Entropy generation minimization on CIC (Cable-In-Conduit) superconductor design

Abstract

The concept. of EGM (Entropy Generation Minimization) is applied to the design of an optimum CIC (Cable-In-Conduit) superconducting cable for large scale superconducting magnets, which is cooled by supercritical helium flow inside a conduit at cryogenic temperature. Three factors are considered to evaluate the conductor performance under various operating conditions of the magnets. First, the void fraction of the CIC conductor is optimized to generate minimum entropy under steady-state operating condition. Second, the surface condition of the superconducting strands is investigated to find the best surface electrical resistance value between two extremities; insulation or perfect conduction. Third, the entropy generation rate is formulated to compare the advantage of hybrid superconducting cable (superconducting strands + pure copper strands) with the integral one (all superconducting strands). This paper presents that the magnet performance can be optimized by considering the design concept of the less entropy-generating conductor. (C) 1999 Elsevier Science Ltd. All rights reserved.