Abstract: Resistors have successfully replaced corona point discharge devices in the control of high voltage gradients, such as those experienced in electrostatic accelerators. An improved resistor for such applications which has a single elongate resistive element, one end of which is mounted on a metal clamp which is adapted to be clamped to the edge of a metal disc of the type used in a supporting column or tube of an electrostatic accelerator. The other (free) end of the resistor is unsupported, but carries a tubular capacitive electrode, which provides, with a cylindrical metal housing which is mounted on the clamp coaxially with the resistive element, a spark gap. The free end of the resistor also supports a light-weight connector, into which or on to which a plug can be inserted or affixed to make an external electrical connection to the resistive element.