Superconducting quantum interference magnotometer having a feedback reset capability to extend the dynamic sensing range

摘要

A superconducting pickup coil is provided for interlinking with an unknown magnetic flux and causing an induction current to flow. A superconducting detector is provided magnetically coupled with the superconducting pickup coil for producing output voltage pulses in response to the unknown magnetic flux. A superconducting feedback circuit is provided connected to the superconducting detector for receiving the output voltage pulses therefrom and feeding back a feedback magnetic flux to the superconducting pickup coil in response to each output voltage pulse such that the feedback magnetic flux counteracts the unknown magnetic flux. A resistance fixture is provided in the vicinity of the superconducting pickup coil for causing a transition in a part of the superconducting pickup coil from a superconducting state to a normal conducting state in response to the drive current. A controller is provided connected to the resistance fixture and the superconducting detector for receiving the output pulses therefrom and producing a drive current for energizing the resistance fixture. Simultaneously with the energization of the resistance fixture, the controller resets the feedback circuit such that the counteracting feedback magnetic flux is deenergized.