General characterization and ionization-recombination properties of electronegative elements present in plasma discharges at plasma current switch operation. Part I
Based on literary sources, we present here the data on electron affinity values for a variety of negative atomic ions, and also, for some molecules and radicals being of interest for current experimental studies. Besides, the ionization potentials are given for nearly all ionization states of some e...
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Національний науковий центр «Харківський фізико-технічний інститут» НАН України
2021
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| Цитувати: | General characterization and ionization-recombination properties of electronegative elements present in plasma discharges at plasma current switch operation. Part I / E.I. Skibenko, V.B. Yuferov, A.N. Ozerov, I.V. Buravilov // Problems of Atomic Science and Technology. — 2021. — № 4. — С. 11-17. — Бібліогр.: 22 назв. — англ. |
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Skibenko, E.I. Yuferov, V.B. Ozerov, A.N. Buravilov, I.V. 2023-12-03T13:46:06Z 2023-12-03T13:46:06Z 2021 General characterization and ionization-recombination properties of electronegative elements present in plasma discharges at plasma current switch operation. Part I / E.I. Skibenko, V.B. Yuferov, A.N. Ozerov, I.V. Buravilov // Problems of Atomic Science and Technology. — 2021. — № 4. — С. 11-17. — Бібліогр.: 22 назв. — англ. 1562-6016 PACS: 52.25.Jm; 52.50.Dg; 41.75.Ak DOI: https://doi.org/10.46813/2021-134-011 https://nasplib.isofts.kiev.ua/handle/123456789/195127 Based on literary sources, we present here the data on electron affinity values for a variety of negative atomic ions, and also, for some molecules and radicals being of interest for current experimental studies. Besides, the ionization potentials are given for nearly all ionization states of some electronegative elements (C, O, F, Cl). For the said elements, the ionization-recombination parameters and the dependences of the fractional values (ionic fraction) for ionization states and on the electron temperature within the framework of ionization equilibrium are given. A comparison is carried out between the calculated and experimental distributions of the fractions of multicharged C⁺⁴ ions versus electron temperature. На основі літературних джерел наведені дані по величинам спорідненості до електрону для ряду негативних атомарних іонів і для деяких молекул і радикалів, що представляють інтерес для експериментальних досліджень, що проводяться. Наведено також потенціали іонізації майже за всіма іонізаційними станами для деяких електронегативних елементів (C, O, F, Cl). Для них же наведені іонізаційно-рекомбінаційні параметри і залежності фракційних значень (ionic fraction) по іонізаційним станам від температури електронів у рамках іонізаційної рівноваги (ionization equilibria). Проведено порівняння розрахункових і експериментальних даних за розподілом частки багатозарядних іонів С⁺⁴ від температури електронів. На основе литературных источников приведены данные по величинам сродства к электрону для ряда отрицательных атомарных ионов и для некоторых молекул и радикалов, представляющих интерес для проводимых экспериментальных исследований. Приведены также потенциалы ионизации почти по всем ионизационным состояниям для некоторых электроотрицательных элементов (C, O, F, Cl). Для них же приведены ионизационно-рекомбинационные параметры и зависимости фракционных значений (ionic fraction) по ионизационным состояниям от температуры электронов в рамках ионизационного равновесия (ionization equilibria). Проведено сравнение расчетных и экспериментальных данных по распределениям доли многозарядных ионов С⁺⁴ от температуры электронов. en Національний науковий центр «Харківський фізико-технічний інститут» НАН України Вопросы атомной науки и техники Relativistic and nonrelativistic plasma electronics General characterization and ionization-recombination properties of electronegative elements present in plasma discharges at plasma current switch operation. Part I Загальна характеристика та іонізаційно-рекомбінаційні властивості електронегативних елементів, присутніх у плазмовому розряді при роботі плазмових комутаторів струму. Частина I Общая характеристика и ионизационно-рекомбинационные свойства электроотрицательных элементов, присутствующих в плазменных разрядах при работе плазменных коммутаторов тока. Часть I Article published earlier |
