Sudden Discharging and Overcurrent Simulations of REBCO Coils Coated With Conductive Epoxy Resin

Mato, Takanobu; Noguchi, So

doi:10.1109/tasc.2021.3057839

Cited by 6 publications

(1 citation statement)

References 17 publications

(22 reference statements)

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“…Therefore, the propagation velocity in the axial direction was low, unlike the case of ρ ct = 10 000 µΩ cm 2 . Incidentally, a similar discussion has been published for a NI REBCO pancake using conductive epoxy resin in [42]. The behaviour of a bypass current along the axial direction, which is related to the ratio between R ct and R sht , as described in figure 22, is similar to the acceleration mechanism of the normal zone propagation velocity of an REBCO conductor with an increased interfacial resistance between the superconducting layer and the stabilizer [43,44].…”

Section: Effects Of Lower Contact Resistivity On the Quench Propagati...mentioning

confidence: 53%

Quench and self-protecting behaviour of an intra-layer no-insulation (LNI) REBCO coil at 31.4 T

Suetomi

Yoshida

Takahashi

et al. 2021

Supercond. Sci. Technol.

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This paper presents experimental results on a quench of an intra-layer no-insulation (LNI) (RE: rare earth)Ba2Cu3O7−δ (REBCO) coil in a 31.4 T central magnetic field and simulated results on the quench. We have been designing a persistent-mode 1.3 GHz (30.5 T) nuclear magnetic resonance (NMR) magnet with a layer-wound REBCO inner coil. Protection of the REBCO coil from quench is a significant issue and the coil employs the LNI method to obtain self-protecting characteristics. We conducted high-field generation and quench experiments on an LNI-REBCO coil connected to an insulated Bi2Sr2Ca2Cu3O x (Bi-2223) coil under a background magnetic field of 17.2 T as a model of the 1.3 GHz NMR magnet. The coils successfully generated a central magnetic field of 31.4 T. Although the LNI-REBCO coil quenched at 31.4 T, this quench did not cause any degradation to the coil. A numerical simulation showed the current distribution during the quench was non-uniform and changed rapidly over time due to current bypassing through copper sheets between layers, resulting in faster quench propagation than in an insulated REBCO coil. During the quench propagation, the peak temperature (T peak) and the peak hoop stress BzJR (σθ, peak) were calculated to be 330 K and 718 MPa, respectively. These are below critical values that cause degradation. The simulation also showed that the high electrical contact resistivity (ρ ct) of 10 000 µΩ cm2, between REBCO conductors and copper sheets in the LNI-REBCO coil winding, played an important role in protection. When ρ ct was as low as 70 µΩ cm2, the quench propagation became too fast and large additional currents were induced, resulting in an extremely high σθ, peak of 1398 MPa, while the T peak was as low as 75 K. In short, the high ρ ct in the present coil caused a high T peak, but succeeded in suppressing σθ, peak and protecting the coil from the quench.

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Section: Effects Of Lower Contact Resistivity On the Quench Propagati...mentioning

confidence: 53%

Quench and self-protecting behaviour of an intra-layer no-insulation (LNI) REBCO coil at 31.4 T

Suetomi

Yoshida

Takahashi

et al. 2021

Supercond. Sci. Technol.

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Interface properties and failures of REBCO coated conductor tapes: Research progress and challenges

Gao,

Zhang,

Wang

et al. 2023

Superconductivity

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Investigation into accuracy of turn-to-turn contact resistance measurement in low-frequency AC method by 3D numerical simulation

Mato¹,

Inoue²,

Ueda³

et al. 2022

Supercond. Sci. Technol.

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In this paper, we discuss two points: (1) the measurement accuracy of a contact resistance by the Low-Frequency AC (LFAC) method and (2) the relation between the contact resistance and the contact resistivity. The LFAC method is a method to measure the turn-to-turn contact resistance of no-insulation (NI) Rare-Earth Barium Copper Oxide (REBCO) pancake coil. We have previously shown the validity of LFAC method by experiments. In this paper, the current distribution of an NI REBCO pancake coil at applying LFAC method is investigated using numerical simulation. The simulation results show the possibility to improve the measurement accuracy. Hence, a correction method is also proposed using the phase difference of the coil voltage and current. The LFAC simulation results also indicate the inconsistency of the well-known relation of the contact resistance and the contact resistivity. Therefore, we investigated the relation through the LFAC and the sudden-discharging test simulations.

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Sudden Discharging and Overcurrent Simulations of REBCO Coils Coated With Conductive Epoxy Resin

Cited by 6 publications

References 17 publications

Quench and self-protecting behaviour of an intra-layer no-insulation (LNI) REBCO coil at 31.4 T

Quench and self-protecting behaviour of an intra-layer no-insulation (LNI) REBCO coil at 31.4 T

Interface properties and failures of REBCO coated conductor tapes: Research progress and challenges

Investigation into accuracy of turn-to-turn contact resistance measurement in low-frequency AC method by 3D numerical simulation

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