Abstract: A power lead for electrically connecting a superconducting coil with a power supply, comprising thermoelectric cooling means, said means including at least an N-type thermoelectric member and a P-type thermoelectric member, being electrically connected to a positive side and a negative side of said power supply, respectively.

Abstract: Superconductivity is inhibited in selected portions of a high temperature superconductor ("HTS") material by patterning the selected portions with a resist. The patterned material is ion-bombarded to implant impurity ions in non-resist-bearing portions of the material. After low temperature annealing, the non-resist-bearing portions of the material lose their superconducting characteristics, but such characteristics are preserved in the material's resist-bearing portions. The material's crystalline structure is preserved, so additional layers can be epitaxially grown atop the inhibited material. Superconductivity is inhibited at a selected depth in a HTS material by subjecting the material to impurity ion bombardment at an energy level controlled to implant ions in the material at the selected depth. After low temperature annealing, the material loses its superconducting characteristics at the selected depth, but such characteristics are preserved at other depths (i.e.

Abstract: An improved high temperature superconducting planar filter wherein the coupling circuit or connecting network is located, in whole or in part, on the side of the substrate opposite the resonators and enables higher power handling capability.

Abstract: An adjustable coupler for coupling electromagnetic energy into or out of a resonant cavity has an input/output line connected to a loop or conductor. A base of the coupler has a passageway into which a bolt is inserted. Threads on a bolt engage threads on a nut attached to the conductor. A head of the bolt is held in place on the outside of the base so that rotation of the head moves the nut and conductor.

Abstract: The present invention relates to a tuneable fringe effect capacitor for conducting radio frequency energy. The capacitor includes a thin film of ferroelectric material, a pair of films of a conductive material deposited on the ferroelectric film with a gap between the films, and a substrate for the ferroelectric material and the conductive films. The capacitance value across the gap is varied by applying a voltage to the ferroelectric material and thereby altering the dielectric constant of the ferroelectric material.

Abstract: High power high temperature superconductor filters having TM.sub.0i0 mode (i=1, 2, 3, . . . ) circular shaped high temperature superconductor planar resonators or symmetrical polygon shaped resonators which eliminates wrap-around H-field and very sharp current peaks at the edge of the resonator are provided.

Abstract: A MMIC high Tc superconducting ferroelectric phase shifter is comprised of as microstrip line on a film of a single crystal ferroelectric material. To operate the phase shifter over a desired bandwidth a quadrature band pass filter, having 1,2,3, . . . coupled lines, is coupled to the phase shifter. The microstrip lines are comprised of a high Tc superconductor such as YBCO, TBCCO.

Abstract: Carbonaceous materials based on the fullerene molecules have been developed which allow for superconductivity. The fullerene materials are soluble in common solvents.

Abstract: A number of MMIC ferroelectric variable time delay devices are presented. Each embodiment has a microstrip configuration deposited on a ferroelectric film which is deposited on a high Tc superconductor substrate connected to the ground. A bias electric field changes the permittivity of the ferroelectric material. As a result, a variable time delay is obtained.

Abstract: Electromagnetic resonators according to the invention comprise a first body, exemplarily a split thin ring, that is disposed between two planar field confining plates. The thickness (t) of the first body is less (typically less than 1/2 or 1/10) of the outer radius (R) of the body, and the distance between the first body and the confining plates is less than R. In preferred embodiments the first body comprises superconducting material. Resonators according to the invention can be readily assembled into relatively compact filters that are easily tunable, can have large quality factor, and offer the possibility of single mode operation. Such filters can advantageously be used in, e.g., wireless communications systems.

Abstract: Lumped element electrical components, such as inductors and capacitors, are formed to include high temperature superconducting materials. In the preferred embodiment, thin film epitaxial high temperature superconductors are patterned to form capacitors and inductors on low loss substrates. Preferably, a ground plane is formed on the back side of the substrate, most preferably being formed of high temperature superconducting material, or other highly conductive materials such as gold or copper. Various advantageous structures include a planar spiral structure, a zig-zag serpentine structure, a single coil structure and a double coil structure. Single layer and multilayer structures are included. Improved narrow bandpass filters and high Q resonator structures are formed.

