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Study of reactions of simple ions in low temperature plasma
Kálosi, Ábel ; Plašil, Radek (advisor) ; Picková, Irena (referee)
The subject of this thesis is the study of the probe diagnostic method of low temperature plasma. The basis of Langmuir probe diagnostics in terms of appli- cation on apparatus CryoFALP II for the study of reactions of simply particles, the principle of the FALP technique and the experimental method of undertaken measurements are described. As a part of the thesis a package of evaluation pro- grams were compiled, which are ready to be a part of the measuring system as described in the thesis. Main results concern verification of the proper application of Langmuir probe technique in conditions characteristic for the apparatus, argon plasma was chosen as the medium of the measurements, where the characteristic loss process is ambipolar diffusion of charged particles. The application of the acquired knowledge is shown on recombination in oxygen plasma.
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A source of cold hydrogen atoms
Podolník, Aleš ; Plašil, Radek (advisor) ; Kaňka, Adolf (referee)
Vodík v molekulární a atomární formě je nejčastější prvek ve vesmíru a proto jsou chemické reakce, ve kterých vystupuje, důležité pro pochopení nejen formace prvních hvězd a galaxií, ale i pro studium současných dějů v mezihvězdném plynu. Studium například reakce H- + H -> H2 + e- (asociativní odtržení) ujasňuje náhled na proces tvorby molekul vodíku a umožňuje upřesnění kvantově-mechanických modelů. Pro tento a další experimenty je na KFPP přítomen zdroj chladného atomárního vodíku. V práci je popsána aparatura zdroje a její operace, navrhováno a částečně realizováno zlepšení uspořádání vnitřní konstrukce a jsou proměřeny základní charakteristiky zdroje.
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Laser absorption spectroscopy
Vyhlídka, Štěpán ; Plašil, Radek (advisor) ; Hrubý, Vojtěch (referee)
Study of recombination of molecular ionts in cold plasma plays a key role in our understanding of chemical kinetics in interstellar space or in upper layers of planetar atmospheres. Various metods are used for its study of which important part is laser absorption spectroscopy. Concentration or temperature of measured ionts can be found from their absorption spectra. In the presented work two spectroscopic techniques are briefly introduced - Cavity ringdown spectroscopy and Laser induced reaction technique. Main me- chanisms for spectral linewidth broadening are described and from absorption spectra of H+ 3 and N+ 2 ionts measured by above-mentioned techniques their kine- tic temperature is discovered. Because it is affected by spectral width of applied laser diodes, a part of this work also deals with description of its measurement by self-heterodyne method or Fabry-Pérot interferometer. The spectral width is found for infrared diode DFB laser. 1
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Modelling of glow discharge positive column of oxygen in the middle pressures region
Laca, Marek ; Hrachová, Věra (advisor) ; Plašil, Radek (referee)
The aim of the presented work was to create model of the glos discharge positive column of the oxygen in the middle pressures (in range 100-1000 Pa) with the methods of the computer physics, specifically with the method of the chemical kinetics. I have focused on the existence of two forms of the discharge positive column in the oxygen, low and high gradient form with axial electrical field about 100 V/m and 1 kV/m. I developed continuous model of the low temperature plasma as the steady state solution of the continuity equation with the neglected divergent member. The model involves twelve different kinds of the particles and reactions among them: electrons, ground and excited states of the atomic and molecular oxygen, of course negative and positive ions. I had numerically solved time evolution of the particle concentration at constant pressure, until the system reached equilibrium state. My numerical results were compared with experimental measurements of the electron density, which had been done in the Department of Surface and Plasma Science. To get a consistency between my results and experimental ones for electron density, I had to variate reaction coefficients of the reactions in which charged particles are produced.
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Reactions of molecular ions in low-temperature plasma
Rubovič, Peter ; Plašil, Radek (advisor) ; Kotrík, Tomáš (referee)
Xdzev pracc: Studinm rca,kci molokularmeh iontu v nizkoteplotnim plazmatu Autor: Peter Rubovic Katedra. (ustav): Katodra. fy/iky povrchu a plazmatu Vedonci bakalarske prace: RNDr. Radok Plasil. Ph.D. o-inail vedouciho: Radek.Plasil«i;n iff.cuni.cz Abstrakt: V predlo/enej ])i;ici skunuune reakcie molekularnych ionov v niz- koteplotnej plazme. Je popisany prineip a konslrukcia aparatury FALP (Flo- wing Afterglow with Langmuir Probe}, ])omocon ktorej skumame dohasinajucu plazmu pouzithn Langmnirovej (elektrostatickej) sondy. Zkonstrnovali snic ki- netieky model ehemickych reakeii a jcho ])ocitacovy model. Diskntnjeme vystup tohoto modelu - cn.sovy vyvoj koiicentracii j(xlnotlivyeh ionov a elektronov y>o- 7A\\7. prndovej trnbico. Zucastnili sine sa na i'i]jra,v<.; aparatnry FALP pro ]>otreby merania pri te])lotiich tekuteho dnsiku. C'ielbm prace je urcit rychlost.ny koefi- eient rekoinbinacie ionu HCO' s elektromni a jeho zavi.slost' na koiicentracii reaktantu ILj a teplote. Z nameranych /avislosti usud/ujeme, ze .sa jedna o di- sociativnn rckombinacin. Klicova slova: FALP, rekombinacia. kinetika reakeii, pocitacovy model Title: Reactions of Molecular Ions in Low-Temperature Plasma Author: Peter Rnbovic Department: Department of Surface and Plasma Science Supervisor: RNDr. Radek PlasiL Ph.D. Supervisor's e-mail...
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Computational study of plasma-solid interaction in multicomponent plasma
Ibehej, Tomáš ; Hrach, Rudolf (advisor) ; Plašil, Radek (referee)
Physical processes ongoing during the interaction of both inert gas and chemically active plasma with surfaces of immersed solids are studied in this work. The technique used is a computer modeling based on experimental data obtained in our department and also taken from the literature. Focus of this work are two-dimensional particle simulations, whose outputs are parameters of a sheath formed around the immersed solid and characteristics of the contained charged particles. The study of multicomponent plasma presents an analysis of both statical and dynamical properties of the sheath depending on electronegativity. The research of influence of the computer modeling technique on the accuracy of the results and effi ciency of the computations is also accented.
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