Sumitomo Electric Industries, Limited

The Tokyo Electric Power Company, Incorporated

Kabushiki Kaisha Toshiba

Other

Toyo Boseki Kabushiki Kaisha

Toshiba Corporation

The Toyko Electric Power Company, Incorporated

Tsukushi Hara

Noriyuki Yoshida

Satoshi Takano

Hideo Ishii

Shigeru Okuda

Takahiko Yamamoto

Kiyoshi Okaniwa

Noriki Hayashi

Kousou Fujino

Kenichi Sato

Jun Fujikami

Kazuyuki Tsurunaga

Takeshi Ohkuma

Daisuke Ito

Nobuhiro Shibuta

Takamitsu Tada

Yoshihisa Masuda

Toshihiro Kashima

Hideaki Maeda

Masahiko Nakade

Takashi Yazawa

Kenji Tasaki

Eriko Yoneda

Shunji Nomura

Atsuhiko Yamanaka

Mitsuhito Sawamura

Provided is an insulated oxide superconducting cable conductor having a high critical current and a high critical current density. The insulated oxide superconducting cable conductor comprises an elongated former, a plurality of tape-shaped multifilamentary oxide superconducting wires which are wound on the former at a bending strain factor of not more than 0.5%, and a spirally wound tape-shaped insulating material covering the tape-shaped multifilamentary oxide superconducting wires. The tape-shaped multifilamentary superconducting wires are superposed on the former in layers, whereby stabilizing materials of the superposed superconducting wires are in contact with each other. The tape-shaped insulating material consists essentially of a material which is contracted at a thermal contraction rate of at least three times that of the tape-shaped multifilamentary wires by cooling from a temperature of 298 K to that of 77 K. The tape-shaped insulating material can apply a pressure to the superposed multifilamentary superconducting wires toward the former while improving electrical contact between the superposed multifilamentary superconducting wires by cooling in employment. The former can be formed of a flexible tube.

High TC superconducting cable conductor employing oxide superconductor

Provided is an oxide superconducting conductor consisting of a plurality of metal-covered multifilamentary superconducting wires which are assembled with each other. Bending is applied to the superconducting conductor for improving its critical current density. It is possible to obtain a compact superconducting conductor having higher capacity, since its critical current density is increased by such application of bending.

Method of preparing an oxide superconducting conductor

In order to provide a flexible oxide superconducting cable conductor which is reduced in ac loss, tape-shaped multifilamentary superconducting wires covered with a stabilizing metal are spirally wound on a flexible former. Each of the multifilamentary superconducting wires has a plurality of filaments. The filament contains an oxide superconductor. The superconducting wires are preferably wound on the former at a bending strain of not more than 0.3 %. In winding on the former, a prescribed number of tape-shaped multifilamentary superconducting wires are wound on a core member in a side-by-side manner, to form a first layer. Then, an insulating layer is provided on the first layer. This insulating layer can be formed by an insulating tape. A prescribed number of tape-shaped superconducting multifilamentary wires are wound on the insulating layer in a side-by-side manner, to form a second layer. The insulating layer is adapted to reduce ac loss of the conductors. When the former is made of a metal, it is more preferable to provide an insulating layer between the former and the multifilamentary superconducting wires.

Superconducting cable conductor

A bobbin for superconducting coils, which is made of a fiber-reinforced plastic material containing: (1) a matrix resin; (2) a polyethylene fiber having a negative thermal expansion coefficient in the fiber lengthwise direction, the angle between the polyethylene fiber and the longitudinal axis of the bobbin being in the range of .+-.35.degree. to 90.degree.; and (3) a substance having an elastic modulus higher than that of the polyethylene fiber. The bobbin of the present invention is useful for superconducting coils because it only exhibits a quite low degree of deformation, even when used under external stress at cryogenic temperatures.

Bobbin for superconducting coils

A current limiter having a plurality of current limiting units provided for electric paths constituting a plurality of phases. Each current limiting unit is constituted by a superconducting coil functioning as a first current limiting element formed in a non-inductive winding manner by connecting two superconducting coils in series, which superconducting coils are wound in opposite directions and equal in size and number of turns, and a superconducting coil functioning as a second current limiting element connected in parallel to the first current limiting element and having a predetermined impedance value. These current limiting units are contained within a cryostat and separated by a magnetic shield member for electromagnetically isolating the respective phases.

Superconducting fault current limiter

A thin film strongly orienting specific crystal axes is deposited on a polycrystalline or amorphous base material in accordance with laser deposition in a simpler device through a simpler process. A target is irradiated with a laser beam, for forming a thin film in accordance with laser ablation of depositing a substance scattered from the target on a base material. In order to form the thin film, prepared are conditions capable of forming a film orienting a specific crystal axis substantially perpendicularly to the base material in substantially parallel arrangement of the target and the base material. Under the conditions, a film is deposited on the base material which is inclined at a prescribed angle .theta. with respect to the target. It is possible to deposit a film strongly orienting a specific crystal axis in a plane substantially parallel to the base material surface by inclining the base material under the specific film forming conditions.

Method of forming single-crystalline thin film

Disclosed herein is an apparatus for manufacturing an oxide superconducting film employing laser ablation method. This apparatus has a thin film forming chamber having a laser-transparent laser entrance window, a target being provided in the thin film forming chamber and containing components of an oxide superconductor, a laser beam source for irradiating the target with a laser beam from the exterior of the thin film forming chamber through the laser entrance window, and apparatus for controlling power of the laser beam which is applied to the target for preventing the power of the laser beam, being applied to the target, from reduction by contamination of the entrance window caused by scattered particles. According to the present invention, it is possible to form an oxide superconducting film having high and uniform characteristics even if a long time is required for film formation, thereby attaining a remarkable effect in improvement of superconductivity of a large area oxide superconducting film.

