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Article
Comparison of Magnetic Probe Calibration At Nano and Millitesla Magnitudes
Review of Scientific Instruments
  • Ryan A. Pahl
  • Joshua L. Rovey, Missouri University of Science and Technology
  • David Pommerenke, Missouri University of Science and Technology
Abstract
Magnetic field probes are invaluable diagnostics for pulsed inductive plasma devices where field magnitudes on the order of tenths of tesla or larger are common. Typical methods of providing a broadband calibration of Ḃ probes involve either a Helmholtz coil driven by a function generator or a network analyzer. Both calibration methods typically produce field magnitudes of tens of microtesla or less, at least three and as many as six orders of magnitude lower than their intended use. This calibration factor is then assumed constant regardless of magnetic field magnitude and the effects of experimental setup are ignored. This work quantifies the variation in calibration factor observed when calibrating magnetic field probes in low field magnitudes. Calibration of two B? probe designs as functions of frequency and field magnitude are presented. The first Ḃ probe design is the most commonly used design and is constructed from two hand-wound inductors in a differential configuration. The second probe uses surface mounted inductors in a differential configuration with balanced shielding to further reduce common mode noise. Calibration factors are determined experimentally using an 80.4 mm radius Helmholtz coil in two separate configurations over a frequency range of 100-1000 kHz. A conventional low magnitude calibration using a vector network analyzer produced a field magnitude of 158 nT and yielded calibration factors of 15 663 ± 1.7% and 4920 ± 0.6% T [over]Vs at 457 kHz for the surface mounted and hand-wound probes, respectively. A relevant magnitude calibration using a pulsed-power setup with field magnitudes of 8.7-354 mT yielded calibration factors of 14 615 ± 0.3% and 4507 ± 0.4% T [over]Vs at 457 kHz for the surface mounted inductor and hand-wound probe, respectively. Low-magnitude calibration resulted in a larger calibration factor, with an average difference of 9.7% for the surface mounted probe and 12.0% for the hand-wound probe. The maximum difference between relevant and low magnitude tests was 21.5%.
Department(s)
Mechanical and Aerospace Engineering
Second Department
Electrical and Computer Engineering
Keywords and Phrases
  • Calibration,
  • Coils,
  • Magnetic Fields,
  • Inductors,
  • Inductance
Document Type
Article - Journal
Document Version
Citation
File Type
text
Language(s)
English
Rights
© 2014 American Institute of Physics (AIP), All rights reserved.
Publication Date
1-1-2014
Citation Information
Ryan A. Pahl, Joshua L. Rovey and David Pommerenke. "Comparison of Magnetic Probe Calibration At Nano and Millitesla Magnitudes" Review of Scientific Instruments Vol. 85 Iss. 1 (2014)
Available at: http://works.bepress.com/david-pommerenke/63/