Investigation of space dependence of plasma parameters in multislit electromagnetic trap “Jupiter 2M”
The experimental researchs of a transitive layer structure in the multislit electromagnetic trap “Jupiter 2M” are offered in the article. The dependencies of average plasma density on a magnetic field, energy and current of injected electrons, the spatial distributions of plasma density and volumetr...
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nasplib_isofts_kiev_ua-123456789-1103362025-02-23T17:10:53Z Investigation of space dependence of plasma parameters in multislit electromagnetic trap “Jupiter 2M” Дослідження просторових розподіленнь параметрів плазми в багатощілинній електромагнітній пастці “Юпітер 2М” Исследование пространственных распределений параметров плазмы в многощелевой электромагнитной ловушке «Юпитер 2М» Lavrent’ev, O.A. Maslov, V.A. Nozdrachev, M.G. Oboznyi, V.P. Skibenko, A.I. Fomin, I.P. Magnetic confinement The experimental researchs of a transitive layer structure in the multislit electromagnetic trap “Jupiter 2M” are offered in the article. The dependencies of average plasma density on a magnetic field, energy and current of injected electrons, the spatial distributions of plasma density and volumetric charge potential are measured. The border of superseded magnetic field is determined. В роботі представлені експериментальні дослідження структури перехідного шару в багатощілинній електромагнітній пастці “Юпітер 2М”. Виміряні залежності середньої густини плазми від напруженості магнітного поля, енергії та струму інжектованих електронів, радіальні профілі густини плазми і потенціалу об’ємного заряду, визначена межа витісненого магнітного поля. В работе представлены экспериментальные исследования структуры переходного слоя в многощелевой электромагнитной ловушке «Юпитер 2М». Измерены зависимости средней плотности плазмы от напряженности магнитного поля, энергии и тока инжектированных электронов, радиальные профили плотности плазмы и потенциала объемного заряда, определена граница вытесненного магнитного поля. 2003 Article Investigation of space dependence of plasma parameters in multislit electromagnetic trap “Jupiter 2M” / O.A. Lavrent’ev, V.A. Maslov, M.G. Nozdrachev, V.P. Oboznyi, A.I.Skibenko, I.P. Fomin // Вопросы атомной науки и техники. — 2003. — № 1. — С. 27-29. — Бібліогр.: 3 назв. — англ. 1562-6016 PACS: 52.55.-s https://nasplib.isofts.kiev.ua/handle/123456789/110336 en Вопросы атомной науки и техники application/pdf Національний науковий центр «Харківський фізико-технічний інститут» НАН України |
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Magnetic confinement Magnetic confinement |
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Magnetic confinement Magnetic confinement Lavrent’ev, O.A. Maslov, V.A. Nozdrachev, M.G. Oboznyi, V.P. Skibenko, A.I. Fomin, I.P. Investigation of space dependence of plasma parameters in multislit electromagnetic trap “Jupiter 2M” Вопросы атомной науки и техники |
| description |
The experimental researchs of a transitive layer structure in the multislit electromagnetic trap “Jupiter 2M” are offered in the article. The dependencies of average plasma density on a magnetic field, energy and current of injected electrons, the spatial distributions of plasma density and volumetric charge potential are measured. The border of superseded magnetic field is determined. |
| format |
Article |
| author |
Lavrent’ev, O.A. Maslov, V.A. Nozdrachev, M.G. Oboznyi, V.P. Skibenko, A.I. Fomin, I.P. |
| author_facet |
Lavrent’ev, O.A. Maslov, V.A. Nozdrachev, M.G. Oboznyi, V.P. Skibenko, A.I. Fomin, I.P. |
| author_sort |
Lavrent’ev, O.A. |
| title |
Investigation of space dependence of plasma parameters in multislit electromagnetic trap “Jupiter 2M” |
| title_short |
Investigation of space dependence of plasma parameters in multislit electromagnetic trap “Jupiter 2M” |
| title_full |
Investigation of space dependence of plasma parameters in multislit electromagnetic trap “Jupiter 2M” |
| title_fullStr |
Investigation of space dependence of plasma parameters in multislit electromagnetic trap “Jupiter 2M” |
