Ion acceleration by short chirped laser pulses

Direct laser acceleration of ions by short frequency chirped laser pulses isinvestigated theoretically. We demonstrate that intense beams of ions with a kinetic energybroadening of about 1% can be generated. The chirping of the laser pulse allows the particlesto gain kinetic energies of hundreds of MeVs, which is required for hadron cancer therapy,from pulses of energies in the order of 100 J. It is shown that few-cycle chirped pulses canaccelerate ions more efficiently than long ones, i.e., higher ion kinetic energies are reachedwith the same amount of total electromagnetic pulse energy.