Study of plasma potential, its fluctuations and turbulence rotation in the T-10 tokamak
Plasma potential, its oscillations and turbulence rotation were studied on T-10 in a wide range of ohmic and ECRH regimes. The potential has negative sign over the whole plasma cross section. Broadband turbulence tends to rotate with E×B drift velocity. Rotation and potential evolve together with pl...
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Національний науковий центр «Харківський фізико-технічний інститут» НАН України
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| Цитувати: | Study of plasma potential, its fluctuations and turbulence rotation in the T-10 tokamak / A.V. Melnikov, V.A. Vershkov, S.A. Grashin, L.G. Eliseev, S.E. Lysenko, V.A. Mavrin, V.G. Merezhkin, S.V. Perfilov, D.A. Shelukhin, R.V. Shurygin, L.I. Krupnik, A.D. Komarov, A.S. Kozachek, A.I. Zhezhera // Вопросы атомной науки и техники. — 2010. — № 6. — С. 40-42. — Бібліогр.: 6 назв. — англ. |
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irk-123456789-174532011-02-27T12:06:48Z Study of plasma potential, its fluctuations and turbulence rotation in the T-10 tokamak Melnikov, A.V. Vershkov, V.A. Grashin, S.A. Eliseev, L.G. Lysenko, S.E. Mavrin, V.A. Merezhkin, V.G. Perfilov, S.V. Shelukhin, D.A. Shurygin, R.V. Krupnik, L.I. Komarov, A.D. Kozachek, A.S. Zhezhera, A.I. Методы создания и нагрева плазмы Plasma potential, its oscillations and turbulence rotation were studied on T-10 in a wide range of ohmic and ECRH regimes. The potential has negative sign over the whole plasma cross section. Broadband turbulence tends to rotate with E×B drift velocity. Rotation and potential evolve together with plasma confinement. Frequency of potential oscillations in the range of geodesic acoustic modes does not change with radius that disagrees with theoretical predictions. Потенциал плазмы, его колебания и вращение исследовались на токамаке T-10 в широком диапазоне омических и ЭЦР-режимов. Потенциал – отрицательный по всему сечению плазмы. Вращение турбулентности соответствует вращению за счет (E×B)-дрейфа. Вращение и потенциал чувствительны к изменениям удержания. Частота колебаний потенциала в диапазоне геодезических акустических мод не меняется по радиусу, что не соответствует локальной теории ГАМ. Потенціал плазми, його коливання та обертання було досліджено на токамаці Т-10 у широкому діапазоні омічних та ЕЦР-режимів. Потенціал має негативну величину по всьому перетину плазми. Обертання турбуленції відповідає обертанню за рахунок (E×B)-дрейфу. Обертання і потенціал чутливі до зміни утримання. Частота коливань потенціалу у діапазоні геодезичних акустичних мод ні змінюється в залежності від радіусу, що не відповідає локальній теорії ГАМ. 2010 Article Study of plasma potential, its fluctuations and turbulence rotation in the T-10 tokamak / A.V. Melnikov, V.A. Vershkov, S.A. Grashin, L.G. Eliseev, S.E. Lysenko, V.A. Mavrin, V.G. Merezhkin, S.V. Perfilov, D.A. Shelukhin, R.V. Shurygin, L.I. Krupnik, A.D. Komarov, A.S. Kozachek, A.I. Zhezhera // Вопросы атомной науки и техники. — 2010. — № 6. — С. 40-42. — Бібліогр.: 6 назв. — англ. 1562-6016 http://dspace.nbuv.gov.ua/handle/123456789/17453 en Національний науковий центр «Харківський фізико-технічний інститут» НАН України |
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Digital Library of Periodicals of National Academy of Sciences of Ukraine |
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DSpace DC |
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English |
| topic |
Методы создания и нагрева плазмы Методы создания и нагрева плазмы |
| spellingShingle |
