The origin of cosmic rays (CRs) is a long standing problem in astrophysics.
CRs spectrum breaks at $10^{15.5}$ eV which is called the knee energy.
A perpendicular shock acceleration has been considered an efficient acceleration mechanism candidate to reach CRs up to the knee energy. It is suggested that the escape process is important to determine the maximum energy and a CRs spectral index. However, the escape process from a perpendicular shock region is still unknown. In this study, we investigate the acceleration time at perpendicular shock and the escape process from this region. Using a test particle simulation, we shows the rapid acceleration at the perpendicular shock and that the diffusion approximation is not valid in the case that the magnetic fluctuation is weak in an upstream stream region and is strong in a down stream region. In addition, we perform the three dimensional global test particle simulation to investigate the escape process from a perpendicular shock region.
We will perform more simulations in the cases of other parameters to understand the escape from a perpendicular shock region.