A 1 MEGAWATT POLYPHASE BOOST CONVERTER-MODULATOR FOR KLYSTRON PULSE APPLICATION (open access)

A 1 MEGAWATT POLYPHASE BOOST CONVERTER-MODULATOR FOR KLYSTRON PULSE APPLICATION

This paper describes electrical design criteria and first operational results a 140 kV, 1 MW average, 11 MW peak, zero-voltage-switching 20 kHz polyphase bridge, boost converter/modulator for klystron pulse application. The DC-DC converter derives the buss voltages from a standard 13.8 kV to 2300 Y substation cast-core transformer. Energy storage and filtering is provided by self-clearing metallized hazy polypropylene traction capacitors. Three ''H-Bridge'' Insulated Gate Bipolar Transistor (IGBT) switching networks are used to generate the polyphase 20 kHz transformer primary drive waveforms. The 20 kHz drive waveforms are chirped the appropriate duration to generate the desired klystron pulse width. PWM (pulse width modulation) of the individual 20 kHz pulses is utilized to provide regulated output waveforms with adaptive feedforward and feedback techniques. The boost transformer design utilizes amorphous nanocrystalline material that provides the required low core loss at design flux levels and switching frequencies. Resonant shunt-peaking is used on the transformer secondary to boost output voltage and resonate transformer leakage inductance. With the appropriate transformer leakage inductance and peaking capacitance, zero-voltage-switching of the IGBT's is attained, minimizing switching losses. A review of these design parameters and the first results of the performance characteristics will be presented.
Date: June 1, 2001
Creator: Reass, W. A.; Doss, J. D. & Gribble, R. F.
System: The UNT Digital Library
10 (micro)m and 5 (micro)m Pinhole-Assisted Point-Projection Backlit Imaging for NIF (open access)

10 (micro)m and 5 (micro)m Pinhole-Assisted Point-Projection Backlit Imaging for NIF

Pinhole-assisted point-projection backlighting with 10{micro}m and 5 {micro}m pinholes placed a small distance of order 1 mm away from the backlighter produces images with large field of view and high resolution. Pinholes placed closely to high-power backlighter sources can vaporize and close due to x-ray driven ablation, thereby limiting the usefulness of this method. A study of streaked 1-D backlit imaging of 25 {micro}m W wires using the OMEGA laser is presented. The pinhole closure timescale for 10 {micro}m pinholes placed 0.45 mm and 1 mm distant from the backlighter is 1.3 ns and 2.2 ns, respectively. Similar timescales for 5 {micro}m pinholes is also presented. Successful wire imaging prior to pinhole closure is clearly demonstrated.
Date: June 5, 2001
Creator: Bullock, A. B.; Landen, O. L. & Bradley, D. K.
System: The UNT Digital Library
2nd Feasibility Study of a Muon Storage Ring Neutrino Factory (open access)

2nd Feasibility Study of a Muon Storage Ring Neutrino Factory

The design and simulated performance of a second feasibility study are presented. The efficiency of producing muons is {approx} 0.17 {micro}/p with 24 GeV protons. This study was sponsored by the BNL Director, with BNL site specific driver and layout. It was a follow on to the First Study[2] sponsored by the Fermilab Director, with Fermilab site specific driver and layout, and was the main US collaboration conceptual effort during the past year. Other studies, and technical work by the collaboration is reported in other papers.
Date: June 18, 2001
Creator: Ozaki, S.; Palmer, R. B. & Zisman, M. S.
System: The UNT Digital Library
Accelerator Physics Issues for Future Electron Ion Colliders (open access)

Accelerator Physics Issues for Future Electron Ion Colliders

Interest continues to grow in the physics of collisions between electrons and heavy ions, and between polarized electrons and polarized protons [1,2,3]. Table 1 compares the parameters of some machines under discussion. DESY has begun to explore the possibility of upgrading the existing HERA-p ring to store heavy ions, in order to collide them with electrons (or positrons) in the HERA-e ring, or from TESLA [4]. An upgrade to store polarized protons in the HERA-p ring is also under discussion [1]. BNL is considering adding polarized electrons to the RHIC repertoire, which already includes heavy and light ions, and polarized protons. The authors of this paper have made a first pass analysis of this ''eRHIC'' possibility [5]. MIT-BATES is also considering electron ion collider designs [6].
Date: June 18, 2001
Creator: Peggs, S.; Ben-Zvi, Ilan; Kewisch, J. & Murphy, J.
System: The UNT Digital Library
Accuracy of Projection Methods for the Incompressible Navier-Stokes Equations (open access)

