Temperature of Bi-2223/Ag samples in the resistive section of I?V curves

Polák, M.; Kvitkovič, J.; Demenčík, E.; Janšák, L.; Mozola, P.

doi:10.1016/j.physc.2003.09.029

Cited by 16 publications

(12 citation statements)

References 3 publications

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“…Then, the thermal boundary conditions can be written as: (7) where is the convective heat transfer coefficient. In this liquid, the convective heat transfer coefficient is approximately 400 according to [7], [8]. In effect, we have to solve the following coupled problem: A finite difference method is used to do it.…”

Section: A Numerical Modelmentioning

confidence: 99%

AC Transport Losses Calculation in a Bi-2223 Current Lead Using Thermal Coupling With an Analytical Formula

Berger¹,

Lévêque²,

Netter³

et al. 2005

IEEE Trans. Appl. Supercond.

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Abstract-When a superconductor is fed with an alternating current, the temperature rise created by the losses tends to reduce the current carrying capacity. If the amplitude of the current exceeds the value of the critical current, then the losses become particularly high and the thermal heating considerable. In this paper, a numerical and an analytical model which allow to estimate AC transport losses are presented. These models, which use the expression of c ( ) and ( ), are available for any applied current (below and above c ). The results are compared and the validity of the analytical model is considered. Then, the analytical formula allows to easily obtain the thermoelectric balance point of the system, when the losses and the temperature do not vary any more. Moreover, a maximum value of the current transport, beyond which the balance point does not exist, is detected. Indeed, when this maximum value is exceeded, the system is not stable and, say, superconducting current leads may quench.Index Terms-AC losses, Bi-2223 current lead, over current, quench, temperature dependence.

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Section: A Numerical Modelmentioning

confidence: 99%

AC Transport Losses Calculation in a Bi-2223 Current Lead Using Thermal Coupling With an Analytical Formula

Berger¹,

Lévêque²,

Netter³

et al. 2005

IEEE Trans. Appl. Supercond.

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“…The heating of the coil is a complicated problem, as the heating and the heat evacuation from the various parts of the coil are different. As shown in [2], even in well cooled short samples of Bi-2223/Ag tapes in the resistive state considerable heating can be observed.…”

Section: Introductionmentioning

confidence: 88%

The effect of epoxy impregnation on the behaviour of a Bi-2223/Ag coil carrying DC or AC current

Polák¹,

Kvitkovič²,

Janšák³

et al. 2006

Supercond. Sci. Technol.

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We studied the behaviour of a superconducting coil consisting of three double pancake coils made of Bi-2223/Ag multifilamentary tape with high critical current, cooled by liquid nitrogen at atmospheric pressure. One double pancake coil located at one edge of the winding had a lower value of critical current than the other ones, as occurs in real coils quite often. We measured DC I -V curves of the complete coil and of all pancake coils and the temperature increase in several parts of the winding at various dI /dt. The coil impregnation resulted in larger heating of the coil. The critical currents of the individual pancakes after impregnation were reduced by 5% to 15% in comparison with the values measured before impregnation. The thermal runaway current was approximately two times larger than the coil critical currents defined by the mean value of the electric field 1 µV cm −1 . The values of safe operation currents are discussed. We also measured the dependence of AC losses and the coil temperature on the coil current with a frequency of 50 Hz. The contribution of the resistive losses in the double pancake coil with reduced critical current to the total AC losses of the whole coil was very small, which is very important for AC applications of Bi-2223/Ag tapes.

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“…In this liquid, the convective heat transfer coefficient is approximately 400 according to [4]. In axially symmetric problems the electric field and the current density have only a non-zero component in the direction, and .…”

Section: B Model Descriptionmentioning

confidence: 99%

“…The temperature change due to the heat generation is described by the heat diffusion equation: (4) where is the temperature, the density, the specific heat capacity, and the thermal conductivity.…”

Section: B Model Descriptionmentioning

confidence: 99%

Influence of Temperature and/or Field Dependences of the $E-J$ Power Law on Trapped Magnetic Field in Bulk YBaCuO

Berger¹,

Lévêque²,

Netter³

et al. 2007

IEEE Trans. Appl. Supercond.

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Temperature, current density and magnetic field distributions in YBCO bulk superconductor during a pulsed-field magnetization (PFM) process are calculated using the finite difference method. Simulations are based on the heat diffusion equation with account of the heat produced by flux motion, and Maxwell's equations. A power law with temperature and magnetic field dependent parameters is used to characterize the electromagnetic behavior of the superconducting material. We analyze how the stored magnetic energy depends on the temperature and field dependences of the power law.

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Temperature of Bi-2223/Ag samples in the resistive section of I?V curves

Cited by 16 publications

References 3 publications

AC Transport Losses Calculation in a Bi-2223 Current Lead Using Thermal Coupling With an Analytical Formula

AC Transport Losses Calculation in a Bi-2223 Current Lead Using Thermal Coupling With an Analytical Formula

The effect of epoxy impregnation on the behaviour of a Bi-2223/Ag coil carrying DC or AC current

Influence of Temperature and/or Field Dependences of the $E-J$ Power Law on Trapped Magnetic Field in Bulk YBaCuO

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