653 Matching Results

Search Results

Advanced search parameters have been applied.
in subjects: "Electron Density"  
Results: 1 - 24 next
open access

Using Plasmon Peaks in Electron Energy-Loss Spectroscopy to Determine the Physical and Mechanical Properties of Nanoscale Materials

Description: In this program, we developed new theoretical and experimental insights into understanding the relationships among fundamental universality and scaling phenomena, the solid-state physical and mechanical properties of materials, and the volume plasmon energy as measured by electron energy-loss spectroscopy (EELS). Particular achievements in these areas are summarized as follows: (i) Using a previously proposed physical model based on the universal binding-energy relation (UBER), we established c… more
Date: May 9, 2013
Creator: Howe, James M.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Final Report Spacially-Resolved Diagnostics and Modeling of Micro-Discharges

Description: Optical emission spectroscopy measurements were performed with added trace probe gases in an atmospheric pressure direct current (DC) helium microplasma. Spatially resolved measurements (resolution {approx} 6 {micro}m) were taken across a 200 {micro}m slot-type discharge. Stark splitting of the hydrogen Balmer-line was used to investigate the electric field distribution in the cathode sheath region. Electron densities were evaluated from the analysis of the spectral line broadenings of H-{beta}… more
Date: August 9, 2012
Creator: Donnelly, Vincent M. & Economou, Demetre J.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Assessment of an ORION-based experimental platform for measuring the opacity of high-temperature and high-density plasma

Description: The following provides an assessment of an experimental platform based on the ORION laser at AWE Aldermasten, England, for measuring the opacity of high-temperature and high-density LTE plasmas. The specific points addressed are (1) the range of electron density and temperature that can be achieved with short-pulse beams alone, as well as (2) by means of compression with a long-pulse beam; (3) the accuracy with which electron density, electron temperature, and absolute emissivity can be measure… more
Date: June 11, 2012
Creator: Beiersdorfer, P; Schneider, M & Shepherd, R
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Nano Catalysts for Diesel Engine Emission Remediation

Description: The objective of this project was to develop durable zeolite nanocatalysts with broader operating temperature windows to treat diesel engine emissions to enable diesel engine based equipment and vehicles to meet future regulatory requirements. A second objective was to improve hydrothermal durability of zeolite catalysts to at least 675 C. The results presented in this report show that we have successfully achieved both objectives. Since it is accepted that the first step in NO{sub x} conversio… more
Date: June 1, 2012
Creator: Narula, Chaitanya Kumar; Yang, Xiaofan; Debusk, Melanie Moses; Mullins, David R; Mahurin, Shannon Mark & Wu, Zili
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Influence of electron beam parameters on coherent electron cooling

Description: Coherent electron cooling (CeC) promises to revolutionize the cooling of high energy hadron beams. The intricate dynamics of the CeC depends both on the local density and energy distribution of the beam. The variations of the local density (beam current) are inevitable in any realistic beam. Hence, in this paper we propose a novel method of beam conditioning. The conditioning provides compensation of effect from such variation by a correlated energy modulation. We use our analytical FEL model f… more
Date: May 20, 2012
Creator: Wang, G.; Hao, Y.; Litvinenko, V. N. & Webb, S.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Imaging of High-Energy X-Ray Emission from Cryogenic Thermonuclear Fuel Implosions on the NIF

Description: Accurately assessing and optimizing the implosion performance of inertial confinement fusion capsules is a crucial step to achieving ignition on the NIF. We have applied differential filtering (matched Ross filter pairs) to provide spectrally resolved time-integrated absolute x-ray self-emission images of the imploded core of cryogenic layered targets. Using bremsstrahlung assumptions, the measured absolute x-ray brightness allows for the inference of electron temperature, electron density, hot… more
Date: May 1, 2012
Creator: Ma, T
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Imaging Thomson scattering measurements of radiatively heated Xe

Description: Uniform density and temperature Xe plasmas have been produced over >4 mm scale-lengths using x-rays generated in a cylindrical Pb cavity. The cavity is 750 {micro}m in depth and diameter, and is heated by a 300 J, 2 ns square, 1054 nm laser pulse focused to a spot size of 200 {micro}m at the cavity entrance. The plasma is characterized by simultaneous imaging Thomson scattering measurements from both the electron and ion scattering features. The electron feature measurement determines the sp… more
Date: May 1, 2012
Creator: Pollock, B.; Meinecke, J.; Kuschel, S.; Ross, J. S.; Divol, L.; Glenzer, S. H. et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Thomson scattering diagnostic for the measurement of ion species fraction

Description: Simultaneous Thomson scattering measurements of collective electron-plasma and ion-acoustic fluctuations have been utilized to determine ion species fraction from laser produced CH plasmas. The CH{sub 2} foil is heated with 10 laser beams, 500 J per beam, at the Omega Laser facility. Thomson scattering measurements are made 4 mm from the foil surface using a 30 J 2{omega} probe laser with a 1 ns pulse length. Using a series of target shots the plasma evolution is measured from 2.5 ns to 9 ns af… more
Date: May 1, 2012
Creator: Ross, J. S.; Park, H. S.; Amendt, A.; Divol, L.; Kugland, N. L.; Rozmus, W. et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Fermi-LAT Discovery of Extended Gamma-Ray Emission in the Direction of Supernova Remnant W51C

