High-current, pulsed electron beam sources with SiC nanowire cathodes

High-current electron beam cathodes based on SiC nanowires have been successfully fabricated. The emission properties of the cathodes were performed in a single high-voltage pulse generator (450 kV, 120 ns) and a repetitive one (300 kV, 6 ns, 100 Hz), respectively. In a single-pulse regime, the high intensity emission from the cathode was obtained and the highest emission current density reached about 1.17 kA/cm2 at an electric field of 90 kV/cm. Emission optical images proved that the formation of plasma on the cathode surface induces the enhancement of electron emission, suggesting the production mechanism of the high current is an explosive electron emission. Under repetition rate mode, typical results of discharge waveforms of 100 Hz are presented, and the pulse-to-pulse instability of the cathode current was below 3.43%. The pressure boost during the pulse series was below 1.4 × 10−2 Pa. The SiC nanowire cathodes appear to be suitable for high-power microwave source applications.