Commissariat a L'energie Atomique

Guy Chiron

Jean-Charles Vidal

Andre Dumont

Louis Debreuil-Monet

Gradient meter to measure the spatial derivatives

Gradient meter with thin magnetic layer

Each end of the rods surrounding the positioning sensor is provided with a coil, through which passes a current, whose intensity is automatically regulated as a function of the sensor readings in order to make the gradient of the magnetic field due to the rods and to the field itself zero within the sensor area.

Device for automatically compensating the magnetism of drill string

This invention relates to methods of measuring magnetic fields and a magnetometer for performing the method. According to the method an alternating magnetic field is applied to a thin magnetic film along its axis of difficult magnetization. The alternating magnetic field applied to the film has an amplitude which is less than the anisotropy field of the film, the direction of magnetization of the film then undergoing an oscillation without reversal. An electrical signal representing variations per unit of time of the magnetic induction in the film is withdrawn and analyzed and to effect the analysis the component of the magnetic field is measured at any of the odd harmonic frequencies of the electrical signal. The electrical signal is obtained by collecting the voltage at the terminals of a conducted loop surrounding the film and having its axis directed along the easy axis of the film.

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Gieres, France

Guy Chiron