Abstract: Lumped element electrical components, such as inductors and capacitors, are formed to include high temperature superconducting materials. In the preferred embodiment, thin film epitaxial high temperature superconductors are patterned to form capacitors and inductors on low loss substrates. Preferably, a ground plane is formed on the back side of the substrate, most preferably being formed of high temperature superconducting material, or other highly conductive materials such as gold or copper. Various advantageous structures include a planar spiral structure, a zig-zag serpentine structure, a single coil structure and a double coil structure. Single layer and multilayer structures are included. Improved narrow bandpass filters, bandreject filters and high Q resonator structures are formed. Chebyshev bandpass filters are formed from multiple series connected zig-zag filter structures.

Abstract: A bandpass filter comprises multiple side-coupled strip line resonators wherein the resonators are staggered or offset with respect to their nearest neighbors by substantially 1/4 wavelength or less. In the preferred embodiment, the strip line bandpass filter structure has substantially parallel resonators arrayed with substantially constant spacing between the resonators with 1/4 wavelength overlap or less. Generally, the amount of stagger between nearest neighbors is reduced for resonators toward the center of the filter. Coupling between resonators is controlled by varying the relative amount of stagger between resonators. The resonators may be formed from normal metal or superconducting materials, such as YBCO or thallium containing superconductors. A strip line structure may be formed by utilizing two mirror structures each comprising a substrate having a ground plane and a patterned staggered resonator array formed on the substrate on a side opposite the ground plane.

Abstract: A filter for processing electromagnetic signals has a housing with resonators located inside the cavity of that housing. The resonators, which may be made in part from superconducting material, have rounded exterior surfaces without corners to provide a more desirable coating surface and uniform electric field around the resonators. The filter housing may be composed of a plurality of housing cells, each containing a resonator. These cells can be removably attached to other cells so that resonators may be added to or removed from the filter as may be required for a particular application.

Abstract: High Tc superconducting limiters are designed to operate at two or more levels of input signals. In one waveguide embodiment, multiple half wavelength branch waveguide lines are connected to a main waveguide line. The half wavelength lines are terminated with tuned circuits of a capacitance, made of a ferroelectric material, and an inductance provided by a waveguide line. In another waveguide embodiment, the branch lines are terminated in tuned cavities each having a ferroelectric material. In a microstrip embodiment, multiple half wavelength branch ferroelectric lines of different impedances are connected to a main line. In a second microstrip line embodiment, tuned circuits, with differing L and C values, are connected to a main transmission line through a half a wavelength branch transmission line. The capacitance is made of a ferroelectric material. The conductor, deposited on the microstrip lines, and the waveguides are made of a single crystal high Tc superconductor.

Abstract: A high-temperature superconductor (HT.sub.c S) in a microstrip configurat which is electrically related to a superconducting coupler and which is controlled by a heater disposed over the superconducting microstrip line. This limiter configuration is used in a series configuration with other circuitry and utilizes the low loss characteristics of the HT.sub.c S material and the wide bandwidth characteristics of microstrip. The structure itself is a five layer microstrip geometry which includes a normal metal ground plane; a dielectric substrate disposed on the metal ground plane; a superconducting microstrip transmission disposed on the substrate; a dielectric film layer disposed on the superconducting microstrip; and a heating element disposed on the dielectric film layer and over the superconducting microstrip.

Abstract: Microwave bandpass filters contain dielectric resonators mounted in dielectric blocks, which are in turn mounted in cavities. There can be more than one dielectric resonator per cavity. Significant size reduction has been achieved over prior art filters. The filters can be operated at cryogenic temperatures and since the results attainable at cryogenic temperatures are repeatable, the filters can be tuned at cryogenic temperatures and returned to room temperature before being returned to cryogenic temperatures for operating purposes. When operated at cryogenic temperatures, the filters contain shorting plates having high temperature superconducting material thereon. The filters can be constructed with various configurations and can be operated in either a single mode or a dual-mode. Previous single mode or dual-mode dielectric resonator filters are larger in size and mass than the filters of the present application.

