Absolute Number Density Measurements of Atomic Species in Air and Nitrogen Plasmas PDF Download
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Author: Jeffrey C Schindler
Publisher:
ISBN:
Category : Laser-induced fluorescence
Languages : en
Pages : 1121
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Book Description
A vehicle reentering Earth's atmosphere at hypersonic velocities violently compresses the air in front of it, creating a shell of plasma at the surface. This plasma imparts energy onto the vehicle's surface via convective, radiative, and chemical heating. Currently, large uncertainties in measurements of surface reaction rates lead to over-designed thermal protection systems. Improvements in the precision of these measurements could substantially decrease the weight of the heat shield, freeing up space for additional fuel or human/scientific payload. This work aims to improve current methods for measurements of atomic number densities in plasmas, so that they may be applied to future measurements of surface reaction rates. In this work, relative number densities are measured by probing atomic species in an inductively coupled plasma with two-photon absorption laser induced fluorescence. The use of a room temperature flow reactor as a reference source allows for absolute calibration of relative number density measurements while removing many constants, and their uncertainties, from the calculation. Temperature and number density measurements in the free stream of air and nitrogen plasmas suggest near equilibrium populations of both oxygen and nitrogen atoms. Improvements in methods for fluorescence lifetime measurements, allow for resolution of the lifetimes between 1.5 and 4 ns which are seen in the plasma. Evidence of collision-induced upper state transfer in the plasma is presented. Off line center excitation of N, O, and NO show evidence of higher quenching than is seen at the line-center. Further work is needed to determine if this is a physical phenomenon, or instrumental error.
Author: Jeffrey C Schindler
Publisher:
ISBN:
Category : Laser-induced fluorescence
Languages : en
Pages : 1121
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Book Description
A vehicle reentering Earth's atmosphere at hypersonic velocities violently compresses the air in front of it, creating a shell of plasma at the surface. This plasma imparts energy onto the vehicle's surface via convective, radiative, and chemical heating. Currently, large uncertainties in measurements of surface reaction rates lead to over-designed thermal protection systems. Improvements in the precision of these measurements could substantially decrease the weight of the heat shield, freeing up space for additional fuel or human/scientific payload. This work aims to improve current methods for measurements of atomic number densities in plasmas, so that they may be applied to future measurements of surface reaction rates. In this work, relative number densities are measured by probing atomic species in an inductively coupled plasma with two-photon absorption laser induced fluorescence. The use of a room temperature flow reactor as a reference source allows for absolute calibration of relative number density measurements while removing many constants, and their uncertainties, from the calculation. Temperature and number density measurements in the free stream of air and nitrogen plasmas suggest near equilibrium populations of both oxygen and nitrogen atoms. Improvements in methods for fluorescence lifetime measurements, allow for resolution of the lifetimes between 1.5 and 4 ns which are seen in the plasma. Evidence of collision-induced upper state transfer in the plasma is presented. Off line center excitation of N, O, and NO show evidence of higher quenching than is seen at the line-center. Further work is needed to determine if this is a physical phenomenon, or instrumental error.
Author: Louis Free
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
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Book Description
This thesis presents a novel, asymmetrical atmospheric pressure plasma jet, that uses air as its working gas, operating in the kilohertz range. The plasma system is designed to be mobile, easily set-up in many environments and has variable controllability, such as voltage, airflow and electrode position. The initial body of work presented in the thesis relates to the design and development of the atmospheric pressure plasma jet used throughout the bulk of the thesis. The key components of the atmospheric plasma jet are introduced. Electrical measurements of the plasma were also preformed and showed that the plasma operated electrically in two modes, the so called noisy and quiet modes. Optical emission spectroscopy was preformed on the plasma jet and showed that the emission spectrum of the jet was complex, containing emissions from many species, both molecular and atomic. These species included but were not limited to atomic species of nitrogen, oxygen and hydrogen and molecular emissions from N2, O2 and OH. In addition to this, it is possible to control the emission intensities from these species by varying the control parameters of the plasma jet such as voltage, airflow and electrode distance. The observed emission spectra were noticed to be lacking in any optical features due to emissions from nitric oxide, while it was believed to be the case that the plasma jet should produce nitric oxide. To test this hypothesis the experimental method laser induced fluorescence was chosen as a means to probe or nitric oxide in the plume region of the plasma. Experimentally it was found that nitric oxide was present within the plume. In addition by again varying the control parameters of the plasma jet the absolute number density of nitric oxide within the plume of the plasma could be varied. Finally, two-photon absorption laser induced fluorescence is used to probe for atomic oxygen in the plume region of the atmospheric pressure plasma jet. Two photon absorption differs from the single photon method in that two photons are simultaneously absorbed by and used to excite the species under investigation, opening up the possibility to probe species with excitation energies that are difficult to reach using conventional lasers systems. Like, the case for nitric oxide, atomic oxygen was confirmed to be present within the plume, although it was not possible to determine an absolute number density. Likewise, by varying the control parameters a change in the trend in the intensity of the fluorescence was observed.
