Transient response of a high-temperature superconductor tube to pulsed magnetic fields

Cha, Y.S.; Askew, T.R.

doi:10.1016/s0921-4534(98)00191-9

Cited by 21 publications

(8 citation statements)

References 14 publications

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“…Earlier work of this type has examined larger, multidomain melt-processed YBCO rings [3] and melt-cast BSCCO tube structures [8]. Three material systems have now been examined with shielding currents in the 10-40 kA range, and the results have been remarkably similar.…”

Section: Comparison To Other Superconducting Rings and Conclusionmentioning

confidence: 91%

“…2. The drive coil consists of 75 turns of AWG 18 copper wire, and is driven by a capacitive-discharge pulsed current supply that is described elsewhere [8]. The integrated signal from a Rogowski coil is used in the conventional way [9,10] to calculate the sum of the current flowing in the drive coil and the induced current flowing around the superconducting ring.…”

Section: Methodsmentioning

confidence: 99%

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Transient response of single-domain Y-Ba-Cu-O rings to pulsed magnetic fields

Askew

Weber

Cha³

et al. 2003

IEEE Trans. Appl. Supercond.

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Abstract-Shielding current limits and magnetic diffusion characteristics have been measured at 77 K for a set of YBCO single-domain rings. These were fabricated from melt-textured cylindrical YBCO monoliths that were densified to nearly 100%, and then oriented from a single seed. The rings were surrounded by a drive coil that can, under pulse conditions, achieve applied magnetic fields in excess of 1 T and induce currents in excess of 50 kA.Simultaneous magnetic characterization with a Rogowski coil and Hall probe was used to determine the induced current in the sample and the magnetic field in the center of the sample. Magnetic fields trapped in the samples were mapped with a scanning Hall probe. When compared with similar measurements on multidomain c-axisoriented YBCO rings, the flux penetration is faster and more uniform around the circumference of the ring. The observed critical current density, 15,000 A/cm 2 at 77 K, is suitable for application in penetration-type fault current limiters. Separate measurements of the trapped magnetic field and critical current density in the rings are compared with results obtained by analysis of magnetic diffusion characteristics.

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Section: Comparison To Other Superconducting Rings and Conclusionmentioning

confidence: 91%

Section: Methodsmentioning

confidence: 99%

Transient response of single-domain Y-Ba-Cu-O rings to pulsed magnetic fields

Askew

Weber

Cha³

et al. 2003

IEEE Trans. Appl. Supercond.

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“…Furthermore, at 77 K, the specific heat of the high-T c superconductors can be two orders of magnitude larger than that of low-temperature superconductors at 4 K. For example, the volumetric specific heat of Nb 3 Sn at 6.2 K is 0.6 x 10 4 J/m 3 -K, whereas that of BSCCO-2212 at 77 K is 1.2 x 10 6 J/m 3 -K. Therefore, a high-T c superconductor will heat up much more slowly than a low-temperature superconductor for a similar amount of dissipation. These factors make the detection of magnetic relaxation [7] and magnetic diffusion [1][2][3] much easier in high-T c superconductors than in low-temperature superconductors.…”

Section: Magnetic Relaxationmentioning

confidence: 99%

“…To accurately determine the voltage drop across the fault current limiter during a fault, a complete map of E as a function of J and T must be known. Recently, Cha [1][2][3] reported that thermal and magnetic diffusion is the mechanism for field penetration of a superconductor tube when it is subjected to a pulsed magnetic field. Similarly, thermal and magnetic diffusion is important for the SSCR because it is based on the shielding capability of a superconductor tube.…”

Section: Introductionmentioning

confidence: 99%

An empirical correlation for E(J, T ) of a melt-cast-processed BSCCO-2212 superconductor under self field

Cha

2003

IEEE Trans. Appl. Supercond.

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Abstract-An empirical correlation is developed for the electrical field strength E(J,T) of a melt-cast processed BSCCO-2212 superconductor. The empirical correlation is based, in part, on the theory of magnetic relaxation and on experimental data at 77 and 87 K. It is developed for temperatures in the range between 77 and 92 K, which is the range of interest for practical devices such as the superconducting fault current limiters. The general form of the correlation may be applicable to other high-Tc superconductors.

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“…This temperature effect is well known, and one would expect that at temperatures below 74 K, the trapped field can be increased by using a larger applied field (a pulsed current larger than 500 A) to facilitate deeper penetration of the applied field into the superconductor. The physics of field penetration under transient conditions is rather complicated and involves the simultaneous propagation of a magnetic field and a temperature field into the superconductor in the radial direction [11][12][13].…”

Section: Resultsmentioning

confidence: 99%