A reversed-field-pinch reactor with superconducting windings

The use of superconducting windings in a pulsed reversed-field-pinch fusion reactor is considered. A conductor consisting of many insulated and transposed niobium-titanium composite strands contained in a steel conduit, force-flow cooled with liquid helium, allows low-pulsed field losses to be achieved together with continuous electrical insulation. The power losses at cryogenic temperature are evaluated and the resultant refrigeration power is shown to be a factor 6 less than the Ohmic dissipation in the equivalent normal windings. The reactor parameters are optimized for minimum station capital cost, and the recirculating power fraction is estimated to be 21% (Q approximately 12). Some of the outstanding engineering problems in such a reactor are highlighted. (author)