Sparc’s reactor uses a tokamak design, which resembles a doughnut. The D-shaped cross section is wound with high-temperature superconducting tape, which when energized, generates a powerful magnetic field that will contain and compress the superheated plasma. Heat generated from the reaction is converted to steam to power a turbine. CFS designed its magnets in collaboration with MIT, where co-founder and CEO Bob Mumgaard worked as a researcher on fusion reactor designs and high-temperature superconductors.