Abstract: A joint device structure for capacitive microwave coupling of a superconducting device arranged on a substrate with room temperature circuitry; including a superconducting wave guide of an oxide superconductor on said substrate from one side to the superconducting device launching microwave to the superconducting device, a pair of superconducting groundplanes of an oxide superconductor arranged at an end of the superconducting wave guide sandwiching the end of the superconducting wave guide with a little gap and a microwave probe-head connected to the room temperature circuitry arranged above the superconducting wave guide with a coupling gap having three probing pins corresponding to the superconducting wave guide and the superconducting groundplanes.

Abstract: A superconductor/insulator metal oxide hetero structure for electric field tunable microwave device, including a dielectric substrate, a first superconducting electrode of an oxide superconductor provided on said dielectric substrate, an insulating layer formed on the first superconducting electrode and a second electrode arranged on the insulating layer in which the conductivity of the first superconducting electrode and/or the dielectric property of the insulating layer can be changed by a dc bias voltage applied between the first and the second electrodes so that surface resistance and/or surface reactance can be changed.

Abstract: A process for manufacturing superconducting magnetic coils from strain-tolerant, superconducting multi-filament composite conductors is described. The method involves winding the precursor to a multi-filament composite conductor and an insulating material or its precursor around a mandrel in order to form a coil, and then exposing the coil to high temperatures and an oxidizing environment. The insulating material or its precursor is chosen to permit exposure of the superconductor precursor filaments to the oxidizing environment, and to encase the matrix-forming material enclosing the filaments, which is reversibly weakened during processing.

Abstract: Periodic and pseudo-periodic slow wave structures comprising a plurality of adjacent sections, each section comprising a dielectric ring in contact with a disk coated with high temperature superconducting thin film, having coupling between the sections and tunable phase velocity for use in particle accelerators and traveling wave tubes are disclosed.

Abstract: A microwave component includes a superconducting signal conductor formed on a first dielectric substrate, and a superconducting ground conductor formed on a second dielectric substrate. The first dielectric substrate is stacked on the superconducting ground conductor of the second dielectric substrate. Each of the superconducting signal conductor and the superconducting ground conductor is formed of an oxide superconductor thin film of which crystals are orientated in such a manner that the c-planes of the crystals are parallel to the direction in which an electro-magnetic field generated by microwave launched to the microwave component changes.

Abstract: There is disclosed a superconducting microwave component including a first substrate of a dielectric material with a conductor line of an oxide superconductor formed in a required pattern on the surface, a second substrate of a dielectric with a grounding conductor of an oxide superconductor formed on the surface, and a third substrate of a dielectric which is laid on the first and the second substrates, with the third substrate sandwiched between the first and the second substrates.

Abstract: Microwave bandpass filters contain dielectric resonators mounted in dielectric blocks, which are in turn mounted in cavities. There can be more than one dielectric resonator per cavity. Significant size reduction has been achieved over prior art filters. The filters can be operated at cryogenic temperatures and since the results attainable at cryogenic temperatures are repeatable, the filters can be tuned at cryogenic temperatures and returned to room temperature before being returned to cryogenic temperatures for operating purposes. When operated at cryogenic temperatures, the filters contain shorting plates having high temperature superconducting material thereon. The filters can be constructed with various configurations and can be operated in either a single mode or a dual-mode. Previous single mode or dual-mode dielectric resonator filters are larger in size and mass than the filters of the present application.

Abstract: There is disclosed a superconducting microwave component including a first substrate having a conductor line formed of an oxide superconductor on the surface thereof, a second substrate having a grounding conductor formed of an oxide superconductor on the surface thereof, and a package of a conducting material housing the first and the second substrates so that they are substantially parallel with each other. At least one portion of the grounding conductor is in contact with the inside of the package, through surface contact.

