Behavior features of the ungrounded antenna potential shift in Uragan-2M torsatron
The potential shift appears at frame antenna during plasma creation in Uragan 2M torsatron. This paper provides experimental study of that potential dynamics (Ump). The measurements showed that Ump value can be both positive and negative. The dependency of Ump from RF generator feeding voltage and w...
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| Zitieren: | Behavior features of the ungrounded antenna potential shift in Uragan-2M torsatron / V.B. Korovin, I.K. Tarasov, A.V. Lozin, M.M. Kozulia, E.L. Sorokovoy, E.D. Kramskoy, V.Yu. Gribanov, D.I. Baron, S.A. Tsybenko // Problems of Atomic Science and Technology. — 2023. — № 1. — С. 9-12. — Бібліогр.: 13 назв. — англ. |
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Korovin, V.B. Tarasov, I.K. Lozin, A.V. Kozulia, M.M. Sorokovoy, E.L. Kramskoy, E.D. Gribanov, V.Yu. Baron, D.I. Tsybenko, S.A. 2023-12-08T14:44:56Z 2023-12-08T14:44:56Z 2023 Behavior features of the ungrounded antenna potential shift in Uragan-2M torsatron / V.B. Korovin, I.K. Tarasov, A.V. Lozin, M.M. Kozulia, E.L. Sorokovoy, E.D. Kramskoy, V.Yu. Gribanov, D.I. Baron, S.A. Tsybenko // Problems of Atomic Science and Technology. — 2023. — № 1. — С. 9-12. — Бібліогр.: 13 назв. — англ. 1562-6016 PACS: 52.50.Qt, 84.30.Ng, 84.40.Ba, 88.80.hp DOI: https://doi.org/10.46813/2023-143-009 https://nasplib.isofts.kiev.ua/handle/123456789/195960 The potential shift appears at frame antenna during plasma creation in Uragan 2M torsatron. This paper provides experimental study of that potential dynamics (Ump). The measurements showed that Ump value can be both positive and negative. The dependency of Ump from RF generator feeding voltage and working gas pressure is given. The cause of positive Ump value is identified. При створенні плазми в торсатроні Ураган 2М рамкова антена набуває постійного потенціалу. Наводиться експериментальне дослідження динаміки цього потенціалу Ump. Вимірювання показали, що величина Ump має як позитивну складову, так і негативну. Наведено залежність потенціалу Ump від напруги живлення ВЧ генератора та від тиску робочого газу. З’ясовується причина наявності позитивної складової. Authors would like to thank V.V. Filippov for the idea of putting filtering resonance circuit at RF generator lead-out. Such connection allowed to determine the source of positive potential shift in antenna middle point and showed the possibility for its elimination. Authors also would like to extend their thanks to Yu.V. Kovtun for discussion of results and critics. en Національний науковий центр «Харківський фізико-технічний інститут» НАН України Problems of Atomic Science and Technology Magnetic confinement Behavior features of the ungrounded antenna potential shift in Uragan-2M torsatron Особливості поведінки постійного потенціалу незаземленої антени в торсатроні Ураган 2М Article published earlier |
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Digital Library of Periodicals of National Academy of Sciences of Ukraine |
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DSpace DC |
| title |
Behavior features of the ungrounded antenna potential shift in Uragan-2M torsatron |
| spellingShingle |
Behavior features of the ungrounded antenna potential shift in Uragan-2M torsatron Korovin, V.B. Tarasov, I.K. Lozin, A.V. Kozulia, M.M. Sorokovoy, E.L. Kramskoy, E.D. Gribanov, V.Yu. Baron, D.I. Tsybenko, S.A. Magnetic confinement |
| title_short |
Behavior features of the ungrounded antenna potential shift in Uragan-2M torsatron |
| title_full |
Behavior features of the ungrounded antenna potential shift in Uragan-2M torsatron |
| title_fullStr |
Behavior features of the ungrounded antenna potential shift in Uragan-2M torsatron |
| title_full_unstemmed |
Behavior features of the ungrounded antenna potential shift in Uragan-2M torsatron |
| title_sort |
behavior features of the ungrounded antenna potential shift in uragan-2m torsatron |
| author |
Korovin, V.B. Tarasov, I.K. Lozin, A.V. Kozulia, M.M. Sorokovoy, E.L. Kramskoy, E.D. Gribanov, V.Yu. Baron, D.I. Tsybenko, S.A. |
| author_facet |
Korovin, V.B. Tarasov, I.K. Lozin, A.V. Kozulia, M.M. Sorokovoy, E.L. Kramskoy, E.D. Gribanov, V.Yu. Baron, D.I. Tsybenko, S.A. |
| topic |
Magnetic confinement |
| topic_facet |
Magnetic confinement |
| publishDate |
2023 |
| language |
English |
| container_title |
Problems of Atomic Science and Technology |
| publisher |
Національний науковий центр «Харківський фізико-технічний інститут» НАН України |
| format |
Article |
| title_alt |
Особливості поведінки постійного потенціалу незаземленої антени в торсатроні Ураган 2М |
| description |
The potential shift appears at frame antenna during plasma creation in Uragan 2M torsatron. This paper provides experimental study of that potential dynamics (Ump). The measurements showed that Ump value can be both positive and negative. The dependency of Ump from RF generator feeding voltage and working gas pressure is given. The cause of positive Ump value is identified.