Accuracy of Projection Methods for the Incompressible Navier-Stokes Equations

Numerous papers have appeared in the literature over the past thirty years discussing projection-type methods for solving the incompressible Navier-Stokes equations. A recurring difficulty encountered is the choice of boundary conditions for the intermediate or predicted velocity in order to obtain at least second order convergence. A further issue is the formula for the pressure correction at each timestep. A simple overview is presented here based on recently published results by Brown, Cortez and Minion [2].
Date: June 12, 2001
Creator: Brown, D L
System: The UNT Digital Library
Acquisition of building geometry in the simulation of energy performance (open access)

Acquisition of building geometry in the simulation of energy performance

Building geometry is essential to any simulation of building performance. This paper examines the importing of building geometry into simulation of energy performance from the users' point of view. It lists performance requirements for graphic user interfaces that input building geometry, and discusses the basic options in moving from two- to three-dimensional definition of geometry and the ways to import that geometry into energy simulation. The obvious answer lies in software interoperability. With the BLIS group of interoperable software one can interactively import building geometry from CAD into EnergyPlus and dramatically reduce the effort otherwise needed for manual input.The resulting savings may greatly increase the value obtained from simulation, the number of projects in which energy performance simulation is used, and expedite decision making in the design process.
Date: June 28, 2001
Creator: Bazjanac, Vladimir
System: The UNT Digital Library
Adjustable permanent quadrupoles for the next linear collider (open access)

Adjustable permanent quadrupoles for the next linear collider

The proposed Next Linear Collider (NLC) will require over 1400 adjustable quadrupoles between the main linacs' accelerator structures. These 12.7 mm bore quadrupoles will have a range of integrated strength from 0.6 to 138 Tesla, with a maximum gradient of 141 Tesla per meter, an adjustment range of +0 to {minus}20% and effective lengths from 324 mm to 972 mm. The magnetic center must remain stable to within 1 micron during the 20% adjustment. In an effort to reduce costs and increase reliability, several designs using hybrid permanent magnets have been developed. Four different prototypes have been built. All magnets have iron poles and use Samarium Cobalt to provide the magnetic fields. Two use rotating permanent magnetic material to vary the gradient, one uses a sliding shunt to vary the gradient and the fourth uses counter rotating magnets. Preliminary data on gradient strength, temperature stability, and magnetic center position stability are presented. These data are compared to an equivalent electromagnetic prototype.
Date: June 22, 2001
Creator: al., James T. Volk et
System: The UNT Digital Library
ADTF SUPERCONDUCTING LINAC DESIGN (open access)

ADTF SUPERCONDUCTING LINAC DESIGN

None
Date: June 1, 2001
Creator: GARNETT, R. W.
System: The UNT Digital Library
Agent-based modeling of complex infrastructures (open access)

Agent-based modeling of complex infrastructures

Complex Adaptive Systems (CAS) can be applied to investigate complex infrastructures and infrastructure interdependencies. The CAS model agents within the Spot Market Agent Research Tool (SMART) and Flexible Agent Simulation Toolkit (FAST) allow investigation of the electric power infrastructure, the natural gas infrastructure and their interdependencies.
Date: June 2001
Creator: North, M. J.
System: The UNT Digital Library
AHF BEAMS TRANSPORT LATTICE CRYOSYSTEMS[Advanced Hydrotest Facility] (open access)

AHF BEAMS TRANSPORT LATTICE CRYOSYSTEMS[Advanced Hydrotest Facility]

None
Date: June 1, 2001
Creator: KELLEY, J. P. & MULHOLLAND, G. T.
System: The UNT Digital Library
AHF MAGNETIC LENS CRYOSYSTEMS[Advanced Hydrotest Facility] (open access)

AHF MAGNETIC LENS CRYOSYSTEMS[Advanced Hydrotest Facility]

None
Date: June 1, 2001
Creator: KELLEY, J. P. & MULHOLLAND, G. T.
System: The UNT Digital Library
All-Ferrite RHIC Injection Kicker (open access)

