Study of poloidal structure of geodesic acoustic modes in the T-10 tokamak with heavy ion beam probing
The poloidal structure of geodesic acoustic modes (GAMs) was studied on the T-10 tokamak by heavy ion beam probing with multichannel energy analyzer. GAMs were mainly pronounced on the plasma electric potential. The poloidal phase shift between the potential oscillations was determined by the two-po...
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| Cite this: | Study of poloidal structure of geodesic acoustic modes in the T-10 tokamak with heavy ion beam probing / V.N. Zenin, L.G. Eliseev, A.S. Kozachek, L.I. Krupnik, S.E. Lysenko, A.V. Melnikov, S.V. Perfilov // Вопросы атомной науки и техники. — 2014. — № 6. — С. 269-271. — Бібліогр.: 11 назв. — англ. |
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Zenin, V.N. Eliseev, L.G. Kozachek, A.S. Krupnik, L.I. Lysenko, S.E. Melnikov, A.V. Perfilov, S.V. 2015-05-23T05:29:11Z 2015-05-23T05:29:11Z 2014 Study of poloidal structure of geodesic acoustic modes in the T-10 tokamak with heavy ion beam probing / V.N. Zenin, L.G. Eliseev, A.S. Kozachek, L.I. Krupnik, S.E. Lysenko, A.V. Melnikov, S.V. Perfilov // Вопросы атомной науки и техники. — 2014. — № 6. — С. 269-271. — Бібліогр.: 11 назв. — англ. 1562-6016 PACS: 52.35.Mw, 52.35.Ra, 52.55.Fa https://nasplib.isofts.kiev.ua/handle/123456789/81969 The poloidal structure of geodesic acoustic modes (GAMs) was studied on the T-10 tokamak by heavy ion beam probing with multichannel energy analyzer. GAMs were mainly pronounced on the plasma electric potential. The poloidal phase shift between the potential oscillations was determined by the two-point correlation technique. It was shown that GAM potential oscillations have the poloidal mode number m=0 in the core plasma. This experimental result agrees with theoretical predictions. На токамаке T-10 с помощью пучка тяжелых ионов исследована полоидальная структура геодезических акустических мод (ГАМ), которые явно видны на потенциале плазмы. Фазовый сдвиг между колебаниями потенциала определялся методом двухточечной корреляции с помощью многоканального энергетического анализатора. Показано, что ГАМ на потенциале имеют полоидальное модовое число m=0. Этот экспериментальный результат согласуется с теоретическими предсказаниями. На токамаці T-10 за допомогою пучка важких іонів досліджена полоїдальна структура геодезичних акустичних мод (ГАМ), що явно видно на потенціалі плазми. Фазове зміщення між коливаннями потенціалу визначається методом двохточечної кореляції за допомогою багатоканального енергетичного аналізатора. Показано, що ГАМ на потенціалі мають полоїдальное модове число m=0. Цей експериментальний результат узгоджується з теоретичними передбаченнями. The research is carried out by financial support of Russian Scientific Foundation project 14-22-00193. REFERENCES en Національний науковий центр «Харківський фізико-технічний інститут» НАН України Вопросы атомной науки и техники Диагностика плазмы Study of poloidal structure of geodesic acoustic modes in the T-10 tokamak with heavy ion beam probing Исследование полоидальной структуры геодезических акустических мод в токамаке Т-10 с помощью пучка тяжелых ионов Дослідження полоїдальної структури геодезичних акустичних мод у токамаці Т-10 за допомогою пучка важких іонів 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 |
Study of poloidal structure of geodesic acoustic modes in the T-10 tokamak with heavy ion beam probing |
| spellingShingle |
Study of poloidal structure of geodesic acoustic modes in the T-10 tokamak with heavy ion beam probing Zenin, V.N. Eliseev, L.G. Kozachek, A.S. Krupnik, L.I. Lysenko, S.E. Melnikov, A.V. Perfilov, S.V. Диагностика плазмы |
| title_short |
Study of poloidal structure of geodesic acoustic modes in the T-10 tokamak with heavy ion beam probing |
| title_full |
Study of poloidal structure of geodesic acoustic modes in the T-10 tokamak with heavy ion beam probing |
| title_fullStr |
Study of poloidal structure of geodesic acoustic modes in the T-10 tokamak with heavy ion beam probing |
| title_full_unstemmed |
Study of poloidal structure of geodesic acoustic modes in the T-10 tokamak with heavy ion beam probing |
| title_sort |
study of poloidal structure of geodesic acoustic modes in the t-10 tokamak with heavy ion beam probing |
| author |
Zenin, V.N. Eliseev, L.G. Kozachek, A.S. Krupnik, L.I. Lysenko, S.E. Melnikov, A.V. Perfilov, S.V. |
| author_facet |
Zenin, V.N. Eliseev, L.G. Kozachek, A.S. Krupnik, L.I. Lysenko, S.E. Melnikov, A.V. Perfilov, S.V. |
| topic |
Диагностика плазмы |
| topic_facet |
Диагностика плазмы |
| publishDate |
2014 |
| language |
English |
| container_title |
Вопросы атомной науки и техники |
| publisher |
Національний науковий центр «Харківський фізико-технічний інститут» НАН України |
| format |
Article |
| title_alt |
Исследование полоидальной структуры геодезических акустических мод в токамаке Т-10 с помощью пучка тяжелых ионов Дослідження полоїдальної структури геодезичних акустичних мод у токамаці Т-10 за допомогою пучка важких іонів |
| description |
The poloidal structure of geodesic acoustic modes (GAMs) was studied on the T-10 tokamak by heavy ion beam probing with multichannel energy analyzer. GAMs were mainly pronounced on the plasma electric potential. The poloidal phase shift between the potential oscillations was determined by the two-point correlation technique. It was shown that GAM potential oscillations have the poloidal mode number m=0 in the core plasma. This experimental result agrees with theoretical predictions.
