Principle of the search coil measurement (from Roux et al., 2008)
The instrument is based upon the combination of a high magnetic permeability material and a large number of turns which passively detect voltage induced by the changing external field (an AC-current measurement). The high magnetic permeability core amplifies the external magnetic field. This core is located inside two types of windings. The main winding is the sensing element; it has a very large number of turns while the secondary winding is used to introduce a flux feedback in order to flatten the frequency response by removing the resonance associated with the main winding. The flux feedback stabilizes the phase response of the instrument, independent of temperature variations.
Frequently Asked Questions
Q: Is it possible to get help or more information concerning the calibration of the SCM data?
A: Yes, please contact Olivier Le Contel (olivier.LeContel@cetp.ipsl.fr).
Q: Are the SCM calibration files updated?
A: No, SCM calibration files have been carefully produced in a French calibration facility (Chambon-la-forêt Observatory) and the SCM frequency response is in principle very steady in time (no temperature drift for instance). However, each SCM frequency response can be checked once per orbit thanks to an injected calibration signal generated by the SCM pre-amplifier.