Magnetic Thermometry

Some magnetic materials create temperature dependent magnetic fields that penetrate conducting materials. By measuring the size of the surrounding magnetic fields, one can determine the temperature of the magnet without contact to the magnet or an object that contains the magnet.Since the magnet can be small and is a solid piece of material it has several advantages, 1) the electronics do not need to travel with the magnet through harsh environments, 2) the magnet can be placed in suspended solids with minimal effect on their motion. The remaining part of the magnetic thermometer consists of a magnetometer that is consistent with the working environment. The magnetometer needs to account for the velocity,position and orientation of the magnet when these quantities are unknown.The result is that by simply moving the magnet past the sensor the temperature of the magnet is determined. At the NCFST a prototype magnetic thermometer has been built to measure temperatures in objects moving through 2" or smaller pipes. The prototype has worked successfully in industrial environments but its performance must be improved. Because of the necessity to have product flow into and out of the sensor, interference can never be perfectly shielded. However, there are ways to improve the shielding and the measurement's immunity to external noise. The magnetic shield can be lengthened and a second layer can be added. By changing the triggering method and data analysis, one can reduce the effect of unshielded signals as well. This should help the system measure smaller magnetic particles or similar sized particles at increased distances. This project should develop a system that would be compatible with other applications as well.