Abstract: A proof mass support system has a pair of alignment coils for controlling the rest position of an elongate proof mass. The alignment coils are constructed to provide a levitation force when they carry electric currents which varies along the length of the proof mass. The relative strength of the electric currents are tuned in the alignment coils to cause the proof mass to take up a predetermined orientation with respect to one or more degrees of freedom defined by the alignment coils. In an alternative, one or more anti-rotation coils may be arranged to apply a restoring force to the proof mass when electric currents pass therethrough. The proof mass is formed so as to cooperate with the restoring force which acts against rotation of the proof mass away from a predetermined orientation. The system is typically provided as part of a superconducing accelerometer or gravity gradiometer.

Abstract: A superconducting six-axis accelerometer (SSA) for measuring the linear and angular acceleration of a superconducting proof mass in all six degrees of freedom at the same point in space time. The proof mass is formed of interlocking plates defining three mutually orthogonal planes and is confined and controlled by superconducting circuitry including superconducting levitation coils which suspend the proof mass against the pull of gravity. Detection of a displacement of the proof mass when an acceleration is applied is possible as the Meissner effect forces the inductance of superconducting sensing coils to change in proportion to the displacement of the proof mass. The sensing coils, which may be the same coils as the levitation coils or may be arranged concentrically with respect to separate levitation coils, are arranged in bridge circuits, each bridge circuit being driven by an independent oscillating current through a tank circuit, having a different carrier frequency.

Abstract: Each accelerometer includes a cylindrical proof mass made of a superconducting material. Each proof mass includes annular upper and lower hollowed out portions longitudinally surrounded by a cylindrical exterior wall. Common mode and differential mode sensing coils are arranged adjacent a bottom-side surface of the proof mass in one hollowed out annular portion and a levitation coil is arranged adjacent a bottom-side surface of the proof mass in the other hollowed out annular portion. The common mode, differential mode and levitation coils are connected in respective first, second and third superconducting circuits. The first circuit produces common mode signals indicative of forces acting on both accelThis invention was made with government support under Contract No. NAS 8-36165 awarded by the National Aeroanutics and Space Administration. The government has certain rights in this invention.