Theory of Transient Electrical Effects in Irradiated Insulators

A theoretical analysis of the transient response of insulators to various types of irradiating particles is given by considering the different nature of the paths of ionized electrons that are formed by the primary radiation. Theory shows that for the class of insulators with a low dielectric constant, the transient response from a densely ionizing particle will be much less than that of a lightly ionizing particle for equal amounts of ionization energy deposition because of direct electron-ion recombination. For insulators with a high dielectric constant, the difference in response to the two types of particles is greatly reduced. In addition, a method for predicting the onset of nonlinear response as a function of radiation dose is given. It is seen that competition between direct electron-ion recombination and change in occupancy of the traps can occur. An interesting result of considering the non-uniform generation of electrons is that the response to irradiation by densely ionizing particles should depend on the orientation of the beam with respect to the applied electric field.