Source: http://www.google.com/patents/US4920011?ie=ISO-8859-1
Timestamp: 2016-02-11 05:11:22
Document Index: 645744908

Matched Legal Cases: ['application No. 60', 'application No. 8101613', 'application No. 24254', 'application No. 62', 'application No. 562092', 'application No. 8806772', 'application No. 8803822']

Patent US4920011 - Magnetic field shield including a superconductive film - Google PatentsSearch Images Maps Play YouTube News Gmail Drive More »Sign inPatentsA magnetic field shield including a superconductive film characterized in that the magnetic field shield comprises a superconductive film layer constituted primarily of a mixed crystalline body of niobium nitride and titanium nitride laminated on a metal substrate, that the magnetic field further comprises...http://www.google.com/patents/US4920011?utm_source=gb-gplus-sharePatent US4920011 - Magnetic field shield including a superconductive filmAdvanced Patent SearchPublication numberUS4920011 APublication typeGrantApplication numberUS 07/260,604Publication dateApr 24, 1990Filing dateOct 20, 1988Priority dateFeb 9, 1988Fee statusPaidAlso published asCA1300253C, DE3833886A1, DE3833886C2Publication number07260604, 260604, US 4920011 A, US 4920011A, US-A-4920011, US4920011 A, US4920011AInventorsSouichi Ogawa, Takao Sugioka, Masaru InoueOriginal AssigneeOsaka Prefecture, Koatsu Gas Kogyo Co. Ltd.Export CitationBiBTeX, EndNote, RefManPatent Citations (5), Referenced by (21), Classifications (17), Legal Events (5) External Links: USPTO, USPTO Assignment, EspacenetMagnetic field shield including a superconductive film
US 4920011 AAbstract
A magnetic field shield including a superconductive film characterized in that the magnetic field shield comprises a superconductive film layer constituted primarily of a mixed crystalline body of niobium nitride and titanium nitride laminated on a metal substrate, that the magnetic field further comprises a nobium-titanium alloy layer or a metal film layer in the above lamination, that the magnetic field comprises a plurality of the above-mentioned layers, and that the magnetic field has a plurality of small holes passing through the layers in the direction of the thickness. The magnetic field shield of the present invention produces an excellent magnetic field shielding effect due to a superconductive characteristic peculiar to the superconductive film layer constituted primarily by a mixed crystalline body of niobium nitride and titanium nitride. The cooling effect of the metal substrate maintains the magnetic field shielding effect at a high level. In addition, due to the use of the niobium-titanium alloy layer, the magnetic field shield has high resistance against peeling, greatly increasing the practical usefulness of the magnetic field shield. In the case of the magnetic field shield with a plurality of the laminated layers, the cooling effect of the metal film layers included in the multiple layers stably maintains the magnetic field shielding effect of the superconductive film layers. In the case of the magnetic field shield with small holes, the electromagnetic shielding and cooling effects of the holes are added to further strengthen the magnetic field shielding effect.
1. A magnetic field shield including a superconductive film wherein said magnetic field shield comprises:a metal substrate of copper, aluminum, nickel, stainless steel, titanium, niobium or niobium-titanium alloy; a niobium-titanium alloy layer; and a superconductive film layer consisting essentially of a mixed crystalline body of niobium nitride and titanium nitride; wherein said niobium-titanium alloy layer and said superconductive film layer are laminated in that order on said metal substrate. 2. A magnetic field shield including a superconductive film wherein said magnetic field shield comprises:a metal substrate of copper, aluminum, nickel, stainless steel, titanium, niobium or niobium-titanium alloy; a niobium-titanium alloy layer; a superconductive film layer consisting essentially of mixed crystalline body of niobium nitride and titanium nitride; and another niobium-titanium alloy layer; wherein said layers are laminated in that order on said metal substrate. 3. A magnetic field shield including a superconductive film wherein said magnetic field shield comprises:a metal substrate of copper, aluminum, nickel, stainless steel, titanium, niobium or niobium-titanium alloy; and a plurality of laminated sandwiches each of which consists essentially of a niobium-titanium alloy layer, a superconductive film layer consisting essentially of a mixed crystalline body of niobium nitride and titanium nitride, and a metal layer in that order; wherein the upmost sandwich layer does not include said metal layer. 4. A magnetic field shield including a superconductive film wherein said magnetic field shield comprises:a metal substrate of copper, aluminum, nickel, stainless steel, titanium, niobium or niobium-titanium alloy; and a plurality of laminated sandwiches each of which consists essentially of a niobium-titanium alloy layer, a superconductive film layer consisting essentially of a mixed crystalline body of niobium nitride and titanium nitride; another niobium-titanium alloy layer; and a metal layer in that order; wherein the upmost sandwich layer does not include said metal layer. 5. A magnetic field shield including a superconductive film according to claim 1, 2, 3 or 4, wherein said shield has a plurality of small holes passing through in the direction of the thickness.
