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Rekombinace a reakce iontů v plazmatu
Varju, Jozef ; Glosík, Juraj (advisor) ; Kaňka, Adolf (referee)
One of the most interesting questions in contemporary interstellar chemistry is the HCN/HNC abundance ratio observed in dense interstellar clouds. The observed ratios vary from 80:1 to 1:5 depending on the object under observation. These ratios represent a striking deviation from thermochemical equilibrium. Dissociative recombination of HCNH+ has been invoked to explain these observations. It is suggested to study details of this recombination using FALP apparatus equipped with NIR Cavity Ringdown Absorption Spectrometer (IR - CRDS). In the presented work we have developed kinetic model describing formation of HCNH+/e- plasma and consequent production of HCN and HNC. Analysed and discussed are conditions of experiment and applicability of IR - CRDS for the proposed study. To confirm our analyses the preliminary experiments were carried out using microwave discharge cell equipped with IR - CRDS. Studies of H3O+ and H2D+ ions were carried out to put together the experiment. The absorption spectra in a plasma containing He/N2/CH4 were measured in order to determine transition frequencies for study of products of recombination of CNH+ ions.
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RE beam generation in MGI disruptions on COMPASS.
Ficker, Ondřej ; Mlynář, Jan ; Macúšová, Eva ; Vlainić, M. ; Weinzettl, Vladimír ; Urban, Jakub ; Čeřovský, Jaroslav ; Farník, Michal ; Markovič, Tomáš ; Papřok, Richard ; Vondráček, Petr ; Imríšek, Martin ; Tomeš, Matěj ; Havlíček, Josef ; Varju, Jozef ; Varavin, Mykyta ; Bogár, Ondrej ; Havránek, Aleš ; Gospodarczyk, M. ; Rabinski, M. ; Jakubowski, M. ; Malinovski, K. ; Zebrowski, J. ; Plyusnin, V. ; Papp, G. ; Pánek, Radomír ; Hron, Martin
In the experiments with the massive gas injection (MGI) triggered disruptions in the COMPASS tokamak, post-disruptive runaway electron (RE) beams are generated occasionally. In this contribution, a relatively large set of discharges from the recent years is analysed in order to improve our understanding of the processes behind the beam generation. It seems that despite the low toroidal field applied in the discharges (typically 1.15 T) the magnetic perturbations may be small enough to allow the acceleration and confinement of the electrons. The influence of the different components and different sections of the frequency spectrum of the magnetic perturbations on the beam generation and RE beam current is examined. Fast visible camera images are also analysed. The relevance of COMPASS runaway electron experiments for large machines is discussed. Moreover, the potential of less common diagnostic tools (Cherenkov detector, vertical ECE, ...) to clarify the role of the pre-disruption fast electron population and the influence of prompt runaway electron losses in the current quench is discussed using the recent test measurements.
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Study of H3+ recombination in selected quantum states
Varju, Jozef ; Glosík, Juraj (advisor) ; Votava, Ondřej (referee) ; Novotný, Oldřich (referee)
Title: Study of H3 + recombination in selected quantum states Author: Jozef Varju Department : Department of Surface and Plasma Science Supervisor of the doctoral thesis: Prof. RNDr. Juraj Glosík, DrSc., Department of Surface and Plasma Science Abstract: In this work measurement of the effective recombination rate coefficient of H3 + dominated and recombination governed afterglow plasma at 77 K and 145 K are presented. Population of para-H3 + in the studied plasma has been varied by using para enriched H2 as a precursor along with normal H2. Time resolved NIR-CRDS was used to in-situ measure the number density evolution of the two lowest rotational states of H3 + . Measurements at different para to ortho H3 + ratios, at otherwise identical conditions, allowed for extrapolation of the effective recombination rate coefficient of pure para-H3 + and ortho-H3 + . From measured dependences on the buffer gas densities the values of the recombination rate coefficients for the binary and ternary channel are determined of para-H3 + and ortho-H3 + . Keywords: recombination, spectroscopy, H3 + , para H2
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Rekombinace a reakce iontů v plazmatu
Varju, Jozef ; Glosík, Juraj (advisor) ; Kaňka, Adolf (referee)
One of the most interesting questions in contemporary interstellar chemistry is the HCN/HNC abundance ratio observed in dense interstellar clouds. The observed ratios vary from 80:1 to 1:5 depending on the object under observation. These ratios represent a striking deviation from thermochemical equilibrium. Dissociative recombination of HCNH+ has been invoked to explain these observations. It is suggested to study details of this recombination using FALP apparatus equipped with NIR Cavity Ringdown Absorption Spectrometer (IR - CRDS). In the presented work we have developed kinetic model describing formation of HCNH+/e- plasma and consequent production of HCN and HNC. Analysed and discussed are conditions of experiment and applicability of IR - CRDS for the proposed study. To confirm our analyses the preliminary experiments were carried out using microwave discharge cell equipped with IR - CRDS. Studies of H3O+ and H2D+ ions were carried out to put together the experiment. The absorption spectra in a plasma containing He/N2/CH4 were measured in order to determine transition frequencies for study of products of recombination of CNH+ ions.
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