HTS twisted stacked-tape cable conductor

Abstract

The feasibility of high field magnet applications of the twisted stacked-tape cabling method with 2G YBCO tapes has been investigated. An analysis of torsional twist strains of a thin HTS tape has been carried out taking into account the internal shortening compressive strains accompanied with the lengthening tensile strains due to the torsional twist. The model is benchmarked against experimental tests using YBCO tapes. The critical current degradation and current distribution of a four-tape conductor was evaluated by taking account of the twist strain, the self-field and the termination resistances. The critical current degradation for the tested YBCO cables can be explained by the perpendicular self-field effect. It is shown that the critical current of a twisted stacked-tape conductor with a four-tape cable does not degrade with a twist pitch length as short as 120 mm. Current distribution among tapes and hysteresis losses are also investigated. A compact joint termination method for a 2G YBCO tape cable has been developed. The twisted stacked-tape conductor method may be an attractive means for the fabrication of highly compact, high current cables from multiple flat HTS tapes.

Strain Distribution in REBCO-Coated Conductors Bent With the Constant-Perimeter Geometry

“…Given the strain dependence of I c , the presented approach allows to determine the expected I c of the REBCO tape after bending [45][46][47][48]. Considering the I c dependence on both strain and magnetic field, one can determine the expected cable and magnet performance in order to assess if the fabrication process has introduced any conductor degradation [49].…”

Development of a Roebel-cable-based cos-theta dipole: design and windability of magnet ends

“…To do so, the cable follows a S-shape bending with a 22-mm radius and an angle of 35°, then a twist of 74° over 80 mm and a second and similar S-shape bending. The strain generated by such a twist on a 12-mm wide tape is ranging from -0.16% to +0.31% from the center of the tape to its edge which is safe [28]. This result is conservative since the meander tapes of the Roebel should not experience such a strain.…”

Research of HTS application on tokamak magnets

“…They are the rectangular conductor type, Rutherford cable type [5], helical winding cable type [6] and helical twisted stacking-tape cable type [7].…”