  Theoretical study of heavy ion acceleration from an ultrathin (20 nm) gold
foil irradiated by sub-picosecond lasers is presented. Using two dimensional
particle-in-cell simulations we identified two highly efficient ion
acceleration schemes. By varying the laser pulse duration we observed a
transition from Radiation Pressure Acceleration to the Breakout Afterburner
regime akin to light ions. The underlying physics and ion acceleration regimes
are similar to that of light ions, however, nuances of the acceleration process
make the acceleration of heavy ions more challenging. Two laser systems are
studied in detail: the Texas Petawatt Laser and the Trident laser, the former
having pulse duration 180 fs, intermediate between very short femtosecond
pulses and picosecond pulses. Both laser systems generated directional gold
ions beams (~10 degrees half-angle) with fluxes in excess of 1011 ion/sr and
normalized energy >10 MeV/nucleon.

Plasma Physics