| institution |
Digital Library of Periodicals of National Academy of Sciences of Ukraine |
| collection |
DSpace DC |
| title |
General characterization and ionization-recombination properties of electronegative elements present in plasma discharges at plasma current switch operation. Part I |
| spellingShingle |
General characterization and ionization-recombination properties of electronegative elements present in plasma discharges at plasma current switch operation. Part I Skibenko, E.I. Yuferov, V.B. Ozerov, A.N. Buravilov, I.V. Relativistic and nonrelativistic plasma electronics |
| title_short |
General characterization and ionization-recombination properties of electronegative elements present in plasma discharges at plasma current switch operation. Part I |
| title_full |
General characterization and ionization-recombination properties of electronegative elements present in plasma discharges at plasma current switch operation. Part I |
| title_fullStr |
General characterization and ionization-recombination properties of electronegative elements present in plasma discharges at plasma current switch operation. Part I |
| title_full_unstemmed |
General characterization and ionization-recombination properties of electronegative elements present in plasma discharges at plasma current switch operation. Part I |
| title_sort |
general characterization and ionization-recombination properties of electronegative elements present in plasma discharges at plasma current switch operation. part i |
| author |
Skibenko, E.I. Yuferov, V.B. Ozerov, A.N. Buravilov, I.V. |
| author_facet |
Skibenko, E.I. Yuferov, V.B. Ozerov, A.N. Buravilov, I.V. |
| topic |
Relativistic and nonrelativistic plasma electronics |
| topic_facet |
Relativistic and nonrelativistic plasma electronics |
| publishDate |
2021 |
| language |
English |
| container_title |
Вопросы атомной науки и техники |
| publisher |
Національний науковий центр «Харківський фізико-технічний інститут» НАН України |
| format |
Article |
| title_alt |
Загальна характеристика та іонізаційно-рекомбінаційні властивості електронегативних елементів, присутніх у плазмовому розряді при роботі плазмових комутаторів струму. Частина I Общая характеристика и ионизационно-рекомбинационные свойства электроотрицательных элементов, присутствующих в плазменных разрядах при работе плазменных коммутаторов тока. Часть I |
| description |
Based on literary sources, we present here the data on electron affinity values for a variety of negative atomic ions, and also, for some molecules and radicals being of interest for current experimental studies. Besides, the ionization potentials are given for nearly all ionization states of some electronegative elements (C, O, F, Cl). For the said elements, the ionization-recombination parameters and the dependences of the fractional values (ionic fraction) for ionization states and on the electron temperature within the framework of ionization equilibrium are given. A comparison is carried out between the calculated and experimental distributions of the fractions of multicharged C⁺⁴ ions versus electron temperature.
На основі літературних джерел наведені дані по величинам спорідненості до електрону для ряду негативних атомарних іонів і для деяких молекул і радикалів, що представляють інтерес для експериментальних досліджень, що проводяться. Наведено також потенціали іонізації майже за всіма іонізаційними станами для деяких електронегативних елементів (C, O, F, Cl). Для них же наведені іонізаційно-рекомбінаційні параметри і залежності фракційних значень (ionic fraction) по іонізаційним станам від температури електронів у рамках іонізаційної рівноваги (ionization equilibria). Проведено порівняння розрахункових і експериментальних даних за розподілом частки багатозарядних іонів С⁺⁴ від температури електронів.
