AC Losses in Bi-2223 Composite Tapes

The self-field ac loss of a monofilamentary Bi-2223/Ag tape has been measured using an improved lock-in amplifier technique. To investigate t h e dependence of the ac power loss on t h e phase-angle error of the lock-in amplifier, theoretical calculations of the ac power loss of a flat superconducting strip in a perpendicular ac magnetic field were performed. The expressions derived also predict the dependence of the apparent loss on the size of t h e lead extension of the voltage contacts. For zero phase-angle error and an infinite lead extension the Norris formula is obtained. The voltage wave-form for ac current amplitudes greater than the tape's ciritcal current has been measured and calculated. Theoretical predictions agree well with t h e experimental data.

show abstract

“…where the derivative of the flux @ with respect to time is given by (4) x, is the size of the lead extension as indicated in Fig. 2.…”

Section: (3)mentioning

confidence: 99%

Self-field ac loss of Bi-2223 superconducting tapes

Müller

Leslie

1997

IEEE Trans. Appl. Supercond.

View full text Add to dashboard Cite

show abstract

“…Although Leghissa et al [1] have also measured losses showing hysteretic I 3 dependence in a two layer conductor, a factor of 3 difference between the measured and calculated losses was observed. Furthermore, the cubic current dependence has also been observed by Fujikami et al [9] in a two layer insulated conductor, though comparisons with a theoretical model were not included In contrast, for a two layer non-insulated conductor Gannon et al [8] have observed a I 2 loss dependence, whereas Mukoyama et al [7] find good agreement with theoretical predictions, though this is only achieved by homogenising current distribution with additional impedance insertion between the layers.…”

Section: Prototype Superconducting Cablementioning

confidence: 83%

“…where E ↓ (x, t) is given in (8). Since E ↓ (x, t) is an odd function k in (11) and (12) may be replaced by k = 2n + 1 where n ≥ 0.…”

Section: Elliptical Conductormentioning

confidence: 99%

“…The significance of these factors on the observed losses and how their influence was minimized for accurate and reproducible measurements is also detailed. There are currently several research groups in the World who are actively involved in AC loss measurements on prototype superconducting cables [1,[7][8][9]. The observed losses in the two layer prototype conductor discussed in this paper are also compared, in addition to theoretical models, with measurements reported by these groups.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Self-field AC Power Dissipation in High-Tc Superconducting Tapes and a Prototype Cable

Awan¹,

Sali²

2002

PIER

View full text Add to dashboard Cite

The measured self-field AC power dissipation in superconducting BiSrCaCuO-2223/Ag tapes and a prototype cable is cable is compared with theoretical models. A brief overview of the theoretical background for AC loss calculations in superconductor tapes with different geometrical shapes is also discussed. New models for the harmonic components of the fundamental frequency and the current dependent non-linear inductance are also derived. It is shown that the latter models can be used to estimate current distribution and the variation of flux penetration in superconducting tapes. Two separate experimental apparatus were designed and constructed for measurements on tapes and prototype cable systems. The observed losses in tapes are reasonably well described by models based on the Critical State Model (CSM). In contrast, the measured losses in the prototype cable are found to be a factor of approximately two higher the predicted values. Further investigations showed that this may be due to inhomogeneous contact resistance between individual tapes and the current joints and the variation in critical current density (J C) distribution between tapes. The significance of current dependence of the loss component, inductive quadrature component, phase error in measurements and the definition of the critical current in the prototype cable are also discussed.

show abstract

“…With alternating current hysteretic and eddy current losses occur resulting in a small but non-negligible effective AC resistance. For the HTS coil used in this demonstration this effective resistance was measured to be about one to two percent of the resistivity of comparable copper coils operating at liquid nitrogen temperatures (Gannon et al, 1993).…”

Section: Magnetostriction Demonstrationmentioning

confidence: 89%

Application of High Temperature Superconducting Wire to Magnetostrictive Transducers for Underwater Sonar

Joshi¹,

Lindberg²,

Clark³

1997

Naval Engineers Journal

View full text Add to dashboard Cite

A low‐frequency underwater acoustic transducer integrating high‐temperature superconducting (HTS) coils and terbium‐dysprosium (TbDy) magnetostrictive material was designed, fabricated and tested. This represents a novel application for high‐temperature superconductivity and is a first example of an integrated system involving HTS coils cooled by a mechanical cryocooler. It also brings HTS technology together with a novel magnetic materials technology. The HTS coils were fabricated using react‐and‐wind BiSrCaCuO‐2223 HTS wires. They produce a peak field of 0.1 Tesla at 50 K. A single‐stage, Stirling‐cycle cryocooler was used to cool the coils and the TbDy driver to cryogenic temperatures (50‐65K). The coils provide an AC magnetic field superimposed on a DC bias field, which produces oscillatory strain within the magnetostrictive rod; this motion is transmitted through a cryostat to two head masses which project sound into the surrounding environment. High power acoustic output can be obtained by operating the transducer at its resonance frequencies of 520 Hz in air and 430 Hz underwater. This development demonstrates that, unlike low temperature superconductors, HTS wires can be considered for AC applications due to the low losses in these superconductors and the higher heat capacities of materials at temperatures above liquid helium.

show abstract

AC Losses in Bi-2223 Composite Tapes

Cited by 10 publications

References 13 publications

Self-field ac loss of Bi-2223 superconducting tapes

Self-field ac loss of Bi-2223 superconducting tapes

Self-field AC Power Dissipation in High-Tc Superconducting Tapes and a Prototype Cable

Application of High Temperature Superconducting Wire to Magnetostrictive Transducers for Underwater Sonar

Contact Info

Product

Resources

About