Методы создания и нагрева плазмы Методы создания и нагрева плазмы Melnikov, A.V. Vershkov, V.A. Grashin, S.A. Eliseev, L.G. Lysenko, S.E. Mavrin, V.A. Merezhkin, V.G. Perfilov, S.V. Shelukhin, D.A. Shurygin, R.V. Krupnik, L.I. Komarov, A.D. Kozachek, A.S. Zhezhera, A.I. Study of plasma potential, its fluctuations and turbulence rotation in the T-10 tokamak |
| description |
Plasma potential, its oscillations and turbulence rotation were studied on T-10 in a wide range of ohmic and ECRH regimes. The potential has negative sign over the whole plasma cross section. Broadband turbulence tends to rotate with E×B drift velocity. Rotation and potential evolve together with plasma confinement. Frequency of potential oscillations in the range of geodesic acoustic modes does not change with radius that disagrees with theoretical predictions. |
| format |
Article |
| author |
Melnikov, A.V. Vershkov, V.A. Grashin, S.A. Eliseev, L.G. Lysenko, S.E. Mavrin, V.A. Merezhkin, V.G. Perfilov, S.V. Shelukhin, D.A. Shurygin, R.V. Krupnik, L.I. Komarov, A.D. Kozachek, A.S. Zhezhera, A.I. |
| author_facet |
Melnikov, A.V. Vershkov, V.A. Grashin, S.A. Eliseev, L.G. Lysenko, S.E. Mavrin, V.A. Merezhkin, V.G. Perfilov, S.V. Shelukhin, D.A. Shurygin, R.V. Krupnik, L.I. Komarov, A.D. Kozachek, A.S. Zhezhera, A.I. |
| author_sort |
Melnikov, A.V. |
| title |
Study of plasma potential, its fluctuations and turbulence rotation in the T-10 tokamak |
| title_short |
Study of plasma potential, its fluctuations and turbulence rotation in the T-10 tokamak |
| title_full |
Study of plasma potential, its fluctuations and turbulence rotation in the T-10 tokamak |
| title_fullStr |
Study of plasma potential, its fluctuations and turbulence rotation in the T-10 tokamak |
| title_full_unstemmed |
Study of plasma potential, its fluctuations and turbulence rotation in the T-10 tokamak |
| title_sort |
study of plasma potential, its fluctuations and turbulence rotation in the t-10 tokamak |
| publisher |
Національний науковий центр «Харківський фізико-технічний інститут» НАН України |
| publishDate |
2010 |
| topic_facet |
Методы создания и нагрева плазмы |
| url |
http://dspace.nbuv.gov.ua/handle/123456789/17453 |
| citation_txt |
Study of plasma potential, its fluctuations and turbulence rotation in the T-10 tokamak / A.V. Melnikov, V.A. Vershkov, S.A. Grashin, L.G. Eliseev, S.E. Lysenko, V.A. Mavrin, V.G. Merezhkin, S.V. Perfilov, D.A. Shelukhin, R.V. Shurygin, L.I. Krupnik, A.D. Komarov, A.S. Kozachek, A.I. Zhezhera // Вопросы атомной науки и техники. — 2010. — № 6. — С. 40-42. — Бібліогр.: 6 назв. — англ. |
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2025-07-02T18:40:31Z |
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| fulltext |
STUDY OF PLASMA POTENTIAL, ITS FLUCTUATIONS
AND TURBULENCE ROTATION IN THE T-10 TOKAMAK
A.V. Melnikov1, V.A. Vershkov1, S.A. Grashin1, L.G. Eliseev1, S.E. Lysenko1, V.A. Mavrin1,
V.G. Merezhkin1, S.V. Perfilov1, D.A. Shelukhin1, R.V. Shurygin1, L.I. Krupnik2,
A.D. Komarov2, A.S. Kozachek2, A.I. Zhezhera2
1Institute of Tokamak Physics RRC ''Kurchatov Institute'', Moscow, Russia;
2 Institute of Plasma Physics NSC “Kharkov Institute of Physics and Technology”, Kharkov, Ukraine
E-mail: melnik@nfi.kiae.ru
Plasma potential, its oscillations and turbulence rotation were studied on T-10 in a wide range of ohmic and ECRH
regimes. The potential has negative sign over the whole plasma cross section. Broadband turbulence tends to rotate with
E×B drift velocity. Rotation and potential evolve together with plasma confinement. Frequency of potential oscillations
in the range of geodesic acoustic modes does not change with radius that disagrees with theoretical predictions.