Description: The discovery of bright gamma-ray emission coincident with supernova remnant (SNR) W51C is reported using the Large Area Telescope (LAT) onboard the Fermi Gamma-ray Space Telescope. W51C is a middle-aged remnant ({approx}10{sup 4} yr) with intense radio synchrotron emission in its shell and known to be interacting with a molecular cloud. The gamma-ray emission is spatially extended, broadly consistent with the radio and X-ray extent of SNR W51C. The energy spectrum in the 0.2-50 GeV band exhibi… more
Date: March 30, 2012
Creator: Abdo, A. A.; Ackermann, M.; Ajello, M.; Baldini, L.; Ballet, J.; Barbiellini, G. et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Energy Spread Reduction of Electron Beams Produced via Laser Wake

Description: Laser wakefield acceleration of electrons holds great promise for producing ultra-compact stages of GeV scale, high quality electron beams for applications such as x-ray free electron lasers and high energy colliders. Ultra-high intensity laser pulses can be self-guided by relativistic plasma waves over tens of vacuum diffraction lengths, to give >1 GeV energy in cm-scale low density plasma using ionization-induced injection to inject charge into the wake at low densities. This thesis descri… more
Date: March 19, 2012
Creator: Pollock, B.
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries Government Documents Department
open access

Recommendation for Mitigations of the Electron Cloud Instability in the ILC

Description: Electron cloud has been identified as one of the highest priority issues for the international Linear Collider (ILC) Damping Rings (DR). An electron cloud Working Group (WG) has evaluated the electron cloud effect and instability, and mitigation solutions for the electron cloud formation. Working group deliverables include recommendations for the baseline and alternate solutions to the electron cloud formation in various regions of the ILC Positron DR, which is presently assumed to be the 3.2 k… more
Date: December 13, 2011
Creator: Pivi, M. T. F.; Wang, L.; Demma, T.; Guiducci, S.; Suetsugu, Y.; Shibata, K. et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Determination of effective axion masses in the helium-3 buffer of CAST

Description: The CERN Axion Solar Telescope (CAST) is a ground based experiment located in Geneva (Switzerland) searching for axions coming from the Sun. Axions, hypothetical particles that not only could solve the strong CP problem but also be one of the favored candidates for dark matter, can be produced in the core of the Sun via the Primakoff effect. They can be reconverted into X-ray photons on Earth in the presence of strong electromagnetic fields. In order to look for axions, CAST points a decommissi… more
Date: November 18, 2011
Creator: Ruz, J
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Coherent electron cooling demonstration experiment

Description: Coherent electron cooling (CEC) has a potential to significantly boost luminosity of high-energy, high-intensity hadron-hadron and electron-hadron colliders. In a CEC system, a hadron beam interacts with a cooling electron beam. A perturbation of the electron density caused by ions is amplified and fed back to the ions to reduce the energy spread and the emittance of the ion beam. To demonstrate the feasibility of CEC we propose a proof-of-principle experiment at RHIC using SRF linac. In this p… more
Date: September 4, 2011
Creator: Litvinenko, V. N.; Belomestnykh, S.; Ben-Zvi, Ilan; Brutus, J. C.; Fedotov, A.; Hao, Y. et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Study of Electron Cloud for MEIC

Description: The Medium Energy Electron Ion Collider (MEIC) at Jefferson Lab has been envisioned as a future high energy particle accelerator beyond the 12 GeV upgrade of the existing Continuous Electron Beam Accelerator Facility (CEBAF). Synchrotron radiation from the closely spaced proton bunches in MEIC can generate photoelectrons inside the vacuum chamber and cause secondary emission due to multipacting in the presence of beam's electric field. This phenomenon can lead to fast build up of electron densi… more
Date: September 1, 2011
Creator: S. Ahmed, J.D. Dolph, G.A. Krafft, T. Satogata, B.C. Yunn
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Proof-of-principle experiment for FEL-based coherent electron cooling

Description: Coherent electron cooling (CEC) has a potential to significantly boost luminosity of high-energy, high-intensity hadron-hadron and electron-hadron colliders. In a CEC system, a hadron beam interacts with a cooling electron beam. A perturbation of the electron density caused by ions is amplified and fed back to the ions to reduce the energy spread and the emittance of the ion beam. To demonstrate the feasibility of CEC we propose a proof-of-principle experiment at RHIC using SRF linac. In this p… more
Date: August 21, 2011
Creator: Litvinenko, V. N.; Belomestnykh, S.; Ben-Zvi, Ilan; Brutus, J. C.; Fedotov, A.; Hao, Y. et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Observation of Spin Coulomb Drag in a Two-Dimensional Electron Gas