| title_full_unstemmed |
Investigation of space dependence of plasma parameters in multislit electromagnetic trap “Jupiter 2M” |
| title_sort |
investigation of space dependence of plasma parameters in multislit electromagnetic trap “jupiter 2m” |
| publisher |
Національний науковий центр «Харківський фізико-технічний інститут» НАН України |
| publishDate |
2003 |
| topic_facet |
Magnetic confinement |
| url |
https://nasplib.isofts.kiev.ua/handle/123456789/110336 |
| citation_txt |
Investigation of space dependence of plasma parameters in multislit electromagnetic trap “Jupiter 2M” / O.A. Lavrent’ev, V.A. Maslov, M.G. Nozdrachev, V.P. Oboznyi, A.I.Skibenko, I.P. Fomin // Вопросы атомной науки и техники. — 2003. — № 1. — С. 27-29. — Бібліогр.: 3 назв. — англ. |
| series |
Вопросы атомной науки и техники |
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2025-11-24T02:18:20Z |
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| fulltext |
INVESTIGATION OF SPACE DEPENDENCE OF PLASMA
PARAMETERS IN MULTISLIT ELECTROMAGNETIC TRAP “JUPITER
2M”*
O.A.Lavrent’ev, V.A.Maslov, M.G.Nozdrachev, V.P.Oboznyi, A. I.Skibenko, I. P. Fomin
Institute of Plasma Physics, National Scientific Center “Kharkiv Institute of Physics and
Technology”, Kharkiv, Ukraine, <lavr@ipp.kharkov.ua>, tel (0572) 35 64 38
The experimental researchs of a transitive layer structure in the multislit electromagnetic trap “Jupiter 2M” are
offered in the article. The dependencies of average plasma density on a magnetic field, energy and current of injected
electrons, the spatial distributions of plasma density and volumetric charge potential are measured. The border of
superseded magnetic field is determined.
PACS: 52.55.-s
In electromagnetic traps shell character of plasma
confinement is realized. In these traps electrons are confined
by a sharp-angle geometry magnetic field and external
electrical field, and ions – by electrical field of a volumetric
electrons charge. The spatial distribution of magnetic field
intensity is characterized by a deep magnetic well - magnetic
field at the center of a trap is equal to zero and abruptly grows
to periphery. In the central part of a trap, where the magnetic
and electric fields are absent, the plasma is in powerless and
thermally equilibrium condition. Such system of the combined
plasma confinement by electrical and magnetic fields has
unique properties allowing tostruggle successfully with
plasma instability of a various type [1]. Between this area and
boundary magnetic surface is transitive (diffusion) layer,
where plasma cooperates with magnetic and electrical fields.
The structure of plasma transitive layer - magnetic field plays
a determining role during plasma accumulation, heating and
confinement. Coefficient of electrons cross diffusion depends
on transitive layer structure. With increase of density and
temperature plasma supersedes a vacuum magnetic field,
condensing diffusion layer and increasing a magnetic field in
it, that results in reduction of electrons diffusion losses. The
structure of an electrical field determines a share of energy,
which ions receive during their acceleration by field of a
volumetric electron charge.
In this work dependencies of plasma density and spatial
distributions of plasma density and potential of a volumetric
electrons charge on magnetic field intensity, injected electrons
current and energy are measured for research of transitive
layer structure.
Plasma density with application of corpuscular and
microwave methods was measured.
Corpuscular method is based on pass of hydrogen neutral
atoms beam perpendicularly to force lines of a magnetic field
confining plasma on a diagonal of installation. Length of
nuclear beam run in plasma is l = 68 cm, and 90 % from it
atoms pass through the central area, where the electrical and
magnetic fields are absent and plasma density is maximal in
the center of a trap. It allows not to take into account spatial
distribution of density, as the mistake at definition n and nmax
does not exceed 5 %. After passage through plasma beam of
atoms is registered with the help of photomultiplier tub, fig. 1.
