On the investigation of fast electron beam filamentation in laser-irradiated solid targets using multi-MeV proton emission

Quinn, M. N. and Carroll, D. C. and Yuan, X. H. and Borghesi, M. and Clarke, R. J. and Evans, R. G. and Fuchs, J. and Gallegos, P. and Lancia, L. and Quinn, K. and Robinson, A. P. L. and Romagnani, L. and Sarri, G. and Spindloe, C. and Wilson, P. A. and Neely, D. and McKenna, P. (2011) On the investigation of fast electron beam filamentation in laser-irradiated solid targets using multi-MeV proton emission. Plasma Physics and Controlled Fusion, 53 (12). -. ISSN 0741-3335

Abstract

The transverse filamentation of beams of fast electrons transported in solid targets irradiated by ultraintense (5 x 10(20) W cm(-2)), picosecond laser pulses is investigated experimentally. Filamentation is diagnosed by measuring the uniformity of a beam of multi-MeV protons accelerated by the sheath field formed by the arrival of the fast electrons at the rear of the target, and is investigated for metallic and insulator targets ranging in thickness from 50 to 1200 mu m. By developing an analytical model, the effects of lateral expansion of electron beam filaments in the sheath during the proton acceleration process is shown to account for measured increases in proton beam nonuniformity with target thickness for the insulating targets.

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