Location dependent performance study on regenerators within a Halbach magnetic field source.

This research describes the characterization of a concentric Halbach magnetic refrigerator using Gadolinium. Experiments are performed with the active regenerator located at three different axial locations in the magnet. Results show that the performance of the regenerator is lower when located near the ends of the Halbach magnets as compared to the center. Numerical simulations are performed using COMSOL to analyze the effects of field distribution, magnitude and demagnetization, in addition to the dead volumes on either side of the regenerator. The numerical results show a large difference between the temperature span of the active part of the regenerator and the end points of the regenerator housing where measurements are taken. These results suggest that proper characterization of the magnetic field and the dead volume is needed to explain the operation of the device.