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Applied Superconductivity, IEEE Transactions on

Issue 1  Part 2 • Date March 2001

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Displaying Results 1 - 25 of 298
  • Conference Author Index

    Publication Year: 2001 , Page(s): 2638 - 2655
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    Freely Available from IEEE
  • Design, fabrication and tests of a 600A HTc current lead for the LHC correction magnets

    Publication Year: 2001 , Page(s): 2543 - 2546
    Cited by:  Papers (8)
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    This paper describes the design and fabrication of four sets of HTc 600 A current leads manufactured by ANTEC in collaboration with three more Institutes to test the feasibility of industrial fabrication of these units. This development has been made in the framework of a CERN programme to build low thermal losses leads for the correction magnets of the LHC. Tests performed at the manufacturer installations are also presented View full abstract»

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  • Optimization of winding geometry of Bi(2223)Ag coils with respect to external magnetic field

    Publication Year: 2001 , Page(s): 2324 - 2327
    Cited by:  Papers (6)
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    A theoretical model, which enables to estimate the critical currents distribution in the winding of HTS cylindrical coils exposed to external magnetic field, was developed. The model takes into account the real angular dependence (anisotropy) of the Ic(B) characteristic of Bi(2223)Ag tape. It is shown how the change in the winding geometry within the same overall tape length and the value of applied external magnetic field parallel with the magnet axis influences both, the critical current and the resulting magnetic field generated by the magnet itself. It is predicted that applying a low magnetic field parallel to the HTS magnet axis may result in a relatively high increase in the magnet critical current (up to 30-40%) if compared with the magnet critical current achieved without the presence of external magnetic field. An example of optimizing the magnet winding geometry by using the different lengths of the Bi(2223)Ag multifilamentary tape of Vacuumschmelze GmbH production is presented View full abstract»

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  • Transport performance of Bi-2212 current leads prepared by a diffusion process

    Publication Year: 2001 , Page(s): 2555 - 2558
    Cited by:  Papers (3)
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    Bi-2212 bulk cylinders have been prepared by the diffusion process for current lead application. The Bi-2212 oxide superconducting layer is synthesized through the reaction between a Sr-Ca-Cu oxide tubular substrate and a Bi-Cu oxide coating layer with Ag addition. The Bi-2212 diffusion layer about 150 μm in thickness with textured structure formed around a tube 20/16 mm in outside/inside diameter. The transport current of the tube specimen exceeds 6.250 A at 4.2 K under self-field, which corresponds to a transport current density of 35,000 A/cm2 . The overall joint resistance is measured to be about 150 mΩ at both ends of the specimen, composed of Cu endcap, Sn-Pb solder and Ag contact on the specimen. The resistivity of the commercial Sn-Pb solders is About 2 nΩm at 4.2 K, and one order of the magnitude higher than that of Cu and Ag. Therefore, the soldering process is important in reducing the joint resistance and the resultant Joule heat. Present Bi-2212 bulk conductors with large transport current are promising as current leads for superconducting magnets View full abstract»

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  • Progress of LHC low-β quadrupole magnets at KEK

    Publication Year: 2001 , Page(s): 1562 - 1565
    Cited by:  Papers (16)
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    Development of the LHC low-β insertion quadrupole magnet has been in progress at KEK since 1995 as a cooperative program between CERN and KEK. Five 1-m short model magnets have been fabricated and three of them have been tested. From the various test results of the first two models, the coil configuration was further optimized to reduce the higher magnetic field harmonic coefficients. The cold test of the third model showed satisfactory performances of the field harmonics. After this R&D work, the authors are at a stage for the fabrication of two prototype magnets which have the same scale as the production magnets. The status of the R&D for the LHC low-beta insertion quadrupole magnet at KEK is described View full abstract»

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  • Analysis of the operational characteristics of discrete-sheet type low-Tc superconducting power supply

