US 3319206 A
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Description (OCR text may contain errors)
May 9, 1967 HANS-JOACH|M HARLOFF 3,319,206
TRANSFORMER FOR LOW TEMPERATURES Filed March 22, 1965 FIG.2
aY d i ATTYS.
United States Patent 9 Claims. Cl. 336-218) For the adaptation of signal lines leading from outside into a system operating at temperatures about the absolute zero point to supraconducting band lines affected with extremely low wave resistance, transformers are necessary. However, the usual transformer materials have, at low temperatures, such low initial permeabilities that they are no longer utilizable as transformer materials.
The basic problem of the invention is to provide a transformer, especially an impulse transformer, which is capable at very low temperatures of fulfilling all the demands to be made on a transformer. This is achieved through the feature that the core consists of at least one thin magnetic layer with single-axial preferential direction of the magnetization, which layer is magnetized by a constant magnetic field into the difficultly magnetizable direction, and in which the magnetization changes are utilized in the manner of the coherent rotation.
In the object of the invention there is utilized the concept that the anisotropic field strength of thin magnetic layers at low temperatures is only about twice as great as at room temperature. With the aid of a constant field acting in hard magnetization direction, which field has to be greater than the anisotropic field strength, the magnetization is turned into the hard direction. The permeability of the layer in the direction of easy magnetizability is then very high. Accordingly, these layers can be used for high frequency transformers.
Two advantageous examples of the invention will be explained with the aid of the drawings, in which:
FIG. 1 is a perspective view, with a portion broken away, of a cylindrical transformer construction; and
FIG. 2 is a perspective view of a transformer of fiat construction.
FIG. 1 illustrates a cylindrical form of transformer construction in which the magnetic layer is applied to a carrier body 1, preferably consisting of a supraconductive materail, which is traversed by a direct current. On it are coaxially disposed the primary winding 3 and the secondary winding 4. The entire system is surrounded by an outer cylindrical shell 2, the inner surface of which likewise carries a thin magnetic layer and which, like the magnetic layer applied to the carrier body 1, has an axial preferential direction. This outer magnetic layer serves as a return path for the magnetic flux components acting in axial direction. Thereby the demagnetization factor of the layers in axial direction remains small. In order to achieve as high as possible an efiiciency of these transformers an effort is made to raise the inductance. This is accomplished by using supraconductive material for the limitation of the magnetic scatter field. The cylinder 2 has, therefore, on its outer surface a layer of supraconducting material, so that all the magnetic fields remain substantially restricted to the interior space. The polarity of the secondary impulses can be reversed, in a known manner, by reversal of the flow direction of the direct current in the carrier body, if the body 1 carrying the inner magnetic layer is utilized as a secondary line.
FIG. 2 illustrates a transformer of fiat construction, which can be produced in especially simple form by utilizing vaporizing-on techniques. The reference numeral 1 designates the upper magnetic layer, 2 the secondary circuit, 3 the primary circuit, 4 the lower magnetic layer and 5 the carrier layer. The two supraconducting layers which terminate the system at the top and bottom have the designation S. In this arrangement, too, the supraconducting layers serve for the spatial limiting of the scatter field. A polarity reversal through the reversal of the constant field can be achieved when the secondary winding is arranged perpendicular to the primary circuit instead of parallel.
Changes may be made within the scope and spirit of the appended claims which define what is believed to be new and desired to have protected by Letters Patent.
1. A transformer, especially an impulse transformer, for use at temperatures near the absolute zero point, comprising at least one core and two windings, one of which forms a primary winding and the other a secondary winding, the core having at least one thin magnetic layer with monoaxial preferential direction of magnetization, which is magnetized by a contant magnetic field in the difficultly magnetizable direction whereby the magnetization changes can be utilized in the manner of the coherent rotation.
2. A transformer according to claim 1, wherein said core is in the form of a carrier body provided with a thin magnetizable layer on which body several wire windings are disposed, and a cylindrical shell, having a thin magnetizable layer on its inner surface, surrounding said body and windings.
3. A transformer according to claim 2, wherein the material of the thin magnetic layer of a cylindrical shell possesses an axial preferential direction.
4. A transformer according to claim 2, wherein the carrier body and the surrounding cylindrical shell consist of supraconducting material.
5. A transformer according to claim 3, wherein at least the surrounding cylindrical shell carries an outer supraconducting layer.
6. A transformer according to claim 1, wherein the two windings consist of a respective fiat conductor, and the core of the transformer comprises two flat thin magnetic layers, between which the two flat conductors are disposed.
7. A transformer according to claim 6, wherein supraconducting layers are disposed exteriorly of the two thin magnetic layers.
8. A transformer according to claim 6, wherein the secondary conductor extends perpendicular to the primary conductor.
9. A transformer according to claim 7, wherein the secondary conductor extends perpendicular to the primary conductor.
References Cited by the Examiner UNITED STATES PATENTS 3,102,973 9/1963 Kunzler 317-158 3,210,707 10/1965 Constantakes 336-200 BERNARD A. GILHEANY, Primary Examiner.
G. HARRIS, JR., Assistant Examiner.