Efficient Proton Acceleration with Ultra-short Laser Pulses

We present a systematic investigation of ultra-short pulse laser acceleration of protons yielding unprecedented maximum proton energies of 19 MeV using the Ti:Sa based high power laser (150 TW) Draco at the Helmholtz-Zentrum Dresden-Rossendorf. For plain few micron thick foil targets a linear scaling of the maximum proton energy with laser power is observed and attributed to the short acceleration period close to the target rear surface*. The influence of laser pulse contrast, laser polarization and laser incidence angle on the proton maximum energy and angular distribution has been investigated. The reliability of the system was improved in order to perform radiobiological studies. Additionally, an increase of laser to proton energy conversion efficiency by use of mass limited Au disks with diameters between 20 µm and 100 µm and sub-micron thickness could have been demonstrated.