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The Electrostatic Potential About an Atomic Nucleus in an Ionized Gas

Description: From introduction: "The object of this paper is to derive a simple approximate expression for the average potential about an atomic nucleus in an ionized gas. It was desired that the expression be simple in the sense that its analytic form would be convenient in Born approximation calculations. It was also desired that the results would be valid over a large range of temperature and density for all elements with perhaps the exception of those with low atomic number."
Date: June 1958
Creator: Kidder, R. E.
Partner: UNT Libraries Government Documents Department

Stereo soft x-ray microscopy and elemental mapping of hematite and clay suspensions

Description: The spatial arrangements of hematite particles within aqueous soil and clay samples are investigated with soft X-ray microscopy, taking advantage of the elemental contrast at the Fe-L edge around E = 707 eV. In combination with stereo microscopy, information about spatial arrangements are revealed and correlated to electrostatic interactions of the different mixtures. Manipulation of a sample mounted to the microscope is possible and particles added while imaging can be detected.
Date: September 1, 2008
Creator: Gleber, S.-C.; Thieme, J.; Chao, W. & Fischer, P.
Partner: UNT Libraries Government Documents Department

Compact High-Current Heavy-Ion Injector

Description: To provide a compact high-brightness heavy-ion beam source for Heavy Ion Fusion (HIF), we have been experimenting with merging multi-beamlets in an injector which uses an RF plasma source. An array of converging beamlets was used to produce a beam with the envelope radius, convergence, and ellipticity matched to an electrostatic quadrupole (ESQ) channel. Experimental results were in good quantitative agreement with simulation and have demonstrated the feasibility of this concept. The size of a driver-scale injector system using this approach will be several times smaller than one designed using traditional single large-aperture beams. The success of this experiment has possible significant economical and technical impacts on the architecture of HIF drivers.
Date: October 5, 2005
Creator: Westenskow, G. A.; Grote, D. P.; Kwan, J. W. & Bieniosek, F.
Partner: UNT Libraries Government Documents Department

The HIBEAM Manual

Description: HIBEAM is a 2 1/2D particle-in-cell (PIC) simulation code developed in the late 1990's in the Heavy-Ion Fusion research program at Lawrence Berkeley National Laboratory. The major purpose of HIBEAM is to simulate the transverse (i.e., X-Y) dynamics of a space-charge-dominated, non-relativistic heavy-ion beam being transported in a static accelerator focusing lattice. HIBEAM has been used to study beam combining systems, effective dynamic apertures in electrostatic quadrupole lattices, and emittance growth due to transverse misalignments. At present, HIBEAM runs on the CRAY vector machines (C90 and J90's) at NERSC, although it would be relatively simple to port the code to UNIX workstations so long as IMSL math routines were available.
Date: February 1, 2000
Creator: Fawley, William M.
Partner: UNT Libraries Government Documents Department

NANOSCALE SCIENCE AND TECHNOLOGY FOR THE DEVELOPMENT OF ENVIRONMENTAL SENSORS

Description: Under this funding, we proposed to: i) develop a ChemFET sensor platform, ii) develop a ChemDiode sensor platform, iii) synthesize receptor molecules suitable for chemical sensing, iv) study the electrostatic potential changes induced by receptor/target binding on surfaces and v) develop VLSI fabrication approaches for micron-scale chemical sensor devices. The accomplishments under these various thrusts are summarized in this section.
Date: January 3, 2007
Creator: Ronald Andres, School of Chemical Engineering, Purdue University David Janes, School of Electrical and Computer Engineering, Purdue University Clifford Kubiak, Dept. of Chemistry, UCSD Ronald Reifenberger, Dept. of Physics, Purdue University
Partner: UNT Libraries Government Documents Department

Electron Cloud induced instabilities in the Fermilab Main Injector(MI) for the High Intensity Neutrino Source (HINS) project

Description: The electrostatic particle-in-cell codeWARP is currently being expanded in order to study electron cloud effects on the dynamics of the beam in storage rings. Results for the Fermilab main injector (MI) show the existence of a threshold in the electron density beyond which there is rapid emittance growth. The Fermilab MI is being considered for an upgrade as part of the high intensity neutrino source (HINS) effort, which will result in a significant increasing of the bunch intensity relative to its present value, placing it in a regime where electron-cloud effects are expected to become important. Various results from the simulations using WARP are discussed here.
Date: April 15, 2006
Creator: Sonnad, Kiran G.; Furman, Miguel A.; Vay, Jean-Luc; Venturini,Marco; Celata, Christine & Grote, David
Partner: UNT Libraries Government Documents Department

