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A highly balanced five-channel high-T[subscript c] second-order SQUID gradiometer is described and discussed.

An innovative cryocooler-based SQUID instrument is described and discussed.

It is shown that high temperature superconductor (HTS) superconducting devices, in the form of single-layer gradiometers,?are promising candidates for nondestructive evaluation technologies . ?

Research describing a step-edge fabrication process for YBCO Josephson junctions is presented. In particular the electrical characteristics of single layer gradiometers at a temperature of 77K are investigated.

Research describing the behavior of high temperature, single layer, superconducting quantum interference device gradiometers is presented. In particular the effect of an anti-parallel two-SQUID coupling scheme is investigated.

Research describing NBCO superconducting quantum interference devices and Josephson junctions is presented. In particular the noise and electrical characteristics of such devices is investigated at an operating temperature of 77K.

A study of the designs of HTS cryogenic current comparators is presented with emphasis on their performance. The comparators, which included a flux concentrator and readout SQUID, were examined for their ability to measure charged-particle-beams.

A high temperature superconductor superconducting quantum interference device (SQUID) electronic gradiometer is proposed for the electromagnetic nondestructive evaluation of sensor movements in aircraft grade aluminum samples. Active field nulling was applied to the SQUIDs to enable fine surface and subsurface structure detection. The depth profiling of simulated flaws in multilayer structures was achieved using a dual frequency eddy current approach.

MgO bicrystals and YBCO thin films grown by pulsed laser deposition were used to develop high temperature superconducting Josephson junctions and direct current superconductive quantum interference devices (SQUIDs). The SQUIDs were designed for nondestructive evaluation applications. Most of the junctions exhibit good resistively shunted junction characteristics and can be used in unshielded environments.

A simple, small, single-layer high-temperature superconductivity superconducting quantum interference device (SQUID) is subjected to non-contacting alternating current electromagnetic non-destructive evaluation (EM NDE) using the induction, or eddy current, technique. EM NDE is analyzed using the finite element method. Results indicate the feasibility of using EM NDE to assess SQUIDs.

The principle of the cryogenic Current Comparator, well-established at liquid helium temperatures, is demonstrated here using liquid nitrogen temperature components. By incorporating a novel current concentrator structure in the cylindrical YBCO thick-film coating, it is applied to the noninvasive sensing of charged particle beams. The significant design parameters for the effective operation of the current concentrator are examined, and experimental measurements are compared with theoretical predictions. The device has been successfully operated in prototype form with ion and electron beam currents, and its inherent current sensitivity is estimated to cover the range from <0.1 nA-20 mA. [ABSTRACT FROM AUTHOR]

Studies the behavior of first-order high temperature superconductor single-layer superconducting quantum interference device (SQUID) gradiometers fabricated on bicrystal substrates. SQUID design; Balance of such devices; Time-dependent behavior in unshielded environments.

Evaluates Josephson junctions and superconducting quantum interference devices (SQUID) fabricated using NdBa[sub 2]Cu[sub 3]O[sub 7] as thin-film material. Surface quality; Structural properties; Electrical and noise characteristics.

We describe an eddy current nondestructive evaluation system using a low-temperature superconductor magnetic field sensor in an electromagnetically unshielded environment. The sensor comprises a niobium dc superconducting quantum interference device (SQUID) integrated with a first-order gradiometric pickup coil to reject spatially uniform interference fields but remain sensitive to flaw induced fields. We demonstrate its use in locating and mapping subsurface flaws in a multilayered aluminum structure using an eddy current excitation field at a frequency of 70 Hz, with no magnetic shielding around the specimen or cryostat. [ABSTRACT FROM PUBLISHER]