Kernforschungszentrum Karlsruhe Gmbh

Forschungszentrum Karlsruhe Gmbh

Wolfgang Schauer

Berthold Krevet

Fritz Wuchner

Milan Polak

Heinz-Peter Schiller

Kai Grube

Hans Reiner

A method and apparatus employs Hall probes for contactless, longitudinal and transversal homogeneity examination of a critical current density j.sub.c in a superconductor tape that is cooled to below a transition temperature T.sub.c. The cooled superconductor tape is pulled through an external, locally limited magnetic field that has a constant gradient and a fixed magnetic field axis. The magnetic field generated by a screening current induced in a region of the superconductor tape penetrated by the external magnetic field is scanned using a first Hall probe at a distance of a few tenths of millimeters to the superconductor tape. The external magnetic field outside of a field range of the induced persistent currents is measured with a second Hall probe. A compensated difference between the first and second Hall probe signals is used as a qualitative measure for a critical current density j.sub.c (x) and its longitudinal homogeneity which varies locally with respect to a longitudinal axis of the superconductor tape. The compensated difference is formed by adjusting a test difference between the two Hall probe signals to zero as a result of measuring the external magnetic field by both Hall probes in a dummy measurement conducted without the superconductor tape. A transverse homogeneity with a linear Hall probe array that is positioned crosswise to the longitudinal axis of the superconductor tape and extends broadside over the superconductor tape is measured after all Hall probes in the array have first been adjusted to zero with a signal from the second probe. Quantitative locally critical current densities are specified from the Hall probe signals by a resistive calibration obtained from a current-voltage measurement.

Method and measuring apparatus for a contactless longitudinal and

A process for the preparation of a compound material composed of a substrate and a metallic layer of a metastable or unstable phase strongly adhering to the substrate surface. This phase contains more than one elemental component, and is deposited onto the substrate from the gas or vapor phase. In this process:

Process for the preparation of superconducting compound materials

A process for the preparation of a compound material composed of a substrate and a metallic layer of a metastable or unstable phase strongly adhering to the substrate surface. This phase contains more than one elemental component, and is deposited onto the substrate from the gas or vapor phase. In this process: (a) the components used for formation of the metastable or unstable phase are very pure, having an impurity concentration of less than 100 ppm by weight; (b) during initial deposition of the layer, up to a thickness of about 5 to 20 nm, the mobility of the components on the substrate is reduced to promote germination; and (c) the components are subsequently deposited for the remainder of the layer up to the desired thickness, onto the substrate which is heated.

Growing community of inventors

Pfinztal, Germany

Wolfgang Schauer