При створенні плазми в торсатроні Ураган 2М рамкова антена набуває постійного потенціалу. Наводиться експериментальне дослідження динаміки цього потенціалу Ump. Вимірювання показали, що величина Ump має як позитивну складову, так і негативну. Наведено залежність потенціалу Ump від напруги живлення ВЧ генератора та від тиску робочого газу. З’ясовується причина наявності позитивної складової.
|
| issn |
1562-6016 |
| url |
https://nasplib.isofts.kiev.ua/handle/123456789/195960 |
| citation_txt |
Behavior features of the ungrounded antenna potential shift in Uragan-2M torsatron / V.B. Korovin, I.K. Tarasov, A.V. Lozin, M.M. Kozulia, E.L. Sorokovoy, E.D. Kramskoy, V.Yu. Gribanov, D.I. Baron, S.A. Tsybenko // Problems of Atomic Science and Technology. — 2023. — № 1. — С. 9-12. — Бібліогр.: 13 назв. — англ. |
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ISSN 1562-6016. Problems of Atomic Science and Technology. 2023. №1(143).
Series: Plasma Physics (29), p. 9-12. 9
https://doi.org/10.46813/2023-143-009
BEHAVIOR FEATURES OF THE UNGROUNDED ANTENNA
POTENTIAL SHIFT IN URAGAN-2M TORSATRON
V.B. Korovin, I.K. Tarasov, A.V. Lozin, M.M. Kozulia, E.L. Sorokovoy, E.D. Kramskoy,
V.Yu. Gribanov, D.I. Baron, S.A. Tsybenko
Institute of Plasma Physics, National Science Center
“Kharkov Institute of Physics and Technology”, Kharkiv, Ukraine
E-mail: korovin@kipt.kharkov.ua
The potential shift appears at frame antenna during plasma creation in Uragan-2M torsatron. This paper provides
experimental study of that potential dynamics (Ump). The measurements showed that Ump value can be both positive
and negative. The dependency of Ump from RF generator feeding voltage and working gas pressure is given. The
cause of positive Ump value is identified.
PACS: 52.50.Qt, 84.30.Ng, 84.40.Ba, 88.80.hp
INTRODUCTION
RF method is used for plasma creation and heating
in stellarator-type fusion device Uragan-2M (U-2M)
torsatron.
The research to reduce breakdown delay or RF
generator idle time with was carried out at U-2M
torsatron. The gas breakdown was thought to be
accompanied with runaway electrons (RE) that appear
at U-2M magnetic fields slopes. It will be shown further
that the positive potential of frame antenna Ump was
several kilovolts depending on anode voltage and the
negative potential didn’t exceed 1 kV. In works [1-3] it
was shown that when a constant potential of any
polarity higher than 50...100 V is applied to a frame
antenna the flow of runaway electrons (RE) is
suppressed. RE flow is generated at the fronts of a
magnetic field pulse. The suppressed RE don’t
participate in the gas breakdown. The mentioned works
also showed that the RE suppression increases the gas
breakdown delay. Thus, the main aim of this work is to
study the dynamics of occurrence and changing of
constant potential on antenna. It is planned to identify
the possibility of the influence of such a potential on the
RE, as well as to search for the possibility of reducing
the positive burst of the potential on the antenna to
reduce the breakdown time of the working gas.
1. EXPERIMENTAL SETUP
AND DIAGNOSTIC METHODS
The RF generators Kaskad-1 and Kaskad-2 served as
electromagnetic field RF sources for plasma creation.
