Magnetic behavior of current-carrying type-II superconducting cylinders
The theoretical magnetic behavior of current-carrying superconducting cylinders in the presence of applied axial fields is investigated. An attempt is made to systematize the complex behavior by carefully accounting for critical current, surface pinning, and surface pitch angle, and by stressing the importance of the magnetic history of the sample. A differential equation is developed relating the thermodynamic field H(B) to the cylinder radius rho. This equation, is readily integrated numerically using a Runge-Kutta technique. The resultant flux profiles are further integrated numerically to obtain the mean magnetization of the cylinder. Careful distinction is maintained between the magnetic flux density B and the magnetic field H inside the cylinder. Results are displayed using a phase-diagrammatic technique, which shows the relative amounts of axial and azimuthal field needed to produce a given field within the cylinder, as a function of the bulk pinning strength and the surface pitch angle. In order to incorporate the magnetic history of a sample, a pair of simultaneous differential equations is developed, relating the field H and time, and the radius rho and the time, in a quasistatic manner. When simultaneously integrated, these equations yield a flux profile H(rho) which accounts for any arbitrary variations in the current and axial field experienced by the sample in progressing from the virgin state to the final flux configuration, provided the surface magnetic field increases with time. This should enable certain laboratory sequences in the application of current and field to be modeled analytically.
- Research Organization:
- Ames Lab., Iowa (USA)
- DOE Contract Number:
- W-7405-ENG-82
- OSTI ID:
- 5223929
- Report Number(s):
- IS-T-751
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
Electronic
Magnetic
Optical
& Thermal Phenomena-- (-1987)
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
CRITICAL CURRENT
CURRENTS
CYLINDERS
DIAGRAMS
ELECTRIC CURRENTS
MAGNETIC FIELDS
MAGNETIC FLUX
MAGNETIC PROPERTIES
PHASE DIAGRAMS
PHYSICAL PROPERTIES
SUPERCONDUCTORS
TYPE-II SUPERCONDUCTORS