Abstract: The design of a high Tc superconducting band pass tunable ferroelectric filter (TFF) is presented. The band pass TFF consists of an edge coupled filter on a ferroelectric substrate. Each input and output microstrip line is a quarter wavelength long. Each intermediate microstrip line is a half wavelength long with the first quarter wavelength being coupled to the preceding microstrip line and the remaining quarter wavelength being coupled to the succeeding microstrip line. Each microstrip line is connected, through an LC filter, to a common bias voltage source. Application of a bias voltage changes the frequency of operation of the filter. For matching the impedances of the input and output of the filter to the impedances of an input and output circuit respectively, matching ferroelectric quarter wavelength transformers are provided.

Abstract: The design of a high Tc superconducting band reject tunable ferroelectric filter (TFF) is presented. The band reject TFF consists of a main microstrip line on a dielectric substrate. One or more half wavelength microstrip resonators, on a ferroelectric substrate, is coupled to the main microstrip line. At a resonant frequency of a resonator, a short circuit is presented on the main microstrip line resulting in a rejection of signal of that frequency. By applying a bias voltage to a resonator, the frequency of the resonator and, as such, the reject band of the filter is changed. Different resonators can be tuned to different frequencies.

Abstract: A filter for an electromagnetic signal is formed of a set of planar resonators, preferably of superconductor material, interspersed among a set of electrically conductive sheets, outermost ones of the sheets serving as ground planes, and the inner ones of the sheets having irises for coupling electromagnetic power between the resonators. The resonators and the sheets have a planar shape, are parallel to each other, and are stacked one upon the other. Dielectric material insulates and serves to support the resonators and the sheets in their respective locations. There are at least two resonators in the set of resonators, and at least one inner sheet of the set of sheets. A first coupling element serves to couple an electromagnetic signal to a first resonator of filter to excite in the first resonator a first mode of electromagnetic vibration in a plane defined by the axis and a point of coupling of the first coupling element.

Abstract: An apparatus and method are described for gyromagnetic interaction between the electromagnetic field generated by an electromagnetic signal conducted by a superconductor and the magnetization contained in a magnetic structure. A ferrite magnetic structure is disposed in close proximity to a superconductor conducting the electromagnetic signal. A magnetization is induced in the magnetic structure with a geometry such that the magnetic flux is confined within the magnetic structure or eliminated from the magnetic structure so as not to produce an external magnetic field to interfere with the superconducting properties of the superconductor. The electromagnetic field of the signal conducted by the superconductor interacts gyromagnetically with the magnetization of the magnetic structure, inducing a phase shift in the electromagnetic signal traversing the superconductor. Thus, the invention induces a phase shift in the signal with minimum insertion loss due to electrical resistance.

Abstract: The disclosure relates to ferroelectric and superconducting thin films used in combination to produce low-loss passive microwave and millimeter wave devices which are frequency tuneable. Various metal oxide superconducting and ferroelectric thin films can be deposited in numerous multilayer geometries via a variety of deposition techniques to produce devices which can manipulate microwave and millimeter wave signals through the application of voltage bias signals across the ferroelectric films. Numerous superconducting microwave and millimeter wave devices, including delay lines, phase shifters, resonators, oscillators, filters, electrically-small antennas, half-loop antennas, directional couplers, patch antennas, and various radiative gratings, are made frequency-tuneable by utilizing voltage-tuneable capacitor structures fabricated from voltage-biased ferroelectric thin films.