Both generators have push-pull scheme [4]. Active
elements (electron lamps) have same parameters if such
scheme is totally symmetric. Control grids voltages are
the same. Nevertheless, their phases are opposite then
equal voltage values with opposite phases appear at
lamp anodes of both generator shoulders. There is a
point on the induction coil Lк of the antenna oscillatory
circuit without voltage difference relatively to the lamp
cathodes in such case. Kaskad generators [5] implement
common (grounded) cathode scheme. So the middle
point of generator load is equipotential with the
common outlet of such device. The middle point of
antenna inside the torsatron chamber and the
autotransformer middle point are such points (Fig. 1).
As far as antenna doesn’t have a lead-out from its
middle point, and matching autotransformer is situated
outside of the vacuum chamber, the autotransformer
middle point is very convenient for high-voltage divider
connection and measurements. The frame antenna
(Fig. 2) is usually used for pre-ionization i.e. it creates
cold low density plasma during standard U-2M regime.
The relatively small power of 50 kW is enough to create
such starting plasma (and pre-ionization regime) [6].
The frame antenna is not connected with the device
chamber, it has bipolar feeder, and so it is convenient
for push-pull RF generator Kaskad connection.
Fig. 1. RF antenna connection scheme
The frame antenna potential shift Ump was measured
at antenna matching device middle point in order to
study the shift dynamics.
Fig. 2. The frame antenna inside U-2M chamber
10 ISSN 1562-6016. Problems of Atomic Science and Technology. 2023. №1(143)
The frame antenna potential shift Ump was measured
at antenna matching device middle point in order to
study the shift dynamics.
The voltage was measured with capacitance and
resistive high-voltage dividers at the antenna lead-outs
and the matching device middle point. The input
impedance of the resistive dividers was in the range of
15...20 kΩ. The plasma startup and the change of
plasma parameters were controlled with optical method
by means of H𝛼 optical line timeline (656.2 nm). All
optical measurements were made along vacuum
chamber central chord.
2. EXPERIMENTAL RESULTS
The potential shift of the Ump point was both
negative and positive during plasma creation with RF
generator.
Fig. 3 shows that RF voltage of antenna changed
corresponding to potential shift in the middle point. This
points at connection of both parameters and confirms
assumption about negative antenna potential shift
caused by plasma interaction.
The RF generator operation with ballast resistance
was aimed to find out the cause of Ump behavior. The
Ump was measured with resistive dividers. The potential
shift turned out to be absent in the middle point of
symmetrical ballast resistance. But the voltage positive
burst stayed both in the middle point and generator
output at the beginning of the RF pulse.
Fig. 3. The measurements of antenna RF voltage (a) and
the antenna middle point potential shift (b),
Нɑ emission (c). Working gas ‒ hydrogen,
Р=3.5·10
-4
Torr, magnetic field ‒ 0.01 T
The paper [7] stated that the frame antenna negative
potential shift was < 1 kV at antenna voltage of 2 kV in
Uragan-3M torsatron. The thorough out examination of
Fig. 3 oscillogram reveals that the RF generator idle
time (the maximum positive amplitude of antenna RF
voltage duration) is almost equal to the positive Ump
burst duration. The gas breakdown delay can be
decreased along with positive potential shift duration.
The positive potential shift Ump maximum was about
3 kV.
The careful examination of Fig. 3 reveals that Нɑ
emission appears at the moment of antenna RF voltage
amplitude sharp change and antenna potential shift
polarity reverse. Нɑ emission detection moment
corresponds with gas breakdown start. This means that
elimination of positive potential shift burst in the RF
pulse beginning can shorten working gas breakdown
delay.
The further Fig. 3 analysis showed that higher
antenna load matches lower negative Ump potential shift
amplitude. The antenna load is indirectly determined
from antenna RF voltage change [8]. It depends from
plasma density, distance between plasma column and
antenna and etc.
The paper [7] states that plasma potential is maximal
in the antenna proximity at the distance less than 1 cm.
The papers [9, 10] are devoted to the study of
electrostatic antenna field influence on periphery plasma
behavior. They mention edge layer in the antenna
proximity and electrons movement from that layer to the
excitation electrode or antenna in this case. The
summary of mentioned above allows to agree with other
authors opinion that potential formation on the isolated
from the device chamber antenna is caused by plasma
influence and can be realized through volume space
charges creation with low density in the antenna or
electrode proximity [11, 12].