На основе литературных источников приведены данные по величинам сродства к электрону для ряда отрицательных атомарных ионов и для некоторых молекул и радикалов, представляющих интерес для проводимых экспериментальных исследований. Приведены также потенциалы ионизации почти по всем ионизационным состояниям для некоторых электроотрицательных элементов (C, O, F, Cl). Для них же приведены ионизационно-рекомбинационные параметры и зависимости фракционных значений (ionic fraction) по ионизационным состояниям от температуры электронов в рамках ионизационного равновесия (ionization equilibria). Проведено сравнение расчетных и экспериментальных данных по распределениям доли многозарядных ионов С⁺⁴ от температуры электронов.
|
| issn |
1562-6016 |
| url |
https://nasplib.isofts.kiev.ua/handle/123456789/195127 |
| citation_txt |
General characterization and ionization-recombination properties of electronegative elements present in plasma discharges at plasma current switch operation. Part I / E.I. Skibenko, V.B. Yuferov, A.N. Ozerov, I.V. Buravilov // Problems of Atomic Science and Technology. — 2021. — № 4. — С. 11-17. — Бібліогр.: 22 назв. — англ. |
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ISSN 1562-6016. ВАНТ. 2021. № 4(134) 11
https://doi.org/10.46813/2021-134-011
GENERAL CHARACTERIZATION AND IONIZATION-
RECOMBINATION PROPERTIES OF ELECTRONEGATIVE
ELEMENTS PRESENT IN PLASMA DISCHARGES AT PLASMA
CURRENT SWITCH OPERATION. PART I
E.I. Skibenko, V.B. Yuferov, A.N. Ozerov, I.V. Buravilov
National Science Center “Kharkov Institute of Physics and Technology”, Kharkiv, Ukraine
E-mail: skibenko38@gmail.com; ozerov@kipt.kharkov.ua
Based on literary sources, we present here the data on electron affinity values for a variety of negative atomic
ions, and also, for some molecules and radicals being of interest for current experimental studies. Besides, the ioni-
zation potentials are given for nearly all ionization states of some electronegative elements (C, O, F, Cl). For the
said elements, the ionization-recombination parameters and the dependences of the fractional values (ionic fraction)
for ionization states and on the electron temperature within the framework of ionization equilibrium are given. A
comparison is carried out between the calculated and experimental distributions of the fractions of multicharged C+4
ions versus electron temperature.
PACS: 52.25.Jm; 52.50.Dg; 41.75.Ak
INTRODUCTION
In the earlier papers [1 - 7] concerned with the prob-
lems of creation and research of a compact pulsed elec-
tron accelerator based on the plasma-filled diode, it has
been indicated that, apart from the natural-origin ele-
ments, the spectrum of residual atmosphere inside the
vacuum chamber may show up the elements of the elec-
tronegative Mendeleyev's group. These elements may
appear as a result of sputtering of key parts and details
of the plasma guns involved in the experiment, and also,
due to the external and internal gas puffing into the sys-
tem for providing optimum conditions and results of
filling the discharge gap of the plasma current switch
(PCS) with plasma. The necessity of achieving this gas
puffing effect was specified as early as at the moment of
setting the problem, viz., creation of high-current elec-
tron accelerators (HCEA) and realization of first ex-
periments. For example, it was suggested in ref. [1] that
the parameters of the PCS, and eventually of HCEA,
could be stabilized through keeping constant the charge-
mass characteristic of the plasma bunch and the total
number of particles contained in it. Further on [2 - 7],
studies were made into the behavior of the switched
current versus the plasma gun voltage, and the energy
content of gun power, the residual gas density in the
PCS chamber. It has been demonstrated that the stability
increase in the PCS (and hence, the HCEA) operating
parameters can be attained by increasing the amount and
density of plasma in the discharge gap, and also, by
making the plasma density distribution along the annu-
lar gap more uniform. At that, the switching current
value can be increased either by enhancing the plasma
injection into the discharge gap, or by applying addi-
tional gas injection, external or internal. Gases with low
atomic number (H2, D2, He) are best suited to the exter-
nal gas injection. The use of planar-type plasma guns
with soft-dielectric surface breakdown, and also, the
cable-type guns [8] may cause plasma contamination
with atoms and ions of electronegative elements, e.g.,
fluorine, carbon and their compounds. In this connec-
tion, it appears of interest and advantage to trace their
effect on the PCS plasma, including the processes of
ionization, recombination, and emission from plasma.
