Abstract: The invention concerns demagnetization devices used in particular for demagnetizing vessels or submarines in fixed stations, wherein one embodiment comprises: three sets of conductors for demagnetizing a vessel according to three directions; a direct current generator; an array of capacitors, a bridge switching device, an inductance coil; a switch allowing to select one of the three assemblies of conductors; a servo device for controlling the charge voltage of the array of capacitors; magnetometers; and a screen and keyboard allowing especially to supply a microprocessor with a reference value fixing the value of the desired residual magnetization; the demagnetization consisting of sending into each set of conductors a sequence of discharges, of smaller and smaller intensity and servo-controlled to the value of the remaining magnetization, in order to cause the magnetization to converge towards the desired value.

Abstract: A process for automatically correcting alignment errors between the measuring magnetometers of a magnetic gradient meter, consists in adding to such a gradient meter two additional magnetometers perpendicular to each other and to the axis of the measuring magnetometers. The measurements delivered by these additional magnetometers allow, with two coefficients obtained by previous calibration, the two main errors terms to be calculated and the measured value of the gradient to be corrected accordingly, which allows the alignment error to be corrected electronically and automatically.