Showing papers in "IEEE Transactions on Applied Superconductivity in 1999"

High critical current density thick MOD-derived YBCO films

Abstract: High critical current density thick MOD (metal-organic-deposition)-derived Ba/sub 2/YCu/sub 3/O/sub 7-x/ (BYC) films have been prepared on latticed matched single crystal lanthanum aluminate substrates. Critical current densities of approximately one million amps per square centimeter (at 77 K) have been obtained from one micron thick BYC films. These superconducting films were prepared from a single MOD coating. Substrate coatings of a mixed metal trifluoroacetate precursor were first converted into high quality mixed metal oxyfluoride films by heat treating under controlled conditions. These films were then patterned and subsequently converted into epitaxial BYC by exposure to water vapor at higher temperatures, High critical current density films were obtained by controlling the conversion kinetics of the mixed metal oxyfluoride films into BYC.

Rapid single flux quantum T-flip flop operating up to 770 GHz

Abstract: Rapid Single Flux Quantum (RSFQ) T-flip flops (TFFs) operating up to 770 GHz have been demonstrated at 4.2 K. The devices, consisting of either resistively shunted or unshunted Josephson junctions, are fabricated using a planarized Nb/AlO/sub x//Nb trilayer process. Electron beam lithography is used to pattern all levels with a minimum junction area less than 0.1 /spl mu/m/sup 2/. Critical current densities of 0.5 mA//spl mu/m/sup 2/ and 2.5 mA//spl mu/m/sup 2/ are used for the shunted (tested at 1.8 K) and unshunted devices (tested at 4.2 K) respectively. The input and output frequencies of the TFFs are obtained from the input and output voltages by the Josephson relation. The output voltage is exactly half of the input voltage when the divide-by-two operation is correct.

Coexisting ferromagnetism and superconductivity in hybrid rutheno-cuprate superconductors

Abstract: We report the observation of microscopically coexisting ferromagnetism and superconductivity in a hybrid ruthenocuprate RuSr/sub 2/GdCu/sub 2/O/sub 8/, with T/sub c//spl les/40 K. By means of various substituents it is established that the superconductivity originates in the CuO/sub 2/ planes and the ferromagnetism in the RuO/sub 2/ planes, as expected. Muon spin relaxation measurements show that the ferromagnetism, with Curie temperature T/sub M/=132 K, is microscopically uniform and originates from the entire sample bulk. This is probably the first confirmed example of uniform microscopic coexistence of superconductivity and atomic ferromagnetism. The material is determined from thermopower measurements to be an underdoped cuprate with a projected T/sub c,max/=90-100 K, typical of a two-layer cuprate. The oxygen isotope effect exponent of /spl alpha//sub Tc/=1.7 is the largest observed in the high-T/sub c/ cuprates. These materials are expected to provide a rich source of new physics and applications.

YBCO films on metal substrates with biaxially aligned MgO buffer layers

Abstract: We successfully deposited high quality YBCO films on metal tapes with biaxially aligned MgO buffer layers. e-gun evaporation on inclined substrates with a very high deposition rate of up to 250 nm/min was used for the deposition of the buffer layers. The MgO layers are biaxially textured with an in-plane full width at half maximum of 80. The MgO [001]-axis is not parallel to the substrate normal but tilted significantly towards the deposition direction. YBCO films were deposited on ISD buffer layers by reactive thermal co-evaporation. The critical current density of the films was found to be anisotropic due to the tilt of the [001]-axis. Critical current densities up to 7.9/spl times/10/sup 5/ A/cm/sup 2/ at 77 K were achieved.

High-T/sub c/ coated conductors-performance of meter-long YBCO/IBAD flexible tapes

Abstract: One meter long tapes based on 50-100 /spl mu/m thick by 1 cm wide nickel alloy substrates have been coated in a continuous process with a textured yttria-stabilized zirconia layer by ion beam-assisted deposition, followed by a 1-2 /spl mu/m thick layer of YBCO by pulsed laser deposition. The best result to date is a tape with a critical current (I/sub c/) at 75 K of 96 A over an 87 cm measurement length. The overall critical current density and engineering current density are 1 MA/cm/sup 2/ and 10 kA/cm/sup 2/, respectively. Using a special probe, individual I-V curves were generated for each centimeter of tape length in order to investigate longitudinal uniformity of the transport properties: the highest and lowest I/sub c/ values fall within a range of /spl plusmn/25%.