Abstract: A cylindrical cavity is loaded with a ferroelectric rod and is resonant at the dominant mode. The loaded cylidrical cavity is a band pass filter. As a bias voltage is applied across the ferroelectric rod, its permittivity changes resulting in a new resonant frequency for the loaded cylindrical cavity. The ferroelectric rod is operated at a temperature slightly above its Curie temperature. The loaded cylindrical cavity is kept at a constant designed temperature. The cylindrical cavity is made of conductors, a single crystal high Tc superconductor including YBCO and a single crystal dielectric, including sapphire and lanthanum aluminate, the interior conducting surfaces of which are deposited with a film of a single crystal high Tc superconductor. Embodiments also include waveguide single and multiple cavity type tunable filters. Embodiments also include tunable band reject filters.

Abstract: A dielectric resonator apparatus for measuring the parameters of high temperature superconducting thin film is disclosed having improved means for positioning the dielectric and substrates, holding the resonator components in place during use, suppressing undesirable modes, adjusting the magnetic dipole coupling, and coupling to an electrical circuit.

Abstract: The high power ferroelectric RF phase shifter contains a ferroelectric material in a microstrip line section. Between the ferroelectric phase shifter and the input, there is a ferroelectric matching transformer. Between the ferroelectric phase shifter and the output, there is a quarter wave ferroelectric matching transformer. A bias field is connected across the top and bottom surfaces of the ferroelectric material. When a bias field is applied across the ferroelectric material, the permittivity is reduced and as such the velocity of propagation is increased. This causes an increase in the effective electrical length of the phase shifter. Increasing the bias voltage increases the phase shift. The ferroelectric RF phase shifter may be constructed of a ferroelectric liquid crystal (FLC). The ferroelectric material is operated above its Curie temperature.

Abstract: A multiple circuit hybrid cryostat power lead has a plurality of laterally spaced, electrically isolated lead elements inside a tubular enclosure. Each lead element has an inner section with a high temperature superconducting (HTS) conductor inward of a divider in the tubular enclosure, and an outer normal conductor section outward of the divider. The outer sections of the lead elements have a pair of copper conductors spirally wound in an annular chamber between an electrically insulating central support and an electrically insulating sleeve to form helical flow passages. Cryogen vapor flows outward in the tubular enclosure inward of the divider over the HTS conductors, through a slotted heat exchanger electrically connecting the HTS and copper conductors at the divider, and through the helical flow passages to vents at outer terminals.

Abstract: A tetrahedral junction waveguide switch having a first length of hollow rangular waveguide and a second length of hollow rectangular waveguide adjacent each other with a ferrite rod longitudinally disposed therebetween. A magnetic field is created by a superconducting switching coil placed around the junction of the two lengths of waveguide. The normally magnetically biased ferrite rod permits electromagnetic wave energy to be transmitted through the first and second lengths of waveguide. An open circuit control means selectively and controllably interrupts the current flowing around the superconducting switching coil causing the longitudinal magnetic field to be removed from the normally magnetically biased ferrite rod. The waveguide switch is thereby placed in a cut off, nontransmission, or reflective mode preventing transmission of electromagnetic wave energy.

Abstract: The Ferroelectric high Tc superconductor RF Phase Shifter contains a ferroelectric medium and a film of a single crystal high Tc superconductor is used as the conductors. Between the ferroelectric medium and the input, there is a quarter-wave, dielectric or ferroelectric or the same material as used for the phase shifter, matching transformer. Between the ferroelectric medium and the output, there is a quarter-wave, dielectric, ferroelectric or the same material as used for the phase shifter, matching transformer. A bias field is connected across the top and bottom surfaces of the active ferroelectric medium. When a bias field is applied across the surfaces of the ferroelectric medium, the permittivity is reduced and as such the velocity of propagation is increased. This causes an increase in the effective electrical length of the phase shifter or a phase difference or time delay. Increasing the bias voltage increases the phase shift.

Abstract: To reduce losses of commercial room temperature couplers, high Tc superconducting waveguides and waveguide flanges are used for couplers. There are two approaches for making these high Tc superconducting waveguide structures. One is to use a single crystal such as YBaCuO (YBCO), cut and machine the crystal to the desired shape, and use high Tc superconducting flanges. In the second method, a good quality dielectric, such as sapphire is used and cut and machined to the desired shape. The conducting surfaces are coated with a single crystal high Tc superconducting material such as YBCO. The waveguides are brazed together. Low loss is important particularly for high power couplers. Significant amount of RF power is lost even with a low loss coupler. The high Tc superconducting couplers will provide a significant benefit in high power RF systems handling power levels such as 0.5 megawatts.

