Effect of proton irradiation on the performance of fluxgate sensors

The fluxgate magnetometers have been used in many space missions due to their stability, low cost, low mass, and good measuring sensitivity and range. Space weather conditions around the Earth and solar system may be dangerous for the sensors of these crucially important devices. Proton irradiation was used to simulate space weather conditions near the Earth’s magnetosphere in Van Allen belts. The effect of proton irradiation on the structural, magnetic, and sensor performance of our fluxgate sensors was studied with irradiation doses up to 60 kRad. Sensor’s materials were prepared using a planar flow casting technique having two different compositions, namely Fe38Co38Mo8CuB15 (Fe38) and Fe42Co42CuB15 (Fe42). Structural investigation of the alloys was performed by X-ray diffraction patterns and SEM micrographs. A magnetic force microscope and vibrating sample magnetometer were used to investigate surface and bulk magnetic properties, respectively. The characterization of the sensors was done by determination of the working field range, transfer function, and noise at 1 Hz. The amorphous structure of the Fe38Co38Mo8CuB15 alloy did not change with irradiation, while some degree of crystallization was depicted in the Fe42Co42CuB15 alloy, probably due to the local heating of the ribbon. The formation of magnetic domains was clearly observed in Fe38Co38Mo8CuB15 alloy in MFM images after the irradiation. On the contrary, it was not observed in Fe42Co42CuB15 alloy due to excessive domain growth. The magnetic parameters, namely coercivity (Hc) and saturation magnetization (Ms) were affected by the proton irradiation in a different way. The former increases with irradiation dose, while the latter first decreases and then rises to its initial value or a little smaller. On the other hand, with increasing doses, for both alloys, the transfer functions of the sensors show a decrease while the noise increases substantially. The noise parameters of the sensors were raised 4–5 times after the maximum irradiation dose; similarly, sensitivities decreased more than 100 times. •Fe38Co38Mo8CuB15 and Fe42Co42CuB15 soft magnetic alloys were produced by planar flow casting method.•The ribbons of the casted alloys were used to prepare sensors of the fluxgate magnetometer.•The proton irradiation was used to check the performance of the fluxgate sensors in space weather conditions.•Crystallization occurred in Fe42 alloy after irradiation due to the local heating.•Magnetic parameters