Stability of Bi-2223/Ag multifilamentary tapes with oxide barriers—a numerical simulation

Majoroš, M.; Glowacki, B.A.; Campbell, A.M.

doi:10.1016/s0921-4534(02)00933-4

Cited by 9 publications

(3 citation statements)

References 5 publications

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“…They were determined at and according to the results presented in [14], [15]. To calculate the temperature dependence of -value, a simple linear temperature approximation (7) was used. The latter allows one to understand the basic role of the temperature dependence of the -value based on this simple relationship.…”

Section: Resultsmentioning

confidence: 99%

Multi-Stable Static Resistive States of High-$T_{\rm c}$ Superconductors With Temperature-Decreasing Power Exponent of Their Voltage-Current Characteristic

Romanovskii

Watanabe²

2010

IEEE Trans. Appl. Supercond.

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The possible resistive states of high-c superconductor without the stabilizing matrix are investigated in the static approximation considering the temperature decreasing dependence of the power exponent ( -value) of its voltage-current characteristics. The analysis is performed for the superconductor placed in a constant external magnetic field at different operating temperature and cooling conditions. It is shown that the stable static resistive states may be observed in the high values of electric field and overheating. Multi-stable resistive modes may occur because of non-trivial changes in the differential resistivity of the superconductor. In the formation of these modes, the primary role plays the interconnected decrease of the critical current density and -value with increasing temperature of a superconductor. The existence of multi-stable resistive states must be taken into account when the stable regimes of high-c superconductors are analysed or the processes occurring in the high-c superconducting magnets during their transition into the normal state are investigated.Index Terms-High-c superconductor, multi-stable resistive state, over-critical regimes, voltage-current characteristic.

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Section: Resultsmentioning

confidence: 99%

Multi-Stable Static Resistive States of High-$T_{\rm c}$ Superconductors With Temperature-Decreasing Power Exponent of Their Voltage-Current Characteristic

Romanovskii

Watanabe²

2010

IEEE Trans. Appl. Supercond.

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“…This study is important for the development of magnetic systems. However, in this case, such numerical calculations are cumbersome and time-consuming because of the complexity of the computation models, which, as a rule, are based on the use of the finite element method (see, for example, [4][5][6]). Therefore, the analyses of the basic physical peculiarities and specific formation of stable and unstable thermo-electrodynamics states are difficult.…”

Section: Introductionmentioning

confidence: 99%

Current instability mechanisms in high-temperature superconductors cooled by liquid coolant

Romanovskii¹

2009

Supercond. Sci. Technol.

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The instability of the steady current state in high-temperature superconductors (Bi 2 Sr 2 CaCu 2 O 8 , Bi 2 Sr 2 Ca 2 Cu 3 O 8 and YBa 2 Cu 3 O 7 ) cooled by a liquid refrigerant (helium, hydrogen and nitrogen) is studied. It is shown that the mechanism of the current instability depends on the type of coolant. Firstly, the destruction of stable current states may occur after transition of the cooling conditions on the surface of the superconductor from the nucleate to film boiling regimes. This instability mechanism is more probable for superconductors cooled by liquid helium. Secondly, the current instability may occur due to the disruption of the stable formation of the voltage-current characteristic of a superconductor even in the nucleate boiling regime of cooling. Such regimes are most probable when liquid nitrogen cools the superconductor. The necessary criteria allowing one to determine the influence of the properties of superconductor and coolant on the current instability mechanism are formulated.

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“…For example, in [5][6][7] the quench processes were investigated using the normal zone propagation model. Numerical finite element simulations with the two-or three-dimensional approach were made in [8][9][10][11][12][13][14] to calculate the temperature and electric field generation inside HTS magnets. A theory based on the simple analytical solutions of the thermal runaway problem was formulated in [15][16][17][18][19], and some qualitative peculiarities of the thermal runaway phenomena were analysed.…”

Section: Introductionmentioning

confidence: 99%

Nonlinear approximation for limiting current-carrying capacity of Ag-sheathed Bi₂Sr₂CaCu₂O₈conductors

Romanovskii

Watanabe

2005

Supercond. Sci. Technol.

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The thermal runaway phenomenon in Ag/Bi 2 Sr 2 CaCu 2 O 8 composite conductors is studied for the nonlinear temperature and magnetic field dependences of their critical current density J c (T , B) and matrix resistivity ρ m (T , B) (nonlinear approximation). The influence of the applied magnetic field, heat transfer coefficient, matrix resistivity and volume fraction of the composite superconductor on the static thermal and electric states were investigated. The used model is based on steady heat and current balance equations. It allows us to investigate the non-isothermal voltage-current characteristic of composite superconductors, that roots the static description of their operating regimes and allows us to determine the limiting quantities of the thermal runaway parameters. It is found that there exist stable jumps of the electric field, current and temperature without the transition of the superconducting composite into the normal state. The presence of these static states is a result of the additional stable branches on the voltage-current characteristics, which appear according to the variation of the differential resistivity of a composite. The latter may have wide range fields due to the coupled thermo-magnetic and current-sharing mechanisms changing the quantities ∂ J c /∂ T and ∂ρ m /∂ T . This variation takes place when the applied magnetic field or operating parameters of a composite exceed some characteristic values. As a result, the non-monotonic temperature dependence of the Joule heat release will take place. Besides, it is shown that the stable voltage (without thermal runaway) may exist when the temperature of the Ag/Bi 2 Sr 2 CaCu 2 O 8 composite stably increases from the coolant temperature up to the critical temperature of a superconductor during current charging. The thermal runaway parameters as a function of the applied magnetic field are numerically derived accounting for the additional stable branches of the voltage-current characteristic.

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Stability of Bi-2223/Ag multifilamentary tapes with oxide barriers—a numerical simulation

Cited by 9 publications

References 5 publications

Multi-Stable Static Resistive States of High-$T_{\rm c}$ Superconductors With Temperature-Decreasing Power Exponent of Their Voltage-Current Characteristic

Multi-Stable Static Resistive States of High-$T_{\rm c}$ Superconductors With Temperature-Decreasing Power Exponent of Their Voltage-Current Characteristic

Current instability mechanisms in high-temperature superconductors cooled by liquid coolant

Nonlinear approximation for limiting current-carrying capacity of Ag-sheathed Bi₂Sr₂CaCu₂O₈conductors

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Stability of Bi-2223/Ag multifilamentary tapes with oxide barriers—a numerical simulation

Cited by 9 publications

References 5 publications

Multi-Stable Static Resistive States of High-$T_{\rm c}$ Superconductors With Temperature-Decreasing Power Exponent of Their Voltage-Current Characteristic

Multi-Stable Static Resistive States of High-$T_{\rm c}$ Superconductors With Temperature-Decreasing Power Exponent of Their Voltage-Current Characteristic

Current instability mechanisms in high-temperature superconductors cooled by liquid coolant

Nonlinear approximation for limiting current-carrying capacity of Ag-sheathed Bi2Sr2CaCu2O8conductors

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Product

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Nonlinear approximation for limiting current-carrying capacity of Ag-sheathed Bi₂Sr₂CaCu₂O₈conductors