Parametric study on coupling loss in subsize ITER Nb/sub 3/Sn cabled specimen

The cable in conduit conductors for the various ITER coils are required to function under pulse conditions and fields up to 13 T. A parametric study, restricted to a limited variation of the reference cable lay out, is carried out to clarify the quantitative impact of various cable parameters on the coupling loss and to find realistic values for the coupling loss time constants to be used in ac loss computations. The investigations cover ac coupling loss measurements on jacketed sub- and full size conductors with variations in type of cabling, twist pitch, void fraction, and thickness of the chromium coating. The results are summarised and conclusions regarding the ITER cable design are presented. Scaling laws for coupling loss versus void fraction and number of cabling stages are presented.