A NOVEL TUBULAR SUPERCONDUCTOR STABILIZED WITH STATIC PRESSURIZED HELIUM

A new superconductor concept for encapsulated, medium-size magnets wit h a significantly increased stability margin is presented. A tubular s uperconductor (TSC) of a few millimeters outer diameter is drawn from a billet (normal metal + superconducting inserts). After winding, the TSC is filled with static gaseous helium under pressure, which serves as an enthalpy stabilizer. The approach is beneficial both for NbTi an d Nb3Sn magnets, including conductively cooled magnets. For example, N b3Sn TSC magnet for 8 T, 8 K operation has a stability margin up to 8 times greater then a corresponding magnet using a conventional conduct or. The stability margin against slow (steady-state) and transient dis turbances has been analyzed for TSC and cable-in-conduit conductors (C ICC). Analytical expressions for the stability margin have been obtain ed and optimal helium cross-section have been determined. Results can be used to design helium-filled conductors for magnets operating to ma ximum stability margin