Kinetic processes in negative glow plasma of low pressure discharge in oxygen

Kinetic processes in negative glow plasma of low pressure discharge in oxygen

It is shown that electron energy distribution function of negative glow plasma of low pressure discharge in oxygen exhibits two-temperature behavior due to the influence of metastable molecules O²(a¹Δg), O²(b¹Σ+g) and excitation of O² vibrational levels. As well, spatial dependencies of the atomic o...

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Datum:2013
Hauptverfasser: Tsiolko, V.V., Matsevich, S.V., Bazhenov, V.Yu., Piun, V.M, Ryabtsev, A.V.
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Sprache:English
Veröffentlicht: Національний науковий центр «Харківський фізико-технічний інститут» НАН України 2013
Schriftenreihe:Вопросы атомной науки и техники
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Плазменно-пучковый разряд, газовый разряд и плазмохимия
Online Zugang:http://dspace.nbuv.gov.ua/handle/123456789/112186
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spelling irk-123456789-1121862017-01-23T22:27:05Z Kinetic processes in negative glow plasma of low pressure discharge in oxygen Tsiolko, V.V. Matsevich, S.V. Bazhenov, V.Yu. Piun, V.M Ryabtsev, A.V. Плазменно-пучковый разряд, газовый разряд и плазмохимия It is shown that electron energy distribution function of negative glow plasma of low pressure discharge in oxygen exhibits two-temperature behavior due to the influence of metastable molecules O²(a¹Δg), O²(b¹Σ+g) and excitation of O² vibrational levels. As well, spatial dependencies of the atomic oxygen concentration on the gas pressure and power density in the discharge plasma are determined by actinometry method. Показано, що функція розподілу електронів по енергіях плазми негативного світіння розряду низького тиску в кисні має двотемпературний характер із-за впливу метастабільних молекул O²(a¹Δg), O²(b¹Σ+g) та збудження коливальних рівнів О². Методом актинометрії встановлено просторові залежності концентрації атомарного кисню від тиску газу та питомої потужності в розряді. Показано, что функция распределения электронов по энергиям плазмы отрицательного свечения разряда низкого давления в кислороде имеет двутемпературный характер из-за влияния метастабильных молекул O²(a¹Δg), O²(b¹Σ+g) и возбуждения колебательных уровней О². Методом актинометрии установлены пространственные зависимости концентрации атомарного кислорода от давления газа и удельной мощности в разряде. 2013 Article Kinetic processes in negative glow plasma of low pressure discharge in oxygen / V.V. Tsiolko, S.V. Matsevich, V.Yu. Bazhenov, V.M. Piun, A.V. Ryabtsev // Вопросы атомной науки и техники. — 2013. — № 4. — С. 166-170. — Бібліогр.: 14 назв. — англ. 1562-6016 PACS: 52.80.-s, 52.25.Ya http://dspace.nbuv.gov.ua/handle/123456789/112186 en Вопросы атомной науки и техники Національний науковий центр «Харківський фізико-технічний інститут» НАН України
institution Digital Library of Periodicals of National Academy of Sciences of Ukraine
collection DSpace DC
language English
topic Плазменно-пучковый разряд, газовый разряд и плазмохимия
Плазменно-пучковый разряд, газовый разряд и плазмохимия
spellingShingle Плазменно-пучковый разряд, газовый разряд и плазмохимия
Плазменно-пучковый разряд, газовый разряд и плазмохимия
Tsiolko, V.V.
Matsevich, S.V.
Bazhenov, V.Yu.
Piun, V.M
Ryabtsev, A.V.
Kinetic processes in negative glow plasma of low pressure discharge in oxygen
Вопросы атомной науки и техники
description It is shown that electron energy distribution function of negative glow plasma of low pressure discharge in oxygen exhibits two-temperature behavior due to the influence of metastable molecules O²(a¹Δg), O²(b¹Σ+g) and excitation of O² vibrational levels. As well, spatial dependencies of the atomic oxygen concentration on the gas pressure and power density in the discharge plasma are determined by actinometry method.
format Article
author Tsiolko, V.V.