Density of plasma in a trap is determined by expression:
ni = - { n0σ01l + ln(N/N0)}/ σ10l. (1)
*The research described in this publication was made possible in
part by Grant #1341 from STCU
Fig. 1
At constant neutral gas concentration in installation first
component does not influence on results of measurements –
the unequivocal connection between easing of neutral atoms
beam and product nl turns out. In a case, when neutral gas
concentration is changed during a pulse of injection, the only
value (n0σ01 + niσ10) is unequivocally determined and the
additional information is necessary for definition of plasma
concentration. In the previous experiments [2] it was
established, that during a pulse of injection the increasing of
neutral gas density in a trap takes place. It connected with it
knockout from surfaces, limiting area of plasma accumulation
and located near the area of plasma accumulation,
(diaphragms, magnetic and electrostatic systems), by charged
particles and radiation from plasma. Oscillograms of injection
current and neutral gas density change during a pulse of
injection are given in fig. 2. In fig. 3 the temporary
dependence of plasma density in a trap calculated from
oscillograms of easing of hydrogen fast atoms beam ( fig. 1) in
view of neutral gas density changes during plasma
accumulation is submitted.
Measurement of average plasma density by a microwave
interferometer is based on change of wave phase, passed
through plasma and caused by change of dielectric
environment constant, unequivocally connected with change
of plasma concentration. Interferometer assembled on the
circuit offered by Wharton was applied [3]. Probing of plasma
by a microwave radiation with wave length λ = 8 mm on
installation "Jupiter 2М" was carried out in a radial direction
Problems of Atomic Science and Technology. 2003. № 1. Series: Plasma Physics (9). P. 27-29 27
mailto:lavr@ipp.kharkov.ua
ander one of thr central magnetic coils. The cross size of
plasma in section of probing is L = 22 cm. The frequency of
klystron generator was changed by submission of a managing
sawtooth voltage with duration 250µs. Oscillogram of linear
plasma density change <nl> from time offered on fig. 4.
Fig. 2
Fig. 3
Fig. 4
The shift of a phase caused by change of dielectric
permeability in the measuring channel, is connected with
plasma concentration by following ratio:
Δφ = 2π{1 - (1 - n/nкр )1/2 }l/λ (2)
At n/nкр < < 1, that is carried out in conditions of our
experiments, we shall receive
nl = 2.8 *1013 Δ φ/2π cm-2 (3)
This ratio allows to determine value <nl> average on section.
The spatial distributions of plasma density measured by a
single Langmuir probe were used for definition of plasma
density in the central part of a trap. Average value l for
oscillogram on fig. 4, calculated from radial density
distribution is 14 cm and plasma density in the central part of a
trap at the end of an injection pulse thus is equal 1.45*1012 сm-
3. It is visible from fig. 3 and 4, that the temporary
dependences of plasma density measured by methods of
corpuscular and microwave diagnostics are similar and in
absolute values differ no more, than on 50 %.
The dependences of plasma density at the center of a trap
from value of magnetic field intensity in a ring magnetic slit at
different energy of injected electrons are given in fig. 5. From
these dependences it is visible, that plasma density at the
center of a trap grows with increase of magnetic field intensity
and energy of injected electrons. Plasma density grows with
increase of injected electrons current too.
Fig. 5
Fig. 6
The spatial distributions of plasma density are measured at
various values of magnetic field intensity (see fig. 6). The
distributions of plasma density were determined by ions
current of saturation of a single Langmuir probe. Plasma
density in the central part of a trap was normalized by results
of density measurements by a microwave interferometer or by
easing a hydrogen atoms beam. It is visible from figure, that
the spatial distribution of density has a plateau in the field of a
weak magnetic field, so in the central part of a trap plasma
core is formed with constant density with a diameter ~10 сm
and length ~ 80 cm. With increase of magnetic field intensity
the structure of density is deformed inside and the core sizes
are decreased. With growth of a current and energy of
injection the core sizes are increased.
28
Plasma potential was measured by a single Langmuir
probe in a floating mode, fig 7. It is visible from figure that the
electrical field is concentrated in a narrow transitive layer, and
at the center of a trap the electrical field is absent. The value of
plasma potential is increased with growth of magnetic field
intensity and plasma parameters, but the structure of potential
thus practically does not change.
