The epitaxial growth of microprotrusions on field emitter tips

One precursor to cathode initiated vacuum arc breakdown is the growth of microprotrusions on the surface of the cathode. Ion bombardment activated surface atom transport in the presence of a large applied electric field has been associated with microprotrusion growth. Previous low-temperature cathode bombardment investigations have been extended into a cathode temperature regime of ∼0.2Tm–0.4Tm, where Tm is the cathode melting point. At cathode temperatures of ∼0.3Tm, helium ion cathode bombardment initiates microprotrusion growth which is epitaxial and confined to particular crystal planes. This form of epitaxial growth is partially associated with the thermally activated component of surface transport present at ∼0.3Tm.