The large gap case for HV insulation in vacuum

A test setup able to accommodate dish shaped electrodes for gaps up to /spl sim/20 cm is being used to study large gap effects. This experiment, in connection with other authors' experiments, underlines the three more characteristic aspects of the large gap case: a voltage effect, a current effect and a gas effect. The difficulty of energy dissipation by surface processes at increasing penetration depth of the energy deposit gives an interesting interpretative perspective to the behavior of large gap, HV devices.