Superconductor Technologies Inc.

Timothy W James

Robert B Hammond

Lincoln C Bourne

Jonathan Zanhong Sun

Michael M Eddy

William L Olson

Douglas J Scalapino

McDonald Robinson

Wallace Y Kunimoto

Boo J Nilsson

Julia S Fleming

A method of tuning a high temperature superconductor (HTS) resonator includes the steps of providing a HTS inductor and a HTS capacitor, the HTS capacitor being electrically connected to the HTS inductor. A tuning body is provided adjacent to the HTS inductor and the HTS capacitor. The relative position of the tuning body with respect to the HTS inductor and the HTS capacitor is altered so as to tune the resonator. A tunable resonant circuit is provided that includes a substrate having a planar surface. At least one resonator formed from HTS material is disposed on the substrate, the resonator having one or more turns that when combined, turn through greater than 360&#xb0;.

Tunable superconducting resonator and methods of tuning thereof

A method of tuning a high temperature superconductor (HTS) resonator includes the steps of providing a HTS inductor and a HTS capacitor, the HTS capacitor being electrically connected to the HTS inductor. A tuning body is provided adjacent to the HTS inductor and the HTS capacitor. The relative position of the tuning body with respect to the HTS inductor and the HTS capacitor is altered so as to tune the resonator. A tunable resonant circuit is provided that includes a substrate having a planar surface. At least one resonator formed from HTS material is disposed on the substrate, the resonator having one or more turns that when combined, turn through greater than 360&deg;.

Control elements for RF antennas including high temperature superconducting capacitors, alone or in combination with other elements, including high temperature superconducting films, structures, and applications are formed. In one embodiment a high temperature superconducting capacitor is coupled to an inductor to form a resonant circuit. In another embodiment a high temperature superconducting capacitor is used to make a low-resistance cross-over for an inductor coil. Additional circuits include circuits which do not use non-superconducting materials in the circuit, circuits which have coupled superconducting inductors to provide low-loss signal coupling, tuning and bandwidth broadening, and circuits which include switches to shut off the superconductivity of a superconducting element including low-loss photoconducting and superconducting thermal switches. These circuits may be used to improve Magnetic Resonance Imaging (MRI).

Superconducting control elements for RF antennas

A Cryogenic Cooling System generally comprises a portable Dewar and a charging station for the Dewar. In the preferred embodiment, a HTSC device, such as a MRI coil, is contained in the Dewar which uses liquid nitrogen as a cryogenic coolant. The Dewar includes a reservoir for holding cryogenic fluid, an optional wicking material, a transfer tube between the reservoir and the HTSC device (or wick), and a vacuum space. Preferably a vent channel is adjacent the reservoir and provides an escape path for evaporating gas from the wick and/or HTSC device. The vent channel preferably provides a feed-back system: as more cryogenic coolant is transferred via the transfer tube, more cool gas is vented through the channel which cools the reservoir and thereby reduces the transfer. A charging system may also be provided as a source of cryogenic coolant. In the preferred embodiment, the charging system comprises a relatively large reservoir for liquid nitrogen.

Cryogenic cooling system

Novel articles are provided of thin super-conductive thallium-based copper oxide layers on inorganic, usually crystalline substrates. Novel methods are provided for ease of producing such articles, particularly involving sol-gel techniques and laser ablation. The articles have a highly oriented superconductive thallium-based copper oxide film, particularly epitaxial, with high superconductive transition temperatures and desirable electrical properties. The subject articles find use in a wide variety of electronic applications, particularly in microwave and millimeter wave devices.

Epitaxial thin superconducting thallium-based copper oxide layers

In situ vapor phase growth of thallium containing superconductors is achieved by controlling thallium volatility. Thallium volatility is controlled by providing active oxygen at the surface of the growing material and by avoiding collisions of energetic species with the growing material. In the preferred embodiment, a thallium containing superconductor is grown by laser ablation of a target, and by provision of oxygen during growth. More specifically, a source of thallium, calcium, barium, copper and oxygen is created by laser ablation of a thallium rich target, generating an ablation plume that is directed onto a heated substrate through the oxygen, with the plume passing through oxygen having a pressure from 10.sup.-2 to ten torr. Epitaxial superconducting thin films of thallium, calcium, barium, copper and oxygen have been grown by this technique. Various superconducting phases may be engineered through use of this method.

In situ growth of TL-containing oxide superconducting films

A method for generating repeatable and reproducible crystallographic grain-boundary junctions is provided by forming a film on a crystalline substrate which has intersecting faces. In a preferred embodiment, a single crystal substrate is etched by an anisotropic etchant to provide a 'V'-groove in one face, and an epitaxial superconducting film is grown on the faces of the V-groove. In another preferred embodiment, a step is etched with an anisotropic etch, and an epitaxial superconducting film grown on the step. Grain-boundary junctions are formed at the points of intersection of the faces with each other, or with the faces and the surface of the substrate. The film may be patterned and etched in the area of the boundary junction to form useful devices.

Method for producing crystallographic boundary junctions in oxide

Methods and reactors are described for the production of thallium cuprate based high temperature superconductor films on a variety of substrates. The reactors provide for low volume cavities, means for rapidly heating and cooling to and from a predetermined elevated temperature and control of the thallium oxide overpressure during the processing. Uniform high temperature superconducting films are obtained while inhibiting reaction between the substrate and superconducting film during the processing.

Controlled thallous oxide evaporation for thallium superconductor films

An epitaxial thallium-based copper oxide superconducting film is formed on a crystalline substrate by metalorganic deposition which comprises forming a film of carboxylate soap solution on said substrate, prepyrolyzing said film at a temperature of 350.degree. C. or less and pyrolyzing said film at a temperature of 800.degree.900.degree. C. in the presence of oxygen and an overpressure of thallium for a sufficient time to produce said epitaxial superconducting film.

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Goleta, CA, United States of America

Timothy W James