Spectral enhancement in the double pulse regime of laser proton acceleration

Markey, K. and McKenna, P. and Brenner, C. M. and Carroll, D. C. and Günther, M.M. and Harres, K. and Kar, S. and Lancaster, K. and Nürnberg, F. and Quinn, M. N. and Robinson, A. P. L. and Roth, M. and Zepf, M. and Neely, D. (2010) Spectral enhancement in the double pulse regime of laser proton acceleration. Physical Review Letters, 105 (19). 195008. ISSN 1079-7114 (https://doi.org/10.1103/PhysRevLett.105.195008)

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Abstract

The use of two separate ultraintense laser pulses in laser-proton acceleration was compared to the single pulse case employing the same total laser energy. A double pulse profile, with the temporal separation of the pulses varied between 0.75-2.5 ps, was shown to result in an increased maximum proton energy and an increase in conversion efficiency to fast protons by up to a factor of 3.3. Particle-in-cell simulations indicate the existence of a two stage acceleration process. The second phase, induced by the main pulse preferentially accelerates slower protons located deeper in the plasma, in contrast to conventional target normal sheath acceleration.