20 Matching Results

Search Results

Advanced search parameters have been applied.

Ultra purification of metals by electrotransport under outer space environmental condition. Final report, April 1, 1974--September 30, 1976. [2 x 10/sup -12/ torr]

Description: A space simulation chamber capable of achieving pressures of 2 x 10/sup -12/ torr (N/sub 2/) was designed, fabricated, and used to develop a preprototype electrotransport experiment. It was demonstrated that the electrotransport purification of refractory metals could be successfully performed in the noncontaminating environment of an orbiting low-density materials laboratory such as the Molecular Shield Device. The zero gravity of outer space will also be advantageous since ''grain-sliding'' will be eliminated. As a result of the various experiments, small quantities of the world's purest thorium metal were prepared and evaluated. The electrotransport sample assembly was tested in several environments including near-zero gravity, simulated solar radiation, coldness, and darkness, and under various pressures of a representative reactive gas. Ultrapure single crystals of ..cap alpha.. thorium were prepared and are presently being characterized. Laboratory electronics for the experiment were also developed, and a totally automatic control system was used to heat the specimen. Complete assembly and line drawings of the components of the experiment and specifications for a high-current power supply are contained in the appendices.
Date: January 1, 1976
Creator: Schmidt, F.A.; Lunde, B.K. & Williams, D.E.
Partner: UNT Libraries Government Documents Department

On the feasibility of tracking with differential-algebra maps in long-term stability studies for large hadron colliders

Description: A time-saving alternative to conventional element-by-element tracking in long-term stability studies is the use of truncated Taylor maps. This report discusses how the non-symplecticity of a moderately high-order truncated Taylor map affects its reliability when the map is used for tracking over several thousand turns. Various machines and two different map-constructing programs are compared. It is found that the discrepancies between the Taylor map results and those obtained by direct tracking grow with amplitude. Thus, such maps are not guaranteed to be sufficient for long-term tracking over millions of turns without suitable symplectification.
Date: January 1, 1992
Creator: Kleiss, R.; Schmidt, F. & Yan, Y.
Partner: UNT Libraries Government Documents Department

Baseline Gas Turbine Development Program. Twentieth quarterly progress report, October 31, 1977

Description: Progress is reported for a program whose goals are to demonstrate an experimental Upgraded gas turbine powered automobile which meets the 1978 Federal Emissions Standards, has significantly improved fuel economy, and is competitive in performance, reliability, and potential manufacturing cost with the conventional piston engine powered, compact-size American automobile. Activity during this twentieth program quarter has continued to emphasize development towards correcting power deficiency in the Upgraded Engine. Though no absolute improvements have been realized in this quarter, ssignificant progress has been made in identifying causes, appropriately adjusting original design constraints, and proceeding with corrective designs. Specifically, to reduce endwall and secondary flow losses, a new low velocity compressor turbine inlet duct, and blading both with an increased height and lighter loading is being designed. A large increase in the power turbine annulus is being used to significantly lower blade Mach number and leaving loss. Progress is also being made in uniforming regenerator flow for better heat recovery, and in the development of control system components. A Public Interest Car has been built and has proved effective in communicating overall program benefits and goals. In the area of advanced engine development, work is now underway towards processing sintered alpha silicon carbide into high temperature turbine stage components.
Date: October 31, 1977
Creator: Schmidt, F W & Wagner, C E
Partner: UNT Libraries Government Documents Department

Measurement and correction of the 3rd order resonance in the Tevatron

Description: At Fermilab Tevatron BPM system has been recently upgraded resulting much better accuracy of beam position measurements and improvements of data acquisition for turn-by-turn measurements. That allows one to record the beam position at each turn for 8000 turns for all BPMs (118 in each plane) with accuracy of about 10-20 {micro}m. In the last decade a harmonic analysis tool has been developed at CERN that allows relating each FFT line derived from the BPM data with a particular non-linear resonance in the machine. In fact, one can even detect the longitudinal position of the sources of these resonances. Experiments have been performed at the Tevatron in which beams have been kicked to various amplitudes to analyze the 3rd order resonance. It was possible to address this rather large resonance to some regular machine sextupoles. An alternative sextupole scheme allowed the suppression of this resonance by a good factor of 2. Lastly, the experimental data are compared with model calculations.
Date: June 1, 2006
Creator: Schmidt, F.; /CERN; Alexahin, Y.; Lebedev, V.; Still, D.; Valishev, A. et al.
Partner: UNT Libraries Government Documents Department

Preparation of thin film solar cells under very low pressure conditions. Final report, October 1, 1976--September 30, 1977

