Theory of flux-line cutting and the critical state in type-II superconductors

Technical Report · Mon Jul 01 04:00:00 EDT 1985

OSTI ID:5296006

Perez-Gonzalez, A

A general critical-state theory, which includes both flux pinning and flux-line cutting, is presented. The electromagnetic response of a type-II superconducting slab subjected to a parallel, constant magnetic field whose direction undergoes either continuous rotation or periodic oscillation is investigated. Vector B, vector J, and vector E field distributions during the approach to quasi-steady state of a slab subjected to a parallel rotating magnetic field are calculated. It is shown that, regardless of the specimen's magnetic history, flux-line-cutting B-consumption leds to a final state in which B has a diamagnetic profile near the surface of the specimen. Hysteretic losses in samples subjected to an oscillating magnetic field oriented at an arbitrary angle with respect to a bias field, both fields being parallel to the surface, are discussed. Analytic expressions for the ac losses are obtained for the case that the amplitude of the oscillating field is small compared with the bias field. The calculations are generalized for the case of arbitrary B dependence of the parameters of the theory, and for arbitrarily large amplitude of the ac field. Numerical solutions to the equations describing the theory are presented.

• Research Organization: Ames Lab., IA (USA)
• DOE Contract Number: W-7405-ENG-82
• OSTI ID: 5296006
• Report Number(s): IS-T-1181; ON: DE85017347
• Country of Publication: United States
• Language: English

Related Subjects

656102* -- Solid State Physics-- Superconductivity-- Acoustic
Electronic
Magnetic
Optical
& Thermal Phenomena-- (-1987)
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
CURRENT DENSITY
ELECTRIC FIELDS
HYSTERESIS
MAGNETIC FIELDS
MAGNETIC FLUX
MATHEMATICAL MODELS
SUPERCONDUCTORS
TYPE-II SUPERCONDUCTORS