Electricity: measuring and testing – Magnetic – Magnetometers
Patent
1998-02-27
2000-02-08
Patidar, Jay
Electricity: measuring and testing
Magnetic
Magnetometers
505846, 505162, G01R 3302, G01R 33035
Patent
active
060231610
ABSTRACT:
The present invention comprises a high-transition-temperature superconducting device having low-magnitude low-frequency noise-characteristics in magnetic fields comprising superconducting films wherein the films have a width that is less than or equal to a critical width, w.sub.C, which depends on an ambient magnetic field. For operation in the Earth's magnetic field, the critical width is about 6 micrometers (.mu.m). When made with film widths of about 4 .mu.m an inventive high transition-temperature, superconducting quantum interference device (SQUID) excluded magnetic flux vortices up to a threshold ambient magnetic field of about 100 microTesla (.mu.T). SQUIDs were fabricated having several different film strip patterns. When the film strip width was kept at about 4 .mu.m, the SQUIDs exhibited essentially no increase in low-frequency noise, even when cooled in static magnetic fields of magnitude up to 100 .mu.T. Furthermore, the mutual inductance between the inventive devices and a seven-turn spiral coil was at least 85% of that for inductive coupling to a conventional SQUID.
REFERENCES:
patent: 5532485 (1996-07-01), Bluzer et al.
patent: 5625290 (1997-04-01), You
R. Cantor, et al. "Low-Noise, Single-Layer YBa.sub.2 Cu.sub.3 O.sub.7-x DC SQUID Magnetometers at 77 K", IEEE Transactions on Applied Superconductivity, vol. 5, No. 2, Jun. 1995, pp. 2927-2930.
Dantsker, et al. Addendum: "Low Noise YBa.sub.2 Cu.sub.3 O.sub.7-x -SrTio.sub.3 -YBa.sub.2 Cu.sub.3 O.sub.7-x Multilayers for Improved Superconducting Magnetometers", Appl. Phys. Lett. 67(5), Jul. 31, 1995, pp. 725-726.
Drung, et al. "Integrated Yba.sub.2 Cu.sub.3 O.sub.7-x Magnetometer for Biomagnetic Measurements", Appl. Phys. Lett. 68 (10), Mar. 4, 1996, pp. 1421-1423.
Dantsker, et al. "High-T.sub.c Super Conducting Quantum Interference Devices with Slots or Holes: Low 1/f Noise in Ambient Magnetic Fields", Appl. Phys. Lett. 70 (15), Apr. 14, 1997, pp. 2037-2039.
Clarke John
Dantsker Eugene
Patidar Jay
The Regents of the University of California
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