Abstract: To reduce the losses, high Tc superconductive waveguide filters are disclosed. There are two approaches to make the filters. In the first approach, all waveguide sections, irises, flanges are made of a single crystal high Tc superconductor. The single crystal is machined to the desired shape and size, the pieces are brazed and connected with flanges. In the second approach all waveguide sections, irises and flanges are made of a single crystal dielectric material the conducting surfaces of which are deposited with a film of a single crystal high Tc superconductor. The waveguide sections, irises and flanges are connected together by brazing or by a similar method. There are two basic types, (1) band pass and (2) band reject, of filters. In the band pass type, a series of resonators are placed one after another with a separation, typically, of three quarters of a wavelength between the centers of adjacent resonators. In the band reject filters, the resonators are in branch lines, i.e.

Abstract: The present invention is a superconducting opto-electronic phase shifter which is achieved by illuminating a superconducting microstrip line, which is fabricated on a dielectric substrate, with an optical beam of a predetermined intensity and shape. Because the superconducting microstrip will exhibit a local surface resistance when and where illuminated, the microstrip line will be artificially narrowed thereby producing a phase shift. This occurs because as the width of a superconducting microstrip line narrows the velocity of the carder signal increases. Therefore, if the illumination of the superconducting microstrip line causes a local surface resistance, then the surface impedance of the microstrip line is increased causing the effective width of the microstrip line to decrease. Hence, the artificial decrease in the width of the microstrip will cause the phase of the carrier signal to shift.

Abstract: The disclosure relates to a Josephson junction formed by a non-superconducting barrier between two superconducting films of the (R) BaCuO (R=rare earth) group. In order to take advantage of the greater coherence length of superconductors along the CuO planes, i.e. perpendicularly to the long axis "c" of the crystal unit cell, the superconducting film is oriented so that the axis "c" is parallel to the plane of the junction. The device can be applied to Josephson junctions and to SQUIDs.

Abstract: An oxide superconductive wire is provided by, for example, forming an oxide superconductive layer on a tape-type flexible base. A preliminary compressive strain is applied to the oxide superconductive layer in the longitudinal direction. The remaining strain can be provided by using a base having thermal expansion coefficient larger than that of the oxide superconductive layer and by cooling the same after heat treatment, due to contraction of the base. Since the preliminary compressive strain is applied to the oxide superconductive layer, degradation of superconductivity of the oxide superconductive layer can be suppressed even if the oxide superconductive wire is bent in any direction, compared with the wire without such strain. Therefore, the oxide superconductive wire can be coiled, for example, without much degrading the superconductivity.

Abstract: A cathode for a secondary emission structure comprised of a superconductive material is described. In one embodiment the cathode comprises a layer of a superconductive material such as yttrium barium cupric oxide, or rare earth substituted neodymium cupric oxides. The layer may be bonded to a metal electrode or preferably the cathode consist of a superconductive or conductive oxide. The use of a superconductive material provides a cathode having suitable secondary emission characteristics and, furthermore, which being conductive at room temperatures, as well as, temperatures of operation of the cathode, obviating the need for a use of a very thin film of a secondary emission material.

Abstract: A superconducting device has a structure of superconductor - normal-conductor (semiconductor) - superconductor. The superconductors constituting the superconducting device are made of a superconducting oxide material of K.sub.2 NiF.sub.4 type crystal-line structure or perovskite type crystalline structure which contains at least one element selected from the group consisting of Ba, Sr, Ca, Mg and Ra; at least one element selected from the group consisting of La, Y, Ce, Sc, Sm, Eu, Er, Gd, Ho, Yb, Nd, Pr, Lu and Tb; Cu; and O.

