MeV-order proton and carbon ion acceleration by irradiation of 60 fs TW laser pulses on thin copper tape

Abstract

We obtained high-energy ions by irradiating 60 fs laser pulses onto a copper tape target of 5 μm thickness. The proton was accelerated with energy of 1.2 MeV at laser intensity of 6.8×1018 W/cm2. The equivalent Boltzmann temperature of the proton was 185 keV which was less than the ponderomotive potential (650 keV) of an electromagnetic standing wave in a laser field. Moreover, we observed the acceleration of carbon ions with energy of more than 0.4 MeV at laser intensity of 3.4×1018 W/cm2.