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Applied Superconductivity, IEEE Transactions on

Issue 3 • Date Sept. 2000

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Displaying Results 1 - 5 of 5
  • Characteristics of driver and receiver circuits with a passive transmission line in RSFQ circuits

    Publication Year: 2000 , Page(s): 1637 - 1641
    Cited by:  Papers (4)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (130 KB)  

    We report simulated results of-rapid single flux quantum (SFQ) circuits having driver, receiver, and passive transmission lines for propagating SFQ pulses to investigate the design criteria. We have studied the equivalent input/output resistance of the driver/receiver in various bias conditions and found that the resistance is almost proportional to the bias current of the driver/receiver. Furthermore, we have proposed inserting a series resistor at the end of the superconducting passive transmission line (PTL) for avoiding undesirable flux trapping in the loop and for isolation in regard to the DC current. We also found that the reduction of the bias margin due to the resistance is rather small when the resistance is much smaller than the impedance of the PTL. An operating margin of more than 30% was obtained in the driver/receiver circuits including the PTL and the series resistor. View full abstract»

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  • Controlled levitation of bulk superconductors

    Publication Year: 2000 , Page(s): 1642 - 1648
    Cited by:  Papers (11)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (207 KB)  

    Levitation of bulk Y-Ba-Cu-O superconductors could successfully be controlled using a Bi-Sr-Ca-Cu-O superconducting electromagnet. It was found that stable levitation without tilting was obtained only when the sample trapped a certain amount of field, the minimum of which depended on the external field and the sample dimensions. We also employed a novel analysis method for levitation based on the total energy balance, which is much simpler than the force method and could be applied to the understanding of general levitation behavior. Numerical analyzes thus developed suggested that stable levitation of superconductors with large dimensions can only be achieved when the induced currents can flow with three dimensional freedom. View full abstract»

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  • Critical current characteristics of YBa/sub 2/Cu/sub 3/O/sub 7/ thin films on [110] SrTiO/sub 3/

    Publication Year: 2000 , Page(s): 1649 - 1656
    Cited by:  Patents (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (140 KB)  

    The material and electrical characteristics of YBa/sub 2/Cu/sub 3/O/sub 7/ (YBCO) thin films deposited by inverted cylindrical magnetron sputtering on [110] SrTiO/sub 3/ (STO) were investigated. X-ray diffractometry shows the grain orientations to be predominantly the YBCO [110] and [103] with no evidence of c-axis grains, Electron micrographs show the film surface to consist of coupled elongated grains parallel to the [110] STO edge. The films were patterned into small 2.5 mm squares parallel to the substrate edges for electrical characterization. Transport currents parallel and perpendicular to the [110] substrate edge showed a 945:1 anisotropy in film resistance and a factor of two in critical current density for temperatures below 60% of the transition temperature (T/sub c/). The temperature dependence of the critical current near T/sub c/ was quadratic-like and strongly dependent on the value of T/sub c/ used in the analysis. For the two orientations, there was nearly a 6 K difference in T/sub c/ as determined by the point at which the critical current became zero. The response of the critical current to small magnetic fields was greater for transport current along the c-axis direction and was observable over a temperature interval nearly four times greater than for current along the basal plain. These YBCO thin films have good response to small magnetic fields and are suitable for vortex flow device development. View full abstract»

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  • Hysteresis of superconducting cylinder in transverse magnetic field

    Publication Year: 2000 , Page(s): 1657 - 1661
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (113 KB)  

    A piecewise continuous distribution of critical currents is used to predict the hysteresis of the superconducting cylinder in the transverse magnetic field slowly oscillating in time. The proposed hysteresis model takes into account that the magnetic field has the peripheral and radial components due to the screening effect of critical currents. The model is used to predict the hysteresis loss in a round superconducting wire. An analytical formula for the hysteresis loss is given. View full abstract»

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  • Possibility of Nd/sub 1.9/Ba/sub 1.1/Cu/sub 3/O/sub 7+/spl delta// and Pr/sub 1.14/Ba/sub 1.86/Cu/sub 3/O/sub 7-/spl delta// single crystals for insulator in high-speed superconducting circuits

    Publication Year: 2000 , Page(s): 1662 - 1666
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (99 KB)  

    Dielectric properties of both Nd/sub 1.9/Ba/sub 1.1/Cu/sub 3/O/sub 7+/spl delta// (NBCO-213) and Pr/sub 1.14/Ba/sub 1.86/Cu/sub 3/O/sub 7-/spl delta// (Pr-rich PBCO) single crystals have been examined at low temperature. These materials have good lattice matching to high-T/sub c/ superconductors (HTS), but they are conductive at room temperature. Below 80 K, they are insulators with low dielectric constants, /spl epsi//sub /spl tau// below 25, and low dielectric loss tan /spl delta/ below 0.1 at 100 kHz. The value of /spl epsi//sub /spl tau// is suitable for insulators in integrated circuits using strip line widths of 10 /spl mu/m order, providing short delay time, no excitation of surface wave, and low radiation loss. The value of tan /spl delta/ is comparable to loss of superconducting surface resistance above 100 GHz. These results indicate the applicability for the insulator layers in multilayer superconducting electronic devices such as Single Flux Quantum (SFQ) circuits operated at high speed. View full abstract»

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Aims & Scope

IEEE Transactions on Applied Superconductivity contains articles on the applications of superconductivity and other relevant technology.

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Editor-in-Chief
Britton L. T. Plourde
Syracuse University
bplourde@syr.edu
http://asfaculty.syr.edu/pages/phy/plourde-britton.html