Oxide superconducting film manufacturing apparatus

An apparatus for manufacturing an oxide superconducting film employing laser ablation method having a thin film forming chamber having a laser-transparent laser entrance window, a target being provided in the thin film forming chamber and containing components of an oxide superconductor, a laser beam source for irradiating the target with a laser beam from the exterior of the thin film forming chamber through the laser entrance window, and a controller for controlling power of the laser beam which is applied to the target for preventing the power of the laser beam, being applied to the target, from reduction by contamination of the entrance window caused by scattered particles. According to the present invention, it is possible to form an oxide superconducting film having high and uniform characteristics even if a long time is required for film formation, thereby attaining a remarkable effect in improvement of superconductivity of a large area oxide superconducting film.

A superconducting current limiting device for limiting overcurrent flowing in a load. The device includes a current limiter with a first superconducting coil, a second superconducting coil arranged coaxially with the first superconducting coil so as to have a negative magnetic coupling condition, and a third superconducting coil arranged coaxially with the first and second superconducting coils so as to have a negative magnetic coupling condition with the second superconducting coil and so as to have a positive magnetic coupling condition with the first superconducting coil. The first and second superconducting coils are electrically connected in series. The device includes a high speed switch connected electrically in series with the third superconducting coil to form a series circuit. The series circuit is electrically connected in parallel with the second superconducting coil. The device further includes a current monitoring circuit for monitoring current flowing in the load and for generating a signal so as to close the high speed switch when the current flowing in the load exceeds a prescribed value.

Superconducting current limiting device

Disclosed herein is a method of forming a single-crystalline thin film having excellent crystallinity on a base material without depending on the material for and crystallinity of the base material. In this method, a base material is provided thereon with a mask which can prevent chemical species contained in a vapor phase from adhering to the base material. The base material is continuously moved along arrow A, to deliver a portion covered with the mask into the vapor phase for crystal growth. Thus, a thin film is successively deposited on the portion of the base material, which is delivered from under the mask, from the vapor phase. A crystal growth end is formed on a boundary region between a portion of the base material which is covered with the mask and that which is exposed to the vapor phase, so that a crystal having the same orientation as the growth end is grown on a portion of the base material newly exposed by the movement.

In a method of preparing an oxide superconducting thin film having a composition of Y-Ba-Cu-O, for example, using laser ablation, which comprises the steps of applying a laser beam to a target containing components of an oxide superconductive material and depositing particles, being thereby scattered from the target, on a substrate, the oxygen gas flow rate during film deposition is set to be at least 50 SCCM, the oxygen gas pressure during film deposition is set to be 10 to 1000 mTorr, the distance between a target 9 and a substrate 10 is set to be 40 to 100 mm, the temperature of the substrate 10 is set to be 600.degree. to 800.degree. C., the energy density of a laser beam 7 on the surface of the target 9 is set to be at least 1 J/cm.sup.2, and the laser pulse energy is set to be at least 10 mJ.

In-situ laser ablation method for forming oxide superconducting films

In order to enable formation of a smooth and dense oxide superconducting film with no clear appearance of grain boundaries in a fine structure even at a high film forming rate, a laser ablation method is employed to apply a laser beam 2 to a target 1 containing components of an oxide superconductive material and deposit particles, which are thus scattered from the target 1, on a substrate 3, while gaseous oxygen is supplied from a gaseous oxygen inlet 7 toward laser plasma 6, which is generated by the application of the laser beam 2.

Method of and apparatus for preparing oxide superconducting film

In order to enable formation of a smooth and dense oxide superconducting film with no clear appearance of grain boundaries in a fine structure even at a high film forming rate, a laser ablation method is employed to apply a laser beam 2 to a target 1 containing components of an oxide superconductive material and deposit particles, which are thus scattered from the target 1, on a substrate 3, while gaseous oxygen is supplied from a gaseous oxygen inlet 7 toward laser plume 6, which is generated by the application of the laser beam 2, and to a portion of the target irradiated with said laser.

Method of preparing oxide superconducting films by laser ablation

In order to prepare an elongated oxide superconducting material which exhibits a high critical current density, a tape-type substrate (7) of silver, for example, formed by unidirectional solidification is prepared and an excimer laser beam (9) is applied to target (8) of an oxide superconductor to deposit atoms and/or molecules being scattered from the target (8) on the substrate (7), thereby forming an oxide superconducting film on the substrate (7).

Laser ablation method of preparing oxide superconducting films on

In a superconducting AC (alternating current) current limiter, quenched trigger coil assembly is quickly recovered to the superconductive state by minimizing a loop current flowing through the trigger coil assembly. The superconducting AC current limiter comprises: a cylindrical core; a superconducting current limiting coil wound on the core, and inserted into an AC power transmission line, for limiting an overcurrent flowing through the AC power transmission line when a failure happens to occur therein; a superconducting trigger coil assembly coaxially wound inside the superconducting current limiting coil on the core, and magnetically coupled to the current limiting coil, for triggering current limiting operation by the current limiting coil when most of the overcurrent flows through the trigger coil assembly, the superconducting trigger coil assembly being arranged by first, second, third and fourth trigger coils in such a manner that the first trigger coil is series-connected to the fourth trigger coil thereby to constitute a first series trigger coil circuit, the second trigger coil is series-connected to the third trigger coil thereby to constitute a second series trigger coil circuit, the first and second series trigger coil circuits are connected in parallel with each other, one end of which is connected to one end of the superconducting current limiting coil and the other end of which is connected via a quenching switch to the other end of the current.

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Chofu, Japan

Tsukushi Hara