PACS: 52.35.Mw, 52.55.Fa
1. INTRODUCTION
The direct experimental study of plasma radial electric
field Er is the key issue to clarify E×B shear stabilization
mechanisms. Comparison of plasma turbulence and Er×B
40
Series: Plasma Physics (16), p. 40-42.
PROBLEMS OF ATOMIC SCIENCE AND TECHNOLOGY. 2010. № 6.
Bt
drift rotation may explain, whether the turbulence moves
together with the plasma or independently. The absolute
value of the core plasma potential ϕ was measured in the
T-10 tokamak (R = 1.5 m, a = 0.3 m), by Heavy Ion Beam
Probing (HIBP) with Tl ions. New high-voltage power
supply and new system of remote control of focal distance
allow us to increase the beam energy E
+
b up to 300 keV
and focus the beam in any desirable point of the detector
grid in plasma. The primary beam current achieved
200 μA and the beam diameter ~ 4 mm. Therefore we can
observe the core potential at high densities
( en ≤ 4.1×10 m ). The ϕ profile in a wide area
(0.2 < r/a < 0.9) was assembled from radial fragments
measured with various E
19 -3
b and injection angles in a series
of reproducible shots. At the limiter, the plasma potential
and density were measured by Langmuir probes. The core
plasma turbulence was studied by correlation
reflectometry (CR). Also we used the standard set of
diagnostics: soft X-rays (SXR), electron cyclotron
emission (ECE), diamagnetic loops and other. Missing
radial distributions of plasma parameters invoked from
transport model with T-11 scaling for diffusivity [1].
2. POTENTIAL MEASUREMENTS
Various regimes with ohmic (OH), on- and off-axis
ECR heating (B
Parameters of studied regimes
Reg. ⎯n, 1019
m-3
Er,
V/cm
Δr, cm BBt, T Ip, kA τE,
ms
1-l 1.3 55 6-30 1.55 140 20
1-h 2.4 65 6-30 1.55 140 36
2 OH 2.5 70 7-22 2.08 165 38
2 EC 2.1 55
/47
7-22 2.08 165
/212
13/12
3 4.1 90 16-27 2.4 210 50
Bt = 1.55…2.4 T, Ip = 140…250 kA,
en = (1.3…4.1)×10 m , P19 -3
EC < 1.5 MW) were first
studied [2]. In first low-BtB , ohmic regime (1-l and 1-h in
the Table) HIBP observed practically the whole plasma
cross-section. Evolution of plasma parameters is shown in
Fig. 1. The density⎯ne rises due to gas puffing, while the
electron temperature Te slightly decreases. The potential
profile evolution is shown in Fig. 2: the potential and Er
tends to decrease with gas puff. The second regime had
additional ECR heating and the current ramps up from
165 to 212 kA (Fig. 3).
Fig. 1. Evolution of density ne, potential ϕ, energy
confinement time τE and electron temperatures Te
at the centre and at 21.7 cm in low-field regime
200 400 600 800 1000
0
10
20
During ECRH phase, the potential well becomes
significantly shallower, Er decreases and confinement
degrades. The potential has a weak dependence on Ip. No
any strong irregularities in the potential near the EC
power deposition radius rEC =15 cm during the slow
(10 ms) timescale are seen: Er inside and outside rECRH
was the same. The high-density ohmic regime 3 has
maximal Er (Fig. 4). In all studied regimes, the potential
was negative and Er(r) ~ const < 0 in the whole radial
range of HIBP measurements, the potential well becomes
deeper, and the mean Er increases with rise of density and
the energy confinement time τE.
