Scheduled System Maintenance:
On Monday, April 27th, IEEE Xplore will undergo scheduled maintenance from 1:00 PM - 3:00 PM ET (17:00 - 19:00 UTC). No interruption in service is anticipated.
By Topic

Applied Superconductivity, IEEE Transactions on

Issue 3 • Date Sept. 1992

Filter Results

Displaying Results 1 - 12 of 12
  • AC losses in HTSC conductor elements

    Publication Year: 1992 , Page(s): 117 - 121
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (513 KB)  

    AC self-field losses and DC dynamic resistivity in HTSC conductor elements have been measured. The data are discussed with reference to the relevant theory. For two very different sample types, the J/sub c/ calculated on the basis of the AC self-field loss is about an order of magnitude lower than the J/sub c/ based on the 1- mu V/cm DC voltage drop criterion often used for HTSC materials. This is attributed to the onset of resistive behavior at currents much lower than the reported J/sub c/ based on the 1- mu V/cm criterion. The J/sub c/ determined from measurements of the dynamic resistivity of a melt-textured YBCO fiber is within 15% of that determined by magnetic measurements.<> View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • High T/sub c/ wire design and power losses on cycling SMES devices

    Publication Year: 1992 , Page(s): 122 - 129
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (704 KB)  

    The present state of the art in high T/sub c/ superconductors is projected to the kilometer-long wires needed for a superconducting magnetic energy storage (SMES) device. It is concluded that silver-clad-bismuth-based superconductor is the only form which is likely to be available in the near future. This wire should have a cross-section of approximately 1 cm/sup 2/ and carry 10 kA in fields up to 10 T. For satisfactory performance it must be made in the form of twisted multifilaments rather than the flat tape form which is presently receiving the most attention. In addition, detailed measurements of J/sub c/ as a function of field and temperature of the wire form as well as thermal conductivity and heat capacity are required in order to properly calculate the stability limits of the wire.<> View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Development of a protection system for an experimental SMES device

    Publication Year: 1992 , Page(s): 130 - 138
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (648 KB)  

    The development and testing of a quench detection and protection system for a small, liquid helium cooled, superconducting coil are described. The coil is being used as part of an experimental superconducting magnetic energy storage (SMES) device for power system applications. Special requirements are placed on the detection and protection system of such a coil as rapid energy exchanges are frequent. The detection signal is derived from a combination of the main coil voltage and a search coil voltage. The protection method is by way of an external parallel resistor. The problem of opening a circuit breaker in series with the coil is analyzed. Actual quench recordings are used to demonstrate the effectiveness of the system. The selection of the dump resistor value is considered.<> View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Josephson voltage standard based on single-flux-quantum voltage multipliers

    Publication Year: 1992 , Page(s): 139 - 142
    Cited by:  Papers (10)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (351 KB)  

    A Josephson single-flux-quantum voltage/frequency multiplier circuit is proposed as the basic building block for a new generation of voltage standards. The circuit uses magnetic coupling to synchronize a series array of independent junction oscillators to the flux flow in a Josephson transmission line. A cascade of these circuits can multiply an arbitrarily low input frequency up to the frequency limit of the circuit ( approximately=250 GHz) and then add the voltages across approximately 30000 oscillators to generate precise voltages up to 10 V. Because the oscillators can be switched on and off with a bias current, the output voltage is rapidly programmable. A complete design for a voltage standard programmable in 1.2- mu V increments to a maximum of 10 V is proposed. Using existing fabrication technology, the circuit would cover a substrate area of about 1 cm/sup 2/ and use 67210 junctions.<> View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • An experimental Josephson digital correlator

    Publication Year: 1992 , Page(s): 143 - 147
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (634 KB)  

    A circuit capable of performing correlation of two sets of 16-sample, one-bit digital data has been designed and tested up to a clock frequency of 12 GHz. The correlator consists of two 16-b shift registers for delay and storage elements and an array of 16 exclusive-OR gates for the multiply-and-add function. It is fabricated using an Nb/AlO/sub x//Nb Josephson-junction process at a critical-current density of 1000 A/cm/sup 2/.<> View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Performance analysis of the Josephson DC flip-flop

    Publication Year: 1992 , Page(s): 148 - 155
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (667 KB)  

