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in subjects: "High-Frequency Discharges"

open access

Nucleation of nanocrystalline diamond by fragmentation of fullerene precursors.

Growth of diamond films from C{sub 60}/Ar microwave discharges results in a nanocrystalline microstructure with crystallite sizes in the range 3-10 nm. Heterogeneous nucleation rates of 10{sup 10} cm{sup {minus}2} sec are required to account for the results. The nucleation mechanism presented here fulfills this requirement and is based on the insertion of carbon dimer, C{sub 2}, molecules, produced by fragmentation of C{sub 60}, into the n-bonded dimer rows of the reconstructed (100) surface of… more

Date: May 4, 1998

Creator: Gruen, D. M.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Time-resolved infrared absorption studies of the dynamics of radical reactions.

There is very little information available about the dynamics of radical+radical interactions. These processes are important in combustion being chain termination steps as well as generating new molecular species. To study these processes, a new experimental apparatus has been constructed to investigate radical-radical dynamics. The first radical or atomic species is produced with a known concentration in a microwave discharge flow system. The second is produced by pulsed laser photolysis of a … more

Date: March 6, 1998

Creator: MacDonald, R. G.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Electron density and collision frequency of microwave resonant cavity produced discharges. [Progress report]

This progress report consists of an article, the abstract of which follows, and apparently the references and vita from a proposal. A review of perturbation diagnostics applied to microwave resonant cavity discharges is presented. The classical microwave perturbation technique examines the shift in the resonant frequency and cavity quality factor of the resonant cavity caused by low electron density discharges. However, modifications presented here allow the analysis to be applied to discharges… more

Date: December 31, 1992

Creator: McColl, W.; Brooks, C. & Brake, M. L.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Design of Microwave Vitrification Systems for Radioactive Waste

Oak Ridge National Laboratory (ORNL) is involved in the research and development of high-power microwave heating systems for the vitrification of DOE radioactive sludges. Design criteria for a continuous microwave vitrification system capable of processing a surrogate filtercake sludge representative of a typical waste-water treatment operation are discussed. A prototype 915 MHz, 75 kW microwave vitrification system or `microwave melter` is described along with some early experimental results t… more

Date: April 1, 1996

Creator: White, T. L.; Wilson, C. T.; Schaick, C. R. & Bostick, W. D.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Ion energy distribution functions in inductively coupled RF discharges in mixtures of chlorine and boron trichloride

Plasma discharges involving mixtures of chlorine and boron trichloride are widely used to etch metals in the production of very-large-scale-integrated circuits. Energetic ions play a critical role in this process, influencing the etch rates, etch profiles, and selectivity to different materials. The authors are using a gridded energy analyzer to measure positive ion energy distributions and fluxes at the grounded electrode of high-density inductively-coupled rf discharges. In this paper, they p… more

Date: February 1, 1997

Creator: Woodworth, J.R.; Nichols, C.A. & Hamilton, T.W.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Plasma and Ion Sources in Large Area Coatings: A Review

Efficient deposition of high-quality coatings often requires controlled application of excited or ionized particles. These particles are either condensing (film-forming) or assisting by providing energy and momentum to the film growth process, resulting in densification, sputtering/etching, modification of stress, roughness, texture, etc. In this review, the technical means are surveyed enabling large area application of ions and plasmas, with ion energies ranging from a few eV to a few keV. Bo… more

Date: February 28, 2005

Creator: Anders, Andre

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Photoionization-photoelectron research.

In the broad sense of a general definition, the fundamental goal of this research program is to explore, understand, and utilize the basic processes of interaction of vacuum UV light with atoms and molecules. In practical terms, this program uses photoionization mass spectrometry and other related techniques to study chemically relevant transient and metastable species that are intimately connected to energy-producing processes, such as combustion, or play-prominent roles in the associated envi… more

Date: March 6, 1998

Creator: Ruscic, B.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Advanced aircraft ignition CRADA final report

Conventional commercial and military turbo-jet aircraft engines use capacitive discharge ignition systems to initiate fuel combustion. The fuel-rich conditions required to ensure engine re-ignition during flight yield less than optimal engine performance, which in turn reduces fuel economy and generates considerable pollution in the exhaust. Los Alamos investigated two approaches to advanced ignition: laser based and microwave based. The laser based approach is fuel ignition via laser-spark bre… more