0,5
1,0
1,5
-700
-650
-600
-550
10
20
30
ϕ
HIBP r = 20 cm
n e (1
018
m
-3
)
t (ms)
##57406-442, B=1.55 T
n
τE
Te (a.u.)
ECE r= -21.7cm
T e (
0)
(k
eV
)
e
ϕ
(V
)
τ E (m
s)
mailto:melnik@nfi.kiae.ru
41
3. E×B AND TURBULENCE ROTATION
The plasma column rotates with E×B drift velocity not as
a rigid body due to the BBt(R) dependence. The typical
values for angular velocity is ΩE×BB ~ 1.5×104 rad/s for
OH, and ΩE×B ~ 1.25×10 rad/s for ECRH stages
(Fig. 5, a,b).
B
5 10 15 20 25 30
4
Broadband drift-wave turbulence tends to rotate together
with the E×B driven bulk plasma. Faster rotation
corresponds to better confinement.
3. FLUCTUATIONS
Geodesic Acoustic Modes (GAMs) may be possible
mechanism of the turbulence self-regulation. The theory
proposes the unified dispersion relation for GAMs and
Beta induced Alfvén Eigenmodes (BAE) [3]. This mode
0
0
2
4
6
ΩTURB by CR
ΩExB by HIBP
r (cm)
OH )
0 5 10 15 20 25 30
Ω
⊥
[1
04 ra
d/
s]
(a
0
2
4
6
ΩTURB by CR
ΩExB by HIBP
Ω
⊥
(1
04 ra
d/
s)
r (cm)
ECRH (b)
Fig. 5. Plasma ExB and turbulence rotation in regime 2,
measured by correlation reflectometer (CR) and ion
beam (HIBP) in ohmic (a) and ECR phases (b)
Fig. 6. Spectra of potential oscillations in regime 2.
Peaks in ellipses are identified as GAMs
0 10 20 30
ECRH + ramp up
ps
d
f, kHz
OH
#57712
ECRH
Fig. 3. The potential profile in regime with additional
heating and current ramp-up; ▲ arks position of EC
resonance
0 10 20 30
-1500
-1000
-500
0
m
r (cm)
ϕ
(V
)
rECRH
##57704 - 57311
Bt = 2.08 T
47 V/cm
EC+Ip ramp-up
70 V/cm, OH
55 V/cm
EC
Fig. 4. The potential profile in high-density ohmic regime
16 18 20 22 24 26 28 30
-1000
-500
0
ϕ
(V
)
r (cm)
t=522
t=693
t=898
Er=90 V/cm
##57641, 57642, 57646,
57649, 57656
Fig. 2. The potential profile assembled from set of
the scans for three densities in time instants
marked by hatched rectangles in Fig. 1
0 5 10 15 20 25 30
ne=1.3x1019, Er=-55 V/cm
-1500
-1000
-500
0
ne=2.0x1019, Er=-60 V/cm
ne=2.4x1019, Er=-65 V/cm
ϕ
(V
)
r (cm)
#57412
а
b
presents a dominant peak in the power spectral density of
potential. In some cases a higher frequency satellite
appears (Fig. 6) [4]. Mode is more pronounced during
ECRH, when the typical frequencies are seen in the band
22…27 kHz over the whole plasma cross-section. In all
regimes the mode frequency is close to a constant over the
investigated radial interval (Fig. 7) that inconsistent with
theoretical predictions for the plasma core [5].
42
However, at the outer edge, ρ = 0.95, the frequency value
is consistent with theoretical prediction [6], which may be
indicative these mode are the edge driven spatially global
eigenmodes. The frequency weakly depends on the
magnetic field and plasma density. With the density rise,
first the satellite and then the main peak consequently
disappear. The amplitude of potential perturbations is
quite pronounced, is about a few tens of Volts in the
ECRH phase, and increases towards the plasma centre.
ACKNOWLEDGEMENT
This work is supported by RFBR Grants 10-02-01385 and
08-02-01326, and STCU Project 4703.
