A Fluxgate Magnetometer for the Applications Technology Satellite

Abstract

A satellite-borne magnetometer used to detect magnetohydrodynamic wave propagation within the magnetosphere is introduced. The instrument is a biaxial, closed-loop, fluxgate magnetometer. The unit consists of the basic magnetometer plus additional sections, including a data processor, a field nulling section, and sensitivity selection logic. The basic magnetometer is discussed briefly, the additional sections in greater detail. It is shown that the use of sum and difference amplifiers in the data processor enable the derivation of magnetic field vectors transverse and parallel to the spacecraft spin axis. The field nulling section involves the use of an offset-field-generator to apply discrete current steps to the sensor offset winding in order to null the ambient sensor field. The use of three sensitivity levels is shown to maintain the analog output within the dynamic range of the instrument. An in-flight calibration section is discussed and referenced to instrument stability and sensitivity. A brief discussion of the ATS satellite mentions the advantages of its orbit, which is favorable for the study of long-term magnetic field variations and for correlation with plasma and particle experiments also onboard.