Propagation of multicomponent plasma oscillations along the magnetic field in the pulsed reflex discharge
The angular velocity of equal-density plasma layer rotations along the magnetic field has been measured. The values obtained in different points are similar that is in accordance with the isorotation law. It has been established that in the plasma the oscillations are propagating along the magnetic...
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| Zitieren: | Propagation of multicomponent plasma oscillations along the magnetic field in the pulsed reflex discharge / Yu.V. Kovtun, A.I. Skibenko, E.I. Skibenko, I.B. Pinos, Yu.V. Larin, V.B. Yuferov // Вопросы атомной науки и техники. — 2012. — № 6. — С. 211-213. — Бібліогр.: 12 назв. — англ. |
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Kovtun, Yu.V. Skibenko, A.I. Skibenko, E.I. Pinos, I.B. Larin, Yu.V. Yuferov, V.B. 2016-11-21T19:44:54Z 2016-11-21T19:44:54Z 2012 Propagation of multicomponent plasma oscillations along the magnetic field in the pulsed reflex discharge / Yu.V. Kovtun, A.I. Skibenko, E.I. Skibenko, I.B. Pinos, Yu.V. Larin, V.B. Yuferov // Вопросы атомной науки и техники. — 2012. — № 6. — С. 211-213. — Бібліогр.: 12 назв. — англ. 1562-6016 PACS: 52.80.Sm https://nasplib.isofts.kiev.ua/handle/123456789/109203 The angular velocity of equal-density plasma layer rotations along the magnetic field has been measured. The values obtained in different points are similar that is in accordance with the isorotation law. It has been established that in the plasma the oscillations are propagating along the magnetic field with a velocity value close to the Alfven velocity V ~ VA. Проведены измерения угловой скорости вращения плазменных слоев одинаковой плотности вдоль магнитного поля, значения которой оказались в различных точках близкими друг к другу, что согласуется с законом изоротации. Установлено, что в плазме вдоль магнитного поля распространяются колебания со скоростью, близкой по величине к aльфвеновской скорости V ~ VA. Проведено вимірювання кутової швидкості обертання плазмових шарів однакової густини уздовж магнітного поля, значення якої в різних точках виявилися близькими одне до одного, що узгоджується із законом ізоротації. Встановлено, що в плазмі уздовж магнітного поля розповсюджуються коливання із швидкістю, близькою по величині до альфвеновської швидкості V ~ VA. en Національний науковий центр «Харківський фізико-технічний інститут» НАН України Вопросы атомной науки и техники Низкотемпературная плазма и плазменные технологии Propagation of multicomponent plasma oscillations along the magnetic field in the pulsed reflex discharge Распространение колебаний многокомпонентной плазмы вдоль магнитного поля в импульсном отражательном разряде Розповсюдження коливань багатокомпонентної плазми уздовж магнітного поля в імпульсному відбивному розряді Article published earlier |
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Digital Library of Periodicals of National Academy of Sciences of Ukraine |
| collection |
DSpace DC |
| title |
Propagation of multicomponent plasma oscillations along the magnetic field in the pulsed reflex discharge |
| spellingShingle |
Propagation of multicomponent plasma oscillations along the magnetic field in the pulsed reflex discharge Kovtun, Yu.V. Skibenko, A.I. Skibenko, E.I. Pinos, I.B. Larin, Yu.V. Yuferov, V.B. Низкотемпературная плазма и плазменные технологии |
| title_short |
Propagation of multicomponent plasma oscillations along the magnetic field in the pulsed reflex discharge |
| title_full |
Propagation of multicomponent plasma oscillations along the magnetic field in the pulsed reflex discharge |
| title_fullStr |
Propagation of multicomponent plasma oscillations along the magnetic field in the pulsed reflex discharge |
| title_full_unstemmed |
Propagation of multicomponent plasma oscillations along the magnetic field in the pulsed reflex discharge |
| title_sort |
propagation of multicomponent plasma oscillations along the magnetic field in the pulsed reflex discharge |
| author |
Kovtun, Yu.V. Skibenko, A.I. Skibenko, E.I. Pinos, I.B. Larin, Yu.V. Yuferov, V.B. |
| author_facet |
Kovtun, Yu.V. Skibenko, A.I. Skibenko, E.I. Pinos, I.B. Larin, Yu.V. Yuferov, V.B. |
| topic |
Низкотемпературная плазма и плазменные технологии |
| topic_facet |
Низкотемпературная плазма и плазменные технологии |
| publishDate |
2012 |
| language |
English |
| container_title |
Вопросы атомной науки и техники |
| publisher |
Національний науковий центр «Харківський фізико-технічний інститут» НАН України |
| format |
Article |
| title_alt |
Распространение колебаний многокомпонентной плазмы вдоль магнитного поля в импульсном отражательном разряде Розповсюдження коливань багатокомпонентної плазми уздовж магнітного поля в імпульсному відбивному розряді |
| description |
The angular velocity of equal-density plasma layer rotations along the magnetic field has been measured. The values obtained in different points are similar that is in accordance with the isorotation law. It has been established that in the plasma the oscillations are propagating along the magnetic field with a velocity value close to the Alfven velocity V ~ VA.
