Energetic electron beam and proton beam generations with the APRI ultrahigh-intensity Ti:sapphire laser system

A 100-TW class ultrashort, ultrahigh-intensity Ti:sapphire laser system is operating and the upgrade to 300-TW is underway in APRI. With this layer system, series of experiments on high field physics, such as high harmonics generation, electron acceleration, proton generation, and x-ray generation, have been performed through domestic or international collaboration. In the electron acceleration experiment, we have observed highly directional electron beams and, in some shots, quasi-monoenergetic electron beams were generated. In the proton generation experiment, we observed protons with the maximum energy of ∼2.4 MeV emitted from a 5-μm thick copper tape target which was irradiated by laser pulses with peak intensity of ∼1.4x1018 W/cm2. The energy conversion efficiency from laser to proton was >1.4%. (author)