Peltier cooling of superconducting current leads Original Research Article

An interesting application of Peltier cooling based on the Peltier materials presently available arises for the cooling of current leads connected to superconducting power electronics. By inserting n-doped and p-doped Peltier tablets at the warm end into the circuit, at their warm side the remaining current leads can be Peltier cooled about 50–60 K below room temperature. We have developed an experimental test apparatus for dc operation up to a current of 200 A. Our experiments, performed with Peltier tablets fabricated from n-doped and p-doped Bi2Te3, well confirmed the expected Peltier cooling. From our results we estimate the reduction of the thermal losses (by typically 13%) and of the electric power losses (by typically 10%) due to the insertion of the Peltier tablets. In addition to the dc experiments, we have also carried out similar experiments using 50 Hz ac and a bridge circuit yielding a rectified output current. Minimization of the electric contact resistance generated at the surfaces of the Peltier tablets (and of the rectifying diodes required for ac operation) represents an important issue.