Developments of electrical joints for aluminum-stabilized superconducting cables

Electrical joints for the aluminum-stabilized conductors of the LHC experim ent magnets have been studied. Two techniques have been tested: electron be am welding and MIG welding. The joint resistance was measured as a function of the magnetic field on ring shaped samples using the MA.RI.S.A. test fac ility, wherein current is induced in the test conductor by a varying magnet ic field. The resistance is obtained by measuring either the voltage drop o r the decay time, Calculation and finite-element simulation have been perfo rmed in order to separate the effect of both the copper-aluminum contact re sistivity and the aluminum resistivity from the effect due to the joint tec hnique (joint configuration, resistivity of the filler material, increasing of aluminum resistivity in the welding zone). The copper-aluminum contact resistivity and the current transfer length were obtained by measurements o f the joint resistance of butt welded samples.