MeV ion jets from short-pulse-laser interaction with thin foils

Collimated jets of carbon and fluorine ions up to 5 MeV/nucleon (similar to100 MeV) are observed from the rear surface of thin foils irradiated with laser intensities of up to 5x10 W-19/cm(2). The normally dominant proton acceleration could be surpressed by removing the hydrocarbon contaminants by resistive heating. This inhibits screening effects and permits effective energy transfer and acceleration of other ion species. The acceleration dynamics and the spatiotemporal distributions of the accelerating E fields at the rear surface of the target are inferred from the detailed spectra.