Optimization of conduction-cooled Peltier current leads

A theoretical investigation for optimization of conduction-cooled Peltier current leads is undertaken. A Peltier current lead (PCL) is composed of a thermoelectric element (TE), a metallic lead and a high Tc superconductor (HTS) lead in the order of decreasing temperature. Mathematical expressions for the minimum heat flow per unit current crossing the TE-metal interface and that flowing from the metal lead to the joint of the metal and the HTS leads are obtained. It is shown that the temperature at the TE-metal interface possesses a unique optimal value that minimizes the heat flow to the joint. It is also shown that this optimal value depends on the material properties of the TE and the metallic lead but not the joint temperature nor electric current. Optimal geometric factors, viz. the ratio of the length to cross-sectional area, of both the TE and the metallic lead are obtained for various joint temperatures. A design procedure for optimizing PCLs is also proposed.