Matsevich, S.V.
Bazhenov, V.Yu.
Piun, V.M
Ryabtsev, A.V.
author_facet Tsiolko, V.V.
Matsevich, S.V.
Bazhenov, V.Yu.
Piun, V.M
Ryabtsev, A.V.
author_sort Tsiolko, V.V.
title Kinetic processes in negative glow plasma of low pressure discharge in oxygen
title_short Kinetic processes in negative glow plasma of low pressure discharge in oxygen
title_full Kinetic processes in negative glow plasma of low pressure discharge in oxygen
title_fullStr Kinetic processes in negative glow plasma of low pressure discharge in oxygen
title_full_unstemmed Kinetic processes in negative glow plasma of low pressure discharge in oxygen
title_sort kinetic processes in negative glow plasma of low pressure discharge in oxygen
publisher Національний науковий центр «Харківський фізико-технічний інститут» НАН України
publishDate 2013
topic_facet Плазменно-пучковый разряд, газовый разряд и плазмохимия
url http://dspace.nbuv.gov.ua/handle/123456789/112186
citation_txt Kinetic processes in negative glow plasma of low pressure discharge in oxygen / V.V. Tsiolko, S.V. Matsevich, V.Yu. Bazhenov, V.M. Piun, A.V. Ryabtsev // Вопросы атомной науки и техники. — 2013. — № 4. — С. 166-170. — Бібліогр.: 14 назв. — англ.
series Вопросы атомной науки и техники
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AT piunvm kineticprocessesinnegativeglowplasmaoflowpressuredischargeinoxygen
AT ryabtsevav kineticprocessesinnegativeglowplasmaoflowpressuredischargeinoxygen
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fulltext ISSN 1562-6016. ВАНТ. 2013. №4(86) 166 KINETIC PROCESSES IN NEGATIVE GLOW PLASMA OF LOW PRESSURE DISCHARGE IN OXYGEN V.V. Tsiolko, S.V. Matsevich, V.Yu. Bazhenov, V.M. Piun, A.V. Ryabtsev Institute of Physics NAS of Ukraine, Kiev, Ukraine E-mail: matsevich@iop.kiev.ua It is shown that electron energy distribution function of negative glow plasma of low pressure discharge in oxy- gen exhibits two-temperature behavior due to the influence of metastable molecules O2(a1Δg), O2(b1Σ+ g) and excita- tion of O2 vibrational levels. As well, spatial dependencies of the atomic oxygen concentration on the gas pressure and power density in the discharge plasma are determined by actinometry method. PACS: 52.80.-s, 52.25.Ya INTRODUCTION At present, oxygen plasma is widely used in various technologies, such as plasma cleaning and modification of surface features of polymer materials, plasma sterili- zation of medical instruments, synthesis of nanostruc- tured materials, etc [1 - 3]. In spite of complex composi- tion of such plasma (electrons, positively charged oxy- gen molecule ions, neutral atoms, oxygen molecules in metastable states), exactly atomic oxygen plays domi- nant role in many practical applications. For measure- ments of atomic oxygen concentration several methods are used, including mass spectrometry, chemical titra- tion using NO, optical absorption techniques such as LIF and TALIF, catalytic probes and such method of emission spectroscopy as actinometry [4 - 6]. Essence of this method is in adding of small known amount of actinometer gas (noble gases are commonly used) to the gas under study, and by means of measurement of inten- sity ratio for certain spectrum lines of actinometer gas and the component of interest, ratio of their concentra- tions is determined. This method is simple in implemen- tation, it does not require costly equipment, and in prin- ciple allows real time measurements. It should be noted, however, that this method requires precise knowledge of plasma electron energy distribution function (EEDF) since the rates of excitation processes are very sensitive to EEDF shape. In the present paper results of experimental investi- gations of parameters of negative glow plasma in the hollow cathode discharge in oxygen are presented. Pe- culiarity