    Publication Year: 2001 , Page(s): 2339 - 2342
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    This paper deals with comparison of characteristics of continuous-sheet type low-Tc superconducting (LTS) power supply and discrete-sheet type LTS power supply. These characteristics have been analyzed through experiments. These power supplies consist of two exciters, a rotor, a stator, and LTS Load. A continuous-sheet type has a single continuous niobium (Nb) sheet attached to the inner surface of on the stator. In the case of discrete-sheet type, four separated Nb sheets are used. This experiment uses a 1.81 mH LTS magnet load and maximum 30 A DC exciter current. A discrete-sheet type is expected to produce much better pumping rate than a continuous-sheet type. The experimental observations have been compared with the theoretical predictions. In this experiment, the maximum pumping-current has reached about 926 A View full abstract»

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  • Superconducting vibrator for low frequency emission

    Publication Year: 2001 , Page(s): 2328 - 2330
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    The feasibility of superconducting magnets using low frequency generators is investigated. Namely superconducting magnet systems consisting of two coaxial DC coils and operating as a magnetic quadrupole is developed. This system generates a radial magnetic field up to 1 T in a “warm” volume of 16 cm in diameter and 20 cm long. In this nearly space-constant field a copper coil is placed at a temperature of 77 K. This coil is energized with DC and AC current in the 1-100 Hz range. Forces and characteristic of the forced vibration of both rotor and rotor with iron core are calculated and measured. An influence of AC magnetic field of the copper coil on losses in the superconducting windings is analyzed measured by a thermocouple inside the winding View full abstract»

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  • Calorimetric measurements of losses in HTS cables

    Publication Year: 2001 , Page(s): 1777 - 1780
    Cited by:  Papers (3)
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    A calorimetric test rig is used to investigate various loss components in a 10 m long superconducting cable model. A calorimetric technique, based on thermocouple measurements, is used to measure the losses of the 10 m long superconducting cable model. The current dependent losses are also measured electrically and compared with the losses obtained with the calorimetric method. The results obtained by the two methods are consistent. Based on an I2 (current) fitting procedure, the loss, caused by the eddy current generated in the stainless steel cryostat housing, and the hysteresis loss generated in the conductor can be separated. From this result, it appears that the two contributions are roughly equal in size View full abstract»

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  • Effect of the geometry of HTS on AC loss by using finite element method simulation with B-dependent E-J power law

    Publication Year: 2001 , Page(s): 2627 - 2630
    Cited by:  Papers (8)
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    Mono and multifilamentary HTS tapes exhibit nonnegligible AC loss in self-field and considerably higher losses in the presence of external magnetic field. The effect of the conductor's geometry on the AC loss has been investigated in this paper. The nonlinear electromagnetic properties of the superconducting material are expressed with a B-dependent E-J power law and are implemented in finite element method commercial software. The critical current density and the power index n dependence on B are obtained from DC measurements of a real Bi-2223 tape. AC loss comparison between monofilamentary conductors of rectangular, elliptical, square and round geometry has been performed in self-field and applied external perpendicular magnetic field. The areas of the cross-section and the superconducting-core-to-Ag ratio have been kept constant in the simulations. To complement the AC loss analysis, the distribution of the current density and the magnetic field of the different geometries are presented View full abstract»

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  • Design, fabrication and test of the react and wind, Nb3Sn, LDX floating coil conductor

    Publication Year: 2001 , Page(s): 1869 - 1872
    Cited by:  Papers (5)  |  Patents (3)
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    The Levitated Dipole Experiment (LDX) is a novel approach for studying magnetic confinement of a fusion plasma. In this approach, a superconducting ring coil is magnetically levitated for up to 8 hours a day in the center of a 5 meter diameter vacuum vessel. The levitated coil, with on-board helium supply, is called the floating coil (F-Coil). Although the maximum field at the coil is only 5.3 tesla, a react-and-wind Nb3Sn conductor was selected because the relatively high critical temperature will enable the coil to remain levitated while it warms from 5 K to 10 K. Since prereacted Nb3 Sn tape is no longer commercially available, a composite conductor was designed that contains an 18 strand Nb3Sn Rutherford cable. The cable was reacted and then soldered into a structural copper channel that completes the conductor and also provides quench protection. The strain fabrication steps such as: soldering into the copper channel, spooling, and coil winding, to prevent degradation of the critical current. Measurements of strand and cable critical during state of the cable was continuously controlled currents are reported, as well as estimates fabrication, winding and operating strains on critical current View full abstract»