Проведены измерения угловой скорости вращения плазменных слоев одинаковой плотности вдоль магнитного поля, значения которой оказались в различных точках близкими друг к другу, что согласуется с законом изоротации. Установлено, что в плазме вдоль магнитного поля распространяются колебания со скоростью, близкой по величине к aльфвеновской скорости V ~ VA.
Проведено вимірювання кутової швидкості обертання плазмових шарів однакової густини уздовж магнітного поля, значення якої в різних точках виявилися близькими одне до одного, що узгоджується із законом ізоротації. Встановлено, що в плазмі уздовж магнітного поля розповсюджуються коливання із швидкістю, близькою по величині до альфвеновської швидкості V ~ VA.
|
| issn |
1562-6016 |
| url |
https://nasplib.isofts.kiev.ua/handle/123456789/109203 |
| citation_txt |
Propagation of multicomponent plasma oscillations along the magnetic field in the pulsed reflex discharge / Yu.V. Kovtun, A.I. Skibenko, E.I. Skibenko, I.B. Pinos, Yu.V. Larin, V.B. Yuferov // Вопросы атомной науки и техники. — 2012. — № 6. — С. 211-213. — Бібліогр.: 12 назв. — англ. |
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ISSN 1562-6016. ВАНТ. 2012. №6(82) 211
PROPAGATION OF MULTICOMPONENT PLASMA OSCILLATIONS
ALONG THE MAGNETIC FIELD IN THE PULSED REFLEX
DISCHARGE
Yu.V.Kovtun, A.I.Skibenko, E.I.Skibenko, I.B.Pinos, Yu.V.Larin, V.B.Yuferov
National Science Center “Kharkov Institute of Physics and Technology”, Kharkov, Ukraine
E-mail: Ykovtun@kipt.kharkov.ua
The angular velocity of equal-density plasma layer rotations along the magnetic field has been measured. The val-
ues obtained in different points are similar that is in accordance with the isorotation law. It has been established that in
the plasma the oscillations are propagating along the magnetic field with a velocity value close to the Alfven velocity
V ~ VA.
PACS: 52.80.Sm
The plasma in the crossed BE × fields is of interest
for solving a wide range of scientific and applied prob-
lems in plasma physics, namely, in the field of investi-
gations on laboratory, fusion and space plasma [1]. A
distinct feature of the plasma being in the crossed
BE × fields is its drift rotation that in the case of a mul-
ticomponent plasma leads to the spatial separation of an
ion component. Possibility to use rotating-plasma de-
vices for substance separation promotes the plasma in-
vestigations and development of facilities and com-
plexes designed for substance separation into the mass
groups and elements [2]. Among the large class of rotat-
ing plasma devices a reflex discharge is a particular
case. The reflex discharge study has many years’ his-
tory, but, by now some problems are not considered or
are studied insufficiently. Examples of such problems
are the excitation and propagation of reflex-discharge
plasma oscillations along the magnetic field.
