Japan Atomic Energy Agency has developed four types of Nb 3 Sn strand which can be used in the ITER TF coils. One is a strand made by an internal tin process strand and the others are bronze process strands. The achieved critical current density is more than 790 A/mm 2 in the bronze process strands and more than 980 A/mm 2 in the internal tin process strand under 4.2 K temperature and 12 T magnetic field and there is hysteresis loss of less than 770 mJ/cc under 3 T cycle. Since these strands are utilized with an external strain, it is necessary to evaluate strain dependency to confirm the ITER conductor design. An apparatus to measure the strain dependency was newly developed. It has a horseshoe-shaped ring to produce uniform axial compressive or tensile strain along the strand length, a strand being soldered on the outer surface of the ring. The detailed strand characteristics were investigated subjecting the developed strands to a magnetic field from 10 T to 13 T, a strain from about 0.8% to 0.5%, and a temperature from 4.2 K to the critical temperature. When the critical current is normalized to that under the conditions where strain is intrinsically zero, the bronze process strands exhibit better performance than the internal tin process strand. However, the three bronze process strands do not exhibit the same I -strain characteristics. Two types of scaling relations are applied to the data, and good expressions of strand performance were obtained by the least square method within 3 A as RMS.
Pressure drop characteristics of the cable-in-conduit conductor adopted in the ITER Central Solenoid Model Coil (CSMC) were first measured through the CSMC experiment in the ITER relevant cooling condition. The conductor has two parallel flow channels such as a bundle channel and a central channel. Previous studies have proposed pressure drop correlations between the friction factor and Reynolds number for the central channel. In this report, the measured pressure drop data were compared with these correlations. Results indicate that the measured pressure drop characteristic shows a large deviation from prediction. Friction factor for the central channel is less sensitive to Reynolds number in comparison with modified Blasius type correlation. The correlations proposed by Colebrook and Zanino show a relatively good prediction.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.