Resistive fault current limiters with YBCO films 100 kVA functional model

Abstract: Within the Siemens current limiter program a 100 kVA functional model has been realized and tested successfully. According to the modular concept of the limiter the functional model is assembled of ten switching elements. YBCO-films with a thickness of 250 nm and a critical current density above 2/spl times/10/sup 6/ A/cm/sup 2/ are deposited by thermal coevaporation (TU Munich) on 4" sapphire wafers. To support homogeneous switching the superconducting film is covered with a 100 nm Au-shunt layer. Good current limiting performance is achieved: the steady limiting current is below the nominal current, the peak fault current increases up to 3 times the nominal current within an action time of one millisecond. The operational recovery time of the limiter, within which the switching elements return to the superconductive state again is about 2 s. Following our limiter program the next step will be a model device with a nominal switching power of 1 MVA.

Filamentary YBCO conductors for AC applications

Abstract: High current density YBCO conductors as they are presently conceived for use at liquid nitrogen temperatures are in the form of tapes, usually the order of a centimeter in width and suitable only for dc use. Possibilities for developing similar YBCO conductors for ac applications are discussed, and the ac loss expected from such conductors is computed. The conversion from a dc to an ac conductor requires breaking up a wide-tape dc conductor into narrow strip-like filaments which spiral about the conductor axis. Various ways of producing this pattern are proposed.

Magnetoencephalogram systems developed at KIT

Abstract: We have developed new systems for magnetoencephalography (MEG). The pick up coil is a coaxial type first-order gradiometer with 50-mm base line. The magnetic field resolution of the system is about 4 fT/Hz/sup 0.5/ or 0.8 (fT/cm)/Hz/sup 0.5/ in white noise region. The unique feature of the system is the gantry-free horizontal dewar, which is fabricated through what we call "ship-in-a-bottle approach". Less than 10-liter/day liquid helium consumption for the 100-liter capacity is realized. One of the merits of the horizontal dewar is that a small room is sufficient for installation because of the low height (0.89 m) of the dewar. Another merit is that the patient can be measured in lying position which is more relaxing compared to the conventional vertical type.

Fabrication and characterisation of YBCO single grain boundary step edge junctions

Abstract: We use ion beam etching techniques to fabricate YBCO step edge junctions (SEJ) on MgO substrates. Argon ion-beam etching (IBE) of the substrate at angles other than at normal incidence is used to define the step height and angle. Thin (/spl sim/300 nm) magnetron sputtered YBCO films are deposited over the step and patterned using microlithography and cold substrate ion-beam etching techniques. The critical current, I/sub c/ of these SEJs can be controlled by varying the angle of the step etched into the substrate. Fabrication techniques are described which produce one grain boundary at the top of the step and include a smooth return path thereby avoiding a second grain boundary at the bottom of the step. At 77 K, the current-voltage (I-V) characteristics show resistively shunted junction behaviour. These junctions routinely demonstrate reasonably large I/sub C/R/sub N/ products (0.1-0.6 mV), making them suitable for applications in high temperature SQUID devices.

Technical and economical benefits of superconducting fault current limiters in power systems

Abstract: There is no doubt that superconducting fault current limiters (SFCL) will be used if their technical and economical benefits are high enough. Up to now a number of studies have been carried out to show suitable applications of SFCL but very few reports have been published on their technical and economical benefits in existing networks. This paper shows favourable places of SFCL in an urban network up to a voltage of 110 kV, lists technical benefits and calculates the economical savings. In the investigated network it was found that feeder locations of power stations and wind generators are the most economical places for SFCL.

HTS wire at commercial performance levels

Abstract: Short rolled multifilamentary BSCCO-2223 oxide-powder-in-tube (OPIT) wire has reached a core critical current density J/sub c/ over 73,000 A/cm/sup 2/ (77 K, self-field, 1 /spl mu/V/cm) in multiple samples, with engineering (full-cross-section) current density J/sub c/ of 22,800 A/cm/sup 2/ (77 K, self-field, 1 /spl mu/V/cm). Regular production wires several hundred meters long show average engineering current density over 10,000 A/cm/sup 2/ (77 K, self-field, 1 /spl mu/V/cm), a benchmark for commercial electric power applications such as cables and motors. Cost studies indicate that cost-performance below $10/kA-m is attainable for full-scale production levels, Next-generation YBCO-123 coated conductor technology offers further potential cost-performance improvements.

