Study Of The Winding Technique Of Superconducting Coil In Superconducting Gravity Instrument And Testing

Superconducting coils are the key parts in superconducting gravity gradiometer(SGG). They interact with the superconducting test mass, thus levitate the test mass anddetect the gravity gradient signal.This paper applied the finite element method to the effective inductance of the coilwith the change of displacement between superconducting coil and superconductor, themutual inductance between two superconducting coils along with the change of spacingbetween superconducting coil and superconductor, the relationship of the magnetic forcebetween superconducting coil and superconductor with the spacing and current, and theother coils influence on effective inductance and magnetic force. According to thecalculation results, and consider the limit on the size and shape of the coil structure of theinstrument, the number of turns of the coil in the superconducting gravity gradiometer canbe ascertained.In this thesis, a method for fabricating single-layer pancake superconducting coils hasbeen developed. Two types of coil are needed for SGG: single-layer niobium disk-shapedcoil for sensitive degree of freedom and single-layer cylindrical curved coil forno-sensitive degree of freedom. To make these two types of coils in a relatively simpleway, the strategy is to first fabricate single-layer pancake coil, then deform the pancakecoil into the required so curved-shaped coil by applying pressure.To fabricate single-layer coils, a number of techniques have been developed in thisthesis. A set of coil winding mould has been developed, whose two faces with spacingslightly larger than the wire diameter confine the winded wire into a single-layer disk coilwith the use of suitable glue, thus a single-layer coil is fabricated successfully.Finally, the fabricated coils are characterized by various measurements both at roomtemperature and at liquid helium temperature.The coils show acceptable parameterconsistency. They are reliable in multiple cooling-recycle. Also, the dependence of theireffective induction on space when reacting with superconductor has been measured. Theresults are close to the calculated relationship.