The plasma influence on RF antenna and antenna
oscillation circuit at U-2M is described in details in [8].
Other papers containing data of Нɑ emission and
antenna RF voltage confirm this influence. For example,
paper [13] shows well Нɑ emission appearance together
with sharp decrease of RF voltage at antenna. This
moment corresponds with sharp RF generator load
increase caused by plasma influence on antenna i.e.
working gas breakdown.
Fig. 4. The dependency of antenna positive potential
shift from RF generator lamps anode voltage.
Р=6.5·10
-5
Torr, В=0.33 Т
The study of antenna positive potential shift
dynamics during RF generator triggering obtained the
dependency of the potential shift value from RF
generator anode voltage (Fig. 4) at almost similar
discharge conditions. The working gas was hydrogen at
Р=4.5·10
-5
Torr, and magnetic field В=0.01 T. The
dependency was obtained during vacuum chamber
cleaning regime with low density RF discharges.
It can be said that positive burst duration weakly
depends from generator lamps anode voltage under the
same vacuum chamber conditions. The positive burst
amplitude shows another behavior. The lowest
ISSN 1562-6016. Problems of Atomic Science and Technology. 2023. №1(143) 11
amplitude is at Ua=3 kV, and the highest one is at
Ua=5 kV. It happens because blocking capacitor charges
to the value of RF generator anode voltage.
Fig. 5. Dependence of antenna positive potential
magnitude and duration from pressure at the RF pulse
beginning. В=0.33 T
The dependence of the duration and amplitude of the
positive burst of a constant potential on the antenna
from the working gas pressure was found (Fig. 5). The
positive potential shift duration shortens with working
gas pressure increase. This can be explained with the
growth of ionization speed while pressure increases in
the device chamber.
Fig. 6. The partial scheme of RF generator Kaskad with
filter attached
The positive potential shift isn’t observed when parallel
circuit filter (Fig. 6) is connected to the RF generator
lead-out. The circuit consists from capacity Сf and
inductance Lf. The inductance is made from short-
circuited section of feeder line. Authors think that the
cause is the discharging of blocking capacitor Ср at RF
generator lead-out. The capacitor charges with the
positive voltage from generator power source.
Fig. 7. The RF voltage pulse at antenna input without
filters (a) and with them (b)
The filter modified scheme connects capacitor to the
common line of the circuit through direct current with
filter inductance Lf whose direct current resistance is
less than Ohm. So the charging current of capacitor
effectively disappears from antenna loading.
Fig. 7 shows no positive burst at RF pulse
oscillogram while filters are connected, and the one
when there is no filters.
The study of ungrounded antenna negative potential
shift dynamics is planned for the next work.
CONCLUSIONS
It has been established that frame antenna voltage
shift Ump, measured during the RF pulse at the antenna
middle point of the matching device, has both positive
and negative polarities. A positive value can reach
several kilovolts and depends on the voltage of the RF
generator power source.
It is shown that the duration of the positive constant
voltage shift on the frame antenna is the majority of the
breakdown time of the working gas. In order to reduce
this time, a solution was proposed to eliminate the
positive potential shift Ump at the beginning of the RF
pulse. To do this, it is proposed to make changes to the
electrical circuit of the RF part of the generator power
source.
In future works, it is planned to study the dynamics
of a constant negative voltage on the frame and two-
half-turn antennas in the U-2M torsatron. A two-half-
turn antenna was installed on the U-2M torsatron in
2020. Its shape is similar to W-7X ICRH antenna.
ACKNOWLEDGEMENTS
Authors would like to thank V.V. Filippov for the
idea of putting filtering resonance circuit at RF
generator lead-out. Such connection allowed to
determine the source of positive potential shift in
antenna middle point and showed the possibility for its
elimination. Authors also would like to extend their
thanks to Yu.V. Kovtun for discussion of results and
critics.
REFERENCES
1. V.E. Moiseenko, V.B. Korovin, I.K. Tarasov,
M.I. Tarasov, D.A. Sitnikov, I.E. Garkusha,
N.V. Zamanov, M.A. Lytova, R.O. Pavlichenko,
A.E. Kulaga, V.K. Pashnev. The effect of an
electrostatic field on runaway electrons in the Uragan-
3M stellarator // Technical Physics Letters. 2014, v. 40,
№ 8, p. 669-672.