SMES for power utility applications: a review of technical and cost considerations

Abstract: Advances in both superconducting technologies and the necessary power electronics interface have made SMES a viable technology for high power utility and defense applications. The power industry's demands for more flexible, reliable and fast active power compensation devices make the ideal opportunity for SMES applications. However, in order to make this technology attractive to the deregulated utility market, it is necessary for industry to provide cost-effective systems. The information presented herein is taken from results to date of a DARPA technology Reinvestment Program SMES Commercialization Demonstration. This program is currently in the design and risk reduction phase. Completion is expected in 2001. This system will provide +/- 100 MW peak and +/- 50 MW oscillatory power with 100 MJ of stored energy. The base line for the coil design assumes a cable-in-conduit conductor (CICC), with rated voltage of 24 kV, and operating at nominal temperature of 4.5 K. This paper reviews the possible utility industry applications and discusses a number of technical issues and trade-offs resulting from the design optimization process for SMES utility applications. The conductor design options, system configuration, current/voltage levels and insulation issues for a low temperature superconducting coil are discussed. The power electronics interfaces (system configuration, circuit topology and devices and switching technologies) are also discussed. Finally, consideration is given to the impact of the new business environment, potential markets and overall cost.

Fabrication of in-plane aligned YBCO films on polycrystalline Ni tapes buffered with surface-oxidized NiO layers

Abstract: Strongly in-plane aligned, c-axis oriented YBCO films were successfully grown on polycrystalline nickel tapes buffered with [100]-oriented NiO layers. The in-plane and out-of-plane alignments of the NiO layer were achieved by a surface-oxidation epitaxy (SOE) technique using a [100] cube-textured nickel tape. The in-plane textures of NiO layers fabricated so far with the full width half maximum (FWHM) values of 11-13 degrees are sufficient for the epitaxial growth of high-J/sub c/ YBCO films. Pulsed laser deposited YBCO layers on the NiO/Ni tapes were not only c-axis oriented with respect to the type surface, but also strongly in-plane aligned. The YBCO films on NiO/Ni tapes have a zero resistance T/sub c/=87 K and J/sub c/=10/sup 4/-10/sup 5/ A/cm/sup 2/ at 77 K.

Loss and inductance investigations in a 4-layer superconducting prototype cable conductor

Abstract: One important issue in the design and optimization of a superconducting cable conductor is the control of the current distribution between single tapes and layers. This presentation is based on a number of experiments performed on a 4-layer three meter long prototype superconducting cable conductor. The self and mutual inductances of the layers are studied theoretically. The current distribution between the superconducting layers is monitored as a function of transport current. The results are compared with the expected current distribution given by the authors' equivalent electrical circuit model. The AC losses are measured as a function of transport current and a given current distribution and compared with the monoblock model. Recommendations for design of future cable conductor prototypes are given.

Self-shunted Nb/AlO/sub x//Nb Josephson junctions

Abstract: We describe the fabrication and properties of high critical current density (J/sub c/) Nb/AlO/sub x//Nb Josephson junctions with deep-submicron dimensions. The junctions are fabricated using a planarized process in which all levels are patterned using a combination of optical and electron-beam lithography. The base and counter electrodes are defined by reactive ion etching using quartz etch masks to give a minimum feature size of 0.2 microns. For J/sub c/=2.1 mA//spl mu/m/sup 2/ and junction area less than 0.1 /spl mu/m/sup 2/ the devices are self-shunted and exhibit nonhysteretic I-V characteristics. A small hysteresis in the larger junctions is caused by heating in the electrodes.

Tools for the computer-aided design of multigigahertz superconducting digital circuits

Abstract: The realization of large integrated circuits depends upon the application of computer-aided design (CAD) tools. This paper summarizes the results of a survey of CAD tools targeting superconducting digital electronics. Five categories of tools: circuit simulators, circuit optimizers, layout tools, inductance estimators, and logic simulators are discussed in detail. Within each category, a comparison of several currently available CAD tools is presented, and a tool which has been adapted for use or developed at the University of Rochester is discussed in greater detail. In addition, tools for timing analysis as well as integrated design environments that permit the effective data interchange among various tools and support libraries of design models are discussed. Future tools for timing optimization, automated logic synthesis, and automated layout synthesis are shown to be necessary for the design of superconducting circuits at the very large scale of integration (VLSI) level of integration. Trends regarding changes in the requirements for effective CAD tools are discussed, and expected improvements to existing tools and features of new tools currently under development are presented.

