The gyrokinetic particle model of an magnetized plasma allows one to describe low-frequency phenomena with computation time much shorter than the ordinary particle model, and with accuracy higher than the drift-kinetic model. The gyrokinetic model has been used from microscopic to macroscopic phenomena, however, a simple gyrokinetic model is not suitable for the case of reflecting boundaries, because the guiding-center models, including gyrokinetic and drift-kinetic model, have a problem when the particles are reflected on the boundary, especially when the magnetic lines of force obliquely incident on the boundary. These conditions are essential in peripheral plasmas and divertor plasmas.

When a particle collides with a boundary, its guiding-center drifts by the impulsive force at the collision, and the leap length is the order of a gyro-radius. The simple gyrokinetic model, however, neglects this drift, and particles gather at some point on the boundary to form a vacant hole. Once this hole is generated, it persists for a long time.

In order to correct this problem, we propose a new scheme which introduces an effective potential with a finite width. We show simulation results for the case of a flat boundary and will extend to the more general case with corners and the case where the periodic boundary and the reflecting boundary are mixed.