Control of contact resistance by strand surface coating in 36-strand NbTi CICCs

Nijhuis, A.; Kate, H. Ten; Duchateau, J.L.; Decool, P.

doi:10.1016/s0011-2275(01)00037-6

Cited by 21 publications

(26 citation statements)

References 8 publications

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“…It can be noted that layer-to-layer R c for the CORC ® -Cu and CORC ® -Sn sample before heat treatment, are in the same order of magnitude and the difference in surface material does not strongly affect the R c . It may be expected that in analogy with the classical NbTi and Nb 3 Sn cabled conductors, in particular, when considering the effect of the heat treatment on the CORC ® -Sn R c , that the surface oxide layer is mostly determining the R c [30][31][32][33][34]. This means that a heat treatment or mechanical cycling [35] alter the R c significantly.…”

Section: Contact Resistance Of Corc ® -Sn Conductormentioning

confidence: 99%

AC loss and contact resistance in REBCO CORC^®, Roebel, and stacked tape cables

Yagotintsev¹,

Anvar²,

Gao³

et al. 2020

Supercond. Sci. Technol.

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Many high-temperature superconductor (HTS) applications require superconducting cables with high currents while operating in an alternating magnetic field. HTS cables should be composed of numerous superconducting tapes to achieve the required current capacity. Alternating current and magnetic fields cause AC losses in such cables and can provoke conductor instability. AC losses and contact resistances were measured of several cable designs based on commercially available REBCO tapes at the University of Twente. The AC loss was measured under identical conditions for eight REBCO conductors manufactured according to three types of cabling methods—CORC® (Conductor on Round Core), Roebel, and stacked tape, including a full-size REBCO CICC (cable in conduit conductor). The measurements were done at T = 4.2 K without transport current in a sinusoidal AC magnetic field of 0.4 T amplitude and frequencies from 5 to 55 mHz. The AC loss was measured simultaneously by calibrated gas flow calorimeter utilizing the helium boil-off method and by the magnetization method using pick-up coils. Also, the AC loss of two CORC® conductors and a Roebel cable was measured at 77 K. Each conductor was measured with and without background field of 1 T. The measured AC coupling loss in the CORC® and Roebel conductors is negligible at 4.2 K for the applied conditions while at 77 K coupling loss was observed for all conductors. The absence of coupling loss at 4.2 K can be explained by shielding of the conductor interior; this is confirmed with measurement and calculation of the penetration field of CORC® and Roebel cables. The inter-tape contact resistance was measured for CORC® and stacked tape samples at 4.2 and 77 K. It was demonstrated that a short heat treatment of CORC® conductor with solder-coated tapes activates tape-to-tape soldering and decreases the contact resistance. The reduction of contact resistance by two orders in magnitude to tens of nΩm is comparable with the interstrand contact resistance in ITER Nb3Sn type conductors.

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Section: Contact Resistance Of Corc ® -Sn Conductormentioning

confidence: 99%

AC loss and contact resistance in REBCO CORC^®, Roebel, and stacked tape cables

Yagotintsev¹,

Anvar²,

Gao³

et al. 2020

Supercond. Sci. Technol.

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“…A series of contact resistance measurements between strands in a triplet is performed in advance, as a function of the input current I up to 50 A, eventually 50 A is selected for the further measurements. Meanwhile, the applied magnetic field increases the average inter-strand resistance due to the magneto-resistance effect of the copper matrix [15], and B dc = 0.35 T is applied.…”

Section: Contact Resistance Measurement In Parallel Fieldmentioning

confidence: 99%

Contact resistance, coupling and hysteresis loss measurements of ITER poloidal field joint in parallel applied magnetic field

Huang

Ilyin

Wessel

et al. 2022

Supercond. Sci. Technol.