Simulations of Electron Cloud Effects on the Beam Dynamics for theFNAL Main Injector Upgrade

Description: The Fermilab main injector (MI) is being considered for an upgrade as part of the high intensity neutrino source (HINS) effort. This upgrade will involve a significant increasing of the bunch intensity relative to its present value. Such an increase will place the MI in a regime in which electron-cloud effects are expected to become important. We have used the electrostatic particle-in-cell code WARP, recently augmented with new modeling capabilities and simulation techniques, to study the dynamics of beam-electron cloud interaction. This work in progress involves a systematic assessment of beam instabilities due to the presence of electron clouds.
Date: April 15, 2006
Creator: G., Sonnad Kiran; Furman, Miguel; Vay, Jean-Luc; Venturini, Marco; Celata, Christine M. & Grote, David
Partner: UNT Libraries Government Documents Department

Electrostatic microvalves utilizing conductive nanoparticles for improved speed, lower power, and higher force actuation.

Description: We have designed and built electrostatically actuated microvalves compatible with integration into a PDMS based microfluidic system. The key innovation for electrostatic actuation was the incorporation of carbon nanotubes into the PDMS valve membrane, allowing for electrostatic charging of the PDMS layer and subsequent discharging, while still allowing for significant distention of the valveseat for low voltage control of the system. Nanoparticles were applied to semi-cured PDMS using a stamp transfer method, and then cured fully to make the valve seats. DC actuation in air of these valves yielded operational voltages as low as 15V, by using a supporting structure above the valve seat that allowed sufficient restoring forces to be applied while not enhancing actuation forces to raise the valve actuation potential. Both actuate to open and actuate to close valves have been demonstrated, and integrated into a microfluidic platform, and demonstrated fluidic control using electrostatic valves.
Date: September 1, 2009
Creator: Ten Eyck, Gregory A.; Branson, Eric D.; Kenis, Paul J. A. (University of Illinois, Champaign Urbana); Desai, Amit (University of Illinois, Champaign Urbana); Schudel, Ben (University of Illinois, Champaign Urbana); Givler, Richard C. et al.
Partner: UNT Libraries Government Documents Department

Polymer/inorganic superhydrophobic surfaces.

Description: We have designed and built electrostatically actuated microvalves compatible with integration into a PDMS based microfluidic system. The key innovation for electrostatic actuation was the incorporation of carbon nanotubes into the PDMS valve membrane, allowing for electrostatic charging of the PDMS layer and subsequent discharging, while still allowing for significant distention of the valveseat for low voltage control of the system. Nanoparticles were applied to semi-cured PDMS using a stamp transfer method, and then cured fully to make the valve seats. DC actuation in air of these valves yielded operational voltages as low as 15V, by using a supporting structure above the valve seat that allowed sufficient restoring forces to be applied while not enhancing actuation forces to raise the valve actuation potential. Both actuate to open and actuate to close valves have been demonstrated, and integrated into a microfluidic platform, and demonstrated fluidic control using electrostatic valves.
Date: September 1, 2009
Creator: Collord, Andrew; Kissel, David J.; Brinker, C. Jeffrey; Apblett, Christopher Alan & Branson, Eric D.
Partner: UNT Libraries Government Documents Department

Design and Formation of a Large, Tetrahedral, Metal-ligand Cluster Using 1,1'-Binaphthyl Ligands

Description: Many chemists have been fascinated with the development of discrete supramolecular structures that encapsulate guest molecules. These structures can be assembled through covalent or hydrogen bonds, electrostatic or metal-ligand interactions. These host structures have provided valuable insight into the forces involved in small molecule recognition. Our work has focused on the design and study of metal-ligand clusters of varying sizes. The naphthalene [M{sub 4}L{sub 6}]{sup 12-} cluster 1, shown in Figure 1, has demonstrated diastereoselective guest binding and chiral induction properties as well as the ability to catalyze reactions carried out inside the cavity in an enzyme-like manner. However, the size of the cavity (ca. 300-500 {angstrom}{sup 3}) has often limited the scope of substrates for these transformations.
Date: March 13, 2008
Creator: Biros, Shannon M.; Yeh, Robert M. & Raymond, Kenneth N.
Partner: UNT Libraries Government Documents Department