1. GENERAL DESCRIPTION
OF ELECTRONEGATIVE ELEMENTS
The choice of electronegative elements C, O, F, Cl
for consideration has been prompted in our case by ex-
perimental conditions, at which by reason of occurrence
of some physical processes (desorption, decomposition,
sputtering, dissociation, ionization, recombination) in
the active vacuum volume there may appear (in con-
trolled/uncontrolled way) and accumulate some
amounts of the mentioned elements or their chemical
species in both neutral (atoms, molecules) or ionized
(positive and negative ions of different multiplicity)
states. So, it stands to mention some of their general
characteristics and properties.
The electron affinity [9], i.e., the energy released at
production of negative ion from the neutral atom and
electron (А+е=А–), together with the ionization poten-
tial [10], are the important quantitative characteristics of
the electronegativity of elements, which plays a large
role in the molecular structure. In fact, the negative ion
concept implies the atom, the molecule or the molecular
group with a negative total charge. Free negative ions
generally carry only unit excess negative charge. The
negative ions in electrolytes and ionic crystals are most
often multicharger. Directly in gas, the negative ions
will be produced either as a result of dissociation of
neutral molecules and molecular ions, or due to the
transfer of one or a few electrons at heavy particle colli-
sions during charge exchange. The additional electron is
easiest to be captured by the atoms, which have single
vacancies in outer shells, and therefore, the halogens (F,
Cl, Br, I, At) should be strongly electronegative. The
atoms with fully filled shells are poorly suited for nega-
tive ion production. Therefore, the inert gases are inca-
pable of producing stable negative ions. For the nega-
tive ion to be stable, its binding energy should exceed
the neutral atom-binding energy. Mathematically, it can
be written as
ISSN 1562-6016. ВАНТ. 2021. № 4(134) 12
0
0
1 1 1
1 1 ( ) 0
z zE E Ei ii i
or
zE E Ei i i
, (1)
where Ei
0 is the binding energy of the i-th atomic elec-
tron prior to additional electron attachment, Ei
– is the
binding energy of the same atomic electron after the
attachment, E1 is the binding energy of the additional
electron after its attachment.
The left-hand side of inequality (1) is called the elec-
tron affinity of the atom. It is represented as the total
energy difference of the ground states of the atom and
the ion, and is denoted as EA. In principle, ЕА is equal
to the energy required for the most weakly attached
electron to separate from the ion (detachment energy for
ion). Table 1 lists the electron affinity values, which
were obtained experimentally, theoretically and empiri-
cally by extrapolation for a number of negative atomic
ions.
Table 2 gives the electron affinity values for a vari-
ety of molecules and radicals. The values were deter-
mined as the energy difference between the neutral
molecule and the corresponding molecular ion.
Table 1
Electron affinity values for some negative atomic ions
Ion H- B- C- N- O- F- Al- Si- Cl- Br- I-
ЕА, eV 0.754 0.33 1.33 0.54 1.465 3.62 0.52 1.46 3.76 3.51 3.17
Table 2
Electron affinity values for a variety of molecules and radicals
Ion H2
- O2
- OH- N2
- NO2
- NO3
- CH- CN- C2
- C3
- SF5
-
ЕА, eV 0.9 0.44 1.78 <0 1.6 3.9 ~1.6 3.1 ~3.2 2.5 3.39
The above-given electron affinity data encourage us
to point out the following.
1. The positive electron affinity points to the nega-
tive ion stability.
2. The experimental and theoretical data are consid-
ered reliable to the accuracy of 0.1 eV, except for Na–
and P–.
3. Determination of electron affinity for the mole-
cules is a much more difficult problem than for atoms,
because it calls for carrying out spectroscopic studies
(measurements) with improved spectral resolution.