Fig. 7
Fig. 8
In fig. 8 the radial distributions of magnetic field intensity
under the coil in the central part of a trap for various values of
magnetic field intensity in a ring magnetic slit are offered. The
magnetic field intensity in section between coils on an axis is
equal to zero. It is visible, that magnetic field intensity at the
center of a trap approximately a hundred times is less than
magnetic field intensity in a ring magnetic slit and in 5 times less
than intensity of a field on a boundary force line and is less than
100 Gs.
It is known, that plasma supersedes a magnetic field from
occupied volume, if its pressure exceeds pressure of a magnetic
field. The border of the superseded magnetic field can be
determined from the equation:
nk(Tе + Tі) = H2 /8π (4)
In conditions of the described experiments plasma with
parameters nе = nі = (0.2 - 2)*1012 cm-3, Tе = 15 еV, Tі = 30
eV is received. For such parameters the area of the superseded
magnetic field is limited by magnetic force lines with
magnetic field intensity H = (20 - 70) Gs. Such value of
magnetic field intensity in conditions of our experiments is
achieved in the central area of a trap by a diameter ~ 10 cm
and length ~ 80 cm. The changes of the sizes of constant
plasma density area depending on a magnetic field, current
and energy of injection, observable on spatial distributions, are
caused by magnetic field replacement from the central area of
a trap. Increase of a diameter of this area with constant plasma
density with growth of a current and energy of injection is
caused by increase of plasma pressure, and compression at
increase of magnetic field intensity, fig. 6, - by growth of
magnetic pressure.
In the field of the superseded magnetic field plasma is in
powerless and thermally equilibrium condition. The peripheral
part of plasma volume between area of the superseded
magnetic field and boundary magnetic surface represents a
transitive layer or a diffusion zone. As it is visible from the
submitted figures, the gradients of plasma density, magnetic
field intensity, electrical field is concentrated in this layer. In
this layer plasma cooperates with a confining magnetic and
electrical field, which character plays a determining role
during plasma accumulation, heating and confinement in an
electromagnetic trap.
REFERENCES
1.S.A. Vdovin, O.A. Lavrent’ev, V.A. Maslov,
M.G.Nozdrachov, V.P. Oboznyj, N.N. Sappa Plasma
storage in the multislit electromagnetic trap “Jupiter
2M”// Voprosy Atomnoj Nauki i tekhniki, Ser:
Termoyadernyj Sintez, Moscow N3, 1988, p. 40-45.
2.O.A.Lavrent’ev, V.A. Maslov, S.V. Germanova, M.G.
Nozdrachev, V.P. Oboznyi, Neutral gas influence on
plasma heating and confinement in the multislit
electromagnetic trap “Jupiter 2M”// Problems of Atomic
Science and Technology, Ser: Plasma Physics (5),
2000, №.3, p. 48-50.
3.M. A. Heald, C. B. Wharton// Plasma Diagnostic with
Microwaves. New York, 1965.
ДОСЛІДЖЕННЯ ПРОСТОРОВИХ РОЗПОДІЛЕННЬ ПАРАМЕТРІВ ПЛАЗМИ В БАГАТОЩІЛИННІЙ
ЕЛЕКТРОМАГНІТНІЙ ПАСТЦІ “ЮПІТЕР 2М”
О. О. Лаврентьєв, В. О. Маслов, М. Г. Ноздрачов, В. П. Обозний, А. І. Скібенко, І. П. Фомін
В роботі представлені експериментальні дослідження структури перехідного шару в багатощілинній
електромагнітній пастці “Юпітер 2М”. Виміряні залежності середньої густини плазми від напруженості
магнітного поля, енергії та струму інжектованих електронів, радіальні профілі густини плазми і потенціалу
об’ємного заряду, визначена межа витісненого магнітного поля.
ИССЛЕДОВАНИЕ ПРОСТРАНСТВЕННЫХ РАСПРЕДЕЛЕНИЙ ПАРАМЕТРОВ ПЛАЗМЫ В
МНОГОЩЕЛЕВОЙ ЭЛЕКТРОМАГНИТНОЙ ЛОВУШКЕ «ЮПИТЕР 2М»
О. А. Лаврентьев, В. А. Маслов, М. Г. Ноздрачев, В. П. Обозный, А. И. Скибенко, И. П. Фомин
В работе представлены экспериментальные исследования структуры переходного слоя в многощелевой
электромагнитной ловушке «Юпитер 2М». Измерены зависимости средней плотности плазмы от
29
напряженности магнитного поля, энергии и тока инжектированных электронов, радиальные профили плотности
плазмы и потенциала объемного заряда, определена граница вытесненного магнитного поля.
30
Fig. 1
Fig. 2
Fig. 8
References
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