of such discharge consists in fact that practi- cally whole applied voltage falls in narrow near-cathode layer, and electric field in the plasma does not exceed several Td. Gas ionization and electron heating in this case are performed by fast electron beam ef with energy Wf ∼ 400…700 eV, coming from the near-cathode re- gion. Spatial distributions of EEDF shape are deter- mined for different oxygen pressure values, and with the use of experimentally measured EEDF dependencies of atomic oxygen concentration on the system parameters are determined. As well, numerical calculations of EEDF are accomplished for the parameters correspond- ing to experimental conditions. 1. EXPERIMENTAL SETUP AND METHODS Experimental setup is schematically represented in Fig. 1. The measurements were performed in the discharge chamber having 38 cm diameter and 42 cm length, which simultaneously served as the discharge cathode, at that the discharge anode having 30.5 cm diameter was located near back side of the chamber. Fig. 1. Scheme of the experimental setup The front of the chamber was closed by glass win- dow with diameter of 26 cm. Chamber evacuation was performed by diffusion pump down to pressure of about 5⋅10-3 Pa, and after that working gas was supplied to the chamber until reaching of predetermined pressure value. For excluding oil vapor coming to the discharge cham- ber, liquid nitrogen cooled trap was used. As working gas, either pure oxygen, or mixture of oxygen with ar- gon (O2 98% + Ar 2%) in case of actinometry studies was used. Working gas pressure in the chamber was varied in range of 1…16 Pa. The discharge power sup- ply was provided by DC source with controlled voltage and current values in ranges of 400…800 V and 100…600 mA, respectively. Power introduced in the discharge varied in range of 50…350 W which corre- sponded to specific power in the discharge ≈ 1…7 W/cm3. The plasma density, electron temperature, electron energy distribution function (EEDF) and electric field in the plasma were measured using single and double Langmuir probes made of a 100 μm tungsten wire, the length of the collecting region being 10…12 mm. The probes could be moved along and across the chamber. To avoid the effect of contamination of the probe sur- face on the probe current-voltage characteristic, the probes were heated to ≈ 800°C after each measurement. The probe characteristic was measured using an original PC-controlled system. The program assigned the probe current with step of 0.1 μA, and the probe voltage (with ISSN 1562-6016. ВАНТ. 2013. №4(86) 167 respect to anode), the discharge voltage, and the dis- charge current were measured at each step. The change in the probe current at each step was calculated in real time using a special algorithm intended for optimizing the signal-to-noise ratio over the entire range of the probe currents (the total number of steps in measuring one current-voltage characteristic was 1500…2000). After measuring the probe current in a given range at a fixed discharge current and fixed discharge voltage, the data on the probe current as a function of the probe volt- age with respect to the anode were stored in a PC. Meas- urements of the current-voltage characteristic at fixed experimental conditions were repeated 10…30 times, and the data stored in the PC were then averaged. The EEDF was determined from the second deriva- tive of the probe current with respect to the voltage, obtained by numerically differentiating the averaged current-voltage characteristic (by using pre-interpolation if necessary) The plasma potential was determined from the inflection point of the probe current-voltage charac- teristic, and the plasma density was calculated from the electron saturation current to the probe. At determining