Radiation Pressure Acceleration by Circularly Polarized Pulses: Three-Dimensional Dynamics and Angular Momentum Absorption

Radiation Pressure Acceleration of thin plasma targets by Circularly Polarized laser pulses is studied by three-dimensional particle-in-cell simulations. The use of flat-top intensity profiles is found to be important to avoid self-induced transparency and to reach high ion energies. A significant degree of absorption of the angular momentum of the laser pulse is observed, giving a signature of irreversible, non-adiabatic effects during the acceleration process.