Increased hold-off voltage in vacuum gaps with coated electrodes

It has been shown that thin film coatings applied to metal electrodes in vacuum increase the breakdown voltage. With a 2 /spl mu/m SiO coating on a stainless steel cathode doubling of the DC breakdown voltage compared to that of a bare electrode was achieved. The electric field at breakdown with a coated electrode reached an average value of 650 kV/cm. A figure of merit for coating materials was developed which predicts further increase in the hold-off voltage by using coating materials with high dielectric constant and low electron affinity.