Pulse jitter and timing errors in RSFQ circuits

Abstract: We have carried out measurements of bit error rate (BER) of Rapid Single-Flux-Quantum (RSFQ) XOR gates with various nominal dc power supply voltages (from 0.1 V to 1.0 mV), operating at speeds up to 25 GHz. (For these gates, implemented using HYPRES' standard, 3.5-/spl mu/m, 10 /spl mu/A//spl mu/m/sup 2/ Nb-trilayer process, this speed is close to maximum.) A special on-chip RSFQ test circuit allowed high-speed measurements of BER in the range from 10/sup -9/ to 10/sup -13/ to be carried out. As a result of these experiments, a new type of thermal-fluctuation-induced digital errors in RSFQ circuits has been identified. These "timing" errors arise at high speed due to time jitter of data and clock pulses. We have developed a simple theory of these errors which allows a fair description of the experimental data. The theory shows that in some cases the timing errors may be an important factor limiting speed performance of RSFQ circuitry. Nevertheless, our XOR gates could operate at 25 GHz with BER below 10/sup -13/ at the standard temperature (4.2 K) at any dc power supply voltage in our range. For the lowest voltage (0.1 Volt) the calculated static power dissipation in the gate was as low as 23 nanowatts, lower than the unavoidable dynamic dissipation (43 nanowatts).

Superconducting magnetic bearings for energy storage flywheels

Abstract: We are investigating the use of flywheels for energy storage. Flywheel devices need to be of high efficiency and an important source of losses is the bearings. In addition, the requirement is for the devices to have long lifetimes with minimal or no maintenance. Conventional rolling element bearings can and have been used, but a noncontact bearing, such as a superconducting magnetic bearing, is expected to have a longer lifetime and lower losses. We have constructed a flywheel system. Designed to run in vacuum this incorporates a 40 kg flywheel supported on superconducting magnetic bearings. The production device will be a 5 kW device storing 5 kWh of retrievable energy at 50000 rpm. The Cambridge University system is being developed in parallel with a similar device supported on a conventional bearing. This will allow direct performance comparisons. Although superconducting bearings are increasingly well understood, of major importance are the cryogenics and special attention is being paid to methods of packaging and insulating the superconductors to cut down radiation losses. The work reported here is part of a three-year program of work supported by the EPSRC.

A concept for a submillimeter-wave single-photon counter

Abstract: We discuss the design for a submillimeter-wave photometer, using a combination of superconducting and single-electron devices, which would have high quantum efficiency, very low noise-equivalent powers, and eventually even submicrosecond timing resolution. The absorption of above-gap photons occurs in a small strip of superconducting Al, whose normal-state resistance can be matched efficiently to an antenna of a higher gap (Nb) superconductor. The quasiparticles produced by photon absorption are then confined via Andreev reflection, and forced to tunnel through a small SIS tunnel junction. The tunneling time is much shorter than the known (>10 /spl mu/s) quasiparticle recombination time, so collection efficiency will be high. The device sensitivity would be limited by the small subgap current in the high-quality Al/AlO/sub x//Al tunnel junction at temperatures (100 mK) well below T/sub c/. Scaling based on the larger junctions used in X-ray detector applications suggests that the total dark current can be <0.1 pA, or of order 10/sup 5/ electrons/second, corresponding to an NEP of less than 10/sup -19/ W//spl radic/Hz at 500 microns (600 GHz). The photocurrent will be measured using a fast single-electron transistor (RF-SET), which allows a shot-noise-limited performance even for the very small currents delivered from this low capacitance and high impedance SIS junction. Results of initial fabrication and dc characterization of an integrated photodetector are also given.

Performance of a 1-MVA HTS demonstration transformer

Abstract: We report on test results for a single phase, 60-Hz, 13.8 kV/6.9 kV, 1-MVA high temperature superconducting (HTS) transformer which was completed in February, 1998. This transformer models in many ways a full scale section of a 30-MVA HTS commercial transformer design. The transformer windings are cryocooled in the range of 25 K and are made with a low-cost, surface-coated BSCCO-2212 conductor. Heat leaks are reduced using a liquid nitrogen thermal ballast and reservoir. The use of high temperature superconductors can substantially reduce transformer losses, weight, size, noise and potential fire and environmental hazards. Designs promise stable operation through faults without thermal degradation, and at temperatures that allow efficient and reliable refrigeration.