atomic oxygen concentration by ac- tinometry method, ratio of the emissions from the states X*/A* is proportional to the concentration ratio [X]/[A] (A and X stand for actinometer and the component of interest, respectively) when the following conditions are fulfilled: - states X* and A* are formed mainly at the expense of electron excitation from ground states of the compo- nents X and A; - X* and A* are deactivated mainly at the expense of emission; - cross sections of electron excitation of X* and A* levels must have similar thresholds and shapes of dependencies on electron energy. At determining atomic oxygen concentrations, emis- sions of oxygen atoms at 844.6 nm wavelength corre- sponding to 3р3Р → 3s3S0 transition, at 777.4 nm (3p5P → 3s5S0 transition) and argon atoms at 750.4 nm corresponding to 2р1 → 1s2 transition (Paschen nota- tion) were measured. Main contribution to formation rates of oxygen excited states under consideration is provided by mechanisms of direct oxygen atom excita- tion by electron hit, and dissociative excitation of O2 molecule under electron hit. It should be noted that cross section of direct excitation for О (844.6) is higher than that for О (777.4) [7]. On the contrary, contribution of dissociative excitation is higher for О (777.4) [8]. Thus, in case of О (777.4) emission, contribution of dissociative excitation is essential and can influence the obtained result. Taking into account processes of quenching of excited levels due to collisions, expres- sions for the emission intensities are, as follows: ∑ + + = j P Q P ij P de P e e P ij OkA OkOknAhCI ][ ][][ 2 33 2 33 3 844844844 ν , (1) ∑ + = j p Q p ij p e e p ij OkA ArknAhCI ][ ][ 2 22 2 2 750750750 11 1 1ν , (2) where C is constant describing peculiarities of the opti- cal system; ν is emission frequency; Aij is Einstein coef- ficient for respective transition; ΣAij is a sum of Einstein coefficients for all transitions from given level; ne is electron concentration; ke, kde, kQ are rate constants for processes of excitation by direct electron hit, dissocia- tive excitation, and quenching, respectively. Rate constants are calculated using formula: ∫ ∞ = 0 )()(2102 ε εεσεε df m ek e , (3) where e and me are electron charge and mass, respec- tively, σ(ε) is cross section of respective process, ε0 is threshold energy of the process, f(ε) is EEDF normal- ized by unity. Division of (1) over (2) gives: 1111 2 3 3 2 2 2 3 3 2 750 844 ][ ][ p e P deP pp e P eP p k kC O O k kC I I += , where ][ ][ ][ ][ 2 2 33 2 22 2 3 750 8443 2 11 11 Ar O OkA OkA A A hv hvC P Q P ij p Q p ij p ij P ijP p ∑ ∑ + + = . Following from this expression, relative atomic oxy- gen concentration is: P e P de P k k I IC O O 3 3 750 844 3 2 ][ ][ −= , (4) where ][ ][ ][ ][ 2 3 2 2 22 2 33 3 2 844 750 3 1 11 1 O Ar k k OkA OkA A A hv hv C P e p e p Q p ij P Q P ij P ij p ij P ∑ ∑ + + = . Similar expression can be also obtained for О(777.4) emission. Spectrum measurements were performed by means of CCD-spectrometer SL40-2-1024USB (SOLAR TII, Minsk, Republic of Belarus). Optical system allowed collecting of the plasma emission from cylindrical re- gion (diameter of about 1 cm) with axis aligned in paral- lel with the chamber one. 0 2 4 6 8 10 12 14 16 18 1E10 C on ce nt ra tio n n e, cm -3 Radius R, cm Fig. 2. Dependencies of plasma concentration ne on the system radius R for different oxygen pressure values. Close points – Р = 4 Pa, Ud = 650 V; open points P = 11 Pa, Ud = 470 V. Wd = 5 mW/cm3 2. EXPERIMENTAL RESULTS Fig. 2 exhibits dependencies of plasma density ne on the system radius R for two oxygen pressure values. (The measurements were performed in the middle plane of the chamber.) One can see from the figure that radial distributions of the plasma density for those