4. The affinity for two and more electrons, i.e., the
energy of doubly- or multi-charged negative ion forma-
tion from the atom and two or more electrons, is always
negative. For example, the formation of the O– ion from
O+2e is supposed to take about 7 eV, whereas the for-
mation of the S– ion from S+2e takes about 3.5 eV. In
the general case, the electric (nuclear) system, consist-
ing of the nucleus and (z+k) electrons, i.e., in the form
of the negative ion A-k, at k1, is always unstable and
must break up with energy release.
5. Doubly charged negative ions were never ob-
served in gases. The reason is that the second electron
experiences a strong electrostatic repulsion. Therefore,
the probability of the second electron attachment is neg-
ligibly small.
Among the parameters of certain elements, called as
electron affinity, another parameter of importance that
characterizes the special their features and electronega-
tiveness of the elements is the potential of ionization
over all ionization states. Table 3 lists this parameter
values [11] for four elements (C, O, F, Cl) being the
subject of the present study.
Table 3
Ionization potentials for C, O, F, Cl
Carbon Oxygen Fluorine Chlorine
i ui, eV i ui, eV i ui, eV i ui, eV
1 11.264 1 13.614 1 17.418 1 13.01
2 24.376 2 35.146 2 34.980 2 23.80
3 47.864 3 54.934 3 62.646 3 39.90
4 64.476 4 77.394 4 87.23 4 53.3
5 391.986 5 113.873 5 114.214 5 67.8±0.2
6 489.84 6 138.08 6 157.117 6 96.6±0.3
- 7 739.114 7 185.139 7 114.2±0.1
- 8 871.12 8 935.8±0.3 8 348.5
- - - 9 1101.8 9 400.3±0.1
- - - - - 10 455.3
- - - - - 11 531.4
- - - - - 12…17 -
ISSN 1562-6016. ВАНТ. 2021. № 4(134) 13
2. IONIZATION-RECOMBINATION
PROPERTIES AND PARAMETERS
OF ELECTRONEGATIVE ELEMENTS
The problem of ionization (coronal) equilibrium be-
longs to the domain of recombination-ionization equi-
librium and the charged-state equilibrium of the ions
under consideration [12]. The time-varying spectral line
intensity of highly ionized ions should be treated in
terms of the rate of ionization and recombination [13].
The stationary populations of ions having different
charges depend not only on the physics of atomic proc-
esses, but also on the ion motion in the plasma. At a low
diffusion rate, the spatial profiles of ions will corre-
spond to the coronal equilibrium, while at a quick ion
motion through the plasma they will correspond to the
non-coronal ionization.
We now mention some collective aspects of the
processes of ionization and recombination. The set of
conditions and parameters necessary for formulating the
equation of balance in the many-particle system (i+, i, e-)
includes the following.
1. The most probable collisions are elastic colli-
sions, which establish the Maxwellian distribution func-
tion.
2. The main collision types are: e– i+ (or e- p+, i.e.,
electrons and protons) + charge-exchange process.
3. Since υe > υp (υi), the have a greater impact on the
ionization/excitation processes.
4. Pair collisions are more important than many-
particle collisions. The three-body recombination is also
of importance.
5. If the processes of photoionization and photoexci-
tation are neglected, then the optically thin plasma ap-
proximation is used.
The equilibrium equation includes the terms of two
types: radiation (radiation-recombination) and colli-
sional terms. Consideration is given to three ionic
groups: 1) excited-state ions, but not metastable;
2) ground-state ions; 3) metastable-state ions. The equa-
tion describing the rate of ion density variation, n(z),
with the charge z has the form
[ ( 1) ( 1, ) ( ) ( , 1)
( ) ( , 1) ( 1) ( 1, )],
dn z
dt
n n z S z z n z z ze
n z S z z n z z z
(2)
where S(z, z+1) is the effective ionization coefficient,
α(z, z-1) is the effective recombination coefficient.
Equation (2) takes no account of the multiple ioniza-
tion. Furthermore, the multiple ionization is regarded as
unlikely, and the contribution of metastable levels is
neglected.
