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Magnetic flux reference standard

With the MPS-Flux Reference magnetic fluxmeters may be calibrated easily and accurately.

The flux reference consists of a permanent magnet system with measuring coils having the windings N₁ and N₂ in the air gap. These are connected differentially so that they only measure the flux change corresponding to the polarisation J_s of a nickel component when this is inserted in the gap, but not the field strength change in the air gap resulting from a change in the working point of the permanent magnet. The fluxmeter to be calibrated is connected to these coils.

The drilling in the pole plate is closed with an iron stopper to which is attached at one end a piece of pure nickel which exactly fits the air gap. Should the two ends of the stopper be interchanged then the air gap is either open or closed with the nickel piece. A change in flux occurs here derived from only the number of windings N₁ and N₂, the cross section A of the nickel and the saturation polarisation J_s of nickel. At room temperature this is J_s = 0.61 Tesla. The change in flux dΦ on the MPS-Flux Reference is 10-2 Vs and at 22 °C accuracy of ±0,5 % is given.

Temperature stability is provided by the temperature coefficient of nickel which is - 0,064 % per Kelvin at room temperature.