oxygen ISSN 1562-6016. ВАНТ. 2013. №4(86) 168 pressure values are essentially different – at P = 4 Pa the plasma density is practically independent on R in central region of the discharge (R ≈ 0…13 cm), whereas at higher pressure the minimum of ne value is observed at the discharge center. That is, in this case primary elec- trons accelerated in the cathode layer up to energy ≈ eUd lose major portion of their energy already at medium radius value, and plasma in paraxial region is formed mainly at the expense of diffusion of particles from pe- riphery regions. Electron energy distribution function for different values of system radius and oxygen pressure are pre- sented in Fig. 3,a,b. On can see from the figure that for both pressure values the EEDF possesses bi-maxwellian behavior at energy variations in range ε ≈ 0…10 eV, at that temperature of “cold” (ec) electrons Te1 (in energy range ε ≈ 0…2 eV) is essentially less than that of “hot” (eh) electrons Te2 (ε ≈ 2…10 eV). 0 2 4 6 8 10 10-4 10-3 10-2 10-1 100 a) R = 8 cmR = 0 cm R = 13 cm R = 16 cm f(ε ), eV 3/ 2 ε, eV 0 2 4 6 8 10 10-4 10-3 10-2 10-1 100 R = 0 cm; 8 cm b) R = 13 cm R = 16 cm f(ε ), eV 3/ 2 ε, eV Fig. 3. Electron energy distribution function f(ε) at different system radius R for two oxygen pressure values. Р = 4 Pa, Ud = 650 V (a); P = 11 Pa, Ud = 470 V (b). Wd = 5 mW/cm3 Such EEDF shape is due to efficient excitation of metastable states ga Δ1 and +Σ gb1 of oxygen molecule having thresholds of 0.98 and 1.64 eV, respectively. It should be also noted that at 4 Pa pressure relative quan- tity of “hot” plasma electrons eh (that is, those responsi- ble for inelastic processes) has maximum at the dis- charge periphery, and decreases practically monoto- nously toward the system axis. At the same time, at 11 Pa pressure relative quantity of electrons eh with ra- dius R decrease from 16 to 13 cm diminishes at first, and with subsequent R decrease remains practically unchanged. Such difference in radial dependencies of EEDF shape is due to the following. At 4 Pa pressure, free run path of fast electrons ef with respect to energy loss due to inelastic processes is essentially longer than analogous value at 11 Pa pressure (both due to decrease of concentration of oxygen molecules, and at the ex- pense of higher electron energy Wf, proportional to Ud). In other words, fast electrons ef at 11 Pa pressure lose the energy at their motion from the cathode toward the system center essentially faster than in case of 4 Pa pressure. Since [9] mean energy of secondary electrons εsec formed at ionization of oxygen molecules by elec- trons ef diminishes with decrease of their energy Wf, it results in slower radial decrease of relative quantity of electrons eh at 4 Pa pressure, as compared with the case of 11 Pa pressure. One can see from radial dependencies of tempera- tures Te1 and Te2 at different oxygen pressure values (Fig. 4,a,b) that: 0 2 4 6 8 10 12 14 16 18 0,0 0,2 0,4 2 3 a) Te1 Te2T e, eV Radius R, cm 0 2 4 6 8 10 12 14 16 18 0,0 0,2 0,4 2 3 b) Te2 Te1 T e, e V Radius R, cm Fig. 4. Dependencies of electron temperatures Te1 and Te2 on system radius R for different oxygen pressure values. P = 4 Pa (a) and P = 11 Pa (b). Wd = 5 mW/cm3 1) Te1 in both cases comprises about 0.2 eV and is practically independent on the system radius. An exclu- sion is represented by R range of 15…17 cm, where at 4 Pa temperature Te1 abruptly decreases from ≈ 0.4 eV to ≈ 0.2 eV; 2) At the same time, behavior of radial de- pendencies of temperature Te2 differs with pressure variation. At P = 11 Pa Te2 decreases toward the center from ≈ 2.3 to ≈ 1.5 eV, whereas in case of lower pres- sure Te2, increase from ≈ 2.2 to ≈ 3.0 eV toward the system center is observed. Decrease of Te2 toward the system center