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Applied Superconductivity, IEEE Transactions on

Issue 4 • Date Dec. 2003

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Displaying Results 1 - 13 of 13
  • Temperature dependence performances of fully integrated DC SQUID magnetometers

    Publication Year: 2003 , Page(s): 3829 - 3832
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (415 KB) |  | HTML iconHTML  

    Temperature dependence of the main characteristics of integrated dc superconducting quantum interference device magnetometers based on niobium technology including an additional positive feedback circuit is reported. Temperatures above 4.2 K have been considered. A nonlinear temperature dependence of the spectral density of the field noise has been observed. The reported measurements show a slow increasing of the field noise up to temperatures of about 5 K, giving a considerable tolerance of the working temperature of niobium magnetometers in some innovative multichannel systems for magnetoencephalography. View full abstract»

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  • Corrections to "Temperature and frequency effects in a high-performance superconducting bearing"

    Publication Year: 2003 , Page(s): 3873 - 3874
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  • Corrections to "The LHC main dipoles and quadrupoles toward series production"

    Publication Year: 2003 , Page(s): 3875 - 3876
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  • Author Index

    Publication Year: 2003 , Page(s): 3878 - 3931
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    Freely Available from IEEE
  • Subject index

    Publication Year: 2003 , Page(s): 3931 - 4012
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  • Microstructures of epitaxial YBa2Cu3O7-δ thick films grown by photoassisted metal-organic chemical vapor deposition

    Publication Year: 2003 , Page(s): 3839 - 3844
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (593 KB)  

    Epitaxial, high-quality YBa2Cu3O7-δ (YBCO) thick films were grown by a photoassisted metal-organic chemical vapor deposition technique with a single liquid precursor delivery system, and characterized by X-ray diffraction (XRD), scanning electron microscopy, and low-high-resolution transmission electron microscopy techniques. Very dense and single-crystal-like film structure was observed in all of these YBCO thick films. Large precipitates on these thick films were identified as BaCu3O4, sprinkled only at surface of these YBCO thick films. YBCO thick films with high crystalline and superconductive quality were confirmed by data of XRD analyses and superconductivity measurements. At the same time, the reason why epitaxial YBCO thick films with high-quality single-crystal-like structure can be grown up to about 4.5 μm thick is illustrated from the point of view of photoactivation. It is also found that these thick films were optimally oxygenated with their superconductive properties in concern. View full abstract»

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  • Quench analysis of a superconducting magnet with 98 coils connected in series

    Publication Year: 2003 , Page(s): 3845 - 3855
    Cited by:  Papers (1)
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    A novel insertion device for electron storage rings called the MAX-Wiggler has been constructed at MAX-lab. The MAX-Wiggler is a cold bore superconducting wiggler magnet with 47 3.5-T poles and a period length of 61 mm aimed for the production of X-rays at the 1.5-GeV electron storage ring MAX-II at MAX-lab. The MAX-Wiggler consists of 98 racetrack coils connected in series in the superconducting magnet and the total stored magnetic energy at the nominal maximum field strength of 3.5 T is 48 kJ. This paper describes the quench analysis of the magnet. Several protection schemes have been evaluated, such as an external dump resistor and safety switch or subdivision of the series of coils into sections with shunt resistors or silicon diodes in parallel to each group of coils in a section. It has been found that the most suitable protection scheme, in order to prevent the superconducting coils from getting overheated, is subdivision with a shunt path containing silicon diodes operating at liquid helium temperatures. The MAX-Wiggler has been commissioned and it has survived the quenches occurring during the initial training of the superconducting coils. View full abstract»

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  • An experimental study of harmonic SIS mixing at 205-235 GHz

    Publication Year: 2003 , Page(s): 3856 - 3861
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    A 230-GHz subharmonically pumped waveguide mixer employing superconducting tunnel junctions has been developed. We present, in this paper, an experimental study of harmonic superconductor-insulator-superconductor (SIS) mixing at 230 GHz, focusing mainly on its noise behavior. The mixer has a double-tuned waveguide structure and employs an array of four 1.7-μm2 Nb-AlOx-Nb SIS junctions in series, with ωRnCj∼3 at 230 GHz. Harmonic quantum mixing occurred over an experimental frequency range of 205-235 GHz (local oscillator: 112.5-117.5 GHz), exhibiting corresponding double sideband noise temperatures of lower than 150 K, with a lowest value of 75 K at ∼230 GHz. The measured mixer noise is believed to be the lowest yet reported for a mixer using subharmonic-pump configuration at this frequency. A phenomenon that we attribute to the third harmonic SIS mixing has also been observed. View full abstract»

