Axial high-temperature superconducting gradiometer with a flexibleflux transformer

Abstract

An axial first-order gradiometer is formed by coupling the input coil of a flexible high-temperature superconducting flux transformer inductively to a directly coupled superconducting quantum interference device magnetometer. The transformer is patterned in a single-layer YBa2Cu3O7−x film on a flexible Hastelloy tape. The tape is bent such that the two outer pickup loops of the transformer are facing each other while perpendicular to the magnetometer plane resulting in a gradiometer baseline of 35mm. A superconducting shield is mechanically adjusted to reduce the gradiometer response to uniform fields applied perpendicularly to both the magnetometer plane and the plane of the transformer pickup loops, by a factor of typically 7000.