at 11 Pa pressure is due to quick spatial relaxation of energy of fast electrons ef and, respec- tively, with decrease of mean energy of electrons εsec. Certain growth of Te2 toward the discharge center at 4 Pa is possibly due to fact that, resulting from cylindri- cal geometry of the discharge cathode, density of fast electrons ef increases toward the system axis, which in turn leads to “heating” of electrons eh. At the same time, at 4 Pa pressure (as well as at 11 Pa) mean energy of plasma electrons, as a whole, decreases toward the dis- charge axis (Fig. 5) a b b a ISSN 1562-6016. ВАНТ. 2013. №4(86) 169 0 2 4 6 8 10 12 14 16 18 0,0 0,4 0,8 1,2 1,6 11 Pa 4 Pa T em ea n Radius R, cm Fig. 5. Dependencies of mean energy of plasma electrons Te mean on the system radius R for different oxygen pressure values. Wd = 5 mW/cm3 Longitudinal electric field in main region of the dis- charge plasma does not exceed ≈ 5 mV/cm and weakly depends on the system radius. At the same time, radial dependence of radial component of electric field Er has non-monotonous behavior – while exhibiting growth in a whole with increase of the system radius, Er conse- quently passes local maximum and minimum with their radial locations being dependent on oxygen pressure. Er value shows certain growth with pressure decrease and at middle system radius is about 15…25 mV/cm. As a whole, at 4 Pa pressure absolute electric field value ⎥E⎥ is in range ≈ 1.5…4.5 Td, and at 12 Pa pressure - ≈ 0.5…1.5 Td. In calculations of atomic oxygen concentrations at different discharge parameters by means of expression (4) cross sections and rates of processes taken from [7, 8, 10, 11] were used. Determining of rates of the proc- esses (3) was accomplished with the use of experimen- tally defined EEDF, approximated up to energy value of 50 eV. As well, it was supposed that gas temperature in considered ranges of variations of pressure and specific power comprised about 400…450 K. -2 0 2 4 6 8 10 12 1E13 5E13 1E14 12 Pa 4 Pa 2 Pa [O ], cm -3 Radius R, cm Fig. 6. Radial dependencies of atomic oxygen concen- tration [O] (obtained by means of I844/I750 ratio) in the discharge plasma for different oxygen pressure values. Wd = 5 mW/cm3 Fig. 6 exhibits radial dependencies of atomic oxygen concentration [O] at different pressure values P obtained with the use of I844/I750 ratio. One can see from the fig- ure that at low pressure values (2 and 4 Pa) [O] in- creases toward the system center, that is in a whole re- produces ne radial dependence (although spatial rate of the increase is somewhat lower). At the same time, at 12 Pa atomic oxygen concentration is practically inde- pendent on the system radius, although plasma density in this case has distinct minimum at the axis. Since tem- perature Te2 in this case also decreases toward the sys- tem axis, possible reason for such “flattening” of [O] dependence is due to diffusion of atomic oxygen toward the system center. One can also see from the figure that at pressure growth, simultaneously with [O] increase, oxygen dissociation degree [O]/[O2] decreases. Particu- larly, at 2 Pa pressure the degree of dissociation at the system axis is ≈ 4.5%, whereas pressure increase up to 12 Pa leads to [O]/[O2] decrease down to ≈ 2.5%. Behavior of [O] radial dependence at the discharge specific power variation is practically unchanged. One can see from Fig. 7 that at 12 Pa [O] at the system axis remains practically the same with specific power variation, whereas [O] growth is observed at lower pressure values. 