Multi-MeV ion production from high-intensity laser interactions with underdense plasmas

Experiments were performed using high-power laser pulses (greater than 50 T W) focused into underdense helium, neon, or deuterium plasmas (n(e) similar to 5 X 10(19) cm(-3)). Ions having energies greater than 300 keV were meas ured to be produced primarily at 90 degrees to the axis of laser propagatio n. Ion energies greater than 6 MeV were recorded from interactions with neo n. Images of the ion emission were also obtained, and it is possible that s patially resolved measurements of the ion energy spectrum can provide a met hod to estimate the intensity of the focused radiation in the interaction r egion.