A cryogenic eddy current microprobe

Eddy current

Eddy currents (also called Foucault currents[1]) are loops of electrical current induced within conductors by a changing magnetic field in the conductor, due to Faraday’s law of induction. Eddy currents flow in closed loops within conductors, in planes perpendicular to the magnetic field. They can be induced within nearby stationary conductors by a time-varying magnetic field created by anAC el...

Isolated ramping current sources for a cryogenic current comparator bridge

The design and perfonnance of a pair of highly isolated ramping and reversing direct-current sources for use with a cryogenic current comparator resistance bridge and dc superconducting quantum interference device (SQUID) detector are described. The current sources are floating and isolated from one another, and are internally programmed to reverse the output current while maintaining the SQUID...

Eddy Current Benchmark Problem – 3

Singularities of eddy current problems

We consider the time-harmonic eddy current problem in its electric formulation where the conductor is a polyhedral domain. By proving the convergence in energy, we justify in what sense this problem is the limit of a family of Maxwell transmission problems: Rather than a low frequency limit, this limit has to be understood in the sense of BOSSAVIT [11]. We describe the singularities of the solu...

Multifrequency eddy current signal analysis

This thesis presents a novel procedure for representing and processing multifrequency eddy current signals. Multifrequency eddy current NDE methods are used extensively for the inspection of steam generator tubes in nuclear power plants. Existing methods utilize computationally expensive time domain procedures to process the data. The procedure outlined in the thesis uses frequency domain metho...