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SQUID technology has recently evolved to the point that it can be used for industrial applications in Non-Destructive Evaluation (NDE). We present the implementation of an HTS SQUID magnetometer in an eddy current testing system to measure very thick structures in large aircraft. We measured a 62 mm-thick, bolted aluminum sample from EADS-Airbus, similar to the three-layered outer wing splice that is being proposed for the Airbus A-380. The combination of field sensitivities of a few pT/ √Hz and a large dynamic range of about 140 dB/ √Hz enabled us to detect defects at a depth of up to 40 mm. However a problem was presented by the fact that deep-lying defects which caused small field variations were superimposed on field changes, in their turn caused by current distortions in the vicinity of the titanium bolts. Separation of these two contributions was achieved through parameter optimization based on FEM simulations and signal processing. We report on the possibilities for flaw detection using adapted eddy current excitation. [ABSTRACT FROM AUTHOR]

Examines step-edge junction radio frequency-superconducting quantum interference device (SQUID) magnetometers and gradiometers fabricated using yttrium-barium-copper-oxide films. Effects of step structures and film properties on yield, optimal operating temperature and SQUID low-frequency noise; Sensitivity to the step structure of devices fabricated on different substrates.

Analyzes the magnetic field behavior of yttrium barium copper oxide step-edge Josephson junctions in radio frequency-washer superconducting quantum interference devices (SQUID). Effects of critical current suppression on SQUID operation; Requirements for operation of the sensors in the Earth's magnetic field.

Describes an approach for fatigue defect detection and classification using a superconducting quantum interference device-based multiple frequency eddy current systems. Ways of distinguishing signals caused by material defects; Analog dynamic range; Flaw construction using adapted feature extraction and neural network techniques.

Analyzes the time series of signal and reference data recorded outside magnetic shielding with high temperature superconducting quantum interference device-based gradiometers using two software gradiometery methods for magnetocardiography. Signal-to-noise ratios for both methods; Signal sensor requirements; Possibility of increasing the signals' bandwidth.

Focuses on high temperature superconducting quantum interference device (SQUID) magnetometer with SQUID vector reference for magnetically shielded operations. Low-frequency crosstalk between axial SQUID; Magnetocardiogram measurement results.

Presents information on an eddy current system in cojunction with a planar Superconducting Quantum Interference Device (SQUID) gradiometer, for detection of deep-lying flaws in aircraft structures. Importance of a mobile system; Results of the operation of high temperature superconductor (HTS) SQUIDs.

Nonaqueous Br-ethanol chemical etching was successfully used for the preparation of the Josephson junctions, vias and crossovers in magnetometers including flux transformers. PrBa/sub 2/Cu/sub 3/O/sub 7-x/ thin films were used for the barrier layer in the Josephson junctions of the SQUIDs and as an insulation in the junctions and in the flux transformers. Dc-SQUID magnetometers with small inductances and even without flux antennas were used for NDE applications which mainly require a high dynamic range. Highly sensitive devices were prepared with flip-chip flux antennas. An ac-bias SQUID electronics significantly improves the sensitivity of the magnetometers at low frequencies. [ABSTRACT FROM PUBLISHER]

We have designed an HTS single-layer planar rf double-hole gradiometer with long and well defined baseline up to 5 mm and small washer areas. We measured a gradient field resolution of about 1 pT/(cm/spl middot//spl radic/Hz) above 10 Hz in an unshielded environment. The gradiometer could be operated placed on a swinging pendulum in the geomagnetic field. This permitted a simple demonstration of a movable SQUID system. We placed a SQUID system on a scanning table and performed two-dimensional eddy-current nondestructive evaluation measurements on realistic samples. [ABSTRACT FROM PUBLISHER]

For the detection of deep-lying flaws in aircraft structures, an eddy current system in conjunction with a planar SQUID gradiometer is being developed. The need for a mobile system imposes additional requirements on cooling regarding mobility, operation independent of spatial orientation, and handling. We present results on the operation of HTS SQUIDs with the commercial Joule-Thomson-cryocooler KC 100 ("cryotiger") by APD and report on cooler characteristics and system performance. Magnetometers and gradiometers of both rf and dc type have been integrated with the cryocooler. Noise spectra both in unshielded and shielded environments have been shown to be orientation independent. Compared to stationary operation, the system sensitivity is reduced by additional noise generated by the movement. With an improved integration scheme, this motion-related noise is nearly eliminated. The system was equipped with a differential eddy current excitation and a synchronized digital lock-in detection. Two-dimensional scans are presented that illustrate the system's capability to find fatigue cracks and corrosion pits hidden below several layers of aluminum. [ABSTRACT FROM PUBLISHER]

We present a new design of a portable nitrogen cryostat for operation of moving SQUIDs. A mixture of liquid and gaseous nitrogen fills a reservoir in direct contact with a copper part for the SQUID integration. The temperature at the SQUID position is 77.8 K or 78.8 K depending on orientation, and varies within /spl plusmn/10 mK during lateral movement. The cryostat can operate as a portable system for 7 hours without refilling. Washer rf SQUIDs and dc gradiometers were integrated with the cryostat. We proved the operation of the system as a moving magnetometer in an unshielded laboratory environment. Noise spectra in shielding and outside were independent of orientation. The system was equipped with a differential eddy current excitation. We show the first non-destructive material evaluation results for fatigue crack detection on stationary samples with moving SQUID sensors. [ABSTRACT FROM PUBLISHER]

To exploit the sensitivity offered by HTS SQUID systems for detection of deep faults inside conductive samples, a new approach was taken to avoid additional noise sources typical of scanning measurements. The excitation fields are rotated by electronic control which permits one to keep the sample and the system stationary during measurements. Flaws of 10 mm and 40 mm length were detected under 12 mm thick covers of aluminum. The orientation of the flaws was mapped by taking advantage of the anisotropic excitation of eddy currents by the chosen differential coils. This approach is particularly promising for ferromagnetically contaminated samples and radially oriented defects, e.g. originating from rivets. [ABSTRACT FROM PUBLISHER]