    A linear analytical model of the Josephson DC flip-flop is proposed. The model describes both the Baechtold's and Hebard's flip-flops. The output signal line is treated as either a single inductance or a transmission line with a finite impedance. The former leads to the lumped model, while the latter leads to the distributed model. The lumped model gives the load condition for successful reset. This is given as a relationship between the CR and L/R time constant, where C is the device capacitance, L is the load inductance, and R is the load resistance. The switching delay is also described as a linear function of the CR and L/R. With the distributed circuit model, the load condition for successful reset is Z/sub 0/>or=R. Minimum delay is obtained at Z/sub 0/=R. Grounding one end of the output signal line reduces the delay more than the nongrounded configuration. The scalar relationship of the switching delay and the power consumption to the design rule is discussed.<> View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Noise analysis of the quantum flux parametron

    Publication Year: 1992 , Page(s): 156 - 164
    Cited by:  Papers (12)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (623 KB)  

    An analysis of the limitations imposed by thermal noise on the application of the quantum flux parametrons (QFPs) as current comparators and timing discriminators is presented. At low operational frequencies, a thermal activation approach is used, while at high frequencies a circuit simulation method is required. At frequencies greater than the Josephson junction plasma frequency, an approximate expression for the noise is given. The calculations are in good agreement with the approximations and the experimental results.<> View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • A fixed tuned broadband matching structure for submillimeter SIS receivers

    Publication Year: 1992 , Page(s): 165 - 175
    Cited by:  Papers (22)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (968 KB)  

    The authors have designed, fabricated, and tested a quasi-optical submillimeter wave receiver with an Nb/AlO/sub x//Nb tunnel junction. This design incorporates a hybrid antenna fed by a planar logarithmic spiral structure in order to couple to the radiation field from the telescope. The novel matching circuit requires several layers of photolithographic processing on top of the actual tunneling device. Computer modeling of the device correctly predicted the measured bandwidth and the characteristic frequencies to within 8%. A good match has been obtained from 200 to 475 GHz between the antenna and a relatively large area (1 mu m/sup 2/) tunnel junction with omega R/sub n/C approximately=2-4. Noise measurements at 318 GHz, 395 GHz, 426 GHz, and 492 GHz yielded uncorrected double sideband receiver noise temperatures of 200 K, 230 K, 220 K, and 500 K, respectively. Using the same optics, coupling efficiencies between the receiver and the Caltech Submillimeter Telescope were found to have values approaching those achieved by the best waveguide-horn-based receiver systems.<> View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • A new contact conductance measurement technique for metal-HTSC film contact

    Publication Year: 1992 , Page(s): 176 - 180
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (398 KB)  

    A four-point contact conductance measurement technique has been developed for measuring the contact conductance of the metal-HTSC film interface. A distributed RG model predicts a small nonzero (residual) resistance from which the contact conductance is determined. The measurement technique is described along with first results.<> View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • A digital technique for the measurement of power losses in high temperature superconductors

    Publication Year: 1992 , Page(s): 181 - 183
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (264 KB)  

    A digital power loss measurement technique that enables the fast and accurate measurement of AC power losses in superconductors is described. This technique allows loss measurements at all frequencies limited only by the maximum sampling rate and buffer memory of the digital measuring device. Using the digital technique, power loss measurements on YBa/sub 2/Cu/sub 3/O/sub 7/ are compared to similar measurements using the analog wattmeter.<> View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Submicron NbN/MgO/NbN Josephson tunnel junctions and their application to the logic circuit

    Publication Year: 1992 , Page(s): 183 - 186
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (403 KB)  

    An improved fabrication process for submicron NbN/MgO/NbN Josephson tunnel junctions has been developed. By introducing a contact layer between the junction and the wiring layer, the critical current of the wiring above the junction was considerably enhanced. A logic circuit composed of four-junction logic gates was fabricated using 0.9- mu m-square junctions. Logic delay measurement was successfully achieved with a minimum logic delay of 3.6 ps/gate and a wide operating margin of +or-17% within 50 gates.<> View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Increased dielectric quality factor in planar resonators by selective dielectric removal

    Publication Year: 1992 , Page(s): 186 - 188
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (221 KB)  

    A means for increasing the effective dielectric quality factor by selective removal of dielectric from a microstrip resonator is discussed. Methods for determining the impedance and effective dielectric constant are included. The reduction in loss compared with an equivalent microstrip resonator is presented.<> View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.

Aims & Scope

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

Full Aims & Scope

Meet Our Editors

Editor-in-Chief
Britton L. T. Plourde
Syracuse University
bplourde@syr.edu
http://www.phy.syr.edu/~bplourde