The ubiquitous SQUID
Abstract
The mode of operation and applications of SQUIDs (Superconducting Quantum Interference Devices) are discussed. SQUIDs can detect small magnetic fluxes, small voltage, and small currents, and exist in two forms, dc SQUIDs also known as SLUGs (Superconducting Low-inductance Undulating Galvanometer) and ac SQUIDs (RF, UHF and microwave). A circulating current in a superconducting ring providing a measure of flux is the operating principle of basic SQUIDs based on theoretical considerations (magnetic flux quantization, the Josephson effects). A single-junction SQUID consists of a superconducting ring and single Josephson junction while the dc SQUID contains two junctions (niobium screws). Applications include quantum voltage standard tests, voltage and resistance measurements, attenuator calibration, temperature measurements, gravity wave detectors and meters, and fractional charge experiments. Military, geophysical, and medical applications are also discussed. Although most of SQUID's applications are still in the research stage, it appears likely that SQUIDs in combination with other equipment will be of increasing value in the future.
- Publication:
-
Contemporary Physics
- Pub Date:
- December 1980
- DOI:
- 10.1080/00107518008210662
- Bibcode:
- 1980ConPh..21..607P
- Keywords:
-
- Network Analysis;
- Squid (Detectors);
- Superconductivity;
- Electric Current;
- Electrical Measurement;
- Josephson Junctions;
- Magnetic Flux;
- Modal Response;
- Noise Spectra;
- Temperature Measurement;
- Instrumentation and Photography