Effect of periodic cyclic deformation on the voltage current transition of Nb₃Sn strands tested in the novel 'TARSIS' setup

The sizable Nb₃Sn cable-in-conduit conductors (CICC) destined for the high field magnets in the International Thermonuclear Experimental Reactor (ITER), engender large transverse forces on the strands pressing the cable against one side of the inner conduit wall. This causes transverse compressive strain in the strands' crossover contacts accompanied by possible pinching and bending strain on top of the strain induced by the differential thermal contraction of the various conductor components. In the "test arrangement for strain influence on strands" (TARSIS), the influence of various principle deformation states (mechanical elasto-plastic behavior) that occur in a CICC can be studied separately and combined. Beside precise displacement and force measurements for stress-strain analysis, the voltage-current characteristics can be studied on strands from virgin state toward multi-cyclic loading. Here we present the first results on periodical strand bending with cyclic loading using four different bending wavelengths.