1,908 Matching Results

Search Results

Advanced search parameters have been applied.

Case study on the US superconducting power transmission program

Description: After the 1911 discovery of superconductivity (the abrupt loss of electrical resistance in certain materials at very low temperatures), attempts were made to make practical use of this phenomenon. Initially these attempts failed, but in the early 1960s (after 50 years of research) they succeeded. By then, the projected growth in the production and consumption of electrical energy required much higher capacity power transmission capabilities than were available or likely to become available from incremental improvements in existing transmission technology. Since superconductors were capable in principle of transmitting huge amounts of power, research programs to develop and demonstrate superconducting transmission lines were initiated in the US and abroad. The history of the US program, including the participants, their objectives, funding and progress made, is outlined. Since the R&D program was terminated before the technology was completely demonstrated, the reasons for and consequences of this action are discussed in a final section.
Date: February 1, 1996
Creator: Hammel, E.F.
Partner: UNT Libraries Government Documents Department

Development of biaxially textured buffer layers on rolled-Ni substrates for high current YBa{sub 2}Cu{sub 3}O{sub 7{minus}y} coated conductors

Description: This paper describes the development of 3 buffer layer architectures with good biaxial textures on rolled-Ni substrates using vacuum processing techniques. The techniques include pulsed laser ablation, e-beam evaporation, dc and rf magnetron sputtering. The first buffer layer architecture consists of an epitaxial laminate of Ag/Pd(Pt)/Ni. The second buffer layer consists of an epitaxial laminate of CeO{sub 2}/Pd/Ni. The third alternative buffer layer architecture consists of an epitaxial laminate of YSZ/CeO{sub 2}/Ni. The cube (100) texture in the Ni was produced by cold rolling followed by recrystallization. Crystallographic orientations of the Pd, Ag, CeO{sub 2}, and YSZ films grown were all (100). We recently demonstrated a critical- current density of 0.73x10{sup 6} A/cm{sup 2} at 77 K and zero field on 1.4 {mu}m thick YBa{sub 2}Cu{sub 3}O{sub 7-y} (YBCO) film. This film was deposited by pulsed laser ablation on a YBCO/YSZ/CeO{sub 2}/Ni substrate.
Date: December 31, 1996
Creator: Paranthaman, M.; Goyal, A. & Norton, D.P.
Partner: UNT Libraries Government Documents Department

Medium Beta Superconducting Accelerating Structures

Description: While, originally, the development of superconducting structures was cleanly divided between low-beta resonators for heavy ions and beta=1 resonators for electrons, recent interest in protons accelerators (high and low current, pulsed and cw) has necessitated the development of structures that bridge the gap between the two. These activities have resulted both in new geometries and in the adaptation of well-known geometries optimized to this intermediate velocity range. Their characteristics and properties are reviewed.
Date: September 1, 2001
Creator: Delayen, Jean
Partner: UNT Libraries Government Documents Department

COMPUTATIONAL SIMULATION OF REFRIGERATION PROCESS FOR BEPC II SUPERCONDUCTING FACILITIES.

Description: The main challenge to build the cryogenic system for the Beijing Electron-Positron Collider Upgrade is to accommodate the strong differences among three types of superconducting devices with regard to their structure, location, as well as the cryogenic operating requirement. Three kinds of cooling methods are applied in the overall cryogenic system, saturated liquid helium cooling for the SRF cavities, single-phase helium cooling for the SCQ magnets, and two-phase helium cooling for the SSM solenoid. The optimization for the BEPCII cryogenic system was carried out by using a large-scale computational simulation package. This paper presents thermal parameters and numerical analyses for the BEPCII cryogenic system.
Date: September 22, 2003
Creator: WANG,L. JIA,L. X. DU,H. P. YANG,G. D.
Partner: UNT Libraries Government Documents Department

