Physics of high intensity proton beam

Physics of high intensity proton beams is presented in the case of proton beams at J-PARC (Japan Proton Accelerator Research Complex) as examples. Space charge effect dominates phenomena on the low energy proton beams such as those in the linear accelerator at J-PARC. Whereas on the high energy proton beams such as those in the synchrotrons at J-PARC, the space charge effects are cancelled with the magnetic field induced by the beam itself, and the collective beam instability which is brought by the interaction between the beam-induced electromagnetic field and the surroundings becomes dominant. It is important to deal with the high intensity proton beam as plasma. (K. Yoshida)