40 th international conference on plasma physics and CF, February 11 – 15, 2013, Zvenigorod.
ELECTRON GAS PARAMETERES IN DBD DISCHARGE OF ATMOSPHERIC
PRESSURE IN OXYGEN WITH AQEOUS ELECTRODE
Bobkova Е.S., Rybkin V.V.
Ivanovo State University of Chemical Technology, Ivanovo, Russia,
Institute of thermodynamics and kinetics of chemical processes, rybkin@isuct.ru
Last time the atmospheric pressure discharges burning over liquid or above it attract attention of the researches. This is due to various applications of such systems. Among them the substances surface modification, sterilization of solutions and tools, water purification from organic substances
[1]. For these purposes the impulse streamer discharge, gliding arc, electrolysis with glow discharge, dielectric barrier discharge (DBD) and other were already tested. Process controlling proceeding in discharges and their optimization requires the knowledge of electron gas parameters and, in the first place, their electron energy function distribution (EEDF). The aim of given study is obtaining such data for atmospheric pressure DBD in oxygen.
The experimental set-up scheme was described by us in [2]. The reactor had the coaxial construction. Outer Pyrex tube served with the dielectric barrier. Inner metal electrode was covered with the hydrophilic material and water flowed on it in film mode. High voltage of 50 Hz was applied between barrier and inner electrode. The discharge burnt in ring gap between water layer in internal part of tube. Wave forms of current and voltage were measured at different voltages. The shape of these wave forms showed that the discharge burns in diffusive mode. On the base of equivalent circuit calculations the active part of current flowing through the plasma and voltage dropping on it were determined. It allowed to calculate the reduced electric field strength E/N . The digital solution of Boltzmann equation for O
2
-H
2
O mixture allowed to calculate the EEDF and on its base the electron gas parameters and to estimate the water vapor influence on these parameters.
The applied voltage increase from 3.6 to 10.3 kV (rms value) resulted in the increase in the rms current from 0.2 to 0.6 mA, in E/N averaged over period from 25 to 50 Td and in electron density from 2.2

10
6
to 4.3

10
6 cm
-3
. In increase in water vapor content influence on EEDF up to
E/N <=60 Td leading to the decrease in process rate constants in any cases. The influence degree was the more the E/N less and the process threshold energy less. Also, calculations showed that the application of E/N averaged over period for determination of process rates results in the overrated values as compared to those which are determined the right averaging the temporal dependencies of rates.
This work was supported by Federal Target Program Scientific and Scientific-Teaching Personal of Innovative Russia on 2009-2013 years (State contract №14.B37.21.0763).
References
[1].
Bobkova E.S., Grinevich V.I., Isakina A.A., Rybkin V.V. // Izv. Vyssh. Uchebn. Zaved.
Khim. Khim. Tekhnol. 2011. V. 54. N 6. P. 3-17 (in Russian).
[2].
Bobkova E.S., Ivantsova N.A., Grinevich V.I., Rybkin V.V. // Plasma Chem Plasma Process.
2012. V. 32. N 1. P. 97-107
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