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  • HTS materials for AC current transport and fault current limitation

    Publication Year: 2001 , Page(s): 2503 - 2506
    Cited by:  Papers (4)  |  Patents (3)
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    The European SUPERPOLI project aims to define a MV fault current limiting power link, and to demonstrate its feasibility by a functional model. It includes the development of two alternative low-AC-loss conductor designs suitable for current limitation: a low-cost composite tubular Bi-2212 conductor with moderate Jc; and a coated tubular Y-123 conductor, presenting a very high Jc. BSCCO tubes are developed by Alcatel HTS (length: 650 mm and diameter: 50 mm) with silver contacts on both ends. These tubes have an effective thickness of the superconducting layer of 1.5 mm. This layer is reinforced by an additional nonsuperconducting layer in order to increase mechanical stability. Based on theoretical simulations, Alcatel HTS seeks to develop tubes with a Jc scattering lower than 2%. The main issue with Y-123 films is to find a way for producing them in long reproducible lengths. A novel high rate PLD technique with a repetition rate of 300 Hz has been developed and used for manufacturing films on large-area substrates, made of flexible stainless steel foils buffered by IBAD. The largest samples prepared are of 34 mm×1 m in size, and present a Jc of 4000 A/mm2 (77 K self-field). For a sample with dimensions of 10 mm×0.5 m, Jc exceeds 6000 A/mm2 View full abstract»

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  • A diagnosis method for properties of superconducting magnet using fast current discharge

    Publication Year: 2001 , Page(s): 2595 - 2598
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    The authors studied a diagnosis method to investigate the properties of superconducting magnets throughout their life. The magnet current, initially held constant, is damped with a short time constant. One can evaluate the properties of the magnet using the normal voltage, which may appear during the damping phase. A bridge circuit, which can adjust both amplitude and phase with over five orders of accuracy, was developed to measure unbalance voltages. Experiments were carried out using a small solenoidal NbTi magnet. By adjusting bridge parameters and numerically processing the voltage waveform, the authors measured the normal transition voltage with the S/N ratio of over 10-4 in the damping phase. The applicability of the diagnosis method was studied in both numerical simulations and experiments View full abstract»

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  • Experimental study on sudden-short-circuit characteristic of synchronous generator with SCFCL

    Publication Year: 2001 , Page(s): 2343 - 2346
    Cited by:  Papers (17)
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    Superconducting fault current limiters (SCFCLs) are expected to improve the reliability of power systems. An SCFCL of a transformer type with adjustable trigger current level was proposed. Three SCFCLs of this type for 3-phase AC power source were designed and made. The trigger current level of each trial SCFCL can be adjusted to equal value, and the SCFCLs can be used as a 3-phase SCFCL. As preliminary tests, sudden-short circuit tests with a 20 kVA synchronous generator are carried out. Limiting tests of the 3-phase SCFCL at fault are carried out with the synchronous generator. The effect of 3-phase SCFCL and the characteristics of the synchronous generator are studied experimentally View full abstract»

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  • Development of react and wind common coil dipoles for VLHC

    Publication Year: 2001 , Page(s): 2172 - 2175
    Cited by:  Papers (3)
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    Common coil magnets are a promising option for post LAC hadron colliders. Fermilab, in collaboration with LBNL, is involved in an R&D program to develop 11 T, 30-40 mm aperture, common coil dipoles. The use of Nb3Sn wound after reaction is chosen in order to address cost reduction that is a key issue for future hadron colliders. The common coil design concept allows a large bending radius at the coil ends and is well suited to the react-and-wind technique with brittle superconductors. The horizontal component of the magnetic forces in a common coil is larger than the radial component in a shell type layout, imposing demanding requirements on the mechanical structure. Both a 2-layer and a single layer design have been studied. The development of the program is presented focusing on the mechanical designs and assembly techniques. R&D activities and plans are also presented View full abstract»

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  • Scaling laws for modeling large superconducting solenoids