The inventors of the present invention carefully reviewed the fundamental characteristics of the above-mentioned second class superconductor and found that even a thin layer was able to deliver a superior magnetic field shielding effect by laminating a superconductive film, which is constituted primarily by a mixed crystalline body of niobium nitride and titanium nitride, on a metal substrate. It is therefore an object of the present invention to provide a novel magnetic field shield including a superconductive film. As described in Japanese patent application No. 60-024254, European patent application No. 8101613.7, U.S. patent application Ser. Nos. 142,282 and 139,604 and Canadian patent application No. 24254/1985, the inventors of the present invention previously found that a magnetic field shield comprising a plurality of superconductive film layers had a far greater shielding effect than a magnetic field shield having a single superconductive layer, even when these two types were the same in overall thickness. Based on this principle, the inventors provided a magnetic field shield including a superconductive film. By following the fundamental technical idea of the above-mentioned prior invention, the present invention provides a practically useful lamination structure having high resistance against peeling. In addition, as described in the Japanese patent application No. 62-068499, U.S. patent application Ser. No. 163,369, Canadian patent application No. 562092, U.K. patent application No. 8806772, French patent application No. 8803822 and West German patent application No. P 3809452.5, the inventors of the present invention proposed a magnetic field shield including a superconductive film, based on application of both the diamagnetic and electromagnetic shielding effects of a superconductive film. The inventors also found that an excellent magnetic field shielding effect were obtained by applying the idea of the present invention to the invention proposed above. The present invention provides a useful magnetic field shield including a superconductive film by incorporating the ideas of these prior inventions.
FIG. 1 is a vertical sectional view illustrating a fundamental example of a first embodiment of the magnetic field shield of the present invention.
The magnetic field shield including a superconductive film of the first embodiment of the present invention comprises a metal substrate 1 of copper, aluminum, nickel, stainless steel or niobium-titanium alloy and a superconductive film 2 constituted primarily by a mixed crystalline body of niobium and titanium nitride (hereafter referred to as NbN and TiN) and laminated on the metal substrate 1.
[I] Layers were laminated on a 40 μm thick titanium substrate with no holes as described below to form magnetic field shields. These magnetic field shields were put in an intense magnetic field and the maximum magnetic field shielding amounts were measured. The measurement results were listed on the tables below. The superconductive film layers were formed by the reactive sputtering method in the atmosphere of argon and nitrogen gases using the Nb-Ti alloy as a target as described above. The NbN.TiN mixed crystal body occupies 80 to 90 weight percent of the formed film. In the table below, *1 represents the thickness of the superconductive film layer and *2 represents the thickness of the Nb-Ti alloy.
TABLE 1______________________________________Example  Shield structure                  Maximum shieldingNo.      *1       Layers   amount (Tesla)______________________________________1        1        1        0.0602        5        1        0.2363        10       1        0.266______________________________________
The metal substrates heated at approximately 300� C. during the above-mentioned sputtering were compared with those not heated during the sputtering.
(3) Examples of the third embodiment
In the same way as described above, the metal substrates heated at approximately 300� C. during the above-mentioned sputtering were compared with those not heated during the sputtering.
(4) Examples of the fourth embodiment
TABLE 6______________________________________Example   Shield structure                    Maximum shieldingNo.       *2    *1       Layers                          amount (Tesla)______________________________________32        1     0.5      10    0.7933        1     0.5      30    2.2134        1     1        10    1.2035        2     0.5      20    2.06______________________________________
(5) Examples of the fifth embodiment
TABLE 7______________________________________Example  Shield structure  Maximum shieldingNo.    *2      *1    *2    Layers                            amount (Tesla)______________________________________36     1       0.5   1     20    1.9637     1       1     1     20    2.7038     2       0.5   2     20    2.90______________________________________
[II] Examples equipped with small holes
A plurality of small holes were provided in the above-mentioned magnetic field shields of the first to fifth embodiments and the maximum magnetic field shielding amounts of the shields were measured. The small holes were 2 mm in diameter and the areal porosity was 20%. Layers were laminated on the substrate.
(1) Examples of the first embodiment with small holes
TABLE 8______________________________________Example  Shield structure                  Maximum shieldingNo.      *1       Layers   amount (Tesla)______________________________________39       1        1        0.05540       5        1        0.26241       10       1        0.315______________________________________
(2) Examples of the second embodiment with small holes
TABLE 9______________________________________Example  Shield structure  Maximum shieldingNo.      *2        *1    Layers  amount (Tesla)______________________________________42       2         0.5   1       0.10043       2         1     1       0.13844       2         5     1       0.30745       10        0.5   1       0.14446       100       0.5   1       0.125______________________________________
(3) Examples of the third embodiment with small holes
TABLE 10______________________________________Example  Shield structure    Maximum shieldingNo.    *2     *1       *2    Layers                              amount (Tesla)______________________________________47     1      0.5      1     1     0.09448     2      0.5      2     1     0.14349     2      1        2     1     0.18050     10     1        10    1     0.23951     100    1        100   1     0.190______________________________________
(4) Examples of the fourth embodiment with small holes
TABLE 11______________________________________Example   Shield structure                    Maximum shieldingNo.       *2    *1       Layers                          amount (Tesla)______________________________________52        2     0.5      10    1.0053        2     0.5      30    3.0054        2     1        10    1.38______________________________________
(5) Examples of the fifth embodiment with small holes
TABLE 12______________________________________Example  Shield structure  Maximum shieldingNo.    *2      *1    *2    Layers                            amount (Tesla)______________________________________55     1       0.5   1     10    0.9456     1       0.5   1     30    2.8257     2       1     2     10    1.80______________________________________
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