3-D modelling by code LA-PLAC of the proposed scheme of electron bunch injection in front of the laser pulse open an opportunity for the production of low emittance and energy spread electron bunches of GeV energies and submicron sizes. The important feature of the discussed scheme of bunch compression and acceleration in a moderately nonlinear wakefield is a controllable phase of the accelerated electron bunch, determined by the laser pulse timing, which permits subsequent use of these bunches for further multistage acceleration in future colliders to higher energies beyond GeV range. Acknowledgements. This work was supported in part by the Programs on fundamental research of Russian Academy of Sciences, by the Russian Foundation for Basic Research - CNRS PICS program (grant 07-02-92160), by the European Community - New and Emerging Science and Technology Activity under the FP6 'Structuring the European Research Area' programme (project EuroLEAP, contract 028514). This work also supported by the Swedish Research Council and the Knut and Alice Wallenberg Foundation.