    Publication Year: 2001 , Page(s): 2292 - 2295
    Cited by:  Papers (1)
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    The neutrino factory cooling system will consist of a long series of superconducting solenoids with a warm bore of 1.2 meters. In order to minimize the cost of the 200 to 300-meter long solenoid muon-cooling channel, the solenoids must be fabricated so that their mass is minimized. This report discuses how one can model the stress, strain and quench behavior of these large solenoid sections by building one-third to one-half scale models of the magnets. The cost of building and engineering the scale model magnets is a small fraction of the cost of fabricating a full-scale magnet section. This report discusses the limitations of the scaling approach as well as the types of superconducting solenoids for which the modeling technique is suitable View full abstract»

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  • 12 Tesla hybrid block-coil dipole for future hadron colliders

    Publication Year: 2001 , Page(s): 2264 - 2267
    Cited by:  Papers (3)
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    A hybrid-coil Nb3Sn/Cu dipole is being developed for use in future hadron colliders. It features stress management within the coil, and the use of pure Cu strands within the coil to minimize the quantity of superconductor while providing quench protection. A first 7 Tesla NbTi model of the design has been built and will soon be tested. Two designs for the first Nb3Sn model have been prepared. In one version, the placement of coil blocks and the inside contour of the steel flux return are shaped to achieve collider-quality field over a 20:1 dynamic range of operating field. In the other version, the flux return provides a close-coupled planar boundary that suppresses persistent-current multipoles by a factor 20, and the same dynamic range is achieved using current programming of the inner and outer coil elements. Both versions use the least superconductor of any high-field collider dipole design View full abstract»

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  • Three-phase fault current limiter with one DC S/N transition element

    Publication Year: 2001 , Page(s): 2398 - 2401
    Cited by:  Papers (4)
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    The authors developed a DC S/N transition type three-phase fault current limiter, the primary element of which, is made of the superconducting bulk material, Bi-2223. This element is connected to secondary windings of transformers, through a modified half control bridge. This unique, single element device simultaneously limits and interrupts fault current, in three-phase power systems. This paper describes the results of tests, using a small scale model and simulation results View full abstract»

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  • Analysis of current after normal transition in a cable-in-conduit conductor

    Publication Year: 2001 , Page(s): 2575 - 2578
    Cited by:  Papers (1)
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    When some strands carry a large current as a result of current imbalance, they may initially become normal and the current is transferred to other superconducting strands. A one-dimensional simulation code for stability and quench of a cable-in-conduit conductor is improved to study this phenomenon using an infinitely long distributed circuit model, in which the current can easily be calculated. The results show the normal zone propagation plays a significant role in the current decay. Also, they are indicated that the conductor is more stable for higher conductance but the stability of the conductor seems more important to prevent instability due to the current imbalance View full abstract»

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  • Field quality in Fermilab-built models of quadrupole magnets for the LHC interaction region

    Publication Year: 2001 , Page(s): 1566 - 1569
    Cited by:  Papers (8)
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    Superconducting quadrupole magnets for the interaction regions of the Large Hadron Collider are being developed by the US-LHC Accelerator Project. These 70 mm bore quadrupole magnets are intended to operate in superfluid helium at 1.9 K with a nominal field gradient of 215 T/m. A series of 2 m model magnets has been built and cold tested at Fermilab to optimize their design and construction and to study the performance of the magnets. Field measurements of the 8 model magnets and comparisons with the required field quality are reported in this paper View full abstract»

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  • Test results of compensation for load fluctuation under a fuzzy control by a 1 kWh/1 MW SMES

    Publication Year: 2001 , Page(s): 1908 - 1911
    Cited by:  Papers (2)
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    A full system of 1 kWh/1 MW SMES (superconducting magnetic energy storage) has been completed. This SMES is the first step to the realization of practical SMES system for power line control. In the field tests the SMES, its function for compensating load fluctuation of 6 kV distribution line with fuzzy control applied, was confirmed. The fuzzy control of the SMES interprets whether power variation in the distribution line increases or decreases. It interprets concurrently whether the energy capacity stored in the SMES increases or decreases. In the tests, the calculated theoretical values almost coincident well with experimental values under the fuzzy control. The test results proved the effectiveness of the fuzzy control system of SMES. These results might be useful for the design of the next larger scale SMES View full abstract»