Experience with capture cavity II

Description: Valuable experience in operating and maintaining superconducting RF cavities in a horizontal test module has been gained with Capture Cavity II. We report on all facets of our experience to date.
Date: June 1, 2007
Creator: Koeth, T.; /Fermilab /Rutgers U., Piscataway; Branlard, J.; Edwards, H.; Fliller, R.; Harms, E. et al.
Partner: UNT Libraries Government Documents Department

Engineering Design and Fabrication of an Ampere-Class Superconducting Photocathode Electron Gun

Description: Over the past three years, Advanced Energy Systems and Brookhaven National Laboratory (BNL) have been collaborating on the design of an Ampere- class superconducting photocathode electron gun. BNL performed the physics design of the overall system and RF cavity under prior programs. Advanced Energy Systems (AES) is currently responsible for the engineering design and fabrication of the electron gun under contract to BNL. We will report on the engineering design and fabrication status of the superconducting photocathode electron gun. The overall configuration of the cryomodule will be reviewed. The layout of the hermitic string, space frame, shielding package, and cold mass will be discussed. The engineering design of the gun cavity and removable cathode will be presented in detail and areas of technical risk will be highlighted. Finally, the fabrication sequence and fabrication status of the gun cavity will be discussed.
Date: November 17, 2008
Creator: Ben-Zvi, Ilan
Partner: UNT Libraries Government Documents Department

Dynamics of Current Driven Disordered Josephson Junction Arrays

Description: We present dynamical simulations of disordered Josephson junction arrays with a bias current. We study the IV characteristics and vortex dynamics as a function of integer frustration f = n, weak frustration f = n + {delta} ({delta} {much_lt} 1) and full frustration pairs close to the critical current i{sub c}. We focus on the study of the plastic flow of vortices (f = n + {delta}), of vortex-antivortex pairs (f = n), and the dynamics of domain walls (f = n + 1/2) close to i{sub c}. We analyze the voltage noise and vortex fluctuations in the plastic flow regimes. We obtain the phase diagram for the different dynamical regimes as a function of disorder and applied current. We also study the dynamical critical behavior of depinning close to i{sub c} in the gauge glass limit of the model, f {yields} {infinity}, calculating critical exponents for the voltage onset and voltage fluctuations. We discuss our results within the context of present theories of the non-linear dynamics of disordered media.
Date: April 1, 1995
Creator: Dominguez, Daniel; Gronbech-Jensen, Niels & Bishop, Alan R.
Partner: UNT Libraries Government Documents Department

Novel low temperature superconducting bolometers

Description: We have designed and fabricated novel antenna-coupled superconducting bolometers for submillimeter and millimeter waves, which make use of the thermal boundary resistance between metals and insulators and the trapping of quasiparticles at metal-superconductor interfaces. We have used these devices to make measurements of the frequency response and optical efficiency of the log-periodic antennas between 90 GHz to 1.8 THz.
Date: November 1, 1992
Creator: Nahum, M.; Richards, P.L. (Lawrence Berkeley Lab., CA (United States)); Gaidis, M. & Prober, D.E. (Yale Univ., New Haven, CT (United States). Dept. of Applied Physics)
Partner: UNT Libraries Government Documents Department

Reduced mass persistent switches for large superconducting magnets in space

Description: Superconducting magnets in space must operate in the persistent mode. This paper describes the characteristics of low mass niobium titanium persistent switches for low mass superconducting magnets which are designed to quench protect themselves through the quench back process. (The whole coil is driven normal shortly after the quench has started and the magnet stored energy is taken up by the coil and the persistent switch.) The concept Of using a resistor and diode in parallel with the persistent switch to reduce the overall mass of the persistent switch system and the helium consumption during magnet charging is discussed in the report. A 1.4 meter diameter free-flyer version of the 11.6 Mi stored energy ASTROMAG magnet and its persistent switch is presented as an example.
Date: August 1, 1992
Creator: Green, Michael A.
Partner: UNT Libraries Government Documents Department

