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open access

Modeling and Optimization of Deflection Slits for Fast-Pulsing of a Low Energy Ion Beam

Description: This paper discusses research on modeling and optimization of deflection slits for fast-pulsing of a low energy ion beam. The authors also investigate simulated slit configurations that reduce the length of the fields along the beam axis, thus optimizing the pulsing mechanism.
Date: March 30, 2006
Creator: Bosca, Ryan & Weathers, Duncan L.
Partner: UNT Honors College
open access

Space-charge-based electrostatic plasma confinement involving relaxed plasma species

Description: In this article, a numerical study is reported on the equilibrium properties of a surface-emitted or edge-confined non-drifting plasma. A self-consistent finite-differences evaluation of the electrostatic potential is carried out for a non-neutral plasma that follows a Boltzmann density distribution.
Date: October 23, 2012
Creator: Pacheco, J. L.; Ordonez, Carlos A. & Weathers, Duncan L.
Partner: UNT College of Arts and Sciences
open access

Artificially Structured Boundary for a high purity ion trap or ion source

Description: This article proposes a plasma enclosed by an Artificially Structured Boundary (ASB) as an alternative to existing ion source assemblies. In accelerator applications, many ion sources can have a limited lifetime or frequent service intervals due to sputtering and eventual degradation of the ion source assembly. Ions are accelerated towards the exit canal of positive ion sources, whereas, due to the biasing scheme, electrons or negative ions are accelerated towards the back of the ion source ass… more
Date: August 1, 2014
Creator: Pacheco, J. L.; Ordonez, Carlos A. & Weathers, Duncan L.
Partner: UNT College of Arts and Sciences
open access

Electrostatic storage ring with focusing provided by the space charge of an electron plasma

Description: Article describes an electronic storage ring that employs the space charge of an electron plasma for focusing. An advantage of the present concept is that slow ions, or even a stationary ion plasma, can be confined. The concept employs an artificially structured boundary, which is defined at present as one that produces a spatially periodic static field such that the spatial period and range of the field are much smaller than the dimensions of a plasma or charged-particle beam that is confined … more
Date: April 19, 2013
Creator: Pacheco, J. L.; Ordonez, Carlos A. & Weathers, Duncan L.
Partner: UNT College of Arts and Sciences
open access

Spatially Periodic Electromagnetic Force Field For Plasma Confinement and Control

Description: In this article, a theoretical understanding is developed of the single-particle reflection properties of a force field, considering the incident charged particles to have a non-drifting, isotropic velocity distribution. Classical trajectory Monte Carlo simulations and analytical modeling are employed. The initiation of an experimental effort to study force fields is described.
Date: April 17, 2012
Creator: Ordonez, Carlos A.; Pacheco, J. L. & Weathers, Duncan L.
Partner: UNT College of Arts and Sciences
open access

Energy Conversion During Expansion of a Solid-Particle-Entrained Gas

Description: This article describes pneumatic energy being converted into solid particle kinetic energy as a solid-particle-entrained gas that flows downward through a vertical nozzle. For the conditions studied, the solid particles serve as a heat exchange medium to enable a gas expansion that is nearly isothermal. Also, the kinetic energy associated with the two-phase fluid is predominantly that associated with subsonic solid-particle motion. The kinetic energy of the solid particles is converted into oth… more
Date: January 10, 2013
Creator: Ordonez, Carlos A.; Weathers, Duncan L. & Traum, Matthew J.
Partner: University of North Texas
open access

Phase space of positron trajectories exiting a charged particle source through a magnetic field point cusp

Description: This article presents a configuration of magnetic fields using properties of cylindrically symmetric permanent magnets as a candidate to produce a high purity charged particle source or trap. Cylindrically symmetric hollow permanent magnets produce magnetic field point cusps on the axis of symmetry. A magnetic field point cusp reflects all particles that lie outside a narrow region of phase space, a region dependent on particle kinetic energies and on the magnetic field intensity.
Date: August 1, 2014
Creator: Kiester, A. S.; Pacheco, J. L.; Ordonez, Carlos A. & Weathers, Duncan L.
Partner: UNT College of Arts and Sciences
open access