На токамаке T-10 с помощью пучка тяжелых ионов исследована полоидальная структура геодезических акустических мод (ГАМ), которые явно видны на потенциале плазмы. Фазовый сдвиг между колебаниями потенциала определялся методом двухточечной корреляции с помощью многоканального энергетического анализатора. Показано, что ГАМ на потенциале имеют полоидальное модовое число m=0. Этот экспериментальный результат согласуется с теоретическими предсказаниями.
На токамаці T-10 за допомогою пучка важких іонів досліджена полоїдальна структура геодезичних акустичних мод (ГАМ), що явно видно на потенціалі плазми. Фазове зміщення між коливаннями потенціалу визначається методом двохточечної кореляції за допомогою багатоканального енергетичного аналізатора. Показано, що ГАМ на потенціалі мають полоїдальное модове число m=0. Цей експериментальний результат узгоджується з теоретичними передбаченнями.
|
| issn |
1562-6016 |
| url |
https://nasplib.isofts.kiev.ua/handle/123456789/81969 |
| citation_txt |
Study of poloidal structure of geodesic acoustic modes in the T-10 tokamak with heavy ion beam probing / V.N. Zenin, L.G. Eliseev, A.S. Kozachek, L.I. Krupnik, S.E. Lysenko, A.V. Melnikov, S.V. Perfilov // Вопросы атомной науки и техники. — 2014. — № 6. — С. 269-271. — Бібліогр.: 11 назв. — англ. |
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2025-11-25T22:42:32Z |
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2025-11-25T22:42:32Z |
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ISSN 1562-6016. ВАНТ. 2014. №6(94)
PROBLEMS OF ATOMIC SCIENCE AND TECHNOLOGY. 2014, №6. Series: Plasma Physics (20), p. 269-271. 269
STUDY OF POLOIDAL STRUCTURE OF GEODESIC ACOUSTIC
MODES IN THE T-10 TOKAMAK WITH HEAVY ION BEAM PROBING
V.N. Zenin
1
, L.G. Eliseev
1
, A.S. Kozachek
2
, L.I. Krupnik
2
, S.E. Lysenko
1
,
A.V. Melnikov
1, 3
, S.V. Perfilov
1
1
Institute of Tokamak Physics, NRC ''Kurchatov Institute'', 123182, Moscow, Russia;
2
Institute of Plasma Physics NSC “Kharkov Institute of Physics and Technology”, Kharkov, Ukraine;
3
National Research Nuclear University MEPhI, Moscow, Russia
E-mail: vitalyzenin@mail.ru
The poloidal structure of geodesic acoustic modes (GAMs) was studied on the T-10 tokamak by heavy ion beam
probing with multichannel energy analyzer. GAMs were mainly pronounced on the plasma electric potential. The
poloidal phase shift between the potential oscillations was determined by the two-point correlation technique. It was
shown that GAM potential oscillations have the poloidal mode number m=0 in the core plasma. This experimental
result agrees with theoretical predictions.
PACS: 52.35.Mw, 52.35.Ra, 52.55.Fa
INTRODUCTION
Geodesic acoustic modes (GAMs) are the high-
frequency branch of zonal flows in toroidal fusion
devices. GAMs are actively studied in tokamaks and
stellarators as one of possible mechanisms of the plasma
turbulence self-regulation by the oscillating radial
electric field [1]. GAMs should transform the radial
turbulent oscillations, which outflow the energy from
plasma, into the torsional plasma oscillations, which do
not transfer the energy radially. Therefore, a linear
theory predicts that the poloidal mode number for GAM
potential oscillations is m=0 [2]. However, this
prediction was not yet validated experimentally in the
core plasma. The presented report contains such
validation.