Assembly and testing of a composite heat pipe thermal intercept for HTS current leads

Description: We are building high temperature superconducting (HTS) current leads for a demonstration HTS-high gradient magnetic separation (HGMS) system cooled by a cryocooler. The current leads are entirely conductively cooled. A composite nitrogen heat pipe provides efficient thermal communication, and simultaneously electrical isolation, between the lead and an intermediate temperature heat sink. Data on the thermal and electrical performance of the heat pipe thermal intercept are presented. The electrical isolation of the heat pipe was measured as a function of applied voltage with and without a thermal load across the heat pipe. The results show the electrical isolation with evaporation, condensation and internal circulation taking place in the heat pipe.
Date: September 1, 1995
Creator: Daugherty, M.A.; Daney, D.E.; Prenger, F.C.; Hill, D.D.; Williams, P.M. & Boenig, H.J.
Partner: UNT Libraries Government Documents Department

A new procedure for making TEM specimens of superconductor devices

Description: A new procedure is developed for making TEM specimens of thin film devices. In this procedure the sample is flatly polished to an overall ion-mill-ready thickness so that any point in the 2-D sample pane can be thinned to an electron-transparent thickness by subsequent ion-milling. Using this procedure, small regions of interest can be easily reached in both cross-section and plan-view samples. This is especially useful in device studies. Applications of this procedure to the study of superconductor devices yield good results. This procedure, using commercially available equipment and relatively cheap materials, is simple and easy to realize.
Date: April 1, 1997
Creator: Huang, Y. & Merkle, K.L.
Partner: UNT Libraries Government Documents Department

Novel design for a high power superconducting delay line

Description: Potential designs for a high power superconducting delay line of approximately 10ms duration are described. The transmitted signal should have low dispersion and little attenuation to recapture the original signal. Such demands cannot be met using conventional metal conductors. This paper outlines a proposal for a new transmission line design using low temperature superconducting material which meets system specifications. The 25W line is designed to carry pulsed signals with an approximate rise time of 8 nsec and a maximum voltage of 25kV. Predicted electrical design and performance of the line is presented.
Date: May 8, 1997
Creator: Chen, Y. J. & Caporaso, G. J.
Partner: UNT Libraries Government Documents Department

Superconducting RF Lab Facility Upgrades at Los Alamos

Description: Research and testing of multi-cell superconducting cavities demands extensive contamination control resources to achieve high-cavity fields. Facility upgrades at Los Alamos National Laboratory (LANL) included the modernization of test equipment, expanding and modernizing cleanroom facilities, improving safety, and expanding the high-pressure rinse cleaning process equipment. Each upgrade was integrated into the facility to enable users to assemble prototype cryomodules. The scope of the upgrades, the new installed capability, and budget and schedule for certain aspects of the project are discussed in this paper.
Date: March 1, 1999
Creator: Katonak, D.J. & Rusnak, B.
Partner: UNT Libraries Government Documents Department

Shipping and Alignment for the SNS Cryomodule

Description: The Spallation Neutron Source (SNS) requires 32 super conducting cryomodules to raise the beam energy of the accelerator to 1.3 GeV. Thomas Jefferson National Accelerator Facility (Jefferson Lab) has been contracted to build and deliver these cryomodules. The SNS cryomodules are being assembled and tested at Jefferson Lab in Newport News Virginia, and installed at the SNS facility in Oak Ridge, Tennessee. The cryomodules will be transported via a flatbed air ride trailer over the approximate 500-mile distance. This paper describes the alignment of the cavities and how it is preserved during the shipping and operation of the cryomodule. It includes a description of the support scheme developed to preserve the alignment during shipping and operation, and how the support scheme forms a very rigid structure with natural frequencies well above the expected 10 Hz driving frequencies. The entire cryomodule is supported by a dampened cradle, which is mounted directly onto the bed of the trailer. The transportation environment was evaluated by instrumenting a similar cryomodule with accelerometers during a road test of approximately 300 miles. A complete modal analysis of the whole system has been performed and the steps taken to minimize any transport-induced loading/deflections are discussed.
Date: June 1, 2001
Creator: Whitlatch, T.; Curtis, C.; Daly, E.; Matsumoto, K.; Mutton, P.; Pitts, J. et al.
Partner: UNT Libraries Government Documents Department

