Parametric scans of HB and LS-RPA regimes employing Petawatt laser

Kar, S. and Kakolee, K. F. and Qiao, B. and Doria, D. and Ramakrishna, B. and Sarri, G. and Quinn, K. and Zepf, M. and Yuan, X. and McKenna, P. and Cerchez, M. and Osterlholz, J. and Willi, O. and MacChi, A. and Borghesi, M. (2011) Parametric scans of HB and LS-RPA regimes employing Petawatt laser. In: 38th EPS Conference on Plasma Physics 2011, EPS 2011 - Europhysics Conference Abstracts. European Physical Society (EPS), Mulhouse, France. ISBN 2914771681

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    Abstract

    By contrast to the Target Normal Sheath acceleration (TNSA) mechanism [1], Radiation Pressure Acceleration (RPA) is currently attracting a substantial amount of experimental [2,3] and theoretical [4-6] attention worldwide due to its superior scaling in terms of ion energy and laser-ion conversion efficiency. Employing Vulcan Petawatt lasers of the Rutherford Appleton Laboratory, UK, both the Hole-boring (HB) and the Light-Sail (LS) regimes of the RPA have been extensively explored. When the target thickness is of the order of hole-boring velocity times the laser pulse duration, highly collimated plasma jets of near solid density are ejected from the foil, lasting up to ns after the laser interaction. By changing the linear polarisation of the laser to circular, improved homogeneity in the jet's spatial density profile is achieved which suggests more uniform and sustained radiation pressure drive on target ions. By decreasing the target areal density or increasing irradiance on the target, the LS regime of the RPA is accessed where relatively high flux (~ 1012 particles/MeV/Sr) of ions are accelerated to ~ 10 MeV/nucleon energies in a narrow energy bandwidth. The ion energy scaling obtained from the parametric scans agrees well with theoretical estimation based on RPA mechanism and the narrow bandwidth feature in the ion spectra is studied by 2D particle-in-simulations.