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  • Effect of thermo-mechanical stress during quench on nb sn cable performance

    Publication Year: 2003 , Page(s): 3877
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  • Recording fetal and adult magnetocardiograms using high-temperature Superconducting quantum interference device gradiometers

    Publication Year: 2003 , Page(s): 3862 - 3866
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (393 KB) |  | HTML iconHTML  

    In this paper, we analyze the influence of the superconducting quantum interference device (SQUID) gradiometer baseline on the recording of magnetocardiographic measurements. The magnetometers consist of high-temperature superconducting radio-frequency SQUIDs fabricated from YBaCuO thin films, and a substrate resonator which serves as tank circuit. The gradiometers are formed using two or three such magnetometers with individual readouts in electronic difference. We have compared the measurement results using a magnetometer and first- and second-order gradiometers with different baselines. In a standard magnetically shielded room, we found not only an increasing signal-to-noise ratio in adult magnetocardiographic measurements, but also a decreasing distortion of the magnetic field map with increasing baseline of the gradiometer. Using a first-order gradiometer with an ultralong baseline of 18 cm, we have successfully measured the heart signal of a fetus in real time. View full abstract»

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  • High-speed bit-error-rate measurement system for high-temperature superconducting digital circuits

    Publication Year: 2003 , Page(s): 3833 - 3838
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (619 KB) |  | HTML iconHTML  

    We have investigated and tried to improve the packaging technologies for a bit-error-rate (BER) measurement system for high-Tc superconducting circuits. Signal cables, test fixture, and magnetic shields were specially designed and assembled for the BER measurement system, taking into account electrical losses, signal reflection, heat inflow, and power consumption of a cryocooler. BER was further improved by changing the way of connection between the semiconductor amplifiers outside the sample vacuum chamber. These improvements led to a BER less than 10-12 at an output voltage (Vout) of 1.7 and 2.3 mV for a 50-Ω standard microstrip transmission line and a superconducting microstrip-line to coplanar-waveguide transmission-line converter, respectively. The temperature rise of the test fixture was as low as about 2 K. These values are approximately one order of magnitude smaller than those in the previous measurement system and small enough to be achieved by using superconducting interface circuits. Furthermore, 1-Gb/s operation of a superconducting quantum interference device array-type interface circuit was demonstrated in the BER measurement system at 40 K. View full abstract»

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  • Numerical Simulation of quantized voltage steps in overdamped Josephson junctions controlled by simple pulse codes

    Publication Year: 2003 , Page(s): 3825 - 3828
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (288 KB) |  | HTML iconHTML  

    Shapiro steps crossing the zero-current axis, i.e., zero-crossing steps, in the overdamped Josephson junction driven with a simple pulse code consisting of single and multiple pulses in each repetition period are studied based on numerical simulations. In this study, it is confirmed that the quantized voltage at which the zero-crossing step appears can be controlled by the number of the additional pulses without changing current bias range. The case in which the additional pulses having small fluctuations in phase is also considered. No visible effect of the fluctuations on the current position of the Shapiro steps is observed, so that the current range with respect to the phase lock between the Josephson oscillation and the pulse code is determined by the number of pulses. View full abstract»

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  • A high-temperature superconducting Butler matrix

    Publication Year: 2003 , Page(s): 3867 - 3872
    Cited by:  Papers (16)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (616 KB)  

    This paper presents a novel configuration of a beamforming 16-port Butler matrix centered on a frequency of 2 GHz. The structure is implemented using high-temperature superconductors (HTS). In communication and remote sensing systems, multibeam antenna systems are gradually replacing single-beam systems. Microwave beamformer circuits for these applications require a large number of couplers and phase shifters, which result in a large circuit size. By using microstrip structures on high permittivity substrates, the circuits can be miniaturized. However, the insertion loss of the beamformer increases due to the conductor loss. The use of HTS allows reduction in the size of the circuit while maintaining low insertion loss, due to the low conductor loss compared to conventional conductors. The Butler matrix described here uses a two-layer configuration, which removes any microstrip line crossovers; it can be constructed by traditional photolithographic methods. In this paper, the design of the matrix is discussed, together with the experimental and simulated results. 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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Meet Our Editors

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