Preliminary studies on current leads for WENDELSTEIN 7-X

A first study on high-temperature-superconductor (HTSC) current leads for the nuclear fusion experiment WENDELSTEIN 7-X is performed, based on reasonable assumptions concerning design and materials. The report describes an analytical and a numerical model to calculate the temperature distribution and heat inleak for copper current leads and HTSC current leads at steady state conditions. Analytical solutions are given for conduction cooled and forced-flow cooled current leads, using the Wiedemann-Franz law. The numerical model is based on a variational method to solve the two-point boundary value problem in an ordinary differential equation. Nonlinear properties (i.e. specific heat, thermal conductivity) are approximated by polynomial fit functions. A comparison of results of the analytical and numerical calculation shows good agreement for both, conduction cooled and forced-flow cooled current leads. Small differences in solutions are mainly due to the approximation by the Wiedemann-Franz law. In general, the analytical method is well suited for parameter studies on different current lead configurations, since the calculating time is much shorter than for the numerical method. (orig.)24 refs.Available from TIB Hannover: RA 71(11/2) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman