Evaluation of Thermoelectric Performance of Peltier Current Leads Designed for Superconducting Direct-Current Transmission Cable Systems

Reduction of heat leakage is a key issue in the development of practical superconducting devices. We evaluated the thermoelectric performance of Peltier current leads (PCLs) designed for superconducting direct-current transmission cable systems using a custom-made test bench. Among several configurations, a minimum heat leak value of 30.0 W/kA was attained with a PCL having shape factors of 41.8 m
^-1
and 1.69 × 10
⁴
m
^-1
for the Peltier element and copper lead, respectively. In addition, a methodology to evaluate the energy flow within the PCL was developed to further improve the thermoelectric performance of practical PCL devices. The results indicate that the contribution of the Thomson heat to the heat-pumping effect possibly become as large as the Peltier heat and Joule heat, and thus cannot be ignored in the heat analysis of PCLs.