Energetic ion emission from periodically modulated metallic surface under intense femtosecond laser irradiation

Experimental study on the impact of periodic surface modulations on energetic ion emission from intense laser produced plasma is presented. The targets are excited by intense (3x1015 - 6x1016 Wcm-2), p-polarized 50 fs laser pulses. The hard x-ray yield representative of 'hot' electron temperature is found to be consistently higher for modulated surfaces compared to polished surface indicating enhanced laser energy coupling to plasma. The maximum ion energy measured in keV-MeV range as well as the angle resolved integral ion flux measurements indicate that the surface modulations not only enhance the total yield of ions but increases the maximum ion energy up to 60% compared to polished surface. The surface structuring also seems to influence the divergence of emitted ion beam