All-Ferrite RHIC Injection Kicker

Ion beams are transferred from the AGS into RHIC in boxcar fashion as single bunches. The nominal design assumes 60 bunches per ring but increasing the number of bunches to gain luminosity is possible, thereby requiring injection kickers with a shorter rise time. The original injection system consists of traveling-wave dielectric loaded kicker magnets and a Blumlein pulser with a rise time adequate for the present operation. Voltage breakdown in the dielectric kickers suggested the use of all-ferrite magnets. In order to minimize the conversion cost, the design of the all-ferrite kicker uses the same components as the dielectric loaded units. The all-ferrite kickers showed in bench measured good breakdown properties and a current rise time of < 50 ns. A prototype kicker has been installed in the blue ring and was tested with beam. Beam measurements indicate suitability of all-ferrite kicker magnets for upgraded operation.
Date: June 18, 2001
Creator: Hahn, H.; Fischer, W.; Ptitsyn, V. I. & Tuozzolo, J. E.
System: The UNT Digital Library
Alpha particle response characterization of CdZnTe (open access)

Alpha particle response characterization of CdZnTe

The coplanar-grid as well as other electron-only detection techniques are effective in overcoming some of the material problems of CdZnTe and, consequently, have led to efficient gamma-ray detectors with good energy resolution while operating at room temperature. The performance of these detectors is limited by the degree of uniformity in both electron generation and transport. Despite recent progress in the growth of CdZnTe material, small variations in these properties remain a barrier to the widespread success of such detectors. Alpha-particle response characterization of CdZnTe crystals fabricated into simple planar detectors is an effective tool to accurately study electron generation and transport. We have used a finely collimated alpha source to produce two-dimensional maps of detector response. A clear correlation has been observed between the distribution of precipitates near the entrance contact on some crystals and their alpha-response maps. Further studies are ongoing to determine the mechanism for the observed response variations and the reason for the correlation. This paper presents the results of these studies and their relationship to coplanar-grid gamma-ray detector performance.
Date: June 28, 2001
Creator: Amman, Mark; Lee, Julie S. & Luke, Paul N.
System: The UNT Digital Library
An Alternative Approach to Low Frequency Rf Accelerators and Power Sources. (open access)

An Alternative Approach to Low Frequency Rf Accelerators and Power Sources.

The Muon Collider and Neutrino Factory projects require low frequency rf cavities because the size and emittance of the muon beam is much larger than is usual for electron or proton beams. The range of 30 MHz to 200 MHz is of special interest. However, the size of an accelerator with low frequency will be impractically large if it is simply scaled up from usual designs. In addition, to get very high peak power in this range is difficult. Presented in this paper is an alternative structure that employs a quasi-lumped inductance that can significantly reduce the transverse size while keeping high gradient. Also addressed is a power compression scheme with a thyratron. This gives a possible solution to provide very high peak power.
Date: June 18, 2001
Creator: Zhao, Y.
System: The UNT Digital Library
An Alternative Scheme for the Neutrino Factory With a High Power Proton Driver. (open access)

An Alternative Scheme for the Neutrino Factory With a High Power Proton Driver.

We describe a scheme to produce an intense and collimated beam of neutrinos for the neutrino-oscillation experiment. The scheme feature is the presence of a Proton Driver that generates a proton beam at very large power (10mA x 15GeV), considerably higher than that proposed elsewhere for this application. With this scheme, because of the high intensity of the proton beam, to produce neutrinos at the same required rates, it is sufficient to collect {pi} and {mu} mesons only around a small angle and at reduced momentum spreads. This eliminates the need for the difficult longitudinal manipulations of the protons and mesons, and of the ionization cooling that still needs to be demonstrated. It is also shown, at the end of the paper, that the Neutrino Factory here proposed can also be used as an injector for a 1 x 1 TeV{sup 2} {mu}{sup +} - {mu}{sup -} collider at large luminosity.
Date: June 30, 2001
Creator: Ruggiero, A. G.
System: The UNT Digital Library
Al Alternative Scheme for the Neutrino Factory With a High Power Proton Driver. (open access)

Al Alternative Scheme for the Neutrino Factory With a High Power Proton Driver.

