Investigation of Helium-Cooled Planar Transformer-Coupled SQUID Magnetometer

Reduction of Radio Frequency Interference to HTS-dc-SQUID by Adding a Cooled Transformer

Effect of an addition of a cooled step-up transformer to a flux locked loop (FLL) circuit was studied to reduce indirect rf interference to HTS-dc-SQUID. First, we demonstrated that a noise level of an HTS-dcSQUID system using the FLL circuit with single room-temperature transformer could be easily degraded by radiation of rf electromagnetic wave to cables in the FLL circuit. It is thought that...

High Sample Rate Optically Pumped Helium Magnetometer

Optically pumped helium magnetometers are important instruments whichhave many applications in military, mass spectroscopy and space applications. In thispaper, the working principles of helium magnetometers have been explained. There isalso an introduction of a new method for finding the resonant frequency, which hasadvantages to the typical method such as more sample r...

Ultimate limitation of the SQUID magnetometer

The Superconducting QUantum Interference Device is used to detect weak biomagnetic signals since in the early seventies. In that time the measurement was based on point contact rf SQUIDs operated at 20 MHz, with to a flux noise of the order of 10-4 Φ 0/ √Hz . After finding methods to fabricate reliable thin-film devices, the dc SQUIDs started gradually replace the rf SQUIDs. [1] The dc SQUID wi...

Helium Cooled Tungsten Heat Sinks

Noninvasive Measurement of Gastric Propagation Using a Squid Magnetometer

A vector Superconducting QUuntum Interference Device (SQUID} magnetometer wus used to meusure the magnetic fields nssociated with propagation of gustric electrical uctivity. Measurements of the magnetic field vector were consistent with the presumed pattern of current propagation in the gastric musculature. Further studies using two SQUID systems ullowed the first noninvasive determination of t...