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Final Report of Project Nanometer Structures for Fuel Cells and Displays, etc.

Description: Low-energy ion beam bombardment induced self-assembly has been used to form various periodic nano-size wave-ordered structures (WOS). Such WOS can be used as hard etching masks to produce nanowire arrays, trenches etc., on other materials by means of traditional etching or ion sputtering. These periodic nano-size structures have a wide range of applications, including flat panel displays, optical electronics, and clean energy technologies (solar and fuel cells, lithium batteries). In order to achieve high throughput of the above processes, a large area RF-driven multicusp nitrogen ion source has been developed for the application of nitrogen ion beam induced surface modification. An integrated ion beam system, which can house either a large area RF-driven multicusp ion source or a commercially available microwave ion source (Roth & Rau AG Tamiris 400-f) have been designed, manufactured, assembled, and tested.
Date: December 15, 2011
Creator: Ji, Qing
Partner: UNT Libraries Government Documents Department

Vector Potential and Stored Energy of a Quadrupole Magnet Array

Description: The vector potential, magnetic field and stored energy of a quadrupole magnet array are derived. Each magnet within the array is a current sheet with a current density proportional to the azimuthal angle 2{theta} and the longitudinal periodicity (2m-1){pi}/L. Individual quadrupoles within the array are oriented in a way that maximizes the field gradient The array does not have to be of equal spacing and can be of a finite size, however when the array is equally spaced and is of infinite size the solution can be simplified. We note that whereas, in a single quadrupole magnet with a current density proportional to cos2{theta} the gradient is pure, such purity is not preserved in a quadrupole array.
Date: March 15, 1999
Creator: Caspi, S.
Partner: UNT Libraries Government Documents Department

R&D Toward a Neutrino Factory and Muon Collider

Description: Significant progress has been made in recent years in R&D towards a neutrino factory and muon collider. The U.S. Muon Accelerator Program (MAP) has been formed recently to expedite the R&D efforts. This paper will review the U.S. MAP R&D programs for a neutrino factory and muon collider. Muon ionization cooling research is the key element of the program. The first muon ionization cooling demonstration experiment, MICE (Muon Ionization Cooling Experiment), is under construction now at RAL (Rutherford Appleton Laboratory) in the UK. The current status of MICE will be described.
Date: March 20, 2011
Creator: Zisman, Michael S
Partner: UNT Libraries Government Documents Department

Time Delays, Bends, Acceleration and Array Reconfigurations

Description: This note was originally one of the parts of the work on a 50 MeV and 500 MeV Rb{sup +} driver and part of work on delay lines for a 60 GeV U{sup +12} driver. It is slightly expanded here to make it more generally applicable. The emphasis is on beam manipulations such as joining and separating beams at the two ends of a driver and providing various time delays between beams as required by the target.
Date: June 24, 2011
Creator: Faltens, A.
Partner: UNT Libraries Government Documents Department

NEUTRAL-BEAM INJECTION

Description: The emphasis in the preceding chapters has been on magnetic confinement of high temperature plasmas. The question of production and heating of such plasmas has been dealt with relatively more briefly. It should not be inferred, however, that these matters must therefore be either trivial or unimportant. A review of the history reveals that in the early days all these aspects of the controlled fusion problem were considered to be on a par, and were tackled simultaneously and with equal vigor. Only the confinement problem turned out to be much more complex than initially anticipated, and richer in challenge to the plasma physicist than the questions of plasma production and heating. On the other hand, the properties of high-temperature plasmas and plasma confinement can only be studied experimentally after the problems of production and of heating to adequate temperatures are solved. It is the purpose of this and the next chapter to supplement the preceding discussions with more detail on two important subjects: neutral-beam injection and radio-frequency heating. These are the major contenders for heating in present and future tokamak and mirror fusion experiments, and even in several proposed reactors. For neutral beams we emphasize here the technology involved, which has undergone a rather remarkable development. The physics of particle and energy deposition in the plasma, and the discussion of the resulting effects on the confined plasma, have been included in previous chapters, and some experimental results are quoted there. Other heating processes of relevance to fusion are mentioned elsewhere in this book, in connection with the experiments where they are used: i.e. ohmic heating, adiabatic compression heating, and alpha-particle heating in Chapter 3 by H.P. Furth; more ohmic heating in Chapter 7, and shock-implosion heating, laser heating, and relativistic-electron beam heating in Chapter 8, both by W. E. Quinn. ...
Date: June 1, 1980
Creator: Kunkel, W.B.
Partner: UNT Libraries Government Documents Department