The basic plasma parameter, which affects the time
of achieving the ionization equilibrium steady-state,
when ionization is balanced by recombination, is the
plasma density. At the same time, the ionic charge state,
attained through realization of ionization equilibrium, is
determined by the electron temperature. Considering
that at the ionization equilibrium state the rates of ioni-
zation and recombination are much the same, the time
of steady-state equilibrium achievement can be esti-
mated by the formula tion. eq=1012·ne
-1, s. For comparison,
Table 4 gives the relaxation time values for some levels
of hydrogen-like atoms.
Table 4
Relaxation times for some levels of hydrogen-like atoms
Θ ne τ, s τ, s τ, s τ, s
К eV cm-3 p=1 p=2 p=3 p=4
2.56·105 22.07 1.0·108 1.3·10-1 2.1·10-9 1.0·10-8 5.5·10-6
1.0·1012 1.3·10-5 2.1·10-9 9.8·10-9 9.8·10-10
1.0·1015 1.3·10-8 9.3·10-10 4.1·10-10 9.8·10-13
1.0·1018 1.3·10-11 1.7·10-12 4.3·10-13 9.8·10-16
Here p is the principal quantum number according to
the Bohr-Sommerfeld theory, equal to the sum of two
(azimuthal n0 and radial nr) quantum numbers. The
p=1, 2, 3, 4 values correspond to the states K, L, M, and
N; Θ and ne are, respectively, the reduced temperature
and density of electrons. The relaxation time values are
inversely related to z4. At that, the time of steady-state
ionization equilibrium achievement must be considera-
bly shorter than the required energy confinement time,
i.e., the relationship tion. eq should be compared with the
Lawson criterion nτE 1014 cm-3s.
In a number of works [14 - 21], within the ionization
equilibrium approximation for different ionization
states, the ionic fractions were determined as functions
of electron temperature for different elements. For ex-
ample, the data are reported for H in [14], for C in [15],
for N, O, Xe in [16], for Ar and Ti in [17], for Kr in [18]
and for multicomponent gas-metal (Ar+Ti) plasma of a
pulsed reflex discharge in [19]. The authors of free-
standing works [20, 21] give the data for the element
groups comprised of 11 and 28 names respectively. For
tasks set in the given case, the work [21] is the most
acceptable. Based on the above-given literary sources
[14 - 21], we have obtained the following information
data for certain electronegative elements (such as car-
bon, oxygen, fluorine, chlorine), in the form of depend-
ences χi = f(Te) of fractional values (ionic fractions),
where χi = -log(Ni/Ntotal), on the electron temperature
within the ionization equilibria (Figs. 1-5). Table 5
gives distribution of investigated energy ranges by ioni-
zation states for different electronegative elements
shown in Figs. 1 to 5.
Note that the left-hand branch of the χi = f(Te) curves
at i1 relates to the recombination part of the ionization
equilibrium process, while the right-hand part at i>1
to the ionization part. Figs. 1-5 show the temperature
dependences of ionic fractions χi = f(Te) for carbon (see
Fig. 1) over the ionization states i=I-VI, for oxygen (see
Fig. 2) over i=I-VIII, for fluorine (see Fig. 3) over i=I-
IX, for chlorine over i=I-IX (see Fig. 4) and over i=X-
ISSN 1562-6016. ВАНТ. 2021. № 4(134) 14
XVII (see Fig. 5). Fig. 2,a,b illustrates the work data of
two corporate authors [20, 21] for oxygen. The differ-
ence between their results varies within 15 to 40%.