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  • Pre-industrialization activities related to CMS coil winding

    Publication Year: 2001 , Page(s): 1717 - 1720
    Cited by:  Papers (3)
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    The CMS coil is a large 4 layer superconducting solenoid involving the use of a new design reinforced conductor. In order to understand the feasibility of the coil manufacture using the inner winding technique for this particular conductor, the CMS Collaboration has developed a pre-industrialization activity. The main objectives were: (1) study of the methods for winding a coil using a stiff conductor; (2) design, construction and testing of a prototype winding line; and (3) construction of a model for the fine tuning of the required operation and procedures. The activities, carried out in cooperation with industry, were successfully completed, giving basic information for the necessary tool and methods to be used for the coil winding View full abstract»

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  • AC loss properties of a 1 MVA single-phase HTS power transformer

    Publication Year: 2001 , Page(s): 1482 - 1485
    Cited by:  Papers (38)
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    We designed and built a single-phase 1 MVA-22/6.9 kV HTS transformer with the multi-layered cylindrical windings composed of Bi2223 parallel conductors. In advance of the design, the AC loss induced in the windings was estimated on the basis of the observed results in a strand. A subcooled liquid nitrogen cryogenic system with the corresponding cooling capacity was developed and attached to the transformer. The actual AC loss was measured by an electrical method. It was a great part of the total heat load and dominated the temperature rise of subcooled liquid nitrogen. We discussed the validity of the present estimation procedure of the AC loss in the windings as compared with the observed results View full abstract»

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  • Improvement of a magnetically levitated stepping motor using high T c bulk superconductor

    Publication Year: 2001 , Page(s): 1972 - 1975
    Cited by:  Papers (2)
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    A magnetically levitated stepping motor using high Tc superconductor has been studied. The levitated stepping motor consists of a cylindrical rotor with superconductors and a stator with eight electromagnets. The rotor measures 10 mm in diameter, 46 mm in length, and 18 g in mass. The superconductors of the rotor are field-cooled in liquid nitrogen. The levitated rotor is driven by four-phase and eight-phase excitations. The rotation angles by each step are 90 and 35 deg, respectively. The rotor spins as the excitation phase shifts one by one. This paper discusses the dynamics of the motor driven by the four-phase and eight-phase excitations View full abstract»

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  • Design and test results of 6.6 kV high-Tc superconducting fault current limiter

    Publication Year: 2001 , Page(s): 2511 - 2514
    Cited by:  Papers (33)
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    A 6.6 kV single-phase fault current limiter (FCL) using a high-Tc superconducting coil as a limiting coil was developed. The development is a preliminary step to investigate the feasibility of the FCL application for high-voltage transmission lines. The FCL is of the rectifier type and is mainly comprised of a limiting coil, a sub-cooled nitrogen cryostat with a cryocooler, and a rectifier bridge. The limiting coil, wound as a solenoid by Ag/Mn sheathed Bi-2223 tapes, has an inductance of 30 mH. It is immersed in a liquid nitrogen bath in the cryostat. A Gifford-McMahon cryocooler cools the cryogen below 77.3 K. A pressure regulator keeps the cryogen at an atmospheric pressure. The coil has a critical current of 70 A at 64 K and endures a 50 Hz overvoltage of 22 kV against the ground. In a fault current limiting test with a short-circuit generator, a short-circuit current of 12.5 kA was limited to 1.2 kA View full abstract»

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  • Optimization of high-temperature superconducting power transformers

    Publication Year: 2001 , Page(s): 1574 - 1577
    Cited by:  Papers (5)
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    The discovery of high-temperature superconductors in 1987 opened new opportunities in the design of power supply equipment. The advantages of a transformer with high-temperature superconducting windings have been discussed and presented in several papers in the past. The design of transformers depends on the operation requirements and the installed position in the power network. In this paper the fundamental equations for the design of transformers are discussed and modified in such a way that an optimization of HTS transformers can be successfully studied. The best design in terms of low load losses or low no-load losses is calculated for different power transformers considering the volume of the transformer and the impedance voltage. The resulting “growth laws” are discussed and analyzed View full abstract»

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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://www.phy.syr.edu/~bplourde