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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,I.
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

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

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, D.; Gronbech-Jensen, N. & Bishop, A.R.
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

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, M.A.
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

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

The integration of liquid cryogen cooling and cryocoolers withsuperconducting electronic systems

Description: The need for cryogenic cooling has been a critical issuethat has kept superconducting electronic devices from reaching the marketplace. Even though the performance of many of the superconductingcircuits is superior to silicon electronics, the requirement forcryogenic cooling has put the superconducting devices at a seriousdisadvantage. This report discusses the process of refrigeratingsuperconducting devices with cryogenic liquids and small cryocoolers.Three types of cryocoolers are compared for vibration, efficiency, andreliability. The connection of a cryocooler to the load is discussed. Acomparison of using flexible copper straps to carry the heat load andusing heat pipe is shown. The type of instrumentation needed formonitoring and controlling the cooling is discussed.
Date: July 9, 2003
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

Gravity gradiometry on high-T{sub c} superconducting sensors

Description: This is the final report of a 1-y LDRD project at LANL. Earth`s gravitational field has minuscule local variations that are difficult to observe with any but the most sensitive instruments. These variations are caused by local variations in the earth`s crust density such as voids or high density material. Such anomalies can be observed directly by mapping the magnitude of the gravitational field (gravimetry) or by measuring the gradient of the gravitational field (gradiometry). It is believed that gradiometry is potentially superior to gravimetry because measurement and interpretation is simpler and less susceptible to masking by other effects, e.g. accelerations. This method introduces no energy or radiation into the region of interest, can be adapted to moving platforms and the capability to take real-time data over large areas is feasible. Scope of this work was to examine feasiiblity and performance of a fieldable gradiometer using high-{Tc} materials.
Date: September 1, 1996
Creator: Kraus, R.; Cogbill, A. & Stettler, M.
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

A SUPER-CONDUCTING LINAC INJECTOR FOR THE BNL-AGS.

Description: This paper reports on the feasibility study of a proton Super-Conducting Linac (SCL) as a new injector to the Alternating Gradient Synchrotron (AGS) of the Brookhaven National Laboratory (BNL). The Linac beam energy is in the range of 1.5 to 2.4 GeV. The beam intensity is adjusted to provide an average beam power of 4 MW at the top energy of 24 GeV. The repetition rate of the SCL-AGS facility is 5 beam pulses per second.
Date: August 21, 2000
Creator: Raparia, D. & Ruggiero, A.G.
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