1. EXPERIMENTAL SETUP
The GAM oscillations are systematically studied at
the circular tokamak T-10 (R=1.5 m, a=0.3 m,
B=1.5…2.5 T, Ipl=0.15…0.3 MA) using heavy ion beam
probing (HIBP) [3, 4]. HIBP is a direct diagnostic for
studying the electric potential and its oscillations, on
which GAMs are very clearly seen. This diagnostic is
especially convenient for study the GAM characteristics
in the plasma core, which is inaccessible for Langmuir
probes usually investigating GAMs at the plasma edge
[5]. Principles of HIBP measurements of potential in T-
10 were described in [6]. In T-10 we used the ions Tl
+
with energy up to Eb<280 keV, provided the spatial and
temporal resolution < 1 cm, <10 s correspondingly.
Varying the beam energy and injection angle, we can
form the detector grid containing the observation points
(sample volumes). For registration we used the energy
analyzer with five slits (Fig. 1). It provided the spatial
and temporal resolution < 1 cm, <10 s correspondingly
at the radial range 6 < r < 30 cm for B=1.5 T [7]. This
new analyzer allows us to carry out simultaneous
measurements in several neighboring sample volumes.
The magnetic flux surfaces in poloidal cross-section of
T-10 are circular. Therefore we can choose sample
volumes at very near flux surfaces that allow us to
estimate the poloidal mode number m for GAMs, which
we seen on the potential oscillations (Fig. 2). Relation
between phase shift and poloidal mode number m can
be derived by the method of two-point correlations,
used in HIBP experiments in the TJ-II stellarator [8].
With this method the poloidal mode number was
detected for electromagnetic modes like Helical Alfvén
Eigenmodes [9, 10] and also for electrostatic modes like
Supra Thermal Electron induced modes in complex
bean-shape geometry of TJ-II plasmas [11].
Fig. 1. The five-slit energy analyzer. B – beam;
D detectors; G – grid; GP – ground plate;
HVP – high-voltage plate; W – window; 5-S entrance
slits
Taking into account the simple circular geometry of
T-10, this method may be simplified as follows. If m=1,
then the phase shift along the whole flux surface, which
presents the circumference with a length 2 r in the
poloidal plane, is equal to 2 . For arbitrary m this phase
shift will be 2 m. As the shift is measured over a small
part of the circumference s, it should be smaller in
proportion of distance between the points on magnetic
mailto:vitalyzenin@mail.ru
270 ISSN 1562-6016. ВАНТ. 2014. №6(94)
Fig. 2. Relation between the phase shift and poloidal
mode number m, shot №62742, sample volumes (stars)
on middle radii. B=2.4 T, Eb=280 keV
surface to the whole length of circumference. So, for the
phase shift 1 2 we obtain:
1 2
s
m
r
. (1)
Using circular symmetry of T-10, we can replace the
relation s/r by more universal value of the angle α
between the points of measurement and the plasma
centre (see Fig. 2). Finally we obtain:
1 2
m . (2)
2. EXPERIMENTAL RESULTS
Data from different sample points are processed
simultaneously; therefore we can perform the spatial
correlation measurements. To obtain information about
oscillations, we performed the spectral analysis of HIBP
data. This allows us to transform the temporal variation
of signal into its frequency components using the fast
Fourier transformation. To determine the poloidal
structure of GAM we used the signals of potential
measured by the central slit of analyzer 3 and by the
edge slit 5. We define the power spectral density
(PSD), coherency and phase shift 1 2. The results of
analysis for shot № 62818 together with time traces of
discharge current Ipl and line-averaged density ne are
shown in Fig. 3.
Signals from both slits are very similar. We see the
main peak and high-frequency satellite with frequencies
about 20 kHz. They have rather good coherency,
coh>0.8, and their cross-phase is near zero. This means
that m=0.
The similar results were obtained for another slits
and for different discharges. Fig. 4 presents the phase
for intermediate slits number 2 and 4 in discharge with
rising density. We see that again m=0.
Fig. 3. Traces of plasma current Ipl and density ne (a);
power spectral densities of potential oscillations
measured by central slit 3 and by edge slit 5 (b) and
(c) at radius r=17 cm, B=2.28 T, their coherency (d)
and cross-phase (e)
Fig. 4. The phase shift between the potential oscillations
and the poloidal mode number m measured by
intermediate slits of analyzer. Discharge parameters
B = 2.3 T, ne = (0.9…2.4 ) 10
19
m
-3
, Ipl = 220 kA
ohmic heating
ISSN 1562-6016. ВАНТ. 2014. №6(94) 271
SUMMARY
The multichannel energy analyzer makes heavy ion
beam probing an effective tool to study the poloidal
structure of geodesic acoustic modes with two-point
correlation technique. It was shown that GAM
associated potential oscillations are poloidally uniform,
so GAM has the poloidal mode number m=0 in potential
of the core plasma. This experimental result agrees with
theoretical predictions [2].
