|
|
Influence of metallic atoms on nitrogen post-discharge
Bocková, Ivana ; Kudrle, Vít (referee) ; Krčma, František (advisor)
The aim of this master thesis is to study the influence of metallic atoms on nitrogen post-discharge. Pure nitrogen post-discharge is a subject study of many works dealing with kinetic processes in plasma. Unfortunately, there are only a few published works that present influence of various traces on nitrogen post-discharge kinetics. This master thesis deals with problems of nitrogen post-discharge containing mercury traces. All experimental data were obtained using optical emission spectroscopy of a DC discharge in a flowing mode, which can achieve appropriate temporal resolution in the order of milliseconds. Spectra emitted during the post-discharge were recorded in the range of 320-780 nm and the following molecular spectral systems were identified: • 1. positive system of nitrogen: N2(B) -> N2(A), • 2. positive system of nitrogen: N2(C) -> N2(B), • 1. negative system of nitrogen: N2+(C) -> N2+(X), • NO-beta system: NO(B) -> NO(X). Besides them we were able to record the mercury line at 254 nm, only (in the spectrum of the first as well as in the second order); no other mercury lines were observed. The mercury vapor was introduced into the system at selected post-discharge time. Dependence of selected molecular band head intensities as well as mercury line intensity on experimental conditions (pressure, discharge power, wall temperature, time of mercury vapor introduction) were observed in time evaluation. The data obtained in pure nitrogen were used as a reference. The obtained results showed very high sensitivity of kinetic processes on mercury atoms presence. If mercury was introduced into the post-discharge the mercury line was observable around the site where mercury vapor was introduced into the discharge. The experimental data showed that mercury line intensity was directly proportional to the mercury atoms concentration and saturation effect could be observed. The energy level diagram demonstrates that the observed mercury line can be excited by collisions with nitrogen ground state molecule excited to vibrational level 18. Thus the mercury can be used for the monitoring of population at this vibrational level. Finally we obtained the population profile at this nitrogen metastable level during the post-discharge. The presented work demonstrates possibility of mercury atoms application for the monitoring of one nitrogen metastable state. Unfortunately, the contemporary data are not sufficient for the measurement of metastable absolute concentration. However, complex understanding of nitrogen post-discharge kinetics is still an open problem. Therefore a lot of future work should be done although the presented work brings a good fundament for such research.
|
|
|
Optical emission spectroscopy of the nitrogen post-discharge plasma with metal trace impurity
Bocková, Ivana ; Mazánková, Věra (referee) ; Krčma, František (advisor)
The bachelor´s thesis deals with the optical emission spectroscopy of the nitrogen post-discharge with metal trace impurity. The analysed sample introduced to the low-temperature plasma was zinc vapor and stannic chloride. As a diagnostic method was choosen optical emission spectroscopy as one of the simplest plasma diagnostic methods. The teoretical part is aimed to information about plasma and processes in the plasma. The special focus is deald for post-discharged plasma and the optical emission spectroscopy. Measurement itself is implemented in flowing regime of DC post-discharge under low pressure. The intensities of selected nitrogen bands and atomic lines are observed as a function of metal vapor presence. The simplified mechanism of the observed phenomen is presented. The possible excitation mechanisms are shown of metallic atoms during the post-discharge.
|
|
|
Influence of metallic atoms on nitrogen post-discharge
Bocková, Ivana ; Kudrle, Vít (referee) ; Krčma, František (advisor)
The aim of this master thesis is to study the influence of metallic atoms on nitrogen post-discharge. Pure nitrogen post-discharge is a subject study of many works dealing with kinetic processes in plasma. Unfortunately, there are only a few published works that present influence of various traces on nitrogen post-discharge kinetics. This master thesis deals with problems of nitrogen post-discharge containing mercury traces. All experimental data were obtained using optical emission spectroscopy of a DC discharge in a flowing mode, which can achieve appropriate temporal resolution in the order of milliseconds. Spectra emitted during the post-discharge were recorded in the range of 320-780 nm and the following molecular spectral systems were identified: • 1. positive system of nitrogen: N2(B) -> N2(A), • 2. positive system of nitrogen: N2(C) -> N2(B), • 1. negative system of nitrogen: N2+(C) -> N2+(X), • NO-beta system: NO(B) -> NO(X). Besides them we were able to record the mercury line at 254 nm, only (in the spectrum of the first as well as in the second order); no other mercury lines were observed. The mercury vapor was introduced into the system at selected post-discharge time. Dependence of selected molecular band head intensities as well as mercury line intensity on experimental conditions (pressure, discharge power, wall temperature, time of mercury vapor introduction) were observed in time evaluation. The data obtained in pure nitrogen were used as a reference. The obtained results showed very high sensitivity of kinetic processes on mercury atoms presence. If mercury was introduced into the post-discharge the mercury line was observable around the site where mercury vapor was introduced into the discharge. The experimental data showed that mercury line intensity was directly proportional to the mercury atoms concentration and saturation effect could be observed. The energy level diagram demonstrates that the observed mercury line can be excited by collisions with nitrogen ground state molecule excited to vibrational level 18. Thus the mercury can be used for the monitoring of population at this vibrational level. Finally we obtained the population profile at this nitrogen metastable level during the post-discharge. The presented work demonstrates possibility of mercury atoms application for the monitoring of one nitrogen metastable state. Unfortunately, the contemporary data are not sufficient for the measurement of metastable absolute concentration. However, complex understanding of nitrogen post-discharge kinetics is still an open problem. Therefore a lot of future work should be done although the presented work brings a good fundament for such research.
|
|
|
Optical emission spectroscopy of the nitrogen post-discharge plasma with metal trace impurity
Bocková, Ivana ; Mazánková, Věra (referee) ; Krčma, František (advisor)
The bachelor´s thesis deals with the optical emission spectroscopy of the nitrogen post-discharge with metal trace impurity. The analysed sample introduced to the low-temperature plasma was zinc vapor and stannic chloride. As a diagnostic method was choosen optical emission spectroscopy as one of the simplest plasma diagnostic methods. The teoretical part is aimed to information about plasma and processes in the plasma. The special focus is deald for post-discharged plasma and the optical emission spectroscopy. Measurement itself is implemented in flowing regime of DC post-discharge under low pressure. The intensities of selected nitrogen bands and atomic lines are observed as a function of metal vapor presence. The simplified mechanism of the observed phenomen is presented. The possible excitation mechanisms are shown of metallic atoms during the post-discharge.
|
guest ::
RSS feed.