Neutron Generators for Spent Fuel Assay

Description: The Next Generation Safeguards Initiative (NGSI) of the U.S. DOE has initiated a multi-lab/university collaboration to quantify the plutonium (Pu) mass in, and detect the diversion of pins from, spent nuclear fuel (SNF) assemblies with non-destructive assay (NDA). The 14 NDA techniques being studied include several that require an external neutron source: Delayed Neutrons (DN), Differential Die-Away (DDA), Delayed Gammas (DG), and Lead Slowing-Down Spectroscopy (LSDS). This report provides a survey of currently available neutron sources and their underlying technology that may be suitable for NDA of SNF assemblies. The neutron sources considered here fall into two broad categories. The term 'neutron generator' is commonly used for sealed devices that operate at relatively low acceleration voltages of less than 150 kV. Systems that employ an acceleration structure to produce ion beam energies from hundreds of keV to several MeV, and that are pumped down to vacuum during operation, rather than being sealed units, are usually referred to as 'accelerator-driven neutron sources.' Currently available neutron sources and future options are evaluated within the parameter space of the neutron generator/source requirements as currently understood and summarized in section 2. Applicable neutron source technologies are described in section 3. Commercially available neutron generators and other source options that could be made available in the near future with some further development and customization are discussed in sections 4 and 5, respectively. The pros and cons of the various options and possible ways forward are discussed in section 6. Selection of the best approach must take a number of parameters into account including cost, size, lifetime, and power consumption, as well as neutron flux, neutron energy spectrum, and pulse structure that satisfy the requirements of the NDA instrument to be built.
Date: December 30, 2010
Creator: Ludewigt, Bernhard A
Partner: UNT Libraries Government Documents Department

The Muon Collider

Description: We describe the scientific motivation for a new type of accelerator, the muon collider. This accelerator would permit an energy-frontier scientific program and yet would fit on the site of an existing laboratory. Such a device is quite challenging, and requires a substantial R&D program. After describing the ingredients of the facility, the ongoing R&D activities of the Muon Accelerator Program are discussed. A possible U.S. scenario that could lead to a muon collider at Fermilab is briefly mentioned.
Date: January 5, 2011
Creator: Zisman, Michael S.
Partner: UNT Libraries Government Documents Department

Commentary on A Conceptual Design of Transport Lines for a Heavy-Ion Inertial-Fusion Power Plant

Description: Some major system features are not stated but can be inferred. For example this is probably an engineering test facility, not a power plant driver, because the standoff from target to final magnet is only 5.0 m. The fusion target takes two-sided illumination with indirect drive using a total of 60 beam pulses: 10 pre-pulses (3.0 GeV) + 20 main pulses (4.0 GeV) from each side. On page 12 it's stated that the charge per beam pulse is 26.8 {micro}C, so we calculate pre-pulse: 20 x 3 GeV x 26.8 {micro}C = 1.608MJ, main pulse: 40 x 4 GeV x 26.8 {micro}C = 4.288MJ, total beam energy 5.896MJ. The beam ion mass ks 200 amu, so the species is Hg{sup +}. Therefore the mid-pulse velocities are: pre-pulse v = .1773c = 5.316 x 10{sup 7} m/s, main pulse v = .2040c = 6.114 x 10{sup 7} m/s, On page 12 it is stated that the pre-compression pulse length is L{sub 0} = 10.0m, and compression is by a 'factor of order 20'. They infer a final pulse length of about .5 m and final durations pre-pulse {tau} {approx} .5/5.316 x 10{sup 7} = 9.4 ns; main pulse {tau} {approx} .5/6.114 x 10{sup 7} = 8.2 ms. The magnetic rigidity of the beam ions is [B{rho}] = {gamma}m v/e = {l_brace} 112.0 T-m - prepulse/129.5 T-m - mainpulse{r_brace}.
Date: April 13, 2011
Creator: Lee, E.P.
Partner: UNT Libraries Government Documents Department

