Analysis of drift effects in a pulsed photocell taking account of the space-charge field

Equations for nonlinear drift effects in a plane photodiode are obtained on the basis of the apparent-charge method. The equations are solved numerically for light-pulse durations that do not exceed the drift time of the first electrons. It is shown that photocathode emission ceases (i.e., is saturated) when the space-charge density is approximately equal to the charge density induced at the cathode in the absence of a photocurrent. The time responses of a photocell are calculated for various load parameters, degrees of saturation, and light-pulse durations.