SUPPRESSION OF VACUUM BREAKDOWN USING THIN-FILM COATINGS

Thin-film metal and metal oxide coatings ion sputter deposited onto the cathode electrode of a parallel-plate high-voltage gap were found to suppress electron emission in high vacuum. Electric fields as high as 60 kV/mm have been sustained across a 1 mm gap for pulse durations of 10 mus. Lesser electric fields were sustained for pulse durations exceeding 10 ms. The behavior of 500 nm thick coatings ws independent of the type of coating used, whereas the breakdown voltage for thinner coatings depended upon the material and the deposition conditions. The breakdown properties of various coatings, as well as a discussion of the suppression of electron emission is presented.