The investigation [3] on the low-frequency oscilla-
tions of helium plasma in the stationary reflex discharge
with an heated cathode has shown that there are regions
with different behavior of oscillations depending on the
magnetic field (B ≤ 0,4 T). The correlation analysis of
probe signals permitted to establish that the phase veloc-
ity of low-frequency oscillation propagation along the
magnetic field is equal to 2·107 cm/s. This value lies in
the range between the velocity of sound (~ 106 cm/s)
and the Alfven velocity (109 cm/s). In [4] measurements
were carried out of the low-frequency (f =
10…100 kHz) helium plasma oscillations under differ-
ent initial conditions (P ≈ 0,013…0,133 Pa, B ≤ 0,03 T,
Id ≤ 30 A) in the stationary reflex discharge with an
heated cathode. From the plot of oscillation frequencies
versus plasma parameters we concluded that the oscilla-
tions observed are due to the excitation in the plasma of
ion-acoustic, slow magneto-compression and Alfven
waves. In [5] the low-frequency oscillations of the
pulsed reflex-discharge plasma in the glass chamber
were investigated using a slit scan of the plasma column
glow by the electron-optical converter. The depend-
ences of the oscillation frequency on the magnetic field
(B ≤ 1,2 T), pressure (P ≈ 0,133…13,3 Pa) and atomic
weight of gas (H2, He, Ar, Kr) evidence that the oscilla-
tions observed belong to the class of drift Alfven waves
in the inhomogeneous plasma.
So, the reflex-discharge plasma oscillation propaga-
tion along the magnetic field is not clearly understood
and requires further investigations.
The present paper gives preliminary experimental
results on the character of multi-component gas-metal
reflex-discharge plasma oscillation propagation along
the magnetic field. The work continues previous inves-
tigations [6-8] on the multi-component gas-metal plas-
ma formed in the pulsed high-current reflex discharge.
The gas-metal plasma has been formed by the discharge
in the medium of firing gas Ar (P ≈ 0,133…1,33 Pa)
and sputtered cathode material (Ti). The maximum
plasma density was Np ≥ 1·1014 cm-3. The discharge vol-
tage and the current were Udis. ≤ 4 kV and Idis. ~ 1,8 kA,
respectively. The pulsed magnetic field of 18 ms dura-
tion had a mirror configuration with a limiting induction
value B0 ≤ 0,34 T in the installation center.
The voltage onto the discharge gap was applied after
magnetic field induction with delay of 2 ms. Plasma
oscillation propagation along the magnetic field was
studied using the microwave fluctuation spectrometry.
Plasma location was carried out with an O-wave having
a wave length of λ = 8 mm.
The angular rotation rate of plasma layers with equal
critical density Ncr. ≥ 1.7·1013 cm-3, distributed along the
magnetic field (see Fig. 1), was determined using the
autocorrelation function (ACF) of reflected microwave
signals which can be calculated by formula [9]:
∑
−
=
+=
1
0
)()(1)(
N
t
kkxx txtx
N
C ττ , (1)
where Сxx(τk) – is the ACF of signal, N – is the number
of points in the signal realization, τk – is the phase shift.
We determine the ACF period and then find the angular
rotation velocity that for the case of a circular symmetry
is obtained from the relation:
Tπωϕ 2= , (2)
where ωφ is the plasma rotation angular velocity, T is
the ACF period.
Comparison of ACF periods of reflected microwave
signal distributed along the magnetic field have shown that
the ACF periods are similar (see Fig. 2,a), i.e. the angular
rotation velocities have close values (see Fig. 2,b).
212 ISSN 1562-6016. ВАНТ. 2012. №6(82)
Fig. 1.Schematic representation of the experimental
assembly and diagnostic facilities. 1 – vacuum chamber
(anode), 2, 9 – cathodes, 3, 8 – detectors, 4, 7 – horn
antennas of microwave reflectometers, 5 – solenoid
magnet, 6 – microwave oscillator
This relationship is in accordance with the isorota-
tion law [1] or with the Ferraro theorem [10], the angu-
lar velocity is constant along the magnetic field lines
ω=ω0=const.
