Magnetic diffusion in high-Tc superconductors

Cha, Y.S.

doi:10.1016/s0921-4534(99)00584-5

Cited by 21 publications

(16 citation statements)

References 8 publications

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“…Three material systems have now been examined with shielding currents in the 10-40 kA range, and the results have been remarkably similar. The observed time constant for penetration in this case (3-4 ms) was shorter than the others, but this is probably due to the smaller size of the samples [12]. The high degree of uniformity among the samples in this study led to a more symmetric penetration process and more distinct and more easily observed changes in the magnetic field inside the ring.…”

Section: Comparison To Other Superconducting Rings and Conclusionmentioning

confidence: 52%

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: 52%

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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“…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%

“…Furthermore, thermal and magnetic diffusion is also important for the trapping of a magnetic field in a superconductor pellet that is using a pulsed current supply [4][5][6]. As pointed out by Cha [1], to model the coupled thermal and magnetic diffusion and understand how the magnetic field and temperature of the superconductor evolve during a transient, complete information on E(J,T) must be known, presumably from experimental measurement. However, such information is difficult to obtain because most researchers only measure the E/J characteristics at one or two temperatures (mostly at 77 K).…”

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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“…The magnetic field H measured by the Hall probe shows a time delay of about 15 ms between NI max and H max . This delay is the result of magnetic diffusion, as is explained in references [1][2][3]. As the excitation current is increased (Fig.…”

Section: Fig 7 (A) (002) and (B) (220) φ-Scans For Mgo Grown By E-bmentioning

confidence: 70%

Practical superconductor development for electrical applications - quarterly report for the period ending June 30, 2002.

Dorris¹

2002

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Magnetic diffusion in high-Tc superconductors

Cited by 21 publications

References 8 publications

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

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

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

Practical superconductor development for electrical applications - quarterly report for the period ending June 30, 2002.

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