Polarity change switch for Peltier current lead

Peltier current lead is a promising method to reduce heat leakage from current lead. This paper reports development of Peltier current lead (PCL) with switching facilities to adopt the PCL to polarity-reversible superconducting magnet. In the present work, two types of the PCL were discussed. We mainly investigated the PCL with switching element installed in the copper part. Numerical analysis revealed that it is preferable to reduce heat leakage at the low temperature end of Peltier element. With switch resistance of /spl sim/100 /spl mu//spl Omega/, which enabled switch induced increment of the heat leakage to be suppressed by less than 10%. A transistor switching module with appropriate resistance were manufactured. We demonstrated that a temperature gradient at the end of the lead, corresponding to the heat leakage, could be reduced compared to a conventional current lead (CCL) even when the module was installed with the PCL.