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Determination of the magnetic permeability of metallic sheets using Lorentz force and Kelvin force measurement techniques

Project description

Magnetic shielding is an indispensible requirement for the measurement of very weak magnetic fields. Such measurements are performed in basic research and material evaluation in physics or in biomagnetics, where the magnetic field produced by humans or animals is analyzed. Typically, the measurement environment is enclosed with highly permeable material, such as Mumetal, arranged in single or multilayer structures composed of metallic sheets. Quality control of such sheets is often problematic since the sheets have to be tested after mounting. The aim of this project is to develop a “Permeameter” for quality control of highly permeable material. A major design criterion is the ability to provide spatially resolved estimation of the permeability. Additionally, the effect of internal and external magnetic fields on the shielding performance and the permeability estimation should be investigated. The theoretical work includes the setup of a simulation environment, simulations of the magnetic field distributions in the various experimental settings and the comparison to the experimental results. The experimental work includes the design and fabrication of suitable test environments, the development of different methods for the estimation of permeability, the design and realization of magnetic field producing and measuring systems, the investigation of Lorentz and Kelvin forces. The experimental approaches should include Impedance spectroscopy, evaluation of the magnetic vector field at the boundary of the sheets, Epstein frame, and Lorentz and Kelvin forces measurement techniques. The interaction of magnetic fields from active magnetic shielding technologies with the local permeability including the effect of highly conducting layer should be investigated. As an important cross project task, the possibility of a separation of Lorentz and Kelvin forces with the help of multi-component measurements should be investigated.

Image 1: Measurement setup for permeameter

Publications & patents

  • Eichardt,R., Baumgarten,D., Di Rienzo,L., Linzen,S., Schultze,V., Haueisen,J.: Localisation of buried ferromagnetic objects based on minimum-norm-estimations: a simulation study. COMPEL, 28(5):1323-1333, 2009
  • Baumgarten,D., Liehr,M., Wiekhorst,F., Steinhoff,U., Münster,P., Miethe,P., Trahms,L., Haueisen,J.: Magnetic Nanoparticle Imaging by means of Minimum Norm Estimates from Remanence Measurements. Medical and Biological Engineering and Computing, 46 (12):1177-1185, 2008
  • Hilgenfeld,B., Haueisen,J.: Simultaneous suppression of disturbing fields and localization of magnetic markers by means of multipole expansion. Biomagnetic Research and Technology, 2:6, 2004
  • Resmer,F.,Nowak,H., Gießler,F., Haueisen,J.: Development of an active magnetic screen to allow a bio-magnetometer to be used in an unshielded environment. Superconductor Science and Technology, 17: 1365-1371, 2004
  • Hilgenfeld,B., Strähmel,E., Nowak,H., Haueisen,J.: Active magnetic shielding for biomagnetic measurement using spatial gradient fields. Physiological Measurement, 24, 661-669, 2003
  • Haueisen,J., Unger,R., Beuker,T., Bellemann,M.E.: Evaluation of Inverse Algorithms in the Analysis of Magnetic Flux Leakage Data. IEEE Transactions on Magnetics, 38, 1481-1488, 2002