Common Coil Magnet System for VLHC

Description: This paper introduces the common coil magnet system for the proposed very large hadron collider (VLHC). In this system, the high energy booster (HEB), the injector to VLHC, is integrated as the iron dominated low field aperture within the coldmass of the common coil magnet design introduced earlier. This 4-in-1 magnet concept for a 2-in-1 machine should provide a major cost reduction in building and operating VLHC. Moreover, the proposed design reduces the field quality problems associated with the large persistent currents in Nb{sub 3}Sn magnets. The paper also shows that the geometric field harmonics can be made small. In this preliminary magnetic design. the current dependence in harmonics is significant but not umnanageable.
Date: February 12, 1999
Creator: Gupta, R.
Partner: UNT Libraries Government Documents Department

Chemistry, phase formation, and catalytic activity of thin palladium-containing oxide films synthesized by plasma-assisted physical vapor deposition

Description: The chemistry, microstructure, and catalytic activity of thin films incorporating palladium were studied using scanning and transmission electron microscopies, X-ray diffraction, spectrophotometry, 4-point probe and catalytic tests. The films were synthesized using pulsed filtered cathodic arc and magnetron sputter deposition, i.e. techniques far from thermodynamic equilibrium. Catalytic particles were formed by thermally cycling thin films of the Pd-Pt-O system. The evolution and phase formation in such films as a function of temperature were discussed in terms of the stability of PdO and PtO2 in air. The catalytic efficiency was found to be strongly affected by the chemical composition, with oxidized palladium definitely playing a major role in the combustion of methane. Reactive sputter deposition of thin films in the Pd-Zr-Y-O system allowed us forming microstructures ranging from nanocrystalline zirconia to palladium nanoparticles embedded in a (Zr,Y)4Pd2O matrix. The sequence of phase formation is put in relation to simple thermodynamic considerations.
Date: November 26, 2010
Creator: Anders, Andre
Partner: UNT Libraries Government Documents Department

Coherent Beam-Beam Interactions in Electron-Positron Colliders

Description: We present the results of a new calculational technique that evaluates the beam-beam force due to an arbitrary charge distribution. We find coherent instabilities that dominate at certain operating points and depend strongly on the degree of damping in the system. We conclude that while these resonances may play a significant role for colliders with low damping, with a careful choice of operating points they should present no danger to the new generation of high luminosity heavy-quark factories under design.
Date: August 1, 1991
Creator: Krishnagopal, S.
Partner: UNT Libraries Government Documents Department

COMET SHOWERS ARE NOT INDUCED BY INTERSTELLAR CLOUDS

Description: Encounters with interstellar clouds (IC) have been proposed by Rampino and Stothers as a cause of quasi-periodic intense comet showers leading to earth impacts, in order to explain the periodicity in marine mass extinctions found by Raup and Sepkoski. The model was described further, criticized and defended. The debate has centered on the question of whether the scale height of the clouds is small enough (in comparison to the amplitude of the oscillation of the solar system about the plane of the Galaxy) to produce a modulation in the rate of encounters. We wish to point out another serious, we believe fatal, defect in this model - the tidal fields of ICs are not strong enough to produce intense comet showers leading to earth impacts by bringing comets of the postulated inner Oort cloud into earth crossing orbits, except possibly during very rare encounters with very dense clouds. We will show that encounters with abundant clouds of low density cannot produce comet showers; cloud density N > 10{sup 3} atoms cm{sup -3} is needed to produce an intense comet shower leading to earth impacts. Furthermore, the tidal field of a dense cloud during a distant encounter is too weak to produce such showers. As a consequence, comet showers induced by ICs will be far less frequent than showers caused by passing stars. This conclusion is independent of assumptions about the radial distribution of comets in the inner Oort cloud.
Date: November 1, 1985
Creator: Morris, D.E.
Partner: UNT Libraries Government Documents Department

PHYSICS OF THE HIGH CURRENT DENSITY ELECTRON BEAM ION SOURCE (EBIS).

