Effect of Ionizing Radiation on Gunn Diode Amplifiers

X-band Gunn diode amplifiers have been tested while exposed to pulsed ionizing radiation. Peak photo currents induced vary as the .65 power of the dose rate, as had been found for oscillator diodes. The principal effect is a transient loss of gain, with the recovery time less than 400 ns for dose rates up to 5×1010 rad (Si)/s. The dependence of gain on dose rate agrees very well with a calculation based on the change in electric field distribution caused by radiation-induced excess carriers. A permanent failure mode was also observed at the maximum operating voltage and dose rate.