Date: March 1, 1997

Creator: Early, J.W.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Large-Volume Resonant Microwave Discharge for Plasma Cleaning of a CEBAF 5-Cell SRF Cavity

We report the preliminary results on plasma generation in a 5-cell CEBAF superconducting radio-frequency (SRF) cavity for the application of cavity interior surface cleaning. CEBAF currently has {approx}300 of these five cell cavities installed in the Jefferson Lab accelerator which are mostly limited by cavity surface contamination. The development of an in-situ cavity surface cleaning method utilizing a resonant microwave discharge could lead to significant CEBAF accelerator performance impro… more

Date: July 1, 2012

Creator: J. Mammosser, S. Ahmed, K. Macha, J. Upadhyay, M. Nikoli, S. Popovi, L. Vuakovi

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

High-intensity sources for light ions

The use of the multicusp plasma generator as a source of light ions is described. By employing radio-frequency induction discharge, the performance of the multicusp source is greatly improved, both in lifetime and in high brightness H{sup +} and H{sup {minus}} beam production. A new technique for generating multiply-charged ions in this type of ion source is also presented.

Date: October 1, 1995

Creator: Leung, K. N.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Buckyball microwave plasmas: Fragmentation and diamond-film growth

Microwave discharges (2.45 GHz) have been generated in C{sub 60}-containing Ar produced by flowing Ar over fullerene-containing soot. Optical spectroscopy shows that the spectrum is dominated by the d{sup 3}{Pi}g-a{sup 3}{Pi}u Swan bands of C{sub 2} and particularly the {Delta}v = {minus}2, {minus}1, 0, +1, and +2 sequences. These results give direct evidence that C{sub 2} is one of the products of C{sub 60} fragmentation brought about, at least in part, by collisionally induced dissociation (C… more

Date: August 1, 1993

Creator: Gruen, D. M.; Liu, Shengzhong; Krauss, A. R. & Pan, Xianzheng

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Atmospheric Pressure Plasma Process And Applications

This paper provides a general discussion of atmospheric-pressure plasma generation, processes, and applications. There are two distinct categories of atmospheric-pressure plasmas: thermal and nonthermal. Thermal atmospheric-pressure plasmas include those produced in high intensity arcs, plasma torches, or in high intensity, high frequency discharges. Although nonthermal plasmas are at room temperatures, they are extremely effective in producing activated species, e.g., free radicals and excited… more

Date: September 1, 2006

Creator: Kong, Peter C. & Myrtle

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Solid target boronization of the MST reversed-field pinch during pulsed discharge cleaning

A solid rod of hot-pressed boron carbide is currently being used as the source of boron during boronization of MST. In previous work the authors have demonstrated that boronization can be effectively accomplished by insertion of a low apparent density B{sub 4}C rod into the edge hydrogen plasma of normal high-power RFP discharges. The authors have now extended that technique and can boronize MST by inserting a negatively biased B{sub 4}C rod into pulsed discharge cleaning (PDC) helium plasmas. … more

Date: June 1, 1994

Creator: Den Hartog, D. J. & Kendrick, R. D.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Plasma chemistries for dry etching GaN, AlN, InGaN and InAlN

Etch rates up to 7,000 {angstrom}/min. for GaN are obtained in Cl{sub 2}/H{sub 2}/Ar or BCl{sub 3}/Ar ECR discharges at 1--3mTorr and moderate dc biases. Typical rates with HI/H{sub 2} are about a factor of three lower under the same conditions, while CH{sub 4}/H{sub 2} produces maximum rates of only {approximately}2,000 {angstrom}/min. The role of additives such as SF{sub 6}, N{sub 2}, H{sub 2} or Ar to the basic chlorine, bromine, iodine or methane-hydrogen plasma chemistries are discussed. T… more

Date: April 1, 1996

Creator: Pearton, S. J.; Vartuli, C. B.; Lee, J. W.; Donovan, S. M.; MacKenzie, J. D.; Abernathy, C. R. et al.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Ion energy and angular distributions in inductively driven RF discharges in chlorine

