Gated Field Emitter Failures: Experiment and Theory

Intrinsic failures of gated field emitters have been studied. The gate-emitter voltage drops from a typical value of 140 V to 10–70 V in less than 10 ns at the onset of a failure. Measurements with an electrostatic probe indicate that plumes of ions and electrons are ejected into vacuum. The measured ion current to the probe is typically 10% of the electron current. The voltage during the event and the ion-to-electron current ratio measured at the probe are characteristic of a cathodic vacuum arc plasma. For series resistors less than 1 kΩ, the arc is continuous while for series resistors greater than 10 kΩ, the the arc is intermittent. Initiation of the failure based on ion-space-charge enhancement of the emitter electric field is modeled with the plasma simulation code PDS1. These structures provide a controlled geometry for studying arcs of micron size dimension.