Abstract: Active superconductive devices are formed having a variable conductive element in electromagnetic contact with a superconductor. In one embodiment, a variable ohmic conductive device, such as a photoconductor, is placed adjacent a superconductor. By varying the optical radiation on the photoconductor, the electromagnetic environment adjacent the superconductor is changed, resulting in changed electrical properties. The superconductor may be patterned as a reject filter, with a photoconductor forming a microwave switch. Alternatively, a delay line plus variable ohmic element forms a phase shifter.

Abstract: Superconducting device include a type having a structure of a superconductor--a normal-conductor (or a semiconductor)--a superconductor, and a type having a superconducting weak-link portion between superconductors.The superconductors constituting the superconducting device are made of an oxide of either of perovskite type and K.sub.2 NiF.sub.4 type crystalline structures, containing at least one element selected from the group consisting of Ba, Sr, Ca, Mg, and Ra; at least one element selected from the group consisting of La, Y, Ce, Sc, Sm, Eu, Er, Gd, Ho, Yb, Nd, Pr, Lu, and Tb; Cu; and O. In addition, the c-axis of the crystal of the superconductor is substantially perpendicular to the direction of current flowing through this superconductor.

Abstract: A thermal plug which provides an electrical connection between first and second regions at different temperatures includes a plurality of interleaved heat transfer resistive laminae and heat conductive laminae. The laminae are stacked together to form a laminate and a plurality of superconducting strands are attached to the stack such that they are in thermal contact with the laminate. The superconducting strands are also in electrical contact with a conductor (e.g., a low temperature superconductor), in the first region and a conductor in the second region to allow the supply and withdrawal of electrical energy to and from the conductor in the first region.

Abstract: The invention is directed to a superconducting microwave resonator, to holding devices for those resonators, and to their methods of manufacture. The superconducting microwave resonator employs at least two superconducting films on substrates positioned on a dielectric. The holding devices include a variety of configurations, such as, a spring loaded device. The superconducting microwave resonators have Q values of as high as microwave resonators formed of Nb, but operate at much higher temperature.

Abstract: An oxide superconductive wire is provided by, for example, forming an oxide superconductive layer on a tape-type flexible base. A preliminary compressive strain is applied to the oxide superconductive layer in the longitudinal direction. The remaining strain can be provided by using a base having thermal expansion coefficient larger than that of the oxide superconductive layer and by cooling the same after heat treatment, due to contraction of the base. Since the preliminary compressive strain is applied to the oxide superconductive layer, degradation of superconductivity of the oxide superconductive layer can be suppressed even if the oxide superconductive wire is bent in any direction, compared with the wire without such strain. Therefore, the oxide superconductive wire can be coiled, for example, without much degrading the superconductivity.

Abstract: A microwave cavity including a pair of opposing clamshell halves, such halves comprised of a metal selected from the group consisting of silver, copper, or a silver-based alloy, wherein the cavity is further characterized as exhibiting a dominant TE.sub.011 mode is provided together with an embodiment wherein the interior concave surfaces of the clamshell halves are coated with a superconductive material. In the case of copper clamshell halves, the microwave cavity has a Q-value of about 1.2.times.10.sup.5 as measured at a temperature of 10K and a frequency of 10 GHz.

Abstract: A superconducting magnetic levitation apparatus for driving a floating body efficiently and controllably, for producing a strong driving force, and for generating a lifting magnetic field having a uniform intensity in a running direction and producing a guidance force in a lateral direction, to stably run the floating body. The superconducting magnetic levitation apparatus includes a lifting magnet for forming a track, a floating body made of a high-T.sub.c superconductor, and a cooling device for keeping the floating body at a superconducting state. A plurality of coils are disposed on the lifting magnet, to be used as propulsion electromagnets, for generating a magnetic field necessary for running the floating body, with each of the coils being a flat, air-core coil, and with the coils being excitable by a polyphase alternating current.