Magnetically tunable superconducting resonators and filters

Abstract: Compact, low-loss, tunable filters are needed for overload protection in the front end of many microwave-frequency systems. We have demonstrated magnetically tunable superconducting resonators and filters comprising microwave circuits coupled to ferrite substrates in monolithic structures using niobium at 4 K and hybrid resonator structures using YBCO at 77 K. A three-pole 1% bandwidth filter with 10-GHz center frequency and 1-dB insertion loss is described. In these devices the tunability results from changes in the magnetization of the ferrite rather than changes in the ferrimagnetic resonance frequency as in conventional YIG filters. Tunability data plotted us a function of magnetic field are fitted to the hysteresis theory developed previously and indicate that a tuning range of 13% is achievable. We have demonstrated switching times of less than one microsecond in structures incorporating closed magnetic paths in the form of a circular toroid.

A 0.5 kWh flywheel energy storage system using a high-T/sub c/ superconducting magnetic bearing

Abstract: A flywheel rotor having a main shaft, two flywheel disks and one permanent magnet for a SMB (superconducting magnetic bearing) was designed and manufactured. The flywheel was made of CFRP material which is light weight and has high tensile strength. The permanent magnet was hooped by CPRP in order to prevent centrifugal bursting. The rotor was levitated by a SMB in the axial direction. The radial vibration of the rotor was damped by active magnetic bearings. The superconducting magnetic bearing was made of YBa/sub 2/Cu/sub 3/O/sub 7-X/ which had a strong pinning force. The whole rotor system was stably accelerated up to 30000 rpm by an induction motor in a vacuum chamber, and then its energy storage value reached 479 Wh. In this paper, the rotor design, bearing and rotational properties of the rotor are discussed.

Field trials using HTS SQUID magnetometers for ground-based and airborne geophysical applications

Abstract: Since December 1992, CSIRO and BHP have been field trialing rf HTS SQUID magnetometers for mineral prospecting applications. Ten field trials in widely varying environments(from -16/spl deg/C to +40/spl deg/C ambient temperatures) in mostly remote locations saw the development of a system which can be operated in many configurations including ground based and airborne Transient ElectroMagnetics (TEM). The magnetometer system has been developed to a point where, at late times in TEM applications, the SQUID system has a higher signal-to-noise level than the competing traditional coil technology. In some trials, a SQUID magnetometer detected anomalies at later times than were observed with the coil system, indicating an enhanced ability to detect highly conductive targets. This paper reviews development of our 3-axis SQUID magnetometer. SQUID systems as B field sensors have advantages over coils which are dB/dt type sensors. We will discuss the importance of these advantages for mineral prospecting in regions with a conducting soil cover or overburden typical of the Australian landscape.

High rate deposition of 5 /spl mu/m thick YBa/sub 2/Cu/sub 3/O/sub 7/ films using the BaF/sub 2/ ex-situ post annealing process

Abstract: We have investigated the crystallization of thick YBCO films under various annealing conditions The films were deposited by high-rate co-evaporation of Y, Cu and BaF/sub 2/ onto room-temperature SrTiO/sub 3/ substrates at rates exceeding 10 nm/s TEM microscopy was performed to establish the microscopic structure of partially processed films and help elucidate the growth mechanism In-situ resistivity measurements were used to monitor the crystallization of the YBCO films during the annealing process Resistivity measurements and TEM microscopy of samples at different stages of the film growth are compared Our results indicate that, in addition to oxygen partial pressure, water vapor pressure is an important parameter which defines the dynamics of film growth and crystallization 5 /spl mu/m thick films with J/sub c/>2/spl times/10/sup 5/ A/cm/sup 2/ (1 T H/spl par/c) have been fabricated

Performance of DC reactor type fault current limiter using high temperature superconducting coil

Abstract: The purpose of this work is to study a DC reactor type fault current limiter (FCL) using high temperature superconducting (HTS) coil which is connected with the secondary winding of a transformer through a diode bridge. The high temperature superconductors provide the advantages of a higher temperature operation and they are preferably applied to the DC reactor type fault current limiters, where a superconducting coil can be operated at both low voltage and DC current. The authors propose a DC reactor type three-phase FCL incorporating only one HTS coil and present its test result. A three-phase FCL for 6.6 kV-2000 A requires one HTS coil of 2.9 MJ.

