Electromechanical behaviour of REBCO tape lap splices under transverse compressive loading

Abstract

Abstract.We have studied the influence of transverse compressive stress on the resistance and critical current (I c ) of soldered REBCO tape lap splices. Internal contact resistances dominate the overall REBCO lap splice resistances. Application of transverse compressive stress up to 250 MPa during the resistance measurements does not alter the resistance and I c of the soldered REBCO splices that were studied. The resistance of unsoldered REBCO tape lap splices depends strongly on the contact pressure. At a transverse compressive stress of 100 MPa to which Roebel cables are typically exposed in high field magnets, the crossover splice contact resistance is comparable to the internal tape resistances.

Contact resistance between two REBCO tapes under load and load cycles

“…Rc of a SuperPower conductor was measured indirectly from the charging time constant at 77 K [18], and a value of 70 µΩ-cm 2 was reported. In contrast, a direct measurement of AMSC conductor [20] reported Rc of 0.7-10.6 µΩ-cm 2 as a function of pressure. Since the reported Rc values varies considerably, a comprehensive study of Rc in REBCO-to-substrate configuration is still needed.…”

“…The R c of NbTi and Nb 3 Sn wires under mechanical load and load cycles has been studied extensively for superconducting cable applications [9][10][11][12]. The R c between REBCO tapes has also been studied by a few research groups [13][14][15][16][17][18][19][20]. It should be noted that the REBCO layers of most REBCO conductors are grown on a substrate that has an insulating oxide buffer layer.…”

Proceedings of the 8th Workshop on Mechanical and Electromagnetic Properties of Composite Superconductors (MEM 2016)

“…Efforts in cabling REBCO coated conductors for use in power transmission cables and high-current magnets have increased significantly during recent years and studying the electromechanical behavior of REBCO tapes under stresses typical in REBCO cables has developed in a fruitful area of interest. Grether et al studied the electromechanical behavior of REBCO tape lap splices under transverse compressive loading as experienced by tapes in Roebel cables that operate at high magnetic fields [6]. The splice resistance and critical current of soldered splices up to 250 MPa transverse stress, while the contact resistance between unsoldered tapes depends strongly on the transverse pressure.…”