A new metal-dielectric cathode with long lifetime

Abstract

Explosive emission cathodes are widely used in high power microwave generation. Conventional metallic cathodes have the disadvantages of bad emission uniformity and short lifetime. In order to improve the emission property of metallic cathodes, a new metal-dielectric cathode is fabricated with the plasma spraying technology. Unlike previous metal-dielectric cathodes, our metal-dielectric cathode adopts a ferroelectric ceramic which possesses a large permittivity. The results of lifetime experiments show the metal-dielectric cathode presents just slight performance deterioration within 2.5 × 105 pulses and thus has a much longer lifetime than the normal copper cathode. The morphology observation demonstrates that the good emission property of the metal-dielectric cathode may benefit from the appearance of irregularities on the dielectric surface, which will have large microscopic field enhancement factors with the help of large permittivity of the ferroelectric material.