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Nové metody záznamu chování volného proudu plazmatu užívající vláknovou optiku
Šonský, Jiří ; Hlína, Jan ; Něnička, Václav
The fibre optics coupling to photodiodes used in plasma jets optical radiation recording enables us to increase the channel count and to add flexibility to an experimental layout for multi-directional observations. These improvements give us opportunity of more detailed and important plasma jets behaviour analysis - reconstruction of luminosity fields (close to relative value of enthalpy) in planes perpendicular to a plasma jet axis, velocities and tracking of plasma jet axis movements. Details of experimental hardware and layount will be also shortly presented.
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Větvení obloukového kanálu ve vnějším magnetickém poli
Mrázek, Josef ; Hlína, Jan
An electric arc burning in mercury vapours exposed to external magnetic field changes its discharge path into a helix according to the Thomson principle of energy minimization. The voltage between the adjacent turns of the helix curvature may result in the critical electric field strenght in the vicinity of the arc channel, that leads to the branching and formation of a new discharge path acting as a turn-to-turn short. We have been interested in the electric field profile and surrounding parameters at the moment of branching, the speed of a new channel warming, temporal evolution of the restoration of a regular spiral channel, development of the arc current and distribution of the voltage between the series resistor and arc channel during the breakdown.
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Diagnostics of Breakdown in Electric Arc Exposed to External Magnetic Field
Hlína, Jan ; Šonský, Jiří
An arc in external magnetic field acquires a helical shape and when the magnetic field exceeds a critical value the arc starts to oscillate. The oscillations may lead to many types of shortenings (breakdowns) between the adjacent windings of the arc path. We have investigated experimentally the steepness of the voltage fall reflecting the breakdown and the influence of mean arc voltage and electrode polarity on this characteristic.
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