Modeling of some nonstationary processes in tokamak plasmas
The results of modeling of shots from two series of experiments in two tokamaks with rather different geometric parameters are presented. The first one includes two shots from the spherical tokamak MAST with current ramp up, and the second one, a number of T-10 shots with periodic gas puffing. The m...
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| Дата: | 2013 |
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Національний науковий центр «Харківський фізико-технічний інститут» НАН України
2013
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| Цитувати: | Modeling of some nonstationary processes in tokamak plasmas / M.A. Borisov, S.V. Cherkasov, A.V. Danilov, Yu.N. Dnestrovskij, A.Yu. Dnestrovskij, A. Field, S.E. Lysenko, H. Meyer, V.A. Vershkov // Вопросы атомной науки и техники. — 2013. — № 1. — С. 96-98. — Бібліогр.: 6 назв. — англ. |
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irk-123456789-1092292016-11-22T03:02:56Z Modeling of some nonstationary processes in tokamak plasmas Borisov, M.A. Cherkasov, S.V. Danilov, A.V. Dnestrovskij, Yu.N. Dnestrovskij, A.Yu. Field, A. Lysenko, S.E. Meyer, H. Vershkov, V.A. Фундаментальная физика плазмы The results of modeling of shots from two series of experiments in two tokamaks with rather different geometric parameters are presented. The first one includes two shots from the spherical tokamak MAST with current ramp up, and the second one, a number of T-10 shots with periodic gas puffing. The modeling was performed with the ASTRA code in the framework of Canonical Profiles Transport Model (CPTM). Представлены результаты моделирования импульсов из двух серий экспериментов на двух разных токамаках, существенно отличающихся геометрическими параметрами. Первая серия включает два импульса с нарастанием тока сферического токамака MAST, а вторая – несколько импульсов Т-10 с периодическим газонапуском. Моделирование осуществлялось с помощью кода ASTRA в рамках транспортной модели канонических профилей (ТМКП). Представлені результати моделювання імпульсів з двох серій експериментів на двох різних токамаках, що істотно відрізняються геометричними параметрами. Перша серія включає два імпульси з наростанням струму сферичного токамака МАST, а друга – декілька імпульсів Т-10 з періодичним газонапуском. Моделювання здійснювалося за допомогою коду ASTRA в рамках транспортної моделі канонічних профілів (ТМКП). 2013 2013 Article Modeling of some nonstationary processes in tokamak plasmas / M.A. Borisov, S.V. Cherkasov, A.V. Danilov, Yu.N. Dnestrovskij, A.Yu. Dnestrovskij, A. Field, S.E. Lysenko, H. Meyer, V.A. Vershkov // Вопросы атомной науки и техники. — 2013. — № 1. — С. 96-98. — Бібліогр.: 6 назв. — англ. 1562-6016 PACS: 52.55.Fa, 52.55.Dy http://dspace.nbuv.gov.ua/handle/123456789/109229 en Вопросы атомной науки и техники 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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English |
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Фундаментальная физика плазмы Фундаментальная физика плазмы |
| spellingShingle |
Фундаментальная физика плазмы Фундаментальная физика плазмы Borisov, M.A. Cherkasov, S.V. Danilov, A.V. Dnestrovskij, Yu.N. Dnestrovskij, A.Yu. Field, A. Lysenko, S.E. Meyer, H. Vershkov, V.A. Modeling of some nonstationary processes in tokamak plasmas Вопросы атомной науки и техники |
| description |
The results of modeling of shots from two series of experiments in two tokamaks with rather different geometric parameters are presented. The first one includes two shots from the spherical tokamak MAST with current ramp up, and the second one, a number of T-10 shots with periodic gas puffing. The modeling was performed with the ASTRA code in the framework of Canonical Profiles Transport Model (CPTM). |
| format |
Article |
| author |
Borisov, M.A. Cherkasov, S.V. Danilov, A.V. Dnestrovskij, Yu.N. Dnestrovskij, A.Yu. Field, A. Lysenko, S.E. Meyer, H. Vershkov, V.A. |
| author_facet |
Borisov, M.A. Cherkasov, S.V. Danilov, A.V. Dnestrovskij, Yu.N. Dnestrovskij, A.Yu. Field, A. Lysenko, S.E. Meyer, H. Vershkov, V.A. |
| author_sort |
Borisov, M.A. |
| title |
Modeling of some nonstationary processes in tokamak plasmas |
| title_short |
Modeling of some nonstationary processes in tokamak plasmas |
| title_full |
Modeling of some nonstationary processes in tokamak plasmas |
| title_fullStr |
Modeling of some nonstationary processes in tokamak plasmas |
| title_full_unstemmed |
Modeling of some nonstationary processes in tokamak plasmas |
| title_sort |
modeling of some nonstationary processes in tokamak plasmas |
| publisher |
Національний науковий центр «Харківський фізико-технічний інститут» НАН України |
| publishDate |
2013 |
| topic_facet |
Фундаментальная физика плазмы |
| url |
http://dspace.nbuv.gov.ua/handle/123456789/109229 |
| citation_txt |
Modeling of some nonstationary processes in tokamak plasmas / M.A. Borisov, S.V. Cherkasov, A.V. Danilov, Yu.N. Dnestrovskij, A.Yu. Dnestrovskij, A. Field, S.E. Lysenko, H. Meyer, V.A. Vershkov // Вопросы атомной науки и техники. — 2013. — № 1. — С. 96-98. — Бібліогр.: 6 назв. — англ. |
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Вопросы атомной науки и техники |
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| fulltext |
96 ISSN 1562-6016. ВАНТ. 2013. №1(83)
MODELING OF SOME NONSTATIONARY PROCESSES IN TOKAMAK
PLASMAS
M.A. Borisov1, S.V. Cherkasov1, A.V. Danilov1, Yu.N. Dnestrovskij1, A.Yu. Dnestrovskij1,
A. Field2, S.E. Lysenko1, H. Meyer2, V.A. Vershkov1
1NRC ''Kurchatov Institute'' Institute of Tokamak Physics, Moscow, Russia;
2Euroatom/CCFE Fusion Association, Culham Science Centre, Abingdon OX14 3DB,UK
The results of modeling of shots from two series of experiments in two tokamaks with rather different geometric
parameters are presented. The first one includes two shots from the spherical tokamak MAST with current ramp up,
and the second one, a number of T-10 shots with periodic gas puffing. The modeling was performed with the
ASTRA code in the framework of Canonical Profiles Transport Model (CPTM).
