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Spectroscopic diagnostics of low temperature atmospheric pressure plasma jets

Qing Xiong UGent (2012)
abstract
Low-temperature atmospheric pressure plasma jets are typical non-equilibrium plasmas. For this type of plasma discharge, the input power from an external electrical field is first coupled with the charged species, i.e., electrons and ions, and then electrons transfer energy to heavy particles through collisions. As electrons are much lighter than ions, electrons are able to quickly respond to the variation of the external electrical field and accumulate energy by traveling therein. This results in the electron temperature (typical below about 10 eV) much higher than the gas temperature characterizing the heavy species: atoms, molecules, and ions (typical below about 5000 K), which makes the plasma exhibit an extreme non-equilibrium thermodynamic property. Because of the high collision frequency between electrons and heavy particles, chemically active species are generated and forms the high plasma chemistry. The enhanced plasma chemistry makes the plasma jets interesting for applications, especially with their low temperature (sometimes close to room temperature) characterization, which attracts increasing interests in the application of biomedical field. Furthermore, the plasma jets generated in open space rather than in confined gaps offer a chamber-less operation and direct treatments without limitation on the size of the object to be treated. These attractive features are extremely important for some applications, such as plasma medicine, which extends the plasma applications to a further level. In order to optimize the processing efficiency of low-temperature plasma jets, many various jet sources have been developed and investigated in recent two decades. One of the main issues causing a lack of fundamental understanding of the physics of plasma jets is that a lot of traditional diagnostic methods are not applicable to these cold micro-discharges. This is ascribed to their small discharge dimensions, low ionization degree operated at atmospheric pressure. Suitable diagnostic techniques are desired to characterize this kind of plasmas. Optical emission spectroscopy, as a traditional diagnostic method, can provide an insight in the physical properties of these micro-discharge jets. Based on optical emission spectroscopy measurements, the plasma gas temperature and electron densities are obtainable. These two physical parameters are important basic characteristics to get insight in the physical and chemical mechanisms of low-temperature plasmas. However, since most particles in plasmas are neutral and not giving radiation, direct information on these species are not available by optical emission spectroscopy. In this case, advanced laser spectroscopy diagnostic techniques are desirable. The laser spectroscopy methods provide another important and attractive way to study the fundamental mechanisms of low-temperature plasmas. This dissertation presents a comprehensive characterization of the low-temperature plasma jets by applying various diagnostic methods with emphasis on achieving a better understanding on the fundamental mechanisms of this type of micro-discharge. The findings of this research can be categorized in the following parts.
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author
promoter
UGent and UGent
organization
alternative title
Spectroscopische studie van een koude atmosferische plasmastraal
year
type
dissertation (monograph)
subject
keyword
Optical emission spectroscopy, Diagnostics, Atmospheric pressure plasma jets, fundamental mechanisms, Low temperature, Laser spectroscopy
pages
168 pages
publisher
Ghent University. Faculty of Engineering and Architecture
place of publication
Ghent, Belgium
defense location
Gent : Faculteit Ingenieurswetenschappen en Architectuur (Jozef Plateauzaal)
defense date
2012-06-18 17:00
ISBN
9789085785200
language
English
UGent publication?
yes
classification
D1
copyright statement
I have transferred the copyright for this publication to the publisher
id
2911353
handle
http://hdl.handle.net/1854/LU-2911353
date created
2012-06-19 09:52:33
date last changed
2012-06-21 10:42:58
@phdthesis{2911353,
  abstract     = {Low-temperature atmospheric pressure plasma jets are typical non-equilibrium plasmas. For this type of plasma discharge, the input power from an external electrical field is first coupled with the charged species, i.e., electrons and ions, and then electrons transfer energy to heavy particles through collisions. As electrons are much lighter than ions, electrons are able to quickly respond to the variation of the external electrical field and accumulate energy by traveling therein. This results in the electron temperature (typical below about 10 eV) much higher than the gas temperature characterizing the heavy species: atoms, molecules, and ions (typical below about 5000 K), which makes the plasma exhibit an extreme non-equilibrium thermodynamic property. Because of the high collision frequency between electrons and heavy particles, chemically active species are generated and forms the high plasma chemistry. The enhanced plasma chemistry makes the plasma jets interesting for applications, especially with their low temperature (sometimes close to room temperature) characterization, which attracts increasing interests in the application of biomedical field. Furthermore, the plasma jets generated in open space rather than in confined gaps offer a chamber-less operation and direct treatments without limitation on the size of the object to be treated. These attractive features are extremely important for some applications, such as plasma medicine, which extends the plasma applications to a further level. In order to optimize the processing efficiency of low-temperature plasma jets, many various jet sources have been developed and investigated in recent two decades. One of the main issues causing a lack of fundamental understanding of the physics of plasma jets is that a lot of traditional diagnostic methods are not applicable to these cold micro-discharges. This is ascribed to their small discharge dimensions, low ionization degree operated at atmospheric pressure. Suitable diagnostic techniques are desired to characterize this kind of plasmas. Optical emission spectroscopy, as a traditional diagnostic method, can provide an insight in the physical properties of these micro-discharge jets. Based on optical emission spectroscopy measurements, the plasma gas temperature and electron densities are obtainable. These two physical parameters are important basic characteristics to get insight in the physical and chemical mechanisms of low-temperature plasmas. However, since most particles in plasmas are neutral and not giving radiation, direct information on these species are not available by optical emission spectroscopy. In this case, advanced laser spectroscopy diagnostic techniques are desirable. The laser spectroscopy methods provide another important and attractive way to study the fundamental mechanisms of low-temperature plasmas. This dissertation presents a comprehensive characterization of the low-temperature plasma jets by applying various diagnostic methods with emphasis on achieving a better understanding on the fundamental mechanisms of this type of micro-discharge. The findings of this research can be categorized in the following parts.},
  author       = {Xiong, Qing},
  isbn         = {9789085785200},
  keyword      = {Optical emission spectroscopy,Diagnostics,Atmospheric pressure plasma jets,fundamental mechanisms,Low temperature,Laser spectroscopy},
  language     = {eng},
  pages        = {168},
  publisher    = {Ghent University. Faculty of Engineering and Architecture},
  school       = {Ghent University},
  title        = {Spectroscopic diagnostics of low temperature atmospheric pressure plasma jets},
  year         = {2012},
}

Chicago
Xiong, Qing. 2012. “Spectroscopic Diagnostics of Low Temperature Atmospheric Pressure Plasma Jets”. Ghent, Belgium: Ghent University. Faculty of Engineering and Architecture.
APA
Xiong, Qing. (2012). Spectroscopic diagnostics of low temperature atmospheric pressure plasma jets. Ghent University. Faculty of Engineering and Architecture, Ghent, Belgium.
Vancouver
1.
Xiong Q. Spectroscopic diagnostics of low temperature atmospheric pressure plasma jets. [Ghent, Belgium]: Ghent University. Faculty of Engineering and Architecture; 2012.
MLA
Xiong, Qing. “Spectroscopic Diagnostics of Low Temperature Atmospheric Pressure Plasma Jets.” 2012 : n. pag. Print.