Development of laser-driven proton and electron sources using AFRI 100-TW Ti : Sapphire laser system

At the Advanced Photonics Research Institute (APRI) in Korea, we have a Ti:sapphire laser system which delivers laser pulses of 100-TW peak power and 32-fs pulse duration at the repetition rate of 10 Hz. This laser facility is being used to develop compact laser-driven proton and electron sources. Energetic protons are produced by irradiating the laser pulse on a thin foil target made of copper and polyimide via the target normal sheath acceleration. Proton beam with maximum energy of up to 4 MeV was generated from a polyimide target, and showed high energy conversion efficiency from laser to proton energy. Generation of high-energy electron beams by the laser wakefield acceleration was performed by focusing the laser pulses onto a 4 mm-long He-gas jet. Quasi-monoenergefic electron beam with peak energy of 45 MeV and maximum energy of 130 MeV was produced. The quality and characteristics of electron beams are strongly dependent on the laser-plasma interaction length which depends on focal length of the focusing optics.