This paper continues the publication cycle on developing the ion plasma electrically powered spacecraft propulsion (EPSP) of the spacecraft. For monitoring and control of the EPSP operation, a feedback system based on a signal proportional to the EPSP plasma radiation intensity has been proposed to be used. It was assumed that the radiation intensity in the ultraviolet, visible and infrared ranges being proportional to the instantaneous thrust value of the EPSP. Accordingly, the introduction of a signal from the radiation registration detector into the feedback loop should allow to create an onboard closed system for monitoring and control of the EPSP operation. A photodetector based on a dynamic pin-diode integrator was considered for use in this system.