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Instrument Description - MFE Linearity


Linearity Plots.


The POLAR fluxgate magnetometer is a highly linear instrument. This linearity is achieved through maintaining a high feedback ratio in the instrument and the careful selection of the amplifiers in the circuits. The greatest contribution to any nonlinearity in fact is the anologue to digital converter, and this is correctable if desired. The figures illustrate the extrame linearity of the magnetometer. Here we have first least square fit a sine wave to the two sensors in the spin plane for each of our two magnetometers, inboard and outboard. The panels display the residual field in raw counts plotted as a function of the field along the sensor. The discontinuity at zero field is at the one count lavel of the A/D converter. Since the same A/D converter was used for all four panels we expect the deviations would be the same in all four panels if they are due to the A/D converter and they are. Since these data were obtained from flight in sunlight, they also show that there is no thermally induced second harmonic ripple on the field, as is present on the WIND spacecraft.



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Last updated: December 31, 1999