We describe a scheme to produce an intense and collimated beam of neutrinos for the neutrino-oscillation experiment. The scheme feature is the presence of a Proton Driver that generates a proton beam at very large power (10mA x 15GeV), considerably higher than that proposed elsewhere for this application. With this scheme, because of the high intensity of the proton beam, to produce neutrinos at the same required rates, it is sufficient to collect {pi} and {mu} mesons only around a small angle and at reduced momentum spreads. This eliminates the need for the difficult longitudinal manipulations of the protons and mesons, and of the ionization cooling that still needs to be demonstrated. It is also shown, at the end of the paper, that the Neutrino Factory here proposed can also be used as an injector for a 1 x 1 TeV{sup 2} {mu}{sup +}-{mu}{sup -} collider at large luminosity.
Date: June 30, 2001
Creator: Ruggiero, A. G.
System: The UNT Digital Library
ANALOG FRONT-END ELECTRONICS FOR BEAM POSITION MEASUREMENT ON THE BEAM HALO MEASUREMENT (open access)

ANALOG FRONT-END ELECTRONICS FOR BEAM POSITION MEASUREMENT ON THE BEAM HALO MEASUREMENT

Enhancements have been made to the log-ratio analog front-end electronics based on the Analog Devices 8307 logarithmic amplifier as used on the LEDA accelerator. The dynamic range of greater than 85 dB, has been extended to nearly the full capability of the AD8307 from the previous design of approximately 65 dB through the addition of a 350 MHz band-pass filter, careful use of ground and power plane placement, signal routing, and power supply bypassing. Additionally, selection of high-isolation RF switches (55dB) has been an integral part of a new calibration technique, which is fully described in another paper submitted to this conference. Provision has also been made for insertion of a first-stage low-noise amplifier for using the circuit under low-signal conditions.
Date: June 1, 2001
Creator: SHURTER, R.B.; COTE, T.J. & GILPATRICK, J.D.
System: The UNT Digital Library
Analysis of a High-Efficiency Natural Gas-Assisted Steam Electrolyzer for Hydrogen Production (open access)

Analysis of a High-Efficiency Natural Gas-Assisted Steam Electrolyzer for Hydrogen Production

This paper presents a description and analysis of a high-efficiency hydrogen production system. The main component of the system is a novel steam electrolyzer. In conventional electrolyzers, oxygen produced from electrolysis is usually released into the environment. In this design, natural gas is used to react with the oxygen produced in the electrolysis, reducing reduce the chemical potential difference across the electrolyzer, thus minimizing electricity consumption. The oxygen produced from the electrolysis is consumed in either a total oxidation or a partial oxidation reaction with natural gas. Experiments performed on single cells shown a voltage reduction as much as 1 V when compared to conventional electrolyzers. A heat recovery system (heat exchangers and catalytic converter) has been incorporated to the electrolyzer to obtain a high efficiency hydrogen production system. Results from a thermodynamic analysis show up to 70% efficiency with respect to primary energy source.
Date: June 26, 2001
Creator: Martinez-Frias, J.; Pham, A. Q. & Aceves, S. M.
System: The UNT Digital Library
Analysis of Combustion Chamber Deposits by ESI-TOF-MS and MALDI-TOF-MS (open access)

Analysis of Combustion Chamber Deposits by ESI-TOF-MS and MALDI-TOF-MS

Combustion chamber deposits (CCDs) in internal combustion engines have been studied by various techniques to understand the relationship of performance degradation with deposit quantity and structure. XPS, XAS, NMR, and elemental analysis have offered insight into the bulk structure of C, H, N, O and metal components [1]. MS has offered some information about compound structure, but results are limited due to the insolubility and complexity of the materials. Recent advances in MS have opened new possibilities for analysis of CCDs. Here we report initial findings on the carbon structure of these deposits determined by ESI-TOF-MS and MADLI-TOF-MS.
Date: June 14, 2001
Creator: Reynolds, J G; Shields, S J & Roos, J W
System: The UNT Digital Library
Analysis of Combustion Chamber Deposits by ESI-TOF-MS and MALDI-TOF-MS (open access)

Analysis of Combustion Chamber Deposits by ESI-TOF-MS and MALDI-TOF-MS

Combustion chamber deposits (CCD) in internal combustion engines have been studied by various techniques to understand the relationship of performance degradation with deposit quantity and structure. XPS, XAS, NMR, and elemental analysis have offered insight into the bulk structure of C, H, N, O and metal components. MS has offered some information about compound structure, but results are limited due to the insolubility and complexity of the materials. Recently, we have reported on the metal structure by XPS and XAS of several deposits from a GM 3800 engine generated using a standard fuel and one that contains low levels of the gasoline anti-knock additive, MMT. Here we report the initial findings on the carbon structure of these deposits determined by ESI-TOF-MS and MADLI-TOF-MS.
Date: June 14, 2001
Creator: Reynolds, J G; Shields, S J & Roos, J W
System: The UNT Digital Library
Analysis of coupling impedance bench measurements using Bethe's diffraction theory (open access)

