Multi-stage Peltier current lead system for liquid helium free magnets

After the Peltier current lead (PCL) was proposed to reduce heat leakage into a low-temperature system and demonstration experiments were performed for liquid helium systems, we study in this paper a PCL application to a liquid helium free magnet (HFM). Numerical calculation codes have been developed previously to optimize the current lead and to analyze the experimental data for single stage PCL. Since multi stage Peltier elements are often used in various kinds of scientific fields, this configuration is applied to the PCL, a computer code is developed and finally a numerical calculation has been performed for several types of multistage PCL. Heat leakage is reduced at the high-temperature end of the HTS, and therefore the stability of the magnet is enhanced, the cooling time of the system shortened and the magnitude of the current increased.