Vortex system dynamics and energy losses in a current-carrying 2D superconducting wafer
- PDF / 345,874 Bytes
- 11 Pages / 612 x 792 pts (letter) Page_size
- 48 Downloads / 144 Views
SORDER, AND PHASE TRANSITIONS IN CONDENSED SYSTEMS
Vortex System Dynamics and Energy Losses in a Current-Carrying 2D Superconducting Wafer D. S. Odintsov, I. A. Rudnev, and V. A. Kashurnikov Moscow Institute of Engineering Physics, Moscow, 115409 Russia e-mail: [email protected] Received December 16, 2005
Abstract—The dynamic processes occurring in the vortex system of a 2D superconducting wafer carrying transport current are investigated using the model of the vortex system of high-temperature superconductors. Calculations are performed by the Monte Carlo method. For the first time, the dynamics of magnetic field penetration in a current-carrying HTSC wafer is demonstrated and the energy losses associated with a change in transport current are calculated. It is shown that changes in the transport current amplitude and in the number of defects lead to a change in the energy liberation mechanism: hysteresis energy losses are replaced by the losses in the saturated layer. PACS numbers: 74.25.–q, 74.25.Qt, 74.25.Sv, 74.72.–h DOI: 10.1134/S1063776106070090
1. INTRODUCTION
The electromagnetic properties are usually analyzed in the Bean model [11] for the magnetic field distribution,
The ability of type II superconductors to carry currents with a density higher than in ordinary resistive conductors makes them promising materials for various electrical engineering applications. Not only low-temperature superconductors (such as NbTi or Nb3Sn) but also various classes of high-temperature superconductors (HTSCs) have found wide application. The most considerable advances were made with multiple-strand Bi2Sr2Ca2Cu3Ox samples in a silver matrix. For example, 1.5-km-long multiple-strand superconducting ribbons with a critical current density jc > 104 A/cm2 at T = 77 K in the intrinsic field of transport current can be manufactured even now [1].
4π dH ------- = ± ------ j c . c dx
(1)
In the framework of this model, contactless methods for determining critical current jc and its magnetic-field and temperature dependences have been developed; the static magnetization of a hard superconductor is calculated, as well as hysteresis loops and magnetizationreversal losses. However, a description based on the Bean model is obviously not always correct, which requires a more detailed theoretical analysis of transport properties of superconductors in a wide range of parameters to set the limits of applicability of phenomenological approaches that are conventionally used. In this study, the results of simulation of magnetization reversal by the field of intrinsic transport current of a 2D wafer with defects, which imitates the current channel in a multiple-strand HTSC ribbon, are reported for the first time in the framework of the model of the vortex system. The energy losses emerging in this case are calculated and the vortex density distributions in a current-carrying superconductor are described. The calculations are based on a method of numerical stochastic simulation (Monte Carlo method). The application of this approach in
Data Loading...