Fig. 2. ACF period (a) and angular velocity of plasma
layers distributed along the magnetic field as a function
of time (for signals received by antennas 4 (○) and 7 (×)
see Fig. 1). P ≈ 0,93 Pa, Udis. = 3,8 kV
Using the phase shift of reflected signals we deter-
mined the radial size of reflected layers and, respec-
tively, calculated the rotation velocity (vφ = ωφr) which
was not higher than vφ ≤ 1·106 cm/s, that is in accor-
dance with results obtained in [7,8].
To determine the time of plasma oscillation propa-
gation along the magnetic field used were cross-
correlation functions calculated in [9] by formula:
∑
−
=
+=
1
0
)()(1)(
N
t
kkxy tytx
N
C ττ , (3)
where Сxy(τk) is the cross-correlation function (CCF)
between the signals x(t) and y(t), N is the number of
points I the realization of signals x(t) and y(t), τk is the
delay time between two signals. Analysis of CCF for
reflected signals has shown that the CCF shift τ practi-
cally decreases with time, and, consequently, the CCF
shift dependence τ differs from the ACF period depend-
ence on time (see Fig. 2,a). It means that the CCF pro-
vides data on the plasma oscillations propagating along
the magnetic field. To be sure that on both the reflecto-
meters the same fluctuations are observed, we have in-
vestigated the coherence function of signals from the
reflectometers which is determined as [9]:
( )
( ) ( ) 1)(
2
2 ≤=
fGfG
fG
f
yx
xy
xyγ , (4)
where Gxy(f) is the function of cross-spectral density of
two signals, Gx(f) and Gy(f) are the functions of spectral
density of signals x(t)and y(t) respectively. A high de-
gree of oscillation coherence (see Fig. 3) recorded at
both the reflectometers evidences that the same oscilla-
tions are moving along the magnetic field.
Fig. 3. Coherence function of reflected microwave sig-
nals
If the CCF phase shift τ and the distance l between
the horns of microwave reflectometers are known it is
possible to determine the plasma fluctuation propaga-
tion velocity as:
τlV = , (5)
The calculation results based on experimental data ob-
tained by formula 5 are given in Fig. 4 for l ≈ 64,5 cm.
As is seen from Fig.4 the plasma fluctuation propaga-
tion velocity is slightly increasing with time. The expla-
nation may be the following: Under conditions of this
experiment the plasma layer density Ncr. ≈ 1.7·1013 cm-3
is constant in time and the magnetic field increases by
∆B = ± 7%, as compared with the average value. Con-
sequently, the plasma fluctuation propagation velocity
can be dependent on the magnetic field value.
Fig. 4. Velocity of oscillation propagation along the
magnetic field, points –experiment, solid line – calcula-
tion by formula 6, dashed line – calculation by formula
(7). (P ≈ 0,93 Pa , Udis. = 3,8 kV)
The wave velocity in the plasma can be determined
from the dispersion equation. We evaluate the ion sound
ISSN 1562-6016. ВАНТ. 2012. №6(82) 213
velocity VS and the Alfven velocity VA as a first ap-
proximation. The ion sound velocity is equal to VS =
(kTe/mi)1/2. Taking kTe ~ 10 eV and mi = Ar ion mass we
obtain VS ≈ 5·105 cm/s, that is by two order of magni-
tude less than the measured one. The Alfven velocity is
determined from the relation of [11]:
ρμ0
BVA = , (6)
where μ0 is the magnetic constant, ρ is the plasma den-
sity. For the multicomponent plasma the Alfven velocity
can be found as in [12].