ACKNOWLEDGEMENTS
The research is carried out by financial support of
Russian Scientific Foundation project 14-22-00193.
REFERENCES
1. A. Fujisawa et al. Experimental progress on zonal
flow physics in toroidal plasmas // Nucl. Fusion. 2007,
v. 47, p. S718.
2. P.H Diamond et al. Zonal flows in plasma – a review
// Plasma Phys. Control. Fusion. 2005, v. 47, p. R35.
3. A.V. Melnikov et al. Investigation of geodesic
acoustic modes oscillations in the T-10 tokamak //
Plasma Phys. Control. Fusion. 2006, v. 48, p. S87.
4. A.V. Melnikov et al. Investigation of the plasma
potential oscillations in the range of geodesic acoustic
mode frequencies by heavy ion beam probing in
tokamaks // Czech. J. Phys. 2005, v. 55, p. 349.
5. W. Chen et al. Observation of energetic-particle-
induced GAM and nonlinear interactions between
EGAM, BAEs and tearing modes on the HL-2A
tokamak // Nucl. Fusion. 2013, v. 53, p. 113010.
6. A.V. Melnikov et al. Electric potential dynamics in
OH and ECRH plasmas in the T-10 tokamak // Nucl.
Fusion. 2013, v. 53, p. 093019.
7. A.V. Melnikov et al. HIBP diagnostics on T-10 //
Review of scientific instruments. 1995, v. 66, p. 317.
8. L.G. Eliseev et al. Two Point Correlation Technique
for the Measurements of Poloidal Plasma Rotation by
Heavy Ion Beam Probe // Plasma Fusion Research.
2012, v. 7, p. 2402064.
9. A.V. Melnikov et al. Internal measurements of
Alfvén eigenmodes with heavy ion beam probing in
toroidal plasmas // Nucl. Fusion. 2010, v. 50, p. 084023.
10. A.V. Melnikov et al. Alfvén Eigenmodes properties
and dynamics in the TJ-II stellarator // Nucl. Fusion.
2012, v. 52, p. 123004.
11. A.V. Melnikov et al. A Quasi-Coherent Electrostatic
Mode in ECRH Plasmas on TJ-II // Plasma Fusion
Research. 2011, v. 6, p. 2402030.
Article received 23.10.2014
ИССЛЕДОВАНИЕ ПОЛОИДАЛЬНОЙ СТРУКТУРЫ ГЕОДЕЗИЧЕСКИХ АКУСТИЧЕСКИХ
МОД В ТОКАМАКЕ Т-10 С ПОМОЩЬЮ ПУЧКА ТЯЖЕЛЫХ ИОНОВ
В.Н. Зенин, Л.Г. Елисеев, А.C. Козачeк, Л.И. Kрупник, С.E. Лысенко, A.В. Мельников, С.В. Перфилов
На токамаке T-10 с помощью пучка тяжелых ионов исследована полоидальная структура геодезических
акустических мод (ГАМ), которые явно видны на потенциале плазмы. Фазовый сдвиг между колебаниями
потенциала определялся методом двухточечной корреляции с помощью многоканального энергетического
анализатора. Показано, что ГАМ на потенциале имеют полоидальное модовое число m=0. Этот
экспериментальный результат согласуется с теоретическими предсказаниями.
ДОСЛІДЖЕННЯ ПОЛОЇДАЛЬНОЇ СТРУКТУРИ ГЕОДЕЗИЧНИХ АКУСТИЧНИХ МОД
У ТОКАМАЦІ Т-10 ЗА ДОПОМОГОЮ ПУЧКА ВАЖКИХ ІОНІВ
В.Н. Зенiн, Л.Г. Єлісєєв, О.С. Козачок, Л.І. Kрупник, С.Є. Лисенко, О.В. Mельников, С.В. Перфілов
На токамаці T-10 за допомогою пучка важких іонів досліджена полоїдальна структура геодезичних
акустичних мод (ГАМ), що явно видно на потенціалі плазми. Фазове зміщення між коливаннями потенціалу
визначається методом двохточечної кореляції за допомогою багатоканального енергетичного аналізатора.
Показано, що ГАМ на потенціалі мають полоїдальное модове число m=0. Цей експериментальний результат
узгоджується з теоретичними передбаченнями.
|