High Energy Gain, High Quality Laser Particle Accelerator Development at JAERI‐APR

Recent activities related to laser‐plasma acceleration at Advanced Photon Research Center, Japan Atomic Energy Research Institute are presented. Gas density measurements of a pulsed gas valve and wakefield measurements have been performed with two types of interferometers. A wakefield of 20 GV/m excited in the gas‐jet plasma has been obtained at a plasma density of 7×1017 cm−3. We have shown by 1D‐3V particle‐in‐cell simulation that a high quality electron beam with a transverse emittance of 0.3 π mm‐mrad and with an energy of 7.0±0.5 MeV can be produced using a colliding optical injection. Our proposed experiments using a 100 TW laser beam and a 150 MeV electron beam are also presented.