VACUUM FLASHOVER ON DIAMOND-LIKE CARBON-COATED INSULATORS

Thin coatings of diamond-like carbon (DLC) were applied to cylindrical alumina and high temperature polyimide insulator samples. The coated insulators and uncoated controls were tested for resistance to surface flashover in vacuum under a dc voltage gradient. The DLC-coated insul ators had significantly higher flashover potential than the controls a nd showed no visible tracking on their surface, even after multiple di scharges. DLC coatings, applied at temperatures < 350 degrees C, show promise for improving the performance of HV vacuum feedthroughs, switc hes, and in other applications.