Experimental investigation of hole boring and light sail regimes of RPA by varying laser and target parameters

Kar, S and Kakolee, K F and Cerchez, M and Doria, D and Macchi, A and McKenna, P and Neely, D and Osterholz, J and Quinn, K and Ramakrishna, B and Sarri, G and Willi, O and Yuan, X H and Zepf, M and Borghesi, M (2013) Experimental investigation of hole boring and light sail regimes of RPA by varying laser and target parameters. Plasma Physics and Controlled Fusion, 55 (12). 124030. ISSN 0741-3335

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    Abstract

    Temporal evolution of plasma jets from micrometre-scale thick foils following the interaction of intense (3 × 1020 W cm-2 ) laser pulses is studied systematically by time resolved optical interferometry. The fluid velocity in the plasma jets is determined by comparing the data with 2D hydrodynamic simulation, which agrees with the expected hole-boring (HB) velocity due to the laser radiation pressure. The homogeneity of the plasma density across the jets has been found to be improved substantially when irradiating the laser at circular polarization compared to linear polarization. While overdense plasma jets were formed efficiently for micrometre thick targets, decreasing the target areal density and/or increasing the irradiance on the target have provided indication of transition from the 'HB' to the 'light sail (LS)' regime of RPA, characterized by the appearance of narrow-band spectral features at several MeV/nucleon in proton and carbon spectra.