Metal working – Method of mechanical manufacture – Electrical device making
Patent
1988-12-05
1991-01-08
Gorski, Joseph M.
Metal working
Method of mechanical manufacture
Electrical device making
428614, 428930, H01L 3924
Patent
active
049824970
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a process for manufacture of a superconductor from a niobium-titanium-tin (sic) or similar filament as conductor core and a sheath surrounding the latter as a stabilizer, which is extruded through the molding cross-section of a die from an aluminum billet which is preferably composed of high purity aluminum.
Superconductivity describes the physical effect that the electrical resistance of certain metals can become zero at temperatures close to absolute zero (-273.degree. C.).
Superconductors are used in metrology, for example for measuring weak magnetic fields and currents and also in computer engineering for superfast stores and logic units. More significant are the fields of application for producing strong magnetic fields, for example for large magnets for nuclear power stations, magnetic levitation railways, particle accelerators, and furthermore for superconducting coils, superconducting cables for loss-free energy transmission, superconducting generators for generating energy or superconducting transformers and energy stores.
Thin filaments (30 to 50 .mu.m diam.) of niobium-titanium or niobium-tin which are normally embedded in a copper wire serve as superconductors. Depending on the application, this wire is sheathed individually or stranded to form a bundle with high purity aluminum which serves as a stabilizer.
Interference in the magnetic field may interrupt the superconductivity for a short time. The stabilizer of high purity aluminum (purity 9.99 (sic) to 99.999%) then has to take over the current for a short time. Aluminum is better suited for this purpose than copper because it has only about 10% of the electrical resistance of copper at 4.2 K.
In the course of the years, increasingly stronger magnetic fields, for example for particle acceleration in nuclear research, were employed. The harmonics, i.e. the variations with time, of these magnetic fields produce eddy currents in the stabilizer of high purity aluminum which generate heat in an undesirable manner and interrupt the superconductivity of the niobium-titanium or niobium-tin filaments. Although it was hitherto possible in the case of fairly low magnetic fields to compensate for the heat generation of the eddy currents by more intense helium cooling, this is no longer possible for very intense magnetic fields.
A process of the type mentioned in the introduction is known from German Patent Specification No. 3,245,903. In that case a conductor core of niobium-titanium or Nb.sub.3 Sn is present which is embedded in a primary stabilizer of high purity copper or high purity aluminum The primary stabilizer is directly surrounded by a secondary stabilizer which is composed of super pure aluminum. Cooling channels through which liquid or boiling helium under pressure is passed during operation are provided on both sides of the conductor core in the extruded profile body of the secondary stabilizer.
The object therefore exists of improving a process of the type mentioned in the introduction for manufacture of a superconductor so that the eddy currents produced in the aluminum stabilizer are kept so low even in the region of very intense magnetic fields that the heat generated by the eddy currents can be removed fast enough, possibly by the helium cooling, but at any rate is so low that the superconductivity is not impaired.
In achieving this object, the invention proceeds from the knowledge that it is necessary to reduce the eddy currents produced in the aluminum sheath employed as stabilizer.
This object is achieved by employing an aluminum billet with structures, extending coaxially to its longitudinal axis and composed of low conductivity material, in the form of cross-sectionally distributed layers, ribbon-like strips or closely spaced longitudinal individual filaments or individual fibers or fiber bundles and extruding it to form a superconductor with markedly reduced electrical conductivity perpendicular to the longitudinal axis of the conductor as a result of the coaxially extending structures embedded in the alu
REFERENCES:
patent: H39 (1986-03-01), Gubser et al.
patent: 3158792 (1964-11-01), Swartz et al.
patent: 3469952 (1969-09-01), Baker
patent: 3576670 (1971-04-01), Hammond
patent: 4285120 (1981-08-01), Nomura et al.
Gorski Joseph M.
Swiss Aluminium Ltd.
LandOfFree
Process for manufacture of a superconductor does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Process for manufacture of a superconductor, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Process for manufacture of a superconductor will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-926159