Laser Ablated Carbon Nanodots for Light Emission

Description: This article reports the synthesis of fluorescent carbon dots-like nanostructures obtained through the laser ablation of a carbon solid target in liquid environment is reported.
Date: September 22, 2016
Creator: Reyes, Delfino; Camacho, Marco; Camacho, Miguel; Mayorga, Miguel; Weathers, Duncan L.; Salamo, Greg et al.
Partner: UNT College of Arts and Sciences
open access

K-shell x-ray-production cross sections in 6C, 8O, 9F, 11Na, 12Mg, and 13Al, by 0.75- to 4.5-MeV protons

Description: Article discussing K-shell x-ray-production cross sections in 6C, 8O, 9F, 11Na, 12Mg, and 13AI, by 0.75- to 4.5-MeV protons.
Date: November 1, 1991
Creator: Yu, Y. C.; McNeir, M. R.; Weathers, Duncan L.; Duggan, Jerome L.; McDaniel, Floyd Del. (Floyd Delbert), 1942- & Lapicki, Gregory
Partner: UNT College of Arts and Sciences
open access

Simultaneous measurement of the average ion-induced electron emission yield and the mean charge for isotachic ions in carbon foils

Description: Article discussing the simultaneous measurement of the average ion-induced electron emission yield and the mean charge for isotachic ions in carbon foils.
Date: February 1997
Creator: Arrale, A. M.; Zhao, Z. Y.; Kirchhoff, J. F.; Weathers, Duncan L.; McDaniel, Floyd Del. (Floyd Delbert), 1942- & Matteson, Samuel E.
Partner: UNT College of Arts and Sciences
open access

Collision-Induced Interaction Cross Sections of 1-7 Mev B₂ Ions Incident on an N₂ Gas Target

Description: This article describes the measurement of collision-induced interaction cross sections for 1-7 MeV diatomic boron molecular ions incident on a nitrogen gas target by using a differentially pumped gas cell.
Date: May 5, 1995
Creator: Kim, Y. D.; Jin, J. Y.; Matteson, Samuel E.; Weathers, Duncan L.; Anthony, J. M.; Marshall, Paul et al.
Partner: UNT College of Arts and Sciences
open access

Mechanism for etching of exfoliated graphene on substrates by low-energy electron irradiation from helium plasma electron sources

Description: Article investigating the mechanism for etching of exfoliated graphene multilayers on SiO₂ by low-energy (50 eV) electron irradiation using He plasma systems for electron sources.
Date: February 26, 2019
Creator: Femi-Oyetoro, John D.; Yao, Kevin; Tang, Runtian; Ecton, Philip A.; Roccapriore, Kevin M.; Mhlanga, Ashley et al.
Partner: University of North Texas
open access

Fabrication of silicon-based optical components for an ultraclean accelerator mass spectronomy negative ion source

Description: Article discussing the fabrication of silicon-based optical components for an ultraclean accelerator mass spectonomy negative ion source.
Date: May 1994
Creator: Kirchhoff, J. F.; Marble, D. K.; Weathers, Duncan L.; McDaniel, Floyd Del. (Floyd Delbert), 1942-; Matteson, Samuel E.; Anthony, J. M. et al.
Partner: UNT College of Arts and Sciences
open access

RBS Study of a Dilute Alloy of Ga(99.8% at.):Bi(0.2% at.)

Description: This paper from the 2016 Conference on Application of Accelerators in Research and Industry conference proceedings describes an attempt to observe an atomic bismuth monolayer with Rutherford backscattering to demonstrate the surface concentration of the bismuth over the alloy in the bulk.
Date: October 26, 2017
Creator: Peterson, Randolph S.; Augustine, Carlyn N.; Beriont, Griffin G.; Farr, Aidan T.; Jenkins, William T. J.; Morris, Taylor A. et al.
Partner: UNT College of Science
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