Description: In this study the feasibility of fabricating backwall Schottky barrier polycrystalline solar cells under ultra-high vacuum conditions of 1 x 10/sup -10/ torr (N/sub 2/) was investigated. Thin films of electron beam vaporized silicon were deposited on cleaned metal substrates of tungsten, tantalum and hafnium. Mass spectra from the quadrapole residual gas analyzer were used to determine the partial pressure of peak heights of 13 residual gases during each processing step. During separate silicon depositions, the substrate temperature was varied between 400 and 750/sup 0/C and deposition rates between 20 and 750 A/min were used. Surface contamination and metal diffusion were monitored by in situ Auger electron spectrometry before and after cleaning, deposition and annealing. Auger depth profiling, x-ray analysis, and SEM in the topographic and channeling modes, were utilized to characterize the samples with respect to silicon-metal boundary layer, interdiffusion, silicide formation and grain size of silicon. The clean metal surface was found to enhance thin film silicide growth. Fine grain silicon films were obtained for all samples that were not completely converted to a metallic silicide. Tungsten, tantalum and hafnium were found to form silicides at temperatures as low as 600/sup 0/C.
Date: January 1, 1977
Creator: Schmidt, F.A.; Shanks, H.R.; Bevolo, A.J. & Campisi, G.J.
Partner: UNT Libraries Government Documents Department

Baseline gas turbine development program. Eighteenth quarterly progress report

Description: Progress is reported for a program whose goals are to demonstrate an experimental upgraded gas turbine powered automobile which meets the 1978 Federal Emissions Standards, has significantly improved fuel economy, and is competitive in performance, reliability, and potential manufacturing cost with the conventional piston engine powered, compact-size American automobile. Initial running of the upgraded engine took place on July 13, 1976. The engine proved to be mechanically sound, but was also 43% deficient in power. A continuing corrective development effort has to date reduced the power deficiency to 32%. Compressor efficiency was increased 2 points by changing to a 28-channel diffuser and tandem deswirl vanes; improved processing of seals has reduced regenerator leakage from about 5 to 2.5% of engine flow; a new compressor turbine nozzle has increased compressor turbine stage efficiency by about 1 point; and adjustments to burner mixing ports has reduced pressure drop from 2.8 to 2.1% of engine pressure. Key compressor turbine component improvements are scheduled for test during the next quarterly period. During the quarter, progress was also made on development of the Upgraded Vehicle control system; and instrumentation of the fourth program engine was completed by NASA. The engine will be used for development efforts at NASA LeRC.
Date: April 30, 1977
Creator: Schmidt, F W & Wagner, C E
Partner: UNT Libraries Government Documents Department

Coupled optics reconstruction from TBT data using MAD-X

Description: Turn-by-turn BPM data provide immediate information on the coupled optics functions at BPM locations. In the case of small deviations from the known (design) uncoupled optics some cognizance of the sources of perturbation, BPM calibration errors and tilts can also be inferred without detailed lattice modeling. In practical situations, however, fitting the lattice model with the help of some optics code would lead to more reliable results. We present an algorithm for coupled optics reconstruction from TBT data on the basis of MAD-X and give examples of its application for the Fermilab Tevatron accelerator.
Date: June 1, 2007
Creator: Alexahin, Y.; Gianfelice-Wendt, E.; /Fermilab; Kapin, V.; Inst., /Moscow Phys. Eng.; Schmidt, F. et al.
Partner: UNT Libraries Government Documents Department

Tevatron End-of-Run Beam Physics Experiments

Description: Before the Tevatron Collider Run II ended in September of 2011, a number of specialized beam study periods were dedicated to the experiments on various accelerator physics concepts and effects during the last year of the machine operation. The study topics included collimation with bent crystals and hollow electron beams, diffusion measurements and various aspects of beam-beam interactions. In this report we concentrate on the subject of beam-beam interactions, summarizing the results of beam experiments. The covered topics include offset collisions, coherent beam stability, effect of the bunch-length-to-beta-function ratio, and operation of AC dipole with colliding beams.
Date: May 1, 2012
Creator: Valishev, A.; Gu, X.; Miyamoto, R.; White, S.; Schmidt, F. & Qiang, J.
Partner: UNT Libraries Government Documents Department

MEASUREMENT OF NON-LINEARITIES USING SPECTRUM ANALYSIS OF DRIVEN BETATRON OSCILLATION.

Description: Resonance driving terms can be derived from the frequency analysis of turn-by-turn betatron oscillation data. This paper demonstrates that the same information can also be drawn from the spectral analysis of a driven oscillation adiabatically excited by an rf dipole. The advantage of this method is that a large betatron oscillation amplitude can be sustained without loosing the coherence signal. The frequency spectrum of the driven oscillation is composed of multiples of the rf dipole modulation frequency which can be interpreted as resonance driving terms. This analysis has been applied to the data taken at the Brookhaven AGS. The adiabatically excited coherent oscillation is also very useful in measuring the betatron tune parasitically. The data taken during the AGS high intensity proton program is also presented.
Date: June 18, 2001
Creator: BAI,M.; BLASKIEWICZ,M.; LEHRACH,A.; ROSER,T.; SCHMIDT,F. & VAN ASSELT,W.
Partner: UNT Libraries Government Documents Department

MEASUREMENT OF NON-LINEARITIES USING SPECTRUM ANALYSIS OF DRIVEN BETATRON OSCILLATION.

