Simple technique for increasing the conductivity of copper for current lead conductors

Abstract Current leads are used mainly as conductors for electrical current to be supplied to superconducting magnets. Low liquid helium losses in the current leads are of great importance and therefore the geometry of the current lead must correspond to a specific optimized current. Here it is shown that, by altering the residual resistivity of the conductor material, one can modify the optimized current of the current lead without changing its original geometry. A relatively easy technique for decreasing the resistivity of commercial electrolytic tough-pitch copper is described. Experimental results of copper annealing in a vacuum of 2.7 × 10 −3 Pa (2 × 10 −5 torr) in the temperature range of 295–703 K are discussed.