FEM Modeling of AC Loss in Rutherford Cables with and without Resistive Cores

摘要

AC losses in Rutherford cables have been calculated using a 3-D finite element method. The approach, while employing FEM, was based on an anisotropic continuum model of the material, rather than a network approach. The model was constructed by segregating the cable cross section into various blocks with anisotropic conductivities. The anisotropic continuum approach dictated modeling a discrete, heterogeneous system as a continuous but anisotropic system. Additionally, we simplified the system by dividing the cable into four or five regions, each with a distinct and uniform conductivity tensor within the given region. The applied field was sinusoidal, and the solution was time-harmonic. A direct solver was used, with approximately 50,000 nodes. Cables with and without inner, resistive cores were investigated, and losses as a function of core width and thickness were calculated. The proper cable pitch, L_p, and aspect ratio dependence of these solutions was demonstrated. Further, calculations were made determining the influence of (i) average transverse conductivity, (ii) inner core conductivity, (iii) core width, and (iv) the presence of additional exterior cable stabilizer. Uncored and cored cable results were compared, and in some cases these results were compared to previous experimental results.