Saturation model for secondary electron multiplier detectors

An analytical saturation model for secondary electron multiplier detectors (SEM) has been developed. This model describes SEM detector operation at high output currents when the significant part of the conduction current of dynodes passes to the electron avalanche current and the dynode potential is nonuniformly redistributed. The following main parameters of the SEM detectors in the saturated mode are predicted: the output current, conduction current and gain depending on input current, the potential, electric field and electron avalanche current distribution along the dynode system. A novel type of the SEM with nonlinear dynode resistance (SEM-NDR) that provides an extended dynamic range is suggested. The model predictions are in good agreement with the experimental results. The samples of the SEM-NDR have also been developed and investigated.