Električni proboji u vazduhu: novi eksperimenti o statistički i numerički modeli
Electrical breakdowns in air: new experiments and statistical and numerical models
Author
Jovanović, Aleksandar P.Mentor
Marković, VidosavCommittee members
Đurović, StevicaPopović, Biljana
Stamenković, Suzana

Šišović, Nikola

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Show full item recordAbstract
Experimental work was carried out in laboratory for physics of
ionized gases and lasers in Faculty of Sciences and
Mathematics in Niš. Scanning electron microscopy and energy
dispersive X-ray spectroscopy of electrodes were carried out in
Faculty of Medicine in Niš, atomic force microscopy were
carried out in Institute of Physics in Belgrade and the
measurements on quantometer were carried out in AD “Kopex
MIN LIV”.
In this dissertation processes occurring before, during and after
the electrical breakdown in synthetic air are studied by
breakdown time delay measurements. Time delay distributions
at different conditions and with different electrodes are
measured, fitted by Gaussian, mixture Gauss-exponential and
exponential distributions and modeled by Monte Carlo
simulation. Mixture distributions are generalized and a relation
for the effective electron yield is derived. The occurrence of
mixture distributions is explained by an increased emissivity of
the cathode due to formation of ...the oxide at the cathode and
increased effective surface area. A new methods for
determination of the formative time delay, electron attachment
coefficient and the drift velocity of the dominant ions are
proposed. The memory curve at low pressure is analyzed and
three distinctive regions are observed. The first regions is
explained by the diffusion losses of the dominant ions. By
applying the analytical model the diffusion coefficients of the
dominant ions are determined. The two-dimensional numerical
model for early and late relaxation is developed. The onedimensional
model is used to calculate stationary glow number
densities of ions which are used as initial number densities for
modelling the relaxation. The results of numerical model
indicate that the dominant ion in the early relaxation is oxygen O+2 ions due to intensive
N+2 ion conversion. Late relaxationis explained by the surface recombination of nitrogen atoms on
borosilicate glass and stainless-steel electrodes. From the
numerical model the coefficients of nitrogen atom surface
recombination are determined.