Description: An electron propagating through a solid carries spin angular momentum in addition to its mass and charge. Of late there has been considerable interest in developing electronic devices based on the transport of spin, which offer potential advantages in dissipation, size, and speed over charge-based devices. However, these advantages bring with them additional complexity. Because each electron carries a single, fixed value (-e) of charge, the electrical current carried by a gas of electrons is si… more
Date: August 19, 2011
Creator: Weber, C.P.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Reconstruction of the Electron Density of Molecules with Single-Axis Alignment

Description: Diffraction from the individual molecules of a molecular beam, aligned parallel to a single axis by a strong electric field or other means, has been proposed as a means of structure determination of individual molecules. As in fiber diffraction, all the information extractable is contained in a diffraction pattern from incidence of the diffracting beam normal to the molecular alignment axis. We present two methods of structure solution for this case. One is based on the iterative projection alg… more
Date: August 12, 2011
Creator: Starodub, Dmitri
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Comment on Li pellet Conditioning in TFTR

Description: Li pellet conditioning in TFTR results in a reduction of the edge electron density which allows increased neutral beam penetration, central heating, and fueling. Consequently the temperature profiles became more peaked with higher central Ti, Te, and neutron emission rates.
Date: May 23, 2011
Creator: Budny, R.V.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Amplification of current density modulation in a FEL with an infinite electron beam

Description: We show that the paraxial field equation for a free electron laser (FEL) in an infinitely wide electron beam with {kappa}-2 energy distribution can be reduced to a fourth ordinary differential equation (ODE). Its solution for arbitrary initial phase space density modulation has been derived in the wave-vector domain. For initial current modulation with Gaussian profile, close form solutions are obtained in space-time domain. In developing an analytical model for a FEL-based coherent electron co… more
Date: March 28, 2011
Creator: Wang, G.; Litvinenko, V. N. & Webb, S. D.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Hydrogen Fuel Cells and Storage Technology: Fundamental Research for Optimization of Hydrogen Storage and Utilization

Description: Design and development of improved low-cost hydrogen fuel cell catalytic materials and high-capacity hydrogenn storage media are paramount to enabling the hydrogen economy. Presently, effective and durable catalysts are mostly precious metals in pure or alloyed form and their high cost inhibits fuel cell applications. Similarly, materials that meet on-board hydrogen storage targets within total mass and volumetric constraints are yet to be found. Both hydrogen storage performance and cost-effec… more
Date: March 28, 2011
Creator: Perret, Bob; Heske, Clemens; Nadavalath, Balakrishnan; Cornelius, Andrew; Hatchett, David; Bae, Chusung et al.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Direct Numerical Modeling of E-Cloud Driven Instability of a Bunch Train in the CERN SPS

Description: The simulation package WARP-POSINST was recently upgraded for handling multiple bunches and modeling concurrently the electron cloud buildup and its effect on the beam, allowing for direct self-consistent simulation of bunch trains generating, and interacting with, electron clouds. We have used the WARP-POSINST package on massively parallel supercomputers to study the buildup and interaction of electron clouds with a proton bunch train in the CERN SPS accelerator. Results suggest that a positiv… more
Date: March 1, 2011
Creator: Vay, J. L.; Furman, M. A. & Venturini, M.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Predictions of Alpha Heating in ITER L-mode and H-mode Plasmas

Description: Predictions of alpha heating in L-mode and H-mode DT plasmas in ITER are generated using the PTRANSP code. The baseline toroidal field of 5.3 T, plasma current ramped to 15 MA and a flat electron density profile ramped to Greenwald fraction 0.85 are assumed. Various combinations of external heating by negative ion neutral beam injection, ion cyclotron resonance, and electron cyclotron resonance are assumed to start half-way up the density ramp. The time evolution of plasma temperatures and, for… more
Date: January 6, 2011
Creator: Budny, R. V.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Observation And Modeling Of Inner Divertor Re-attachment In Discharges With Lithium Coatings in NSTX

Description: In the National Spherical Torus Experiment (NSTX), modifications to the inner divertor plasma regimes are observed in high triangularity, H-mode, NBI heated discharges due to lithium coatings evaporated on the plasma facing components. In particular, the drop in the recombination rate, the reduced neutral pressure and the reduced electron density (inferred from Stark broadening measurements of high−n deuterium Balmer lines) suggested that the inner divertor, which is usually detached in dischar… more
Date: January 4, 2011
Creator: Scotti, Filippo; Soukhanovskii, V. A.; Adams, M. L.; Scott, H. A.; Kugel, H. W.; Kaita, R. et al.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Laboratory Calibration of Density-Dependent Lines in the EUV and Soft X-Ray Regions

Description: We analyzed spectral data of Fe XXII and Ar XIV from laboratory sources in which the electron density varies by several orders of magnitude to help benchmark density-sensitive emission lines useful for astrophysics and to test the atomic models underlying the diagnostic line ratios. We found excellent agreement for Fe XXII, but poorer agreement for Ar XIV. A number of astrophysically important emission lines are sensitive to electron density in the EUV and soft X-ray regions. Lines from Fe XXII… more
Date: December 9, 2010
Creator: Lepson, J K; Beiersdorfer, P; Gu, M F & Desai, P
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
Back to Top of Screen