DC SQUID As an Enhanced Magnetometer
Original Publication Date: 1986-Jul-01
Included in the Prior Art Database: 2005-Mar-09
The DC SQUID Chain is an enhanced magnetometer consisting of a chain of SQUIDs (Superconducting Quantum Interference Devices) 11 connected in series. In a chain of N SQUIDs, each one is coupled inductively to an input circuit consisting of N coupling coils 12 which are connected in series with N matched superconducting input coils 13 for magnetometer applications, or to a voltage source with source resistance increased by a factor of N over the optimal value for a single inductively coupled SQUID magnetometer used as a linear voltage amplifier. The figure shows the basic structure for N=4. In order to avoid chaotic interference between the coupled non-linear SQUIDs, the devices must either have widely dissimilar Josephson oscillation frequencies, or must be coupled to the input circuit through a low-pass filter.