Description: Interest in upgrading present heavy particle accelerators has led to study of EBIS as a possible source of high Z ions, e.g,, Ar{sup +18}. The present work has been motivated primarily by the results reported by CRYEBIS, which indicate that a space charge neutralized, external electron gun can achieve current densities of 10{sup 5} A/cm{sup 2}. Scaling relationships are developed as a basis for understanding CRYEBIS operation. The relevance of collective effects to beam equilibrium and stability is pointed out, Single electron impact ionization scaling and beam neutralization scaling indicate that higher beam voltage may be the easiest way of increasing both ionization rate and particle intensity. Consideration of radial ion confinement suggests that beam collapse to high current density may be related to the highest charge state which is energetically accessible.
Date: February 1, 1980
Creator: Vella, M.C.
Partner: UNT Libraries Government Documents Department

High Field Magnet R&D in the USA

Description: Accelerator magnet technology is currently dominated by the use of NbTi superconductor. New and more demanding applications for superconducting accelerator magnets require the use of alternative materials. Several programs in the US are taking advantage of recent improvements in Nb{sub 3}Sn to develop high field magnets for new applications. Highlights and challenges of the US R and D program are presented along with the status of conductor development. In addition, a new R and D focus, the US LHC Accelerator Research Program, will be discussed.
Date: October 1, 2003
Creator: Gourlay, S.A.
Partner: UNT Libraries Government Documents Department

Forces and Stored Energy in Thin Cosine (n0) Accelerator Magnets

Description: We wish to compute Lorentz forces, equilibrium stress and stored energy in thin multipole magnets (Fig.1), that are proportional to cos(n{theta}) and whose strength varies purely as a Fourier sinusoidal series of the longitudinal coordinate z (say proportional to cos (2m-1){pi}z/L where L denotes the half-period and m = 1,2,3...). We shall demonstrate that in cases where the current is situated on such a surface of discontinuity at r = R (i.e. J = f({theta},z)), by computing the Lorentz force and solving the state of equilibrium on that surface, a closed form solution can be obtained for single function magnets as well as for any combination of interacting nested multi function magnets. The results that have been obtained, indicate that the total axial force on the end of a single multipole magnet n is independent (orthogonal) to any other multipole magnet i as long as n {ne} i. The same is true for the stored energy, the total energy of a nested set of multipole magnets is equal to the some of the energy of the individual magnets (of the same period length 2L). Finally we demonstrate our results on a nested set of magnets a dipole (n = 1) and a quadmpole (n=2) that have an identical single periodicity {omega}{sub 1}. We show that in the limiting 2D case (period 2L tends to infinity), the force reduces to the commonly known 2D case.
Date: March 18, 1996
Creator: Caspi, S.
Partner: UNT Libraries Government Documents Department

Forces in a Thin Cosine (nTheta) Helical Wiggler

Description: We wish to calculate the Lorentz body force associated with pure multipole helical magnetic fields (i.e, proportional to cos(n{theta})) whose strength varies purely as a Fourier sinusoidal series of the longitudinal coordinate z (say proportional to cos(2m-1){pi}z)/L, where L denotes the half-period of the wiggler field and m= 1,2,3... We also wish to apply such forces to the current sheet, and solve for the stress distribution required to maintain such a coil in equilibrium. In the calculations of Lorentz forces we include the self field contribution as well as possible contributions arising from additional nested helical windings. We shall demonstrate that in cases where the current is situated on a surface of discontinuity at r=R (i.e. J=f({theta},z)) and the Lorentz body force is integrated on that surface, a closed form solution for the stress distribution can be obtained and such a solution includes contributions from possible nested multi pole magnets. Finally we demonstrate that in the limiting 2D case where the field strength does not vary with z ( period 2L tends to infinity) the stress reduces to known 2D expressions.
Date: May 2, 1997
Creator: Caspi, S.
Partner: UNT Libraries Government Documents Department

Study of an HHG-Seeded Free-Electron Laser for the LBNL Next Generation Light Source

