Method to Evaluate CIC Conductor Performance by Voltage Taps Using CSMC Facility

Abstract

A method for evaluating the critical current of conductors is discussed in the context of the relationship between the electric field of the conduit surface and the superconducting cable in CIC conductors used for nuclear fusion reactors. The potential detected by voltage taps located on the surface of the conduit is the average potential of strands that have contact with the virtual surface area of the cable. This area is defined in terms of contact resistance between the conduit and strands as well as conduit resistance. Considering that a strand is uniformly distributed in a conductor due to the cabling effect, it is possible to replace in calculations the distribution of the electric field of a strand along the length of the conductor with the distribution of a cross section of the conductor, a replacement which renders possible statistical approach. As a result, the voltage measured by a pair of voltage taps located along the length of the conductor can be expressed in terms of a general formula which establishes a relationship between the electric field of the conduit surface and the superconducting cable including statistic errors. Using this formula, the electric field of the cable and the consequent superconducting properties of the conductor may be estimated with an acceptable degree of accuracy. Assessment of the experimental results and performance of the ITER conductors are introduced with discussion of temperature measurement issue, and the validity of the formula is discussed.