Description: Resonance driving terms can be derived from the frequency analysis of turn-by-turn betatron oscillation data. This paper demonstrates that the same information can also be drawn from the spectral analysis of a driven oscillation adiabatically excited by an rf dipole. The advantage of this method is that a large betatron oscillation amplitude can be sustained without loosing the coherence signal. The frequency spectrum of the driven oscillation is composed of multiples of the rf dipole modulation frequency which can be interpreted as resonance driving terms. This analysis has been applied to the data taken at the Brookhaven AGS. The adiabatically excited coherent oscillation is also very useful in measuring the betatron tune parasitically. The data taken during the AGS high intensity proton program is also presented.
Date: June 18, 2001
Creator: BAI,M.; BLASKIEWICZ,M.; LEHRACH,A.; ROSER,T.; SCHMIDT,F. & VAN ASSELT,W.
Partner: UNT Libraries Government Documents Department

Improved method of preparing composite superconducting wire

Description: An improved method of preparing composite multifilament superconducting wire of Nb/sub 3/Sn in a copper matrix which eliminates the necessity of coating the drawn wire with tin is described. A generalized cylindrical billet of an alloy of copper containing at least 15 weight percent niobium, present in the copper as discrete, randomly distributed and oriented dendritic-shaped particles, is provided with at least one longitudinal opening which is filled with tin to form a composite drawing rod. The drawing rod is then drawn to form a ductile composite multifilament wire containing a filament of tin. The ductile wire containing the tin can then be wound into magnet coils or other devices before heating to diffuse the tin through the wire to react with the niobium forming Nb/sub 3/Sn. Also described is an improved method for making large billets of the copper-niobium alloy by consumable-arc casting.
Date: April 24, 1981
Creator: Verhoeven, J.D.; Gibson, E.D.; Finnemore, D.K.; Ostenson, J.E.; Schmidt, F.A. & Owen, C.V.
Partner: UNT Libraries Government Documents Department

The Accelerator Markup Language and the Universal Accelerator Parser

Description: A major obstacle to collaboration on accelerator projects has been the sharing of lattice description files between modeling codes. To address this problem, a lattice description format called Accelerator Markup Language (AML) has been created. AML is based upon the standard eXtensible Markup Language (XML) format; this provides the flexibility for AML to be easily extended to satisfy changing requirements. In conjunction with AML, a software library, called the Universal Accelerator Parser (UAP), is being developed to speed the integration of AML into any program. The UAP is structured to make it relatively straightforward (by giving appropriate specifications) to read and write lattice files in any format. This will allow programs that use the UAP code to read a variety of different file formats. Additionally, this will greatly simplify conversion of files from one format to another. Currently, besides AML, the UAP supports the MAD lattice format.
Date: October 6, 2006
Creator: Sagan, D.; Forster, M.; /Cornell U., LNS; Bates, D.A.; /LBL, Berkeley; Wolski, A. et al.
Partner: UNT Libraries Government Documents Department

Accelerator Physics Code Web Repository

Description: In the framework of the CARE HHH European Network, we have developed a web-based dynamic accelerator-physics code repository. We describe the design, structure and contents of this repository, illustrate its usage, and discuss our future plans, with emphasis on code benchmarking.
Date: October 24, 2006
Creator: Zimmermann, F.; Basset, R.; Bellodi, G.; Benedetto, E.; Dorda, U.; Giovannozzi, M. et al.
Partner: UNT Libraries Government Documents Department

First use of a laser-driven polarized H/D target at the IUCF cooler.

Description: The HERMES Laser-Driven Target Task Force (Argonne, Erlangen and Illinois) is charged with developing a polarized H/D target for use in the HERA ring at DESY. Rapid progress was made in the beginning of 1996, leading us to the decision to test the target in a realistic experimental environment. In particular, polarizations of 0.6 and flows above 10{sup 18} atoms{center_dot}s{sup {minus}1} have been achieved on the bench. The laser-driven target and a simple detector system are currently installed in Cooler storage ring at the Indiana University Cyclotron Facility in order to test its applicability to nuclear physics experiments. Target polarizations are being measured using the {rvec H}(p, p) and {rvec D}(p, p) reactions. Initial tests were reasonably successful and the target is well along toward becoming viable for nuclear physics.
Date: December 5, 1997
Creator: Bailey, K.; Brack, J.; Cadman, R. V.; Cummings, W. J.; Fedchak, J.; Fox, B. et al.
Partner: UNT Libraries Government Documents Department