Description: The Next Generation Light Source (NGLS) is a high repetition rate free-electron laser facility proposed by Lawrence Berkeley National Laboratory (LBNL). The proposed facility will provide multiple FEL lines with varying spectral characteristics to satisfy a broad soft X-ray physics programme. At this stage of the project a number of FEL technologies and concepts are being investigated for possible implementation on the facility. In this report we consider a free-electron laser seeded by a Higher Harmonic Generation (HHG) source in which a high power (and consequently relatively low repetition rate) laser pulse is injected into a chamber of inert gas. Through a process of ionisation and recombination coherent higher harmonics of the laser are emitted from the gas and can be injected into an FEL system as a seed field. Further harmonic upconversion can be done within the FEL system to enable temporally coherent FEL output at wavelengths much shorter than, and pulse energies orders of magnitude higher than, the HHG source emission. The harmonic conversion within the FEL works in the following way. The seed field induces an energy modulation within the electron bunch at the start of the modulator. This energy modulation grows within the modulator due to the FEL interaction and starts to convert into a density modulation, or bunching, at the seed wavelength. However, this bunching also has components at higher harmonics which retain the longitudinal coherence of the initial seed. The beam passes through a magnetic chicane, which shears the longitudinal phase space to maximise the bunching at the required harmonic, then a further undulator which is tuned to this harmonic. If this second undulator is short it acts as a further modulator, and because the beam is pre-bunched at the modulator resonance there is a strong coherent burst of radiation which acts to modulate ...
Date: October 20, 2010
Creator: Thompson, Neil
Partner: UNT Libraries Government Documents Department

STUDY OF FODO STRUCTURES FOR A SYNCHROTRON LIGHT SOURCE

Description: Synchrotron radiation is a helpful tool to Investigate a wide range of physical, chemical and biological phenomena. Extremely high flux, brilliance synchrotron radiation can be achieved in low emittance electron storage rings with wigglers and undulators. The Advanced Light Source (ALS) is a synchrotron radiation source with 1.5 GeV design energy. The lattice is designed with 12 superperiods each containing a 6 m long straight section to accomodate the insertion devices. Two straight sections are reserved for injection elements and accelerating cavities. To minimize source width and angular divergence the dispersion is matched to zero in the straight sections. The goals for the design of such a lattice are low emittance, flexibility and large dynamic apertures after chromaticity correction, at low cost. The most economical, and therefore most frequently used structure in the past is that suggested by Chasman and Green. It has become apparent recently that alternative designs with excellent characteristics have been proposed for synchrotron light sources. Therefore a new lattice design study for the ALS has been carried out. The Triple Bend Achromat (TBA) lattice proposed by Vignola has been compared with the Chasman-Green lattice. An expanded Chasman-Green lattice proposed by Hutton was reviewed for the ALS. Finally the FODO achromat lattice as proposed by Wiedemann for the SSRL has been studied as a candidate for the ALS. The results for the FODO achromat lattice are presented here. In part II the minimum emittance of the FODO achromat has been derived in a semianalytical approach. It has been shown, that after performing two optimization steps, the emittance can be reduced far below the minimum emittance of a pure FODO structure. In part III, three examples of the FODO achromat lattices for the ALS are presented. For the relatively short structure of the ALS, the minimum emittance unfortunately ...
Date: July 1, 1986
Creator: Wrulich, A.
Partner: UNT Libraries Government Documents Department

Test Results on D-12A-2

Description: The purpose of this report is to describe the recent tests of D-12A-2. The tests of D-12A-2 began on April 30 and ended on May 8. The unusually long test period was a result of an extensive series of magnetic field measurements in which we attempted to determine the shielding affects of a sextupole compensating coil and the decay of the currents induced in this coil. This report is short, but much of the data from the tests are included or summarized. We begin with a description of the coil and conductor, continue with the training history, the results of magnetic measurements, including the use of a sextupole compensating coil and then describe the results of heater induced quenches including estimates of axial and transverse quench propagation velocities.
Date: August 8, 1984
Creator: Hassenzahl, W.
Partner: UNT Libraries Government Documents Department

DEFLECTION MEASUREMENTS OF 25 mm ALUMINUM COLLARS

Description: This report is a summary of mechanical load-deflection tests performed on prototype collars. The individual collar plates were N.C. machined from 0.125 inch thick 7075-T6 aluminum alloy plate. Inside corners were finished by EDM and outside corners and keyways were finished with an end milling operation. The last step was done with all the individual collar plates (98 pieces) assembled on pins to form the cross section shown in Fig. 1. Figure 1 also shows some of the basic collar dimensions.
Date: October 1, 1984
Creator: Peters, C.
Partner: UNT Libraries Government Documents Department

