Several critical applications of superconducting electronics that have been successfully commercialized are the Josephson voltage standard, superconducting quantum interference device (SQUID) magnetometers, superconductor-insulator-superconductor (SIS) mixers, and analog filters. More recently, digital and mixed-signal circuits based on rapid single flux quantum (RSFQ) logic have also made an impression on the high-speed/high-frequency electronics application markets.

Quantum Sensitivity: Superconducting Quantum Interference Filter-Based Microwave Receivers

The impressive explosion of the satellite communication systems during the last few years has led to new constraints in regards to filtering requirements. The development of multimedia satellites and the saturation of the operational frequency bands, necessitates an increase in frequency coverage. This paper presents the design of High Temperature Superconducting (HTS) preselect receive fitters for communication satellites. Attention has been focused on obtaining low insertion loss and small dimensions, at frequencies of 4 GHz and 30 GHz.

Planar Ka-band high temperature superconducting filters for space applications

A systematic study of the surface morphology of epitaxial thin films of YBa2Cu3O7−δ on (100) LaAlO3 wafers is reported. The films were prepared by high pressure dc sputtering or laser ablation deposition, on wafers of 0.5–2.8 mm thickness and 2 or 3 inch diameter. Optical and atomic force microscopy (AFM) were used to characterize the surfaces, while transport was used to verify the high quality of the films. For films prepared under the same conditions, we found a systematic increase in size and number of extended defects in the films with wafer thickness. In some cases, a clear correlation was observed between the defect structure and the twin boundaries of the LaAlO3 substrate. We specify the conditions for minimizing these defects.

Is LaAlO3 a viable substrate for the deposition of high quality thin films of YBa2Cu3O7−δ?

Characterization of physicochemical properties of high-temperature superconductor surfaces using nitrogen adsorption

In this paper the theoretical approach and applications of Cahn ultramicrobalance to kinetic study on the thermal decomposition of the high-temperature Y1Ba2Cu3O7-x superconductor are presented. Thermogravimetric in situ measurements of oxygen loss from Y1Ba2Cu3O6 samples heated isothermally in a relatively high dynamic vacuum were performed with a Cahn RG electrobalance. Single-phase orthorhombic samples of composition Y1Ba2Cu3O7-x (highest oxygen content) were synthesized from stoichiometric (1:2:3) mixtures of high-purity Y2O3, BaCO3 and CuO. The original 1:2:3 mixture was prepared by the two-stage procedure described earlier. The crystal structure of the sample in the original orthorhombic phase was controlled by the X-ray powder method (CuKα radiation) using a Stadi P Stoe diffractometer with a position-sensitive detector. Activation energy is estimated from appropriate Arrhenius plots.

Kinetic study on thermal decomposition of the high-temperature superconductor in vacuum microbalance

A K-band receiver terminal has been designed for /spl ap/77-K operation to support the NASA Glenn Research Center's direct-data-distribution (D/sup 3/) spare experiment. The D/sup 2/ experiment involves a 256-element phased-array antenna, aboard the Space Shuttle, transmitting dual 622-Mb/s beams to the ground terminal. The beams are left- and right-hand-side circularly polarized for isolation. The terminal consists of a Cassegrain reflector antenna with a corrugated feed horn, a six-pole YBa/sub 2/Cu/sub 3/O/sub 7/(-/spl delta/) microstrip bandpass filter, a three-stage InP high electron-mobility transistor monolithic-microwave integrated-circuit amplifier, and a 1-W at 80-K Stirling cycle cryocooler.

A. Smith

Papers

A cryogenic K-band ground terminal for NASA'S direct-data-distribution space experiment