Wire detection system

Abstract

A SQUID (Superconducting Quantum Interference Device) magnetometer, by far the most sensitive means for detecting small magnetic field variations, is utilized to detect defects inadvertently produced in the manufacture and draw-down of wires. Detection is effected by moving any electrically-conducting wire directly under a shielded SQUID magnetometer with a small aperture to permit the sensing of the magnetic field associated with injected or induced alternating electrical current. Shielding may be provided either by a mu-metal cylinder with a small concentric bottom hole or an open superconducting cylinder strategically placed around the SQUID sensor. Initially, the position of the cryogenic containment vessel (dewar) is oriented to produce a null magnetic signal at the squid sensor location. Any phase-sensitive-detected) signal that appears after wire is spooled under the sensor must be related to non-concentric deviations of the current path in the wire. These deviations can be caused by foreign inclusions, structural anomalies or an irregular geometrical cross section. This technique is especially effective in verifying the integrity of composite wires where it is not possible to visually inspect the embedded wire components, e.g., multifilament superconducting wire encased in a copper matrix. The region of non-uniform current can be localized immediately, and appropriate action can be taken whether to terminate the spooling process or to note the effect for future action.

Dependencies are inferred from the claim text.