2. V.E. Moiseenko, I.K. Tarasov, M.I. Tarasov,
D.A. Sitnikov, V.B. Korovin, A.D. Komarov, A.S. Ko-
zachek, L.I. Krupnik, A.I. Zhezhera, R.O. Pavlichenko,
N.V. Zamanov, A.Ye. Kulaga, A.N. Shapoval,
M.A. Lytova, S.M. Maznichenko, S.I. Solodovchenko,
A.F. Shtan. Сontrol оf the runaway electron flow in
torsatron // Problems of Atomic Science and Technology.
Series “Plasma Physics” (94). 2014, № 6, p. 266-268.
3. V.B. Korovin, I.K. Tarasov, E.D. Kramskoi,
D.A. Sitnikov, N.B. Dreval, A.V. Lozin, M.M. Kozulya.
12 ISSN 1562-6016. Problems of Atomic Science and Technology. 2023. №1(143)
Suppression of Runaway Electron Flows and Specific
Features of Working Gas Breakdown in the Uragan-2M
Torsatron // Technical Physics. 2018, v. 63, № 7, p. 960-
964.
4. M.S. Neiman. Kurs radioperedauschih ustroistv.
М.: “Sovetskoe radio”, 1957, p. 123-176 (in Russian).
5. E.D. Kramskoy, V.B. Korovin. Radio-frequency
equipment for Uragan stellarators // Problems of Atomic
Science and Technology. Series “Plasma Physics” (82).
2012, №6, p. 19-21.
6. V.E. Moiseenko, A.V. Lozin, M.M. Kozulia, et al.
Alfven plasma heating in stellarator Uragan-2M //
Ukrainian Journal of Physics. 2017, v. 62, № 4, p. 311-
317.
7. Ya.F. Leleko, L.I. Grigor’eva, V.V. Chechkin,
D.L. Grekov. Influence of the frame-type antenna on the
RF-discharge peripheral plasma parameters in the
Uragan-3M torsatron // Problems of Atomic Science and
Technology. Series “Plasma Physics” (107). 2017, № 1,
p. 40-43.
8. V.B. Korovin, V.V. Filippov, M.M. Kozulya, et al.
Effect of plasma on the radio-technical characteristics of
the Uragan-2M torsatron matching RF systems //
Problems of Atomic Science and Technology.
Series “Plasma Physics” (94). 2014, № 6, p. 41-43.
9. L.I. Grigor’eva, A.V. Pashchenko, B.I. Smerdov,
V.V. Chechkin. Investigation of the processes of plasma
potential formation and particle transfer under the
influence of an external alternating electric field.
Preprint. KIPT 84-8, M.: TsNII AtomInform, 1984.
10. L.I. Grigor’eva, B.I. Smerdov, V.V. Chechkin.
On the question of the influence of the electrostatic field
of an antenna on the behavior of peripheral plasma
during RF heating: Preprint KIPT 86-13, M.: TsNII
AtomInform, 1986.
11. V.A. Godyak, А.А. Kuzovnikov. On valve properties
of RF discharges // Fizika Plazmy. 1975, v. 1, № 3,
p. 496-503 (in Russian).
12. S.M. Levitsky. Space potential and sputtering of
electrodes in a radio-frequency discharge // Zhurnal
Tekhnicheskoi Fiziki. 1957, v. 27, № 5, p. 1001-1009 (in
Russian).
13. V.E. Moiseenko, A. Lyssoivan, T. Wauters, et al.
Radio-frequency plasma start-up at Uragan-3M
stellarator // Problems of Atomic Science and
Technology. Series “Plasma Physics” (107). 2017, № 1,
p. 54-59.
Article received 19.12.2022
ОСОБЛИВОСТІ ПОВЕДІНКИ ПОСТІЙНОГО ПОТЕНЦІАЛУ НЕЗАЗЕМЛЕНОЇ АНТЕНИ
В ТОРСАТРОНІ УРАГАН-2М
В.Б. Коровін, I.К. Тарасов, О.В. Лозін, М.М. Козуля, Е.Л. Сороковий, Є.Д. Крамський, В.Ю. Грібанов,
Д.І. Барон, С.А. Цибенко
При створенні плазми в торсатроні Ураган-2М рамкова антена набуває постійного потенціалу. Наводиться
експериментальне дослідження динаміки цього потенціалу Ump. Вимірювання показали, що величина Ump
має як позитивну складову, так і негативну. Наведено залежність потенціалу Ump від напруги живлення ВЧ-
генератора та від тиску робочого газу. З'ясовується причина наявності позитивної складової.
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