Interstrand Contact Resistance and Magnetization of ${\hbox {Nb}}_{3}{\hbox {Sn}}$ Rutherford Cables With Cores of Different Materials and Widths

Although the high-temperature superconducting (HTS) REBa 2 Cu 3 O x (REBCO, RE = rare earth elements) material has a strong potential to enable dipole magnetic fields above 20 T in future circular particle colliders, the magnet and conductor technology needs to be developed. As part of an ongoing development to address this need, here we report on our CORC ® canted cos θ magnet called C2 with a target dipole field of 3 T in a 65 mm aperture. The magnet was wound with 70 m of 3.8 mm diameter CORC ® wire on machined metal mandrels. The wire had 30 commercial REBCO tapes from SuperPower Inc., each 2 mm wide with a 30 µm thick substrate. The magnet generated a peak dipole field of 2.91 T at 6.290 kA, 4.2 K. The magnet could be consistently driven into the flux-flow regime with reproducible voltage rise at an engineering current density between 400 -550 A mm −2 , allowing reliable quench detection and magnet protection. The C2 magnet represents another successful step towards the development of high-field accelerator magnet and CORC ® conductor technologies. The test results highlighted two development needs: continue improving the performance and flexibility of CORC ® wires and develop the capability to identify locations of first onset of flux-flow voltage.

Section: Feedback On Corc ® Wire Developmentmentioning

confidence: 91%

Development and performance of a 2.9 Tesla dipole magnet using high-temperature superconducting CORC^® wires

Wang

Abraimov

Arbelaez

et al. 2020

“…The thermal stability of different designs of LTS Rutherford cables has been analysed by several groups [17][18][19][20][21][22], where the effect on quench characteristics of strand coating, individually insulated strands, contact resistance between strands, as well as the presence of a resistive core inside the cable (between the upper and lower layers of the cable) has been studied.…”

Section: Introductionmentioning

confidence: 99%

Quench dynamics in MgB₂Rutherford cables

Cubero

Navarro

Kòváč

et al. 2018

The generation and propagation of quench induced by a local heat disturbance or by overcurrents in MgB 2 Rutherford cables have been studied experimentally. The analysed cable is composed of 12 strands of monocore MgB 2 /Nb/Cu10Ni wire and has a transposition length of about 27 mm. Measurements of intra-and inter-strand voltages have been performed to analyse the superconducting-to-normal transition behaviour of these cables during quench. In case of external hot-spots, two different time-dynamic regimes have been observed, a slow stage for the formation of the minimum propagation zone (MPZ), and a fast dynamics once the quench is triggered and propagates to the rest of the cable. Significant local variations of the quench propagation velocity across the strands around the MPZ have been observed, but with average quench propagation velocities closely correlated with the predictions given by one-dimensionalgeometry models. For quench induced by overcurrents (i.e. with applied currents higher than the critical current) the nucleation of many normal zones distributed within the cable, which overlap during quench propagation, gives a distinctive and faster quench dynamics.

“…A possible reason of the discrepancy between theory (3), (4) and experiment is the fact that the field amplitude B m = 0.05 T is not high enough for achieving a fully penetrated state (figures 15 and 16) which is a condition of validity of equations ( 3) and ( 4). From published data on Rutherford cables [11,13] one can see that equations (3) (and ( 4)) fits the experimental data satisfactorily within the range of its applicability (the period of applied magnetic field is much larger than the time constant of the cable and magnetic field amplitude is well above the full penetration field). Based on this we conclude that equations ( 3), ( 4) can be used to estimate coupling loss and coupling magnetization of our Roebel cable in low frequency region (<46 Hz) and at sufficiently high magnetic fields.…”

Section: Coupling Magnetization and Lossmentioning

confidence: 56%

Inter-strand current sharing and ac loss measurements in superconducting YBCO Roebel cables

Majoroš

Sumption

Collings

et al. 2015

A Roebel cable, one twist pitch long, was modified from its as-received state by soldering copper strips between the strands to provide inter-strand connections enabling current sharing. Various DC transport currents (representing different percentages of its critical current) were applied to a single strand of such a modified cable at 77 K in a liquid nitrogen bath. Simultaneous monitoring of I–V curves in different parts of the strand as well as in its interconnections with other strands was made using a number of sensitive Keithley nanovoltmeters in combination with a multi-channel high-speed data acquisition card, all controlled via LabView software. Current sharing onset was observed at about 1.02 of strand Ic. At a strand current of 1.3Ic about 5% of the current was shared through the copper strip interconnections. A finite element method modeling was performed to estimate the inter-strand resistivities required to enable different levels of current sharing. The relative contributions of coupling and hysteretic magnetization (and loss) were compared, and for our cable and tape geometry, and at dB/dt = 1 T s−1, and our inter-strand resistance of 0.77 mΩ, (enabling a current sharing of 5% at 1.3Ic ) the coupling component was 0.32% of the hysteretic component. However, inter-strand contact resistance values of 100–1000 times smaller (close to those of NbTi and Nb3Sn based accelerator cables) would make the coupling components comparable in size to the hysteretic components.