Hardness of a Dielectric Switch to Ionizing Radiation

The effect of transient and steady state radiation on a dielectric switch has been investigated. The dielectric switch is a solid state device which remains, indefinitely, in either a low resistance or a high resistnace state. It trips from the former to the latter by the application of a high current pulse. The reverse procedure is accomplished by a high voltage pulse. For the transient study, pulses from a 55-Mev Linac and 600-kev flash X-rays were used. Gamma rays from a Co-60 source were used for the steady state study. The device appears impervious to a Linac dose rate of 2.4 x 1010 rads (Si)/sec or an X-ray dose rate of 7.47 x 107 rads (Si)/sec. Below a Co-60 dose of 8 x 107 rads, negligible changes in resistance occur but above this level radiation induced switching (on-to-off) occurs as well as increases in resistance. The devices, however, recovered completely after the test was completed. Possible explanations for the responses are offered on the basis of a model developed for device operation.