High-voltage diode robustness during short-circuit type III

A harsh high-voltage diode commutation as a result of a short circuit can destroy the diode. The ruggedness of the diode is given by the cathode design which can suppress an cathode-side filament. Measurements on 3.3-kV and 6.5-kV diodes with and without improved cathode design show the diode behavior during the short. The results are compared and similarities are found. Without an improved cathode a failure in succession of a cathode-side filament can be observed. This behavior is simulated and confirms the destruction mechanism.