MeV proton generation with a kHz femtosecond laser

Summary form only given. Recent experimental investigations of laser-plasmas produced by high-intensity ultra-short pulse lasers from solid targets have shown the generation of copious fluxes of collimated MeV protons, predominantly from the rear-side of the target. The intensity scaling of both the proton energy and their conversion efficiency from laser light appears to be more than linear, prompting suggestions that at higher laser intensities, such collimated beams of multi-MeV protons might be used for proton tomography, proton therapy for cancer treatment and other similar applications. So far these protons have only been generated with multi-stage CPA laser systems operating in either the single shot regime, or at a few Hz. However, the peak intensity capabilities of high repetition-rate ultra-short (<100 fs) Ti:sapphire laser systems are now reaching levels where they too may be used to investigate this proton generation. We report the first experiments made in this regime.