Table 5
Distribution of the studied energy ranges by ionization states for various electronegative elements
Ionization state i=1 2 3 4 5 6 7 8 9 10 11
С
Δε, eV
0.86±
16.38
0.86±
31.90
2.41±
55.17
5.52±
319
7.07±
862
39.7±
862
О
Δε, eV
0.86±
16.38
0.86±
39.7
3.97±
47.41
6.29±
62.93
7.84±
163.79
16.38±
551.72
31.90±
3189.7
70.68±
6293
F
Δε, eV
0.86±
8.62
0.86±
31.89
3.96±
55.17
6.29±
70.68
7.84±
78.44
16.38±
318.96
31.89±
706.8
39.65±
4741.4
78.44±
8620.7
Cl
Δε, eV
0.86±
6.29
0.86±
24.14
2.41±
47.41
3.96±
55.17
6.29±
62.93
7.84±
78.44
16.38±
163.79
24.14±
396.55
47.71±
474.1
62.93±
551.7
78.44±
629.3
i 12 13 14 15 16 17
El
em
en
ts
an
d
En
er
gy
ra
ng
es
Δ
ε
Cl
Δε, eV
86.2±
784.5
163.8±
1637.9
241.4±
4741
319±
7844
319±
47414
551.7±
47414
Fig. 1. Carbon ionic fractions versus electron tempera-
ture for ionization states ranging from I to VI,
according to J.M. Shull and M. van Steenberg [20]
Fig. 2a. Oxygen ionic fractions versus electron
temperature for ionization states ranging from I to VIII,
according to P. Mazzotta et al [21]
Fig. 2b. Oxygen ionic fractions versus electron tem-
perature for ionization states ranging from I to VIII,
according to J.M. Shull and M. van Steenberg [20]
Fig. 3. Fluorine ionic fractions versus electron
temperature for ionization states ranging from I to IX,
according to P. Mazzotta et al [21]
ISSN 1562-6016. ВАНТ. 2021. № 4(134) 15
Fig. 4. Chlorine ionic fractions versus electron
temperature for ionization states ranging from I to IX,
according to P. Mazzotta et al [21]
Fig. 5. Chlorine ionic fractions versus electron
temperature for ionization states ranging
from X to XVII, according to P. Mazzotta et al [21]
Fig. 6. Fluorine ionic fractions distribution in different
ionization states in the temperature range
from 104 to109 K (0.862…86207 eV)
The distributions of fluorine/chlorine ionic fractions
over different ionization states were also obtained in the
temperature range 104…109 К (~1…104 eV) (Figs. 6-8).
In this case, with the use of data from ref. [20] and
Fig. 1, calculations were performed to determine the
fraction distributions of the multicharged ions C+4 in the
energy range from 5.52 to 55.17 eV. The resulting rela-
tionship Ni=4/Ntotal=f(T) (Fig. 9,a) has made it possible
to determine (from the half width of the curve in the
region of Ni/Nt>1% and at ΔT from 23 down to 13 eV)
the average C+4 fraction value which is ~ 15%, even
though the maximum fraction value in the narrow en-
ergy range (≤ 8 eV) may reach ~ 70%.
Fig. 7. Fluorine ionic fractions distribution in different
ionization states versus electron temperature:
1 – the black line is plotted by the computational points;
2 – the red line is plotted by the averaged
temperature ranges
Fig. 8. Chlorine ionic fractions distribution in different
ionization states at electron temperatures ranging
from 104 to 109 K
a
b
Fig. 9. Temperature dependence of the relative amount
of multicharged C4+ ions, calculated with regard
to the data of Fig. 1,а; Comparison between
the carbon multicharged ionic fractions as functions of
temperature, calculated with regard to the data of [20]
and Fig. 1, and determined by experiment [22] (b)
ISSN 1562-6016. ВАНТ. 2021. № 4(134) 16
The studies [22] into the special features of the en-
ergy-mass composition of the plasma of the nanosecond
coaxial vacuum surface discharge have revealed the
presence of differently charged carbon ions (C+1, C+2,
C+3, C+4). A correlation was made between the experi-
mental fractions of the multicharged C+4 ions with the
computational estimates. The results of the correlation
are presented in Fig. 9,b. On the left, curve 1 shows the
calculated C+4 ionic fraction distribution obtained with
the use of the data from ref. [20] under the assumption
of the ionization equilibrium. At the right top of Fig. 9,b
the curves show the experimental results of work [22] at
different polarities of the electrode-dielectric (high pres-
sure polyethylene) pair (+ : curve 2, - : curve 3).
