Current distribution in Cable-In-Conduit Conductors

Technical Report · Sun May 01 04:00:00 EDT 1994

DOI:https://doi.org/10.2172/10190603· OSTI ID:10190603

Ferri, M A

A numerical study of the current distribution in Cable-In-Conduit Conductors (CICC`s) experiencing linearly ramping transport currents and transverse magnetic fields was conducted for both infinitely long, periodic cables and finite length cables terminated in low resistance joints. The goal of the study was to gain insight into the phenomenon known as Ramp Rate Limitation, an as yet unexplained correspondence between maximum attainable current and the ramp time taken to reach that current in CICC superconducting magnets. A discrete geometric model of a 27 strand multiply twisted CICC was developed to effectively represent the flux linkages, mutual inductances, and resistive contact points between the strands of an experimentally tested cable. The results of the numerical study showed that for fully periodic cables, the current imbalances due to ramping magnetic fields and ramping transport currents are negligible in the range of experimentally explored operating conditions. For finite length, joint terminated cables, however, significant imbalances can exist. Unfortunately, quantitative results are limited by a lack of knowledge of the transverse resistance between strands in the joints. Nonetheless, general results are presented showing the dependency of the imbalance on cable length, ramp time, and joint resistance for both ramping transverse magnet fields and ramping transport currents. At the conclusion of the study, it is suggested that calculated current imbalances in a finite length cable could cause certain strands to prematurely ``quench`` -- become non-superconducting --thus leading to an instability for the entire cable. This numerically predicted ``current imbalance instability`` is compared to the experimentally observed Ramp Rate Limitation for the 27 strand CICC sample.

• Research Organization: Massachusetts Inst. of Tech., Cambridge, MA (United States). Plasma Fusion Center; Oak Ridge Inst. for Science and Education, TN (United States)
• Sponsoring Organization: USDOE, Washington, DC (United States)
• DOE Contract Number: FC02-93ER54186; AC05-76OR00033
• OSTI ID: 10190603
• Report Number(s): DOE/ER/54186--T5; PFC/RR--94-6; ON: DE95001820; BR: 35AT15000/AT1500000
• Country of Publication: United States
• Language: English

Related Subjects

665412
70 PLASMA PHYSICS AND FUSION TECHNOLOGY
700430
700480
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
COMPONENT DEVELOPMENT
CURRENT DENSITY
DISTRIBUTION
MAGNET COILS AND FIELDS
MATERIALS STUDIES
MATHEMATICAL MODELS
NUMERICAL ANALYSIS
SUPERCONDUCTING CABLES
SUPERCONDUCTING DEVICES
SUPERCONDUCTING MAGNETS
TOKAMAK DEVICES