Electrothermal quench modeling for the 100 kW SX3 thruster using superconducting coils

Applied-Field Magnetoplasmadynamic Thrusters (AF-MPDT) can generate very high thrust densities accompanied by comparably high specific impulse, due to theadditional magnetic field and force applied by magnetic coils. On laboratory level, copper coils are used for generating these fields, but they have the drawback of large size and mass, and high-power requirements (for cooling and generating fields), which can limit their scalability and, in addition, their applicability for space flight is not adequately given. A good and practical alternative for copper is to use High Temperature Superconducting (HTS) coils in AF-MPDT, as they have high current densities at low power requirements, which can lead to very strong magnetic fields, and consequently higher thrust values. HTS coils are prone to electrothermal quench, where the temperature of the coils rises rapidly when the current in the coil rises above electrothermal quench current at part of the coil, or when unexpected damage occurs. This limits the total current in the coil, as well as the magnetic field and hence thrust. We have implemented our numerical models to design practical HTS coils for 100 kW SX3 thruster, to replace the copper coils in the SX3 system. Initial field mapping by HTS coils shows good agreement for applied field and thrust values measured by copper coils, and thus stronger fields of up to 1 T is simulated and thruster’s performance is discussed. Fail safe methods, like voltage limitation, for electrothermal quench is simulated for unexpected damage in HTS coils in SX3 thruster context, which shows considerable retained thrust values even after quenching of HTS magnets.