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The inter-strand contact resistance and AC losses were measured on an ITER PF Coil joint in a parallel applied AC magnetic field. In addition, the hysteresis loss was measured as a function of the angle with the applied magnetic field on a NbTi strand of the same type as in the joint with a Vibrating Sample Magnetometer (VSM). The AC loss measurements were performed at four applied field conditions for combinations of 0 or 1 T offset field and 0.2 or 0.4 T sinusoidal amplitude. The hysteresis loss of the joint was compared with the measured AC loss density of the NbTi strand for the same field conditions as the joint AC loss measurement but with varying the angle of the applied field. The subsequent cable twist angles affect the hysteresis loss since the critical current and penetration field depend on the angle of the applied field. It is found that 15.5° is an effective angle for the calculation of the hysteresis loss of joint when compared to the single strand measurement. The inter-strand contact resistance measurements cover all the typical strand combinations from the five cabling stages of the individual conductors, as well as the strand combinations across the two conductors to characterize the inter-strand including the copper sole resistivity. It’s the first time to measure the contact resistances and AC losses of the full-size ITER PF joint. By comparing the measured and simulated data in the JackPot-ACDC model, it’s also the first time to obtain the accurate inter-strand, inter-petal and strand to copper sole contact resistivities, which are the main input parameters for the further quantitative numerical analysis of the PF joints, in any current and magnetic field conditions.

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“…Just like twin-box joint, in the resistance calculation model of petals overlap joint, Figure 11(a) shows the current flows direction, the current is carried by superconducting filaments only in the cable, while the copper matrix, indium layers, silver layers, and copper soles carry the current together in the joint, thus the joint resistance consists of copper matrix resistances, indium layer resistances, silver layer resistances, copper sole resistances, and contact resistances. The filament-to-matrix contact resistances could be estimated by the comparison of simulation with experimental results in the Twente Press Experiment [27][28][29][30]. As shown in Figure 11(b),in the joint resistance calculation model, the two cables were equivalent to a homogeneous superconductor plus an equivalent resistance layer, the equivalent resistance layer represented the resistance of filament-to-matrix and copper matrix.…”

Section: The Joule Heating and Ac Losses Of Petal Overlap Jointmentioning

confidence: 99%

Some Research Method about Superconducting Magnet Systems of TOKAMAK

Rong¹

2022

Advances in Fusion Energy Research - From Theory to Models, Algorithms, and Applications

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The superconducting magnet operates in conditions of complex electromagnetics, which could cause hysteresis loss and coupling losses, the so-called AC losses. In this chapter, the AC losses calculation of superconductor will be discussed in detail. Usually, the superconducting magnets are wound by superconducting coils, which are twisted by superconducting wires. The length of superconducting wires is hundreds of meters, while the length of coils is millions of meters; thus, joints are needed to join the coils. The design of different patterns of joints, such as twin-box joint, butt joint, and petal overlap joint, will be introduced in detail. Joule heat and AC losses in the joint may cause locality quench, and if the design stability margin of the magnet could not cover the joule heat and losses, the locality quench will cause global quench of the magnet. The temperature rise caused by joule heat and AC losses will be discussed in detail. Furthermore, the magnetic Lorentz force and mechanical displacement could cause locality quench, which may cause a global quench, once the coolant could not take away the heating pulse. The simulation of the stability and quench behavior of the superconducting cable-in-conduit conductor will be introduced in detail.

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Control of contact resistance by strand surface coating in 36-strand NbTi CICCs

Cited by 21 publications

References 8 publications

AC loss and contact resistance in REBCO CORC^®, Roebel, and stacked tape cables

AC loss and contact resistance in REBCO CORC^®, Roebel, and stacked tape cables

Contact resistance, coupling and hysteresis loss measurements of ITER poloidal field joint in parallel applied magnetic field

Some Research Method about Superconducting Magnet Systems of TOKAMAK

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Control of contact resistance by strand surface coating in 36-strand NbTi CICCs

Cited by 21 publications

References 8 publications

AC loss and contact resistance in REBCO CORC®, Roebel, and stacked tape cables

AC loss and contact resistance in REBCO CORC®, Roebel, and stacked tape cables

Contact resistance, coupling and hysteresis loss measurements of ITER poloidal field joint in parallel applied magnetic field

Some Research Method about Superconducting Magnet Systems of TOKAMAK

Contact Info

Product

Resources

About

AC loss and contact resistance in REBCO CORC^®, Roebel, and stacked tape cables

AC loss and contact resistance in REBCO CORC^®, Roebel, and stacked tape cables