Measurement and Analysis of Thermal Materials in the Thermally Actuated Magnetization Flux Pumping Method

In this paper, potential thermal materials utilized in thermally actuated magnetization (TAM) flux pumping have been explored and their magnetic and thermal properties have been tested and analyzed. TAM flux pumping is a practical technique which only requires a small magnetic field which can be generated by permanent magnets and will lead to a much higher field trapped within the superconductor after multiple pumps. A thermal material (TM) whose permeability drops strongly as its temperature exceeds a given point has been used as a magnetic flux regulator to create a travelling magnetic field. Ferrites with different dopants were synthesized by ceramic method as TMs. Various testing methods have been used to investigate the characteristics of ferrite samples, including non-destructive test, SEM, and SQUID. The T_C sweep of TMs was obtained at temperatures ranging from 77 K to 300 K. Gadolinium (Gd)-epoxy composites with different volume fractions were also made as TMs due to their better thermal properties compared to ferrites. A 1-D thermal modeling of Gd-epoxy composite has been built up to optimize the thermal diffusivity and the relative permeability of the composite. This work aims to investigate the variation of the thermal and magnetic properties of two TM candidates and gives a smart insight of finding better TM which is more efficient for the TAM flux pumping method.