Superconducting Coils for Small Nuclear Fusion Rocket Engines

This proposal focuses on the superconducting coils subsystem, a critical subsystem for the PFRC reactor and Direct Fusion Drive and other fusion and electric propulsion technologies. Our goal will be to design space coils using the latest high temperature superconductors. The coils will be operated at medium temperature, between 20 and 30 K, which eases the cooling requirements and temperature margins compared to 4K low-temperature conductors. This also increases the critical currents providing more margin for neutron radiation damage, possibly reducing shielding. The coils will have highly efficient cooling systems, be low mass and require minimum structural mass. Bath cooling and conduit cooling will be compared. There is likely an optimum operating temperature which minimizes the mass of both the conductors, shielding, and cooling systems. Given the rapid advancement of HTS materials determining the feasibility of such an optimal coil design requires detailed research into the state-of-the-art. Our partner, PPPL, will provide expertise on coil specifications and magnet design. PPPL is the only institution in the world where active research on the physics and technology of small, steady-state fusion devices is being performed. PSS will manage the design process and study closed loop cooling issues. We will design a Phase II experiment to build one or more 2 Tesla coils and potentially integrate them into the existing plasma experiment at PPPL. Our example mission will be a Neptune orbiter which is on the NASA roadmap as a high priority mission and present a challenging on-orbit radiation environment.