TUNE FEEDBACK AT RHIC

Description: Preliminary phase-locked loop betatron tune measurement results were obtained during RHIC 2000 with a resonant Beam Position Monitor. These results suggested the possibility of incorporating PLL tune measurement into a tune feedback system for RHIC 2001. Tune feedback is useful in a superconducting accelerator, where the machine cycle time is long and inefficient acceleration due to resonance crossing is not comfortably tolerated. This is particularly true with the higher beam intensities planned for RHIC 2001. We present descriptions of a PLL tune measurement system implemented in the DSP/FPGA environment of a RHIC BPM electronics module and the feedback system into which the measurement is incorporated to regulate tune. In addition, we present results from the commissioning of this system during RHIC 2001.
Date: June 18, 2001
Creator: Cameron, P.; Cerniglia, P.; Connoly, R.; Cupolo, J.; Dawson, W. C.; Degen, C. et al.
Partner: UNT Libraries Government Documents Department

Testing Procedures and Results of the Prototype Fundamental Power Coupler for the Spallation Neutron Source

Description: High-power RF testing with peak power in excess of 500 kW has been performed on prototype Fundamental Power Couplers (FPC) for the Spallation Neutron Source superconducting (SNS) cavities. The testing followed the development of procedures for cleaning, assembling and preparing the FPC for installation in the test stand. The qualification of the couplers has occurred for the time being only in a limited set of conditions (travelling wave, 20 pps) as the available RF system and control instrumentation are under improvement.
Date: June 1, 2001
Creator: Stirbet, M.; Campisi, I.E.; Daly, E.F.; Davis, G.K.; Drury, M.; Kneisel, P. et al.
Partner: UNT Libraries Government Documents Department

A test of a superconducting solenoid for the MuCool RF experiment

Description: This report describes the results of a series of tests of a 440-mm warm bore split solenoid used for testing 805 MHz RF cavities. The solenoid consists of two coils each 250-mm long separated by a gap of 140 mm. The solenoid was designed to operate in two modes; a solenoid mode with the two coils hooked in the same polarity and a gradient mode with the two coils hooked in opposite polarity. In the solenoid mode, the magnet is designed to produce an induction of 5 T over a region that is about 400 mm long. In the gradient mode, the solenoid produces a field gradient of 25 T per meter along the axis over a distance of about 300-mm. The solenoid was designed to carry a force of over 3 MN that pushes the two coils apart, when the magnet is operated in the gradient mode. In order to carry this force, the coils are encased within aluminum shells, both inside and outside. Since this solenoid is encased in aluminum and the coils are potted, training was observed. The magnet training history and magnet field measurements are presented in this report.
Date: August 12, 2000
Creator: Green, Michael A.; Chen, J.Y. & Wang, S.T.
Partner: UNT Libraries Government Documents Department

Prototype 350 MHz niobium spoke-loaded cavities.