Development of an Electrostatic Dust Detector for use in a Tokamak Reactor

Description: Initial results from a novel device to detect dust particles settling on remote surfaces are presented. Dust particle inventories are a concern in next-step fusion devices. The increase in duty cycle will lead to a scale-up in the amount of particles generated by plasma material interactions. These particles will be chemically and radiologically hazardous and it will be important to establish that the in-vessel particle inventory is within regulatory limits. The detection device consists of two interlocking combs of closely spaced conductive traces on a Teflon circuit board. When a DC bias is applied impinging dust creates a transient short circuit between the traces. The increase in bias current generates a signal pulse that is counted by standard nuclear counting electronics. We present data on the response of the device in air and vacuum to carbon particles.
Date: September 10, 2003
Creator: Bader, A.; C.H. Skinner, A.L. Roquemore & Langish, S.
Partner: UNT Libraries Government Documents Department

Semiconductor bridge, SCB, ignition studies of Al/CuO thermite

Description: The authors briefly summarize semiconductor bridge operation and review their ignition studies of Al/CuO thermite as a function of the capacitor discharge unit (CDU) firing set capacitance, charge holder material and morphology of the CuO. Ignition thresholds were obtained using a brass charge holder and a non-conducting fiber-glass-epoxy composite material, G10. At - 18 C and a charge voltage of 50V, the capacitance thresholds were 30.1 {mu}F and 2.0 {mu}F respectively. They also present new data on electrostatic discharge (ESD) and radio frequency (RF) vulnerability tests.
Date: April 1, 1997
Creator: Bickes, R.W. Jr.; Wackerbarth, D.E. & Mohler, J.H.
Partner: UNT Libraries Government Documents Department

IMAP: Interferometry for Material Property Measurement in MEMS

Description: An interferometric technique has been developed for non-destructive, high-confidence, in-situ determination of material properties in MEMS. By using interferometry to measure the full deflection curves of beams pulled toward the substrate under electrostatic loads, the actual behavior of the beams has been modeled. No other method for determining material properties allows such detailed knowledge of device behavior to be gathered. Values for material properties and non-idealities (such as support post compliance) have then been extracted which minimize the error between the measured and modeled deflections. High accuracy and resolution have been demonstrated, allowing the measurements to be used to enhance process control.
Date: March 10, 1999
Creator: Jensen, B.D.; Miller, S.L. & de Boer, M.P.
Partner: UNT Libraries Government Documents Department

Status and Directions in Electroseparations

Description: In this presentation, a summary of research conducted in the area of electroseparations at the Chemical Technology Division of Oak Ridge National Laboratory is presented. Fields-driven processes, including (1) phase equilibria modification by electric fields and (2) magnetically seeded separations, as well as transport-enhancement processes by electric fields,including (1) surface area generation and (2) electroconvection, are discussed.It is shown that electric fields can change the concentration of the vapor phase during the distillation of a binary mixture, which may have applications in separations by distillation that consume significant amounts of energy. It is also shown that addition of colloidal seed particles of high magnetic susceptibility to a suspension of non-magnetic particles and subsequent flocculation between seed and non-magnetic particles form paramagnetic flocs that can be removed by high- gradient magnetic filtration. Inverse electrostatic spraying, which is the spraying of a non-conductive fluid (such as air) into a conductive fluid (such as water), is introduced and compared with normal electrostatic spraying, which is the spraying of conductive fluid into a non-conductive fluid. Applications of normal electrostatic spraying, including the development of a bioreactor for oil desulfurization, and inverse electrostatic spraying, including ozonation of an aqueous system, are discussed. It is also shown that electroconvection, caused by electric fields,may result in simultaneous pumping, spraying, and mixing of fluids. In summary,new phenomena caused by electric fields are introduced and their potential applications in electroseparations are discussed.
Date: December 31, 1997
Creator: Tsouris, Costas
Partner: UNT Libraries Government Documents Department

Simple Simulations of DNA Condensation

Description: Molecular dynamics simulations of a simple, bead-spring model of semiflexible polyelectrolytes such as DNA are performed. All charges are explicitly treated. Starting from extended, noncondensed conformations, condensed structures form in the simulations with tetravalent or trivalent counterions. No condensates form or are stable for divalent counterions. The mechanism by which condensates form is described. Briefly, condensation occurs because electrostatic interactions dominate entropy, and the favored Coulombic structure is a charge ordered state. Condensation is a generic phenomena and occurs for a variety of polyelectrolyte parameters. Toroids and rods are the condensate structures. Toroids form preferentially when the molecular stiffness is sufficiently strong.
Date: July 12, 2000
Creator: STEVENS,MARK J.
Partner: UNT Libraries Government Documents Department

