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Měření excitačních a ionizačních teplot v expandujícím proudu H2O-Ar plazmatu
Sember, Viktor ; Mašláni, Alan
Optical emission spectroscopy is used to determine the temperature in a plasma jet expanding from the H2O-Ar dc arc torch into a chamber maintained at a pressure of 10 kPa. The excitation and rotational temperatures are derived from relative intensities of argon atomic and ionic lines, and from the UV OH band at 306.357 nm, respectively. The ionization temperature is obtained from the intensity ratio of argon ionic and atomic lines, using electron number density calculated from the Stark broadening of hydrogen H line. The structure of the plasma jet is characterized by isocontours of electron number density and intensity of atomic and ionic lines. In the expansion region, the ionic excitation temperature is found close to the ionization temperature and much higher than the excitation temperature of argon atoms, which is close to the rotational temperature of OH radical. In the normal shock region, all the measured temperatures tend to be equal.
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Procesy v Gerdienovem oblouku generovaném hybridním plynově-vodním plazmatronem
Kavka, Tetyana ; Chumak, Oleksiy ; Sember, Viktor ; Hrabovský, Milan
In the present work the basic principles of the Gerdien arc are described. The arc was generated in the plasma torch with hybrid stabilisation of the arc by water and argon. The paper discusses physical processes determining the arc behaviour and governing plasma generation. As the main mechanism of the plasma generation in the water stabilized part is evaporation from the inner surface of the water vortex, heating and ionisation of vapour, the plasma gas flow rate and composition depends on the working parameters of the torch. The amount of the evaporated water cannot be directly measured and was estimated from the mass and power balances of the torch. The flow rate and composition of the generated plasma for different arc currents and argon flow rates have been studied. Increase of the arc current resulted in higher amount of evaporated water, while modification of the argon flow rate did not influence the evaporation rate.
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Studium expandujícího proudu termického plazmatu s využitím molekulových spekter
Mašláni, Alan ; Sember, Viktor
Thermal plasmas generated by plasma torches are well-known for their high temperatures and high enthalpies. Therefore optical emission spectroscopy is appropriate diagnostic method because of strong emission of radiation corresponding to the visible light. The decay of excited atoms, ions and molecules causes emission of the light at characteristic wavelengths. Except spectral lines of atoms and ions, also some molecular bands can be seen in the spectra of the plasma jet. Especially expanding thermal plasma jet operated under low pressure conditions offers possibility of observing molecular transitions. Pressure lower than atmospheric may cause the presence of supersonic flow and departures from thermodynamic equilibrium. Spectra of OH radical have been investigated using computer code LIFBASE, which contains a lot of data regarding spectra of diatomic molecules. Radial profiles of rotational and vibrational temperatures have been found in several regions of the jet.
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Measurements on Hot Gas Mixture Free Jet
Gregor, Jan ; Jakubová, I. ; Mendl, Tomáš ; Šenk, J. ; Sember, Viktor
The measurements of temperature, velocity and composition of the free jet generated by a hybrid water-argon torch "cold" part of the jet (T<2500K) are presented.Parameters of the jet at the torch output are calculated by the continuity and energy equations using the spectroscopicaly measured temperature distribution.Temperature and velocity fields are measured respecively by thermo.
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