RESULTS AND CONCLUSIONS
The conducted investigations are mainly aimed at
evaluating the impact of some factors, which cause the
plasma-bridge formation and decay in the PCS electrode
gap, on the efficiency of the PCS operation in attaining
the maximum current values and voltage multiplication.
Among these factors is the electronegativeness of cer-
tain elements that enter into the weight composition of
plasma in the form of ionized and neutral particles.
The main results of the present work can be summa-
rized as follows.
1. General characterization has been given for sev-
eral electronegative elements (C, O, F, Cl) that present
some features of interest for the current studies. The
data include the electron affinity values and the values
of ionization potentials in different ionization states.
2. With due regard to the ionization-recombination
properties and the parameters of the electronegative
elements under consideration, studies have been made
to determine the distributions of fluorine and chlorine
ionic fractions in different ionization states in the con-
text of ionization equilibrium. At that, the electron tem-
perature was varied in the range from 1 to 104 eV.
3. Comparison has been made between the calcu-
lated and experimental data on the distribution of mul-
ticharged C+4 ionic fractions as a function of electron
temperature.
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Article received 25.05.2021
ISSN 1562-6016. ВАНТ. 2021. № 4(134) 17
ОБЩАЯ ХАРАКТЕРИСТИКА И ИОНИЗАЦИОННО-РЕКОМБИНАЦИОННЫЕ СВОЙСТВА
ЭЛЕКТРООТРИЦАТЕЛЬНЫХ ЭЛЕМЕНТОВ, ПРИСУТСТВУЮЩИХ В ПЛАЗМЕННЫХ
РАЗРЯДАХ ПРИ РАБОТЕ ПЛАЗМЕННЫХ КОММУТАТОРОВ ТОКА. ЧАСТЬ I
Е.И. Скибенко, В.Б. Юферов, А.Н. Озеров, И.В. Буравилов
На основе литературных источников приведены данные по величинам сродства к электрону для ряда от-
рицательных атомарных ионов и для некоторых молекул и радикалов, представляющих интерес для прово-
димых экспериментальных исследований. Приведены также потенциалы ионизации почти по всем иониза-
ционным состояниям для некоторых электроотрицательных элементов (C, O, F, Cl). Для них же приведены
ионизационно-рекомбинационные параметры и зависимости фракционных значений (ionic fraction) по иони-
зационным состояниям от температуры электронов в рамках ионизационного равновесия (ionization equilib-
ria). Проведено сравнение расчетных и экспериментальных данных по распределениям доли многозарядных
ионов С+4 от температуры электронов.
ЗАГАЛЬНА ХАРАКТЕРИСТИКА ТА ІОНІЗАЦІЙНО-РЕКОМБІНАЦІЙНІ ВЛАСТИВОСТІ
ЕЛЕКТРОНЕГАТИВНИХ ЕЛЕМЕНТІВ, ПРИСУТНІХ У ПЛАЗМОВОМУ РОЗРЯДІ ПРИ РОБОТІ
ПЛАЗМОВИХ КОМУТАТОРІВ СТРУМУ. ЧАСТИНА I
Є.І. Скібенко, В.Б. Юферов, О.М. Озеров, І.В. Буравілов
На основі літературних джерел наведені дані по величинам спорідненості до електрону для ряду негати-
вних атомарних іонів і для деяких молекул і радикалів, що представляють інтерес для експериментальних
досліджень, що проводяться. Наведено також потенціали іонізації майже за всіма іонізаційними станами для
деяких електронегативних елементів (C, O, F, Cl). Для них же наведені іонізаційно-рекомбінаційні парамет-
ри і залежності фракційних значень (ionic fraction) по іонізаційним станам від температури електронів у ра-
мках іонізаційної рівноваги (ionization equilibria). Проведено порівняння розрахункових і експерименталь-
них даних за розподілом частки багатозарядних іонів С+4 від температури електронів.
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