Description: This paper reports the development of 350 MHz superconducting cavities of a spoke-loaded geometry, intended for the velocity range 0.2 < v/c < 0.6. Two prototype single-cell cavities have been designed, one optimized for velocity v/c = 0.4, and the other for v/c = 0.29. Construction of the prototype niobium cavities is nearly complete. Details of the design and construction are discussed, along with the results of cold tests.
Date: May 10, 1999
Creator: Delayen, J. R.; Kedzie, M.; Mammosser, J.; Piller, C. & Shepard, K. W.
Partner: UNT Libraries Government Documents Department

Design and development of the vacuum systems for the APT project ED & D cryomodule

Description: The mechanical design for both the insulating vacuum system and the cavity vacuum system of the APT ED and D Cryomodule is summarized. The pre-cooldown pressure limits for the insulating vacuum and the cavity vacuum are 10{sup {minus}5} Torr and 10{sup {minus}6} Torr, respectively. In addition, the cold cavity operating pressure limits are 10{sup {minus}6} Torr for the insulating system and 10{sup {minus}8} Torr for the cavity system. The designs of these systems utilize both turbomolecular pumps and the cold surfaces of the superconducting Nb cavities to arrive at and maintain their operating vacuum pressures. A synopsis of the analysis undertaken to predict the vacuum system performance is also presented.
Date: March 25, 1999
Creator: Hansen, G; Kishiyama, K; Shen, S & Shoaff, P V
Partner: UNT Libraries Government Documents Department

First Lasing of the Jefferson Lab IR Demo FEL

Description: As reported previously [1], Jefferson Lab is building a free-electron laser capable of generating a continuous wave kilowatt laser beam. The driver-accelerator consists of a superconducting, energy-recovery accelerator. The initial stage of the program was to produce over 100 W of average power with no recirculation. In order to provide maximum gain the initial wavelength was chosen to be 5 mu-m and the initial beam energy was chosen to be 38.5 MeV. On June 17, 1998, the laser produced 155 Watts cw power at the laser output with a 98% reflective output coupler. On July 28th, 311 Watts cw power was obtained using a 90% reflective output coupler. A summary of the commissioning activities to date as well as some novel lasing results will be summarized in this paper. Present work is concentrated on optimizing lasing at 5 mu-m, obtaining lasing at 3 mu-m, and commissioning the recirculation transport in preparation for kilowatt lasing this fall.
Date: May 1, 1999
Creator: Benson, Stephen; Biallas, George; Bohn, Court; Douglas, David; Dylla, H.F.; Evans, R. et al.
Partner: UNT Libraries Government Documents Department

Toward a fourth-generation x-ray source.

Description: The field of synchrotron radiation research has grown rapidly over the last 25 years due to both the push of the accelerator and magnet technology that produces the x-ray beams and the pull of the extraordinary scientific research that is possible with them. Three successive generations of synchrotrons radiation facilities have resulted in beam brilliances 11 to 12 orders of magnitude greater than the standard laboratory x-ray tube. However, greater advances can be easily imagined given the fact that x-ray beams from present-day facilities do not exhibit the coherence or time structure so familiar with the optical laser. Theoretical work over the last ten years or so has pointed to the possibility of generating hard x-ray beams with laser-like characteristics. The concept is based on self-amplified spontaneous emission (SASE) in flee-electron lasers. A major facility of this type based upon a superconducting linac could produce a cost-effective facility that spans wave-lengths from the ultraviolet to the hard x-ray regime, simultaneously servicing large numbers experimenters from a wide range of disciplines. As with each past generation of synchrotrons facilities, immense new scientific opportunities would result from fourth-generation sources.
Date: May 19, 1999
Creator: Monction, D. E.
Partner: UNT Libraries Government Documents Department

Model for l/f Flux Noise in SQUIDs and Qubits

Description: We propose a model for 1/f flux noise in superconducting devices (f is frequency). The noise is generated by the magnetic moments of electrons in defect states which they occupy for a wide distribution of times before escaping. A trapped electron occupies one of the two Kramers-degenerate ground states, between which the transition rate is negligible at low temperature. As a result, the magnetic moment orientation is locked. Simulations of the noise produced by a plausible density of randomly oriented defects yield 1/f noise magnitudes in good agreement with experiments.
Date: January 19, 2007
Creator: Koch, Roger H.; DiVincenzo, David P. & Clarke, John
Partner: UNT Libraries Government Documents Department