Secondary electron multipacting in proton bunch

The electron cloud instability is believed to be an obstacle for the high intensity proton accelerators. The secondary electron multipacting is responsible for the development of the electron cloud. It can be explained by the energy gain and motion of electrons. For acquiring the density and the distribution of the electron cloud, a program has been developed to simulate the evolution of the electron cloud. This paper analyzes the motion of electrons under beam force, and proposes the reason for the secondary electron multipacting. The analyses are in agreement with the simulation result.