Superconducting windings and screening techniques for MHD thrusters

Naval propulsion using MHD needs very high magnetic fields in large volumes to reach attractive efficiencies. On the other hand, the electromagnetic stealth leads to use multi modular thrusters to minimize the leak fields, and to use internal and external shields, made with magnetic or superconducting materials in case of damaged operation. Up to now, the low temperature superconductors are the only materials able to fulfill these requirements. The encountered problems are of the same order than in fusion reactor systems, such as the ITER program now under study, but a MHD thruster has to be set aboard a ship (submarine for example). The sum of the electromagnetic, cryogenic, hydrodynamical and electrochemical problems will require long studies before the possibility to replace the classical line shafts by MHD thrusters can be foreseen. (author). 18 refs., 6 figs., 2 tabs