( )22110
, NmNm
BV multA +
=
μ
, (7)
where m1 and m2 are the masses of ions ( sort 1 and sort
2), N1 and N2 are their concentrations. The results of
Alfven velocity evaluation by formulas 6 and 7 for ρ =
1.137·10-9 g/cm3 (100% Ar) and N1 = N2 = 8.5·1012 cm-3
(50% Ar, 50% Ti) are given in Fig. 4. As is seen, the
measured velocity value is close to the Alfven velocity
V ~ VA ~ 107 cm/s.
CONCLUSIONS
The presented paper reports about the initial stage of
investigations on the oscillations of multicomponent
gas-metal plasma in the pulsed reflex discharge.
The summary of investigation results is the follow-
ing:
1. Comparison of the autocorrelation functions of re-
flected microwave signals, distributed along the mag-
netic field, has shown that the periods of these functions
are similar, i.e. the angular rotation velocities are close
and such a relationship is in accordance with the isoro-
tation law or with the Ferraro theorem.
2. Investigation of the cross-correlation functions of
reflected microwave signals distributed along the mag-
netic field permitted to determine the time of plasma
oscillation propagation along the magnetic field and to
calculate the propagation velocity that is close to the
Alfven velocity V ~ VA.
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4. Y. Tanaka, K. Yamamoto // Japanes J. Appl. Phys.
1967, v. 6, № 4, p. 520-554.
5. A.P. Williams, L.A. Dushin, I.K. Nicholas et
al.//High-frequency properties of the plasma. 1968, Is-
sue 3, р. 39-46.
6. Yu.V. Kovtun, A.I. Skibenko, E.I. Skibenko, et al. //
Plasma Phys. Reports. 2010, v.36, №12, p. 1065-1071.
7. Yu.V. Kovtun, A.I. Skibenko, E.I. Skibenko, et al. //
Ukr. J. Phys. 2010, v.55, №12, p. 1269-1277.
8. Yu.V. Kovtun, A.I. Skibenko, E.I. Skibenko, et al. //
Problems of Atomic Science and Technology. Series
«Plasma Physics». 2010, Issue 16, № 6(70), p. 153-
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9. J.S. Bendat, A.G. Piersol. Engineering applications
of correlation and spectral analysis. John Wiley &
Sons. 1980, 315 p.
10. V.C.A. Ferraro // Mon. Not. Roy. Astr. Soc. 1937,
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11. H. Alfven // Nature. 1942, v. 150, № 3805, p. 405-
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Article received 07.09.12
РАСПРОСТРАНЕНИЕ КОЛЕБАНИЙ МНОГОКОМПОНЕНТНОЙ ПЛАЗМЫ ВДОЛЬ
МАГНИТНОГО ПОЛЯ В ИМПУЛЬСНОМ ОТРАЖАТЕЛЬНОМ РАЗРЯДЕ
Ю.В. Ковтун, А.И. Скибенко, Е.И. Скибенко, И.Б. Пинос, Ю.В. Ларин, В.Б. Юферов
Проведены измерения угловой скорости вращения плазменных слоев одинаковой плотности вдоль маг-
нитного поля, значения которой оказались в различных точках близкими друг к другу, что согласуется с
законом изоротации. Установлено, что в плазме вдоль магнитного поля распространяются колебания со
скоростью, близкой по величине к aльфвеновской скорости V ~ VA.
РОЗПОВСЮДЖЕННЯ КОЛИВАНЬ БАГАТОКОМПОНЕНТНОЇ ПЛАЗМИ УЗДОВЖ МАГНІТНОГО
ПОЛЯ В ІМПУЛЬСНОМУ ВІДБИВНОМУ РОЗРЯДІ
Ю.В. Ковтун, А.І. Скибенко, Є.І. Скібенко, І.Б. Пінос, Ю.В. Ларін, В.Б. Юферов
Проведено вимірювання кутової швидкості обертання плазмових шарів однакової густини уздовж магні-
тного поля, значення якої в різних точках виявилися близькими одне до одного, що узгоджується із законом
ізоротації. Встановлено, що в плазмі уздовж магнітного поля розповсюджуються коливання із швидкістю,
близькою по величині до альфвеновської швидкості V ~ VA.
|