Analyses of Transient Behaviors of No-Insulation REBCO Pancake Coils During Sudden Discharging and Overcurrent

Wang, Tao; Noguchi, So; Wang, Xudong; Arakawa, Issei; Minami, Katsuhiko; Monma, Katsutoshi; Ishiyama, Atsushi; Hahn, Seungyong; Iwasa, Y.

doi:10.1109/tasc.2015.2393058

Cited by 168 publications

(96 citation statements)

References 7 publications

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“…Also as reported in [4], it is suggested that the NI coil can be used as a low-pass filter. Charging, discharging, and overcurrent behaviors of the NI coil are investigated by using a comprehensive equivalent NI coil circuit grid model [5][6][7][8].…”

Section: Introductionmentioning

confidence: 99%

An Experimental Investigation of the Transient Response of HTS Non-insulation Coil

Zhang

Kim

et al. 2016

J Supercond Nov Magn

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A single pancake coil without turn-to-turn insulation was tested in this paper to investigate the transient responses under different situations. We performed charging and discharging test, AC current test, and regional quench emulation test on the non-insulated (NI) coil. The experimental test results show a significant time delay for charging and discharging characteristics of NI coil and can be validated by a simple proposed equivalent electrical circuit. Under the AC operating current, the NI coil can bypass nearly all the AC current from the coil spiral path to the radial path such that it is not possible for NI coil to store or be affected by the AC magnet field. Additionally, while carrying AC current, the AC loss dissipation of NI coil is inversely proportional to the frequency of the AC operating current. When a regional quench occurs, the NI coil can bypass the current in the regional quench zone to avoid further temperature accumulated and protect the NI coil itself.

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Section: Introductionmentioning

confidence: 99%

An Experimental Investigation of the Transient Response of HTS Non-insulation Coil

Zhang

Kim

et al. 2016

J Supercond Nov Magn

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“…Insulated coils -in which the coil is either co-wound with an electrical insulator or the conductor itself has an insulator coating -suffer from stability issues and are prone to damage due to local defects. Non-insulated (NI) coils [4], where the HTS tapes are wound without turn-to-turn insulation, are also actively researched [5][6][7][8][9][10][11] as an alternative. One of the main benefits of such coils is their proven selfprotecting behavior [4,12,13] due alternative current paths via the turn-to-turn resistances.…”

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confidence: 99%

Fluorescent thermal imaging of a non-insulated pancake coil wound from high temperature superconductor tape

Gyuráki

Benkel

Schreiner

et al. 2019

Supercond. Sci. Technol.

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We have wound a 157-turn, non-insulated pancake coil with an outer diameter of 85 mm and we cooled it down to 77 K with a combination of conduction and gas cooling. Using high-speed fluorescent thermal imaging in combination with electrical measurements we have investigated the coil under load, including various ramping tests and over-current experiments. We have found found that the coil does not heat up measurably when being ramped to below its critical current. Two over-current experiments are presented, where in one case the coil recovered by itself and in another case a thermal runaway occurred. We have recorded heating in the bulk of the windings due to local defects, however the coil remained cryostable even during some over-critical conditions and heated only to about 82-85 K at certain positions. A thermal runaway was observed at the center, where the highest magnetic field and a resistive joint create a natural defect. The maximum temperature, ∼100 K, was reached only in the few innermost windings around the coil former.

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“…illustrates the equivalent circuit of NI single pancake coil. The NI coil is divided into N units, where N is the number of turns [18,19]. Each unit contains an inductance ∑ in series with the resistance .…”

Section: Establishment Of Fem-circuit Modelmentioning

confidence: 99%

Numerical Simulation of a No-Insulation BSCCO Toroidal Magnet Applied in Magnetic Confinement Fusion

Zhang

Tang

et al. 2018

Science and Technology of Nuclear Installations

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At present, the Tokamak has become a mainstream form of the magnetic confinement fusion device. The toroidal field (TF) magnet in the Tokamak system is required to generate a high-steady field to confine and shape the high temperature plasma. To secure high current density and high thermal stability, the no-insulation (NI) winding technique is used in the fabrication of the TF magnet. During plasma operation, heat is generated in the TF magnet caused by the interaction with central solenoid (CS) coils, poloidal field (PF) coils, and the plasma current. The heat generated in NI coils is complex owing to the existence of current flow between adjacent turns. Thus, it is necessary to calculate the thermal problems. Taking into consideration the effect of turn-to-turn contact resistance, this paper presents the thermal behavior of a NI toroidal magnet under different operating conditions. The NI toroidal magnet is composed of 10 double-pancake (DP) coils wound with BSCCO tapes. The analysis procedure combines the finite element method (FEM) with an equivalent circuit model. This analysis has applicability and practical directive to the design of cryogenic cooling system for NI toroidal magnet.

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Analyses of Transient Behaviors of No-Insulation REBCO Pancake Coils During Sudden Discharging and Overcurrent

Cited by 168 publications

References 7 publications

An Experimental Investigation of the Transient Response of HTS Non-insulation Coil

An Experimental Investigation of the Transient Response of HTS Non-insulation Coil

Fluorescent thermal imaging of a non-insulated pancake coil wound from high temperature superconductor tape

Numerical Simulation of a No-Insulation BSCCO Toroidal Magnet Applied in Magnetic Confinement Fusion

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