Development of Superconducting Strang and Cable with Improved Properties for Use in SSC Magnets

Description: The critical current requirement for the NbTi superconductor strand was set at 2750 A/mm{sup 2} (5 T, 4.2 K) in the SSC Conceptual Design, compared with a value of 1800 A/mm{sup 2} which was specified for the strand used in the Tevatron dipoles. In addition, a filament diameter of 5 {micro}m, instead of the 9 {micro}m diameter used in the Tevatron. was chosen to reduce field distonion at injection. In order to meet the requirements for field homogeneity, the dimensional requirements for both strand and cable were also tightened. The technical solutions employed to achieve these improved properties and the resulting specifications will be discussed.
Date: February 1, 1989
Creator: Scanlan, R. M.
Partner: UNT Libraries Government Documents Department

PARAMETRIC STUDIES OF ALADDIN LATTICES

Description: This paper presents the results of a parametric investigation of the various Aladdin lattices that have been considered as part of the Aladdin Upgrade Study, the overall purpose of which is to assess the problems with the existing Aladdin storage ring and recommend corrective action. In particular, the Study is to confirm the parameters of a full-energy injector for Aladdin and to identify those components that need upgrading or redesigning to guarantee satisfactory performance with the new injector. As part of the Study, an investigation has been carried out on several different lattices, referred to in this document as Aladdin-1, Aladdin-2, and Aladdin-3. These lattices have been provided as part of the activities of the Lattice Group (led by A. Ruggiero) by various members of the Argonne National Laboratory. The first lattice is intended to be identical to the presently operating Aladdin; the second lattice has the same spatial arrangement of magnets but - by the addition of power supplies - more flexibility in optimizing lattice functions (e.g., for injection or for the eventual inclusion of insertion devices); the third lattice corresponds closely to the working BESSY lattice and would require the physical relocation of various magnets (while providing the potential advantage of a significantly improved natural emittance). An abridged parameter list for the three lattices is given in Table I.
Date: March 1, 1985
Creator: Zisman, M.S.
Partner: UNT Libraries Government Documents Department

PECULIAR OPTICAL AND IR BEHAVIOUR IN TYPE I SUPERNOVAE, AND THE ORIGIN OF THE 1.2 ABSORPTION

Description: A small number of type I supernovae exhibit well defined peculiarities. In particular some type I supernovae do not have the characteristic 6150 {angstrom} feature and some do not have the 1.2 {micro}m absorption. It is noted that all SN which lack the infrared absorption also lack the 6150 {angstrom} feature which is attributed to Si II. It is proposed that these supernovae constitute a single sub-class and that Si could be responsible for the strong unidentified infrared absorption which is characteristic of classical SNI. Si I has a dense array of strong lines in the near infrared so this ion could be responsible for the dominant features of SNIa IR behaviour. If this hypothesis is vindicated by subsequent observations or by calculation of synthetic spectra then it is most likely that the difference between ordinary supernovae and these peculiar ones is the abundance of Si.
Date: November 1, 1985
Creator: Graham, J.R.
Partner: UNT Libraries Government Documents Department

Considerations Against a Force Compensated Coil

Description: The cost of structural components in a large superconducting coil may well exceed the coil and cryostat cost. As a result, the idea of constructing a system composed of two different coil types assembled in such a way that the forces balance and reduce the total structural requirement is oft proposed. A suitable geometry has never been found for the fundamental reason that there can be no force compensated solution. In this paper, the general problem is presented and an analysis of the energy stored and stresses produced in the structure are described in a fundamental way. Finally, the relation between structural mass M and stored energy E, M {ge} {rho}E/{sigma}{sub w}, that is valid for all, magnetic systems is developed, where {rho} is the density of the structure and {sigma}{sub w} is the working stress in the structure.
Date: August 1, 1988
Creator: Hassenzahl, W.
Partner: UNT Libraries Government Documents Department