1LOr1A-03 : Operation of an HTS magnet in heat flux and radio blackout mitigation experiments in plasma wind tunnels

In the framework of the European project MEESST (Magneto-Hydro-Dynamic Enhanced Entry System for Space Transportation), a high-temperature superconducting (HTS) magnet has been developed, commissioned and set in operation for radio-blackout and heat-flux-mitigation experiments in plasma wind tunnels at the Von Karman Institute for Fluid Dynamics (VKI, Belgium) and at the Institute of Space Systems (IRS, Germany), respectively.
Radio Blackout and high heat fluxes are crucial problems affecting the atmospheric entry of spacecraft into celestial bodies’ atmospheres. The compressed and partially ionized gas in front of the spacecraft not only leads to strong heating of the surface, but can also block radio waves leading to a complete loss of GPS data, telemetry, or communication with ground stations. The MEESST project investigates magnetohydrodynamic (MHD) based mitigation of both effects by developing suitable simulation tools and ground-based plasma experiments. A non-insulated, conduction-cooled HTS magnet produces the magnetic field required in the plasma experiments. Operation of the magnet in the plasma environment, however, turned out to be challenging due to the harsh environment accompanied e.g. ... mehrby the high heat fluxes and due to the ionized particles causing electronic noise in temperature and voltage signals. Melting of a water-cooled heat shield protecting cables, vacuum and cryogenic transfer lines, as well as shorts in the current circuit due to melted cable insulation were issues that had to be solved during the experimental campaigns at VKI. Despite the underestimated issues, it was possible to operate the non-insulated magnet stably in the experimental campaigns.
After a short introduction to heat-flux and radio-blackout-phenomena during (re-)entry, we present design and construction of the MEESST magnet. The magnet consists of five non-insulated pancakes wound with 4 mm wide REBCO (Rare-Earth Barium Copper Oxide) tapes. The main focus will be on the performance of the magnet and cryogenic system during the radio-blackout-mitigation experiments at VKI in 2023. If available, results from magnet operation in heat-flux-mitigation experiments at IRS will be presented. These experiments are scheduled for the first half of 2024.