PACS: 52.55.Fa, 52.55.Dy
1. CURRENT RAMP UP IN MAST
1.1. OHMIC DISCHARGE
The motivation for the current ramp up pulses
modeling was the solution of the issue, whether the
neoclassical conductivity is suitable for the description
of the current diffusion in the MAST. The results of
modeling for two MAST discharges: Ohmic (#24433)
and NBI-heated (#24434) are presented. For both pulses
the plasma current ramped up during 170 ms until value
Ip = 0.85 MA, while the chord averaged plasma density
until 3.5×1019 m-3 during 200 ms, the magnetic field was
BT = 0.5 T, the NBI power deposition for the pulse
#24434 was at the level of 1.5 MW.
The modeling was performed in two stages. In the
first stage only the plasma current distribution was
modeled with prescribed experimental electron
temperature and plasma density. Then the full transport
CPTM model [1] was used. Two expressions for
neoclassical conductivity were under study: Hirshman
[2] and Sauter-Angioni conductivity [3].
The results of Ohmic shot modeling with prescribed
electron and ion temperatures and plasma density are
presented in Fig. 1 for four time slices t = 30, 75, 130
and 250 ms. Hirshman expression for plasma
conductivity was used in this run. The simulated safety
factor profiles (q) met the measured profiles obtained by
MSE diagnostics during the whole time period under
consideration. This conclusion is somewhat different
from the results of previous work on this topic [4]. One
of the possible reasons might be the different
representation of plasma boundary in the codes (3
moments in ASTRA and 6 moments in TRANSP). The
same reason may respond for some deviations of
calculated q profiles from measurements at the plasma
edge. The clarification of this variance needs further
investigation with wider set of pulses.
Similar results were obtained with Te and ne
modeling by means of CPTM transport model. This
similarity is connected with the proximity of the
modeled electron temperature to the experimental one
(Fig. 2).
Fig. 1. Profiles of plasma values at different times for
Ohmic shot #24433. Crosses are measurements, solid
lines are calculations. Notations: j is current density
(MA/m2), TE, TI are electron and ion temperatures
(keV, TI = TE), q is safety factor, Ne is density
(10191/m3), Zeff is effective charge, Upl is voltage (V),
j0 is j profile at the start of the run (t = 25 ms)
t=30 ms
t=75 ms
t=130 ms
t=250 ms
ISSN 1562-6016. ВАНТ. 2013. №1(83) 97
0.0 0.1 0.2
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
T e(0
) (
ke
V)
time (s)
CPTM
exp
0,00 0,05 0,10 0,15 0,20 0,25 0,30
0
5
10
15
Ip
CPTM HR
CPTM SA
MSE, EFIT
q(
0)
time, s
0,0
0,2
0,4
0,6
0,8
1,0
I p,
M
A
0.2 0.4 0.6 0.8 1.0 1.2 1.4
0.0
0.5
1.0
1.5
MAST #24434
Te, model
Te, TRANSP
Ti, TRANSP
Ti, CXRS
Te, TS
T e, T
i (k
eV
)
R (m)
t=250 ms
Fig. 2. Comparison of modeled (CPTM) and
experimental (exp) central electron temperature values
for the Ohmic discharge
Fig. 3. Comparison of central safety factor values for
Hirshman (HR) and Sauter-Angioni (SA) conductivities
with experiment (MSE) for Ohmic discharge
During the CPTM Ohmic discharge modeling, the
comparison of Hirshman and Sauter-Angioni
conductivities has been performed. The results are
presented in Fig. 3. As it can be seen, the central safety
factor values are very similar in these cases and the
agreement with experiment is even better for more
simple Hirshman expression.
1.2. NBI-HEATED DISCHARGE
The results obtained for NBI-heated pulse #24434
are very similar for those for Ohmic discharge. We
consider here only the results of CPTM modeling of
electron temperature and plasma density. The safety
factor calculated with Hirshman conductivity is