In this paper, the authors report values of ion energy distributions and ion angular distributions measured at the grounded electrode of an inductively-coupled discharge in pure chlorine gas. The inductive drive in the GEC reference cell produced high plasma densities (10{sup 11}/cm{sup 3} electron densities) and stable plasma potentials. As a result, ion energy distributions typically consisted of a single peak well separated from zero energy. Mean ion energy varied inversely with pressure, de… more

Date: March 1, 1996

Creator: Woodworth, J. R.; Riley, M. E. & Hamilton, T. W.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Experiments and modeling with a large-area inductively coupled plasma (ICP) source

We describe initial experiments with a large (30 in.) plasma source chamber to explore the problems associated with large-area Inductively coupled plasma (ICP) sources to produce high density plasmas useful for processing 400 mm semiconductor wafers. Our experiments typically use a 25 in. diameter planar ICP coil driven at 13.56 MHz. Plasma and system data are taken in Ar and N{sub 2} over the pressure range 3--50 mtorr. R.F. Inductive power was run up to 2000W, but typically data were taken ov… more

Date: June 1, 1995

Creator: Benjamin, R. D.; DiPeso, G.; Egan, P. O.; Parker, G. J.; Richardson, R. A. & Vitello, P.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Verification of frequency scaling laws for capacitive rf discharges using two-dimensional simulations

Weakly ionized processing plasmas are studied in two-dimensions using a bounded particle-in-cell (PIC) simulation code with a Monte Carlo Collision (MCC) package. The MCC package models the collisions between charged and neutral particles, which are needed to obtain a self-sustained plasma and the proper electron and ion energy loss mechanisms. A two-dimensional capacitive RF discharge is investigated in detail. Simple frequency scaling laws for predicting the behavior of some plasma parameters… more

Date: December 15, 1992

Creator: Vahedi, V.; Birdsall, C. K.; Lieberman, M. A.; DiPeso, G. & Rognlien, T. D.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Electrical characterization of rf plasmas

Radio-frequency (rf) electrical sources are commonly used to generate plasmas for processing of industrial materials and for related experimental work. Published descriptions of such plasmas usually include generator-power measurements, and occasionally include plasma dc-bias measurements. One or both of these quantitites are also used in industrial feedback ccontrol systems for setpoint regulation. Recent work at Sandia an elsewhere with an experimental rf discharge device (the GEC RF Referenc… more

Date: August 1, 1991

Creator: Miller, P.A.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Microwave production of hydrogen and sulfur from hydrogen sulfide wastes

A waste-treatment process is being developed that uses ``cold`` microwave plasma-chemical reactions to split hydrogen sulfide into elemental hydrogen and sulfur. A clean sulfur product can be recovered and sold, while product gases are purified and separated into seams containing hydrogen, hydrogen sulfide for recycle, and the process purge containing carbon dioxide and water. Experiments with pure hydrogen sulfide at 0.5 to 1.5 L/min flow rates and microwave powers of 400 to 1000 W confirmed t… more

Date: January 1, 1992

Creator: Harkness, J. B. L. & Doctor, R. D.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Microwave production of hydrogen and sulfur from hydrogen sulfide wastes

A waste-treatment process is being developed that uses cold'' microwave plasma-chemical reactions to split hydrogen sulfide into elemental hydrogen and sulfur. A clean sulfur product can be recovered and sold, while product gases are purified and separated into seams containing hydrogen, hydrogen sulfide for recycle, and the process purge containing carbon dioxide and water. Experiments with pure hydrogen sulfide at 0.5 to 1.5 L/min flow rates and microwave powers of 400 to 1000 W confirmed tha… more

Date: January 1, 1992

Creator: Harkness, J. B. L. & Doctor, R. D.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Potential applications of a new microwave ECR (electron cyclotron resonance) multicusp plasma ion source

A new microwave electron cyclotron resonance (ECR) multicusp plasma ion source using two ECR plasma production regions and multicusp plasma confinement has been developed at Oak Ridge National Laboratory. This source has been operated to produce uniform and dense plasmas over large areas of 300 to 400 cm{sup 2}. The plasma source has been operated with continuous argon gas feed and pulsed microwave power. The discharge initiation phenomena and plasma properties have been investigated and studie… more

Date: January 1, 1990

Creator: Tsai, C.C.

Item Type: Article

Partner: UNT Libraries Government Documents Department