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Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 884
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Author: Ewen Austin McLennan
Publisher:
ISBN:
Category : Atoms
Languages : en
Pages : 168
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Book Description
Densities of ground-state N, O and H atoms, formed by dissociation of the parent molecular gases in dc and rf discharges, were measured over the range 10 to the 10th power to 10 to the 16th power/cc. Sensitive and unambiguous measurements that did not disturb the system under study were made by electron spin resonance (ESR) and atomic resonance absorption spectroscopy (RAS). Quantitative measurements were made by calibration of the atomic ESR resonance lines against an O2 ESR resonance line standard. Densities determined by ESR and by gas titration agreed within 20 per cent. Densities of ground -state atoms were investigated in the afterglows of pulsed and continuous rf discharges, and pulsed dc discharges, in both stationary and flowing gases. Dissociation of the parent molecular gas was found to be a strong function of the type of discharge and of the gas impurity content: rf discharges in gases with a few tenths per cent H2O impurity typically produced four orders of magnitude more atoms than did pulsed dc discharges in 'pure' gases. Atomic densities were measurable up to 10 sec in rf discharge afterglows. The slow recombination of the atoms provides a long-lived energy source throughout the afterglow. Experiments were performed to show that the concentration of N atoms in the afterglow of a pulsed dc discharge in N2 markedly affects the electron density, temperature, and collision frequency.
Author:
Publisher:
ISBN:
Category : Nuclear energy
Languages : en
Pages : 1550
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Book Description
Author: J. Leon Shohet
Publisher: CRC Press
ISBN: 1482214318
Category : Technology & Engineering
Languages : en
Pages : 1654
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Book Description
Technical plasmas have a wide range of industrial applications. The Encyclopedia of Plasma Technology covers all aspects of plasma technology from the fundamentals to a range of applications across a large number of industries and disciplines. Topics covered include nanotechnology, solar cell technology, biomedical and clinical applications, electronic materials, sustainability, and clean technologies. The book bridges materials science, industrial chemistry, physics, and engineering, making it a must have for researchers in industry and academia, as well as those working on application-oriented plasma technologies. Also Available Online This Taylor & Francis encyclopedia is also available through online subscription, offering a variety of extra benefits for researchers, students, and librarians, including: Citation tracking and alerts Active reference linking Saved searches and marked lists HTML and PDF format options Contact Taylor and Francis for more information or to inquire about subscription options and print/online combination packages. US: (Tel) 1.888.318.2367; (E-mail)
[email protected] International: (Tel) +44 (0) 20 7017 6062; (E-mail)
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Author: Tian Ding
Publisher: Springer Nature
ISBN: 9811618275
Category : Technology & Engineering
Languages : en
Pages : 357
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Book Description
This book provides readers with a comprehensive overview of cold plasma technology for tackling the various food-related hazards in a wide range of food sectors. The principles and characteristics of cold plasma generation in gas and its interaction with liquids, as well as its combating modes of action for common hazards (e.g., bacteria, spores, biofilms, fungi, and fungal toxins) are emphasized in this book. It also presents the applications of cold plasma or its hurdles with other techniques to assure the microbiological safety of the key food classifications, including fruits, vegetables, cereals, grains, meat, aquatic products, liquid food products (e.g., juices, milk), nuts, spices, herbs, and food packaging. This book is useful for researchers to grasp the comprehensive understandings of how food safety can be controlled with cold plasma technology. This book also provides adequate information for engineers in food industry for better development and optimization of the plasma-generating systems. Government institutions that are responsible for food safety regulations can understand more knowledge about the intricacies and influencing factors, which should be considered for regulating the applications of cold plasma technology in food.
Author: XinPei Lu
Publisher: CRC Press
ISBN: 0429620721
Category : Science
Languages : en
Pages : 388
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Book Description
Nonequilibrium atmospheric pressure plasma jets (N-APPJs) generate plasma in open space rather than in a confined chamber and can be utilized for applications in medicine. This book provides a complete introduction to this fast-emerging field, from the fundamental physics, to experimental approaches, to plasma and reactive species diagnostics. It provides an overview of the development of a wide range of plasma jet devices and their fundamental mechanisms. The book concludes with a discussion of the exciting application of plasmas for cancer treatment. The book provides details on experimental methods including expert tips and caveats. covers novel devices driven by various power sources and the impact of operating conditions on concentrations and fluxes of the reactive species. discusses the latest advances including theory, modeling, and simulation approaches. gives an introduction, overview and details on state of the art diagnostics of small scale high gradient atmospheric pressure plasmas. covers the use of N-APPJs for cancer applications, including discussion of destruction of cancer cells, mechanisms of action, and selectivity studies. XinPei Lu is a Chair Professor in the School of Electrical and Electronic Engineering at Huazhong University of Science and Technology. Stephan Reuter is currently Visiting Professor at Université Paris-Saclay. In a recent Alexander von Humboldt research fellowship at Princeton University, he performed ultrafast laser spectroscopy on cold plasmas. Mounir Laroussi is Professor of Electrical and Computer Engineering and director of the Plasma Engineering and Medicine Institute at Old Dominion University. He is a Fellow of IEEE and recipient of an IEEE Merit Award. DaWei Liu is Professor in the School of Electrical and Electronic Engineering at Huazhong University of Science and Technology.
Author:
Publisher:
ISBN:
Category : Aeronautics
Languages : en
Pages : 996
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Book Description
Author: Shinya Toyokuni
Publisher: Academic Press
ISBN: 012815005X
Category : Science
Languages : en
Pages : 460
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Book Description
Plasma Medical Science describes the progress that has been made in the field over the past five years, illustrating what readers must know to be successful. As non-thermal, atmospheric pressure plasma has been applied for a wide variety of medical fields, including wound healing, blood coagulation, and cancer therapy, this book is a timely resource on the topics discussed. - Provides a dedicated reference for this emerging topic - Discusses the state-of-the-art developments in plasma technology - Introduces topics of plasma biophysics and biochemistry that are required to understand the application of the technology for plasma medicine - Brings together diverse experience in this field in one reference text - Provides a roadmap for future developments in the area