Fig. 7. Comparison of potential oscillations in
regime 2 with analytical theory (lines) and 5-fields
code calculations (star). Rectangle shows the
region of the code validity
0 5 10 15 20 25 30
0
10
20
30
40
50
t=540 ms, n=1.3x1019m-3
t=540 ms, satellite
t=800 ms, n=2.1x1019m-3
f (
kH
z)
r (cm)
fTheory
GAM / BAE
5-fields code
REFERENCES
1. V.G. Merezhkin, V.S. Mukhovatov, A.R. Polevoj // J.
Plasma Phys. 1988, v. 14, p. 69.
2. A.V. Melnikov, et al. Measurements of plasma
potential, radial electric field and turbulence rotation
velocity in the T-10 tokamak // 37th EPS Conference
on Plasma Physics. Dublin, 2010. Rep. O5.128.
3. W.W. Heidbrink, et al. What is the "beta-induced
alfven eigenmode?" // Phys. Plasmas. 1999, v. 6,
p. 1147-1161.
4. A.V. Melnikov, et al. Investigation of geodesic acoustic
mode oscillations in the T-10 tokamak // Plasma Phys.
Control. Fusion. 2006, v. 48, p. S87-S110.
5. A.I. Smolyakov, et al. Electromagnetic effects on
geodesic acoustic modes and beta Alfvén eigen
modes // Nucl. Fusion. 2010, v. 50, p. 054002.
6. R.V. Shurygin, A.V. Melnikov. Turbulent dynamics of
helical perturbations in the edge plasma of the T-10
tokamak // Plasma Phys. Rep. 2009, v. 35, N 4,
p. 259-278.
Article received 13.09.10
ИССЛЕДОВАНИЕ ПОТЕНЦИАЛА ПЛАЗМЫ, ЕГО ФЛУКТУАЦИЙ И ВРАЩЕНИЯ
ТУРБУЛЕНТНОСТИ В ТОКАМАКЕ T-10
A.В. Mельников, В.A. Вершков, С.A. Грашин, Л.Г Eлисеев, С.E. Лысенко, В.A. Maврин, В.Г. Meрeжкин,
С.В. Перфилов, Д.A. Шелухин, Р.В. Шурыгин, Л.И. Kрупник, A.Д. Koмаров, A.С. Koзачек, A.И. Жежера
Потенциал плазмы, его колебания и вращение исследовались на токамаке T-10 в широком диапазоне
омических и ЭЦР-режимов. Потенциал – отрицательный по всему сечению плазмы. Вращение турбулентности
соответствует вращению за счет (E×B)-дрейфа. Вращение и потенциал чувствительны к изменениям удержания.
Частота колебаний потенциала в диапазоне геодезических акустических мод не меняется по радиусу, что не
соответствует локальной теории ГАМ.
ДОСЛІДЖЕННЯ ПОТЕНЦІАЛУ ПЛАЗМИ, ЙОГО ФЛУКТУАЦІЙ ТА ОБЕРТАННЯ
ТУРБУЛЕНЦІЇ У ТОКАМАЦІ Т-10
О.В. Mельніков, В.О. Вершков, С.A Грашин, Л.Г Єлісеєв, С.E. Лисенко, В.О. Maврін, В.Г. Meрeжкін,
С.В. Перфілов, Д.О. Шелухін, Р.В. Шуригін, Л.І. Kрупнік, О.Д. Koмаров, О.С. Koзачок, О.І. Жежера
Потенціал плазми, його коливання та обертання було досліджено на токамаці Т-10 у широкому діапазоні
омічних та ЕЦР-режимів. Потенціал має негативну величину по всьому перетину плазми. Обертання
турбуленції відповідає обертанню за рахунок (E×B)-дрейфу. Обертання і потенціал чутливі до зміни утримання.
Частота коливань потенціалу у діапазоні геодезичних акустичних мод ні змінюється в залежності від радіусу,
що не відповідає локальній теорії ГАМ.
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