Abstract: Apparatus for generating a magnetic field includes a superconducting coil winding and a conducting, non-magnetic electrical field member in proximity to and insulated from the winding. The winding is energized by a direct-current source, reaching a predetermined electrical potential when in the superconducting state. The electrical field member is held at a positive potential relative to the winding and the electrical field between the field member and the turns of the winding enables the winding to remain superconductive at current magnitudes exceeding the critical value that would have existed in the absence of such electrical field.