Method and apparatus for mapping the open circuit demagnetisation curve of a sample of magnetic material to a closed circuit demagnetisation curve
OwnerJames CLEWETT, Robin CORNELIUS +1inventors
InventorsJames CLEWETT, Robin CORNELIUS, Jack WADE
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Abstract
A method and apparatus for accurately mapping the closed magnetic circuit demagnetisation curve to and from a open magnetic circuit demagnetisation curve. The method utilises open circuit data from a pulsed field magnetometer (PFM) and computer modelling of both the PFM (open circuit) and permeameter (closed circuit) apparatus. This method is more accurate than previous methods and can calculate the closed circuit curve within the precision of both the PFM and the permeameter apparatus.
Claims12
A method of mapping the open circuit demagnetisation curve of a sample of magnetic material to a closed circuit demagnetisation curve:
- (i) measure the open circuit demagnetisation curve of the sample using pulsed field magnetometry;
- (ii) remove from the demagnetisation curve linear eddy current effects due to the applied field sweep rate;
- (iii) remove from the demagnetisation curve non-linear eddy current effects due to the sample demagnetisation;
- (iv) remove the effects of sample geometry from the demagnetisation curve;
- (v) add to the demagnetisation curve the effects of an idealised steel permeameter core.
Apparatus for mapping the open circuit demagnetisation curve of a sample of magnetic material to a closed circuit demagnetisation curve:
- (i) means to measure the open circuit demagnetisation curve of the sample using pulsed field magnetometry;
- (ii) means to remove from the demagnetisation curve linear eddy current effects due to the applied field sweep rate;
- (iii) means to remove from the demagnetisation curve non-linear eddy current effects due to the sample demagnetisation;
- (iv) means to remove the effects of sample geometry from the demagnetisation curve;
- (v) means to add to the demagnetisation curve the effects of an idealised steel permeameter core.
Dependencies are inferred from the claim text.