Fluxgate magnetometers are widely-used space science and space weather instruments, but they depend on a legacy component—a ferromagnetic core—that was developed and manufactured for the U.S. Navy using technology that has been subsequently lost to the civilian community.
The UI team manufactures new fluxgate cores using a method that does not rely on legacy processes or materials and then integrates these cores into modern spaceflight magnetometers. The ferromagnetic cores are produced starting from base metal powders that are melted into custom alloys, rolled into thin foils, formed into the desired geometry of the fluxgate core, and artificially aged using heat to optimize their magnetic properties. The resulting cores are integrated into a complete fluxgate sensor ready for spaceflight applications.
Designing, prototyping, and manufacturing the cores, sensors, and paired electronics in house allows the team to explore new sensor geometries that are compatible with different missions. Most recently, the UI team developed a new core to be used in the Space Weather Iowa Magnetometer (SWIM). While the SWIM core is based on a core previously developed for the MAGnetometers for Innovation and Capability (MAGIC) Tesseract sensor that recently launched on NASA’s TRACERS (Tandem Reconnection and Cusp Electrodynamics Reconnaissance Satellites) mission the SWIM core is miniaturized and retains the same level of performance. The first flight opportunity for the SWIM fluxgate is on the University of Oslo’s ICI-5bis sounding rocket mission that is scheduled to launch in winter 2025/2026 from the Andoya Space Sub-Orbital range in Norway.
Integration of the SWIM sensor for the ICI-5bis Suborbital Sounding Rocket. Fluxgate magnetometers sense the magnetic field by detecting the electromagnetic force (EMF) induced by the changing magnetic flux. Current is driven into the drive winding (the interior winding on the fluxgate core) creating a magnetic field. When the ferromagnetic material in the cores experiences the magnetic field, its relative permeability (the intrinsic magnetic property of the metal within the core) changes. As the relative permeability changes, a voltage is induced in the sense winding (the outer winding on the core). By knowing the amount of current driven into the core and the voltage that was induced in the sense winding, we can understand the magnetic field that the sensor is experiencing. Most in-space magnetometers are not located onboard the main body of the spacecraft; instead, they are placed on booms to ensure that the magnetic fields produced by the electronics and magnetic materials onboard the spacecraft do not interfere with the sensor.
Example noise plot of a SWIM fluxgate core showing