Computation of superconductor critical current densities and magnetization curves

Conference · Mon Jan 01 04:00:00 EST 1990

DOI:https://doi.org/10.1063/1.348222· OSTI ID:6632186

Hodgdon, M L

Using a constitutive law for superconductor hysteresis and the ideas of the critical state model, a system of equations is developed for the critical current density J{sub c}, the equilibrium magnetization M{sub e}, the upper and lower portions, M{sub U} and M{sub L}, of the major hysteresis loop, and their derivatives with respect to the applied field. The constitutive law consists of a differential equation relating the time rate of change of the flux density B to that of the applied field, {dot B} = {alpha}(H){vert bar}{dot H}{vert bar}(f(H) {minus} B) + {dot H}g(H), and a rule governing the abrupt changes observed at the turning points of H. For the case presented here in which f, g, and {alpha} have analytic forms, the constitutive law yields an easily differentiable expression for the major loop. Hysteresis curves computed from this constitutive law are shown to be in good agreement with experiments. Calculations of the critical current densities and equilibrium magnetization for the case in which the derivatives are neglected, i.e., the Bean model with J{sub c} {proportional to} M{sub U} {minus} M{sub L} and M{sub e} {proportional to} M{sub U} + M{sub L}, are compared with J{sub c} and M{sub e} computed using a system of equations that takes into account the first two derivatives of all quantities. Exponential approximations are given for the critical current densities of several samples of Y--Ba--Cu--O at temperatures between 5 K and 60 K. 7 refs., 4 figs., 1 tab.

• Research Organization: Los Alamos National Lab., NM (USA)
• Sponsoring Organization: DOE/AD
• DOE Contract Number: W-7405-ENG-36
• OSTI ID: 6632186
• Report Number(s): LA-UR-90-2708; CONF-901004--2; ON: DE90016567
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360204 -- Ceramics
Cermets
& Refractories-- Physical Properties
656100* -- Condensed Matter Physics-- Superconductivity
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ALKALINE EARTH METAL COMPOUNDS
BARIUM COMPOUNDS
CHALCOGENIDES
COPPER COMPOUNDS
COPPER OXIDES
CRITICAL CURRENT
CURRENT DENSITY
CURRENTS
DIFFERENTIAL EQUATIONS
ELECTRIC CURRENTS
EQUATIONS
HIGH-TC SUPERCONDUCTORS
HYSTERESIS
MAGNETIC FIELDS
MAGNETIZATION
OXIDES
OXYGEN COMPOUNDS
SUPERCONDUCTORS
TEMPERATURE DEPENDENCE
TRANSITION ELEMENT COMPOUNDS
YTTRIUM COMPOUNDS