Analysis of coupling impedance bench measurements using Bethe's diffraction theory

In this paper we study the validity of coupling impedance bench measurements, comparing two of the most commonly used formulas to the result obtained, applying a modified version of Bethe's theory of diffraction to a lumped impedance in a coaxial beam pipe. The equations found provide a quantitative expression for the influence of the wire thickness used in the measurement of the real and imaginary part of the longitudinal impedance. The precision achievable in an actual measurement is therefore discussed. The method presented can also be applied in the presence of distributed impedances as well as to the analysis of transverse impedance measurements.
Date: June 1, 2001
Creator: De Santis, Stefano
System: The UNT Digital Library
ANALYTIC PROPERTIES OF THE LONGITUDINAL BEAM TRANSFER FUNCTION. (open access)

ANALYTIC PROPERTIES OF THE LONGITUDINAL BEAM TRANSFER FUNCTION.

The frequency dependence of the longitudinal beam transfer function (BTF) in a storage ring, when expressed in a basis of azimuthal harmonics of the line density, is the Fourier transform of a causal function that depends on the radio-frequency potential well in which the bunch moves. The effect of all synchrotron harmonics are included in this function, which is derived from Krinsky and Wang's expression for the BTF expressed in the same basis (S. Krinsky and J.-M. Wang, Part. Accel. 17, 109-139 (1985)). Analytic properties of the terms of the BTF expressed in a series of synchrotron harmonics, which are approximately Shaposhnikova's BTF matrix elements (E. Shaposhnikova, CERN Report No. SL-94-19-RF (1994)), are studied through the large-argument asymptotics of corresponding causal functions.
Date: June 18, 2001
Creator: TOWNE, N.
System: The UNT Digital Library
Analytical laboratory quality audits (open access)

Analytical laboratory quality audits

Analytical Laboratory Quality Audits are designed to improve laboratory performance. The success of the audit, as for many activities, is based on adequate preparation, precise performance, well documented and insightful reporting, and productive follow-up. Adequate preparation starts with definition of the purpose, scope, and authority for the audit and the primary standards against which the laboratory quality program will be tested. The scope and technical processes involved lead to determining the needed audit team resources. Contact is made with the auditee and a formal audit plan is developed, approved and sent to the auditee laboratory management. Review of the auditee's quality manual, key procedures and historical information during preparation leads to better checklist development and more efficient and effective use of the limited time for data gathering during the audit itself. The audit begins with the opening meeting that sets the stage for the interactions between the audit team and the laboratory staff. Arrangements are worked out for the necessary interviews and examination of processes and records. The information developed during the audit is recorded on the checklists. Laboratory management is kept informed of issues during the audit so there are no surprises at the closing meeting. The audit report …
Date: June 11, 2001
Creator: Kelley, William D.
System: The UNT Digital Library
Analytical laboratory quality control charting (open access)

Analytical laboratory quality control charting

In life the importance of setting goals is stressed. The desired end result must be envisioned to chart a path and determine indicators to provide feedback on the process. Quality does not happen by accident but is achieved through a constant process of setting goals, process development, monitoring process indicators, fine tuning the process, and achieving results. These goals are to be focused and clearly measurable. In industry and life the setting of goals with clear process indicators is often difficult because of the variable end result and scarcity of measurements. Laboratories are fortunate in that they have a plethora of measurements with known or desired end results (controls) to monitor the process and give instantaneous feedback on quality. A key quality tool used by the laboratory to monitor and evaluate the lab processes is control charting. When properly utilized Quality Control (QC) Charts allow labs to be proactive in addressing problems rather than reactive. Several methods are available for control charting and some are listed in the references/information sources. The content for this paper is based on the control-charting program utilized at the Department of Energy's Fernald site. This control-charting program has specific areas of emphasis, simple charts, trend …
Date: June 11, 2001
Creator: O'Bryan, Ervin F.
System: The UNT Digital Library