MAGNETODYNAMICS OF SUPERCONDUCTORS.
Interim progress rept. 1 Aug 66-31 Jan 67,
UNION CARBIDE CORP INDIANAPOLIS IN LINDE DIV
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AC losses determined with a helium boil-off calorimeter qualitatively agree with those predicted from DC magnetization measurements for a number of niobium and niobium-zirconium superconducting samples. This is consistent with a hysteretic model of AC losses in Type II superconductors. Surface condition of the sample appears to significantly affect the magnitude of AC losses. Noibium of exceptional purity has been prepared by high temperature vacuum outgassing of electroplated niobium ribbons. The highest resistivity ratio achieved to date is 14,000, which represents an improvement in purity by more than a factor of 6 over that of niobium prepared by other methods. DC magnetization measurements indicate that AC losses at low magnetic fields are reduced as the purity is increased. Magnetic instabilities in Type II superconductors are strongly influenced by the quality of surface finish, the presence of a normal metal on the surface, and the motion of the superconductor within a magnetic field. Author
- Electricity and Magnetism
- Plasma Physics and Magnetohydrodynamics