[WBP2] Bulk, Assembled Conductors, AC Loss

[WBP2-17] Finite Element Analysis of Voltage Generation near Current Leads in High Temperature Superconducting Composite Conductors

*Riichiro Tashiro¹, Ginta Utsunomiya¹, Masayoshi Inoue¹ (1. FIT (Japan))

Keywords:

High Temperature Superconducting Composite Conductors,Current Distribution,Finite Element Analysis

High-temperature superconducting composite conductors consisting of REBa₂Cu₃O_y (REBCO) tapes and low-resistance materials (Cu, Al, etc.) for high-current devices are currently under development. However, localized heat generation near the current leads is one of the issues. Therefore, it is necessary to clarify the current and voltage distribution near the current leads in order to reduce heat generation. In this study, we created a composite conductor model consisting of a single REBCO tape and a 100 µm thick copper plate, and carried out finite element analysis to obtain the current-electric field (I-E) characteristics and heat generation at various positions of the composite conductor. I-E characteristics were obtained from 0.5 mm to 1.5 mm from the current leads. Linear resistance was observed in the low electric field region below the critical current (I_c = 81 A), and this result generally reproduced the experimental results. This is thought to reflect the flow of current into the superconducting layers through the copper plate soldered to the upper surface of the REBCO tape. Additionally, a comparison was made between the apparent value predicted from the I-E characteristics and the actual value derived from the current density distribution regarding the heat generation of the conductor at 60 A. The current diverted to the copper plate soldered to the upper surface of the REBCO tape accounted for approximately 0.004 % of the total, and the actual heat generation was approximately five orders of magnitude lower than the value predicted from the I-E characteristics. This result suggests that the heat generation in the conductor portion is not as high as predicted from the I-E characteristics and does not significantly affect the quench of the conductor. However, at the joint between the current leads and the conductor, heat generation was observed to be six to seven orders of magnitude higher than the actual heat generation of the conductor. This heat generation is attributed to the flow of current from the current leads to the conductor and is considered to contribute significantly to conductor quench. Detailed results will be discussed in the presentation.