Torsional Ratcheting Actuating System

Description: A new type of surface micromachined ratcheting actuation system has been developed at the Microelectronics Development Laboratory at Sandia National Laboratories. The actuator uses a torsional electrostatic comb drive that is coupled to an external ring gear through a ratcheting scheme. The actuator can be operated with a single square wave, has minimal rubbing surfaces, maximizes comb finger density, and can be used for open-loop position control. The prototypes function as intended with a minimum demonstrated operating voltage of 18V. The equations of motion are developed for the torsional electrostatic comb drive. The resonant frequency, voltage vs. displacement and force delivery characteristics are predicted and compared with the fabricated device's performance.
Date: January 24, 2000
Creator: BARNES,STEPHEN MATTHEW; MILLER,SAMUEL L.; RODGERS,M. STEVEN & BITSIE,FERNANDO
Partner: UNT Libraries Government Documents Department

ADVANCED HYBRID PARTICULATE COLLECTOR

Description: A new concept in particulate control, called an advanced hybrid particulate collector (AHPC), is being developed under funding from the US Department of Energy. The AHPC combines the best features of electrostatic precipitators (ESPs) and baghouses in an entirely novel manner. The AHPC concept combines fabric filtration and electrostatic precipitation in the same housing, providing major synergism between the two methods, both in the particulate collection step and in transfer of dust to the hopper. The AHPC provides ultrahigh collection efficiency, overcoming the problem of excessive fine-particle emissions with conventional ESPs, and solves the problem of reentrainment and recollection of dust in conventional baghouses. Phase I of the development effort consisted of design, construction, and testing of a 5.7-m{sup 3}/min (200-acfm) working AHPC model. Results from both 8-hour parametric tests and 100-hour proof-of-concept tests with two different coals demonstrated excellent operability and greater than 99.99% fine-particle collection efficiency.
Date: December 1, 2000
Creator: Miller, Stanley J.; Schelkoph, Grant L. & Dunham, Grant E.
Partner: UNT Libraries Government Documents Department

ADVANCED HYBRID PARTICULATE COLLECTOR

Description: A new concept in particulate control, called an advanced hybrid particulate collector (AHPC), is being developed under funding from the US Department of Energy. The AHPC combines the best features of electrostatic precipitators (ESPs) and baghouses in a manner that has not been done before. The AHPC concept consists of a combination of fabric filtration and electrostatic precipitation in the same housing, providing major synergism between the two collection methods, both in the particulate collection step and in transfer of the dust to the hopper. The AHPC provides ultrahigh collection efficiency, overcoming the problem of excessive fine-particle emission with conventional ESPs, and it solves the problem of reentrainment and collection of dust in conventional baghouses.
Date: November 13, 1998
Creator: Miller, Stanley J. & Schelkoph, Grant L.
Partner: UNT Libraries Government Documents Department

Compact electron beam focusing column

Description: A novel design for an electron beam focusing column has been developed at LBNL. The design is based on a low-energy spread multicusp plasma source which is used as a cathode for electron beam production. The focusing column is 10 mm in length. The electron beam is focused by means of electrostatic fields. The column is designed for a maximum voltage of 50 kV. Simulations of the electron trajectories have been performed by using the 2-D simulation code IGUN and EGUN. The electron temperature has also been incorporated into the simulations. The electron beam simulations, column design and fabrication will be discussed in this presentation.
Date: July 13, 2001
Creator: Persaud, Arun; Leung, Ka-Ngo & Reijonen, Jani
Partner: UNT Libraries Government Documents Department

POC-SCALE TESTING OF A DRY TRIBOELECTROSTATIC SEPARATOR FOR FINE COAL CLEANING

Description: During the past quarter, several modifications were made to the TES unit and the materials handling system. The cylindrical electrodes were replaced by a set of screen electrodes to provide a more uniform electrostatic field. The problem with the recycle conveyor neutralizing the particle charge was also corrected by replacing it with a bucket elevator. In addition, problems with the turbocharger were corrected by increasing the number of charging stages from one to two. These modifications have significantly improved the separation performance and have permitted the POC-scale unit to achieve results in line with those obtained by the bench-scale separator. The testing phase of the project was continued at a rapid pace during this quarter. The test work showed that the modifications to the TES unit and the reduction in feed size from 28 mesh to 35 mesh resulted in significant overall improvement in yield and combustible recovery compared to the data reported in the last quarter. At that time, there was a significant discrepancy between the bench-scale and the pilot-scale results. The pilot-scale test work is now approaching the bench scale test results. However, further pilot-scale test work is required to further improve the results and duplicate the bench-scale test work.
Date: January 1, 2000
Creator: Yoon, R.-H.; Luttrell, G.H. & Walters, A.D.
Partner: UNT Libraries Government Documents Department