High voltage high current regulator circuit for regulating current is interposed between first and second terminals connected to an external circuit and comprises at least one main-current carrying cold-cathode field emission electron tube conducting current between the first and second terminals. First and second grid-control cold-cathode field emission electron tubes provide control signals for first and second grids of the at least one main-current carrying cold-cathode field emission electron tube for positive and negative excursions of voltage on the first and second terminals, respectively. The current regulator circuit may be accompanied by a voltage-clamping circuit that includes at least one cold-cathode field emission electron tube. At least two cold- cathode field emission electron tubes, configured to operate at high voltage and high current, are preferably contained within a single vacuum enclosure and are interconnected to provide a circuit function, so as to form a high voltage high current vac
