Enhanced isochoric heating from fast electrons produced by high-contrast, relativistic-intensity laser pulses

Thin, mass-limited targets composed of V/Cu/Al layers with diameters ranging from 50 to 300μm have been isochorically heated by a 300 fs laser pulse delivering up to 10 J at 2×1019W/cm2 irradiance. Detailed spectral analysis of the Cu x-ray emission indicates that the highest temperatures, of the order of 100 eV, have been reached when irradiating the smallest targets with a high-contrast, frequency-doubled pulse despite a reduced laser energy. Collisional particle-in-cell simulations confirm the detrimental influence of the preformed plasma on the bulk target heating.