0 2 4 6 8 1E13 5E13 1E14 12 Pa 8 Pa 2 Pa[O ], cm -3 Wd, mW/cm3 Fig. 7. Dependencies of atomic oxygen concentration [O] (obtained with the use of I844/I750 ratio) at the system axis on specific power in the discharge Wd for different oxygen pressure values Analogous dependencies of [O] on the system pa- rameters were also obtained in case of use of intensity ratio I777/I750. However, oxygen concentration values obtained in this case were several times higher. It is possibly due to neglecting other processes of atomic oxygen formation (particularly, dissociation of metasta- ble molecules O2, which may provide essential influ- ence on [O] calculation by means of I777/I750 ratio) or incorrect approximation of EEDF behavior from energy range ε = 0…10 eV to higher energy values, since cal- culation of the rates of excitation processes requires exact knowledge of high energy portion of the EEDF. Unfortunately, method of Langmuir probes does not allow precise measurements of EEDF shape for energy values above 10…15 eV, and for this reason EEDF cal- culations were performed for comparison with experi- mental data. 3. CALCULATIONS AND DISCUSSION For determining EEDF appearance, Boltzman equa- tion is solved in two-term approximation [12]. At that, transport cross section for electron scattering on oxygen molecules is taken from [11], and main processes taken into account in the integral of inelastic collisions are listed in Table. In our model we consider that one half of power introduced into the discharge is spent on oxy- gen ionization in the discharge volume, and this ioniza- tion occurs homogeneously in the whole discharge vol- ume with rate w/(2εi), where w is specific power intro- duced into the discharge, and εi is oxygen ionization energy (12,2 eV). Energy distribution of secondary elec- trons is taken proportional to 1/(εs 2+ε0 2), where εs is ISSN 1562-6016. ВАНТ. 2013. №4(86) 170 secondary electron energy, and ε0 = 17.4 eV is parame- ter, which is close to actual distribution [7]. N Reactions Threshold, eV Ref. 1 O2 + e O2(v) + e 0.195 11 2 O2 + e O2(1Δg) + e 0.98 13 3 O2 + e O2(b1Σg +) + e 1.64 13 4 O2 + e O2(A3Σu +) + e 4.5 11 5 O2 + e O2 * + e 6.0 13 6 O2 + e O2 + + e + e 12.2 7 7 O2 + e O + O- 3.6 11 One can see from Fig. 8 that, as it was expected, two-temperature EEDF behavior in energy range of ≈ 0…10 eV is, first of all, due to influence of excitation of metastable states and vibrational levels of О2. At the same time, one can see that calculated EEDF exhibits a bend not only at energy ≈ 2 eV, but as well, at about 10 eV, at that temperature/mean energy of electrons at energy values > 10 eV is several times higher than tem- perature Te2. Such EEDF behavior may be a reason for discrepancy in measured [O] values. 0 5 10 15 20 25 1E-6 1E-5 1E-4 1E-3 0,01 0,1 1 10 f(ε ), eV 3/ 2 ε, eV - with O2 metast + O2 vibr - without O2 metast - without O2 metast + O2 vibr Fig. 8. Calculated EEDF. P = 12 Pa, ⎥E⎥ = 1 Td REFERENCES 1. U. Cvelbar, M. Mozetic, and M. 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Рябцев Показано, что функция распределения электронов по энергиям плазмы отрицательного свечения разряда низкого давления в кислороде имеет двутемпературный характер из-за влияния метастабильных молекул O2(a1Δg), O2(b1Σ+ g) и возбуждения колебательных уровней О2. Методом актинометрии установлены простран- ственные зависимости концентрации атомарного кислорода от давления газа и удельной мощности в разряде. КІНЕТИЧНІ ПРОЦЕСИ В ПЛАЗМІ НЕГАТИВНОГО СВІТІННЯ РОЗРЯДУ НИЗЬКОГО ТИСКУ В КИСНІ В.В. Ціолко, С.В. Мацевич, В.Ю. Баженов, В.М. Піун, А.В. Рябцев Показано, що функція розподілу електронів по енергіях плазми негативного світіння розряду низького тиску в кисні має двотемпературний характер із-за впливу метастабільних молекул O2(a1Δg), O2(b1Σ+ g) та збудження коливальних рівнів О2. Методом актинометрії встановлено просторові залежності концентрації атомарного кисню від тиску газу та питомої потужності в розряді.

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