1 volt DC programmable Josephson voltage standard

Abstract: NIST has developed a programmable Josephson voltage standard (JVS) that produces intrinsically stable voltages that are programmable from -1.1 V to +1.1 V. The rapid settling time (1 /spl mu/s), large operating current margins (2 to 4 mA), and inherent step stability of this new system make it superior to a conventional JVS for many dc measurements. This improved performance is made possible by a new integrated-circuit technology using intrinsically shunted superconductor-normal-superconductor (SNS) Josephson junctions. These junctions operate at lower excitation frequencies (10 to 20 GHz) than a conventional JVS and have 100 times greater noise immunity. The Josephson chip consists of a binary array sequence of 32 768 SNS Josephson junctions. The chip has been integrated into a completely automated system that is finding application in mechanical/electrical watt-balance experiments, evaluation of thermal voltage converters, electron-counting capacitance standards, and metrology triangle experiments.

1.9 K test facility for the reception of the superconducting cables for the LHC

Abstract: A new test facility (FRESCA-Facility, reception of superconducting cables) is under construction at CERN to measure the electrical properties of the LHC superconducting cables. Its main features are: independently cooled background magnet, test currents up to 32 kA, temperature between 1.8 and 4.5 K, long measurement length of 60 cm, field perpendicular or parallel to the cable face, measurement of the current distribution between the strands. The facility consists of an outer cryostat containing a superconducting NbTi dipole magnet with a bore of 56 mm and a maximum operating field of 9.5 T. The magnet current is supplied by an external 16 kA power supply and fed into the cryostat using self-cooled leads. The lower bath of the cryostat, separated by means of a so called lambda-plate from the upper bath, can be cooled down to 1.9 K using a subcooled superfluid refrigeration system. Within the outer cryostat, an inner cryostat is installed containing the sample insert. This approach makes it possible to change samples while keeping the background magnet cold, and thus decreasing the helium consumption and cool-down time of the samples. The lower bath of the inner cryostat, containing the sample holder with two superconducting cable samples, can as well be cooled down to 1.9 K. The samples can be rotated while remaining at liquid helium temperature, enabling measurements with the background field perpendicular or parallel to the broad face of the cable. Several arrays of Hall probes are installed next to the samples in order to estimate possible current imbalances between the strands of the cables.

Superconducting reluctance motors with YBCO bulk material

Abstract: Superconducting reluctance motors with YBCO bulk material have been built and tested up to more than 10 kW. They have been operated in liquid nitrogen at 77 K, at different frequencies (speeds) and loads. The specific power achieved is significantly higher than that in conventional motors. The small size and low weight of such motors can be considered as important advantages for special applications. The test results and the theory applied are in good accordance.

High-temperature superconducting edge-type Josephson junctions with modified interface barriers

Abstract: This paper describes recent results on the fabrication, electrical characteristics, and microstructure of high-temperature superconducting edge-type Josephson junctions with modified interface barriers. The barriers are formed by surface modification of the YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta// base layer. This process involves structural and chemical modification by ion irradiation and crystallization by annealing. The junctions showed resistively and capacitively shunted junction-like current-voltage characteristics and excellent uniformity. The spread in the critical current for one hundred junctions was smaller than 1/spl sigma/=10% at 4.2 K. The uniformity is now approaching 1/spl sigma/=5%. The junction characteristics have remained the same after two-year room-temperature storage. They also showed no change after high-temperature processing at about 700/spl deg/C. High-resolution transmission electron microscopy revealed that both the crystal structure and chemical composition in relatively thick barriers are different from those of YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta//.

Hysteresis and reluctance electric machines with bulk HTS rotor elements

Abstract: Two new types of HTS electric machines are considered. The first type is hysteresis motors and generators with cylindrical and disk rotors containing bulk HTS elements. The second type is reluctance motors with compound HTS-ferromagnetic rotors. The compound HTS-ferromagnetic rotors, consisting of joined alternating bulk HTS (YBCO) and ferromagnetic (iron) plates, provide a new active material for electromechanical purposes. Such rotors have anisotropic properties (ferromagnetic in one direction and diamagnetic in perpendicular one). Theoretical and experimental results for HTS hysteresis and reluctance motors are presented. A series of hysteresis HTS motors with output power rating from 1 kW (50 Hz) up 4 kW (400 Hz) and a series of reluctance HTS motors with output power 2-9 kW (50 Hz) was constructed and successfully tested by the cooperation of MAI (Moscow, Russia) and IPHT (Jena, Germany). It was shown that HTS reluctance motors could reach 2-5 times higher specific output than conventional asynchronous motors of the same size and will have higher values of power factor (cos/spl phi//spl ges/0.7-0.8).