Abstract: Discharge chamber is the main area where the plasma is generated by the ion thruster.The electric potential downstream of the hollow cathode oscillates during the ion thruster operation and it makes lots of high-energy ions to be produced.Then ions are accelerated by the electric field in the discharge chamber and they will bombard and sputter the keeper electrode surface.The keeper electrode is completely eroded away by the end of the test,exposing the cathode orifice plate to the thruster discharge chamber,which significantly erodes the cathode orifice plate and the sheath-heater surfaces.An analysis method is proposed in this paper to investigate the effect of the magnetic field and the electric field on the ion’s trajectory and the plasma oscillation frequency.The discharge process and the plasma oscillation are described mathematically.Finally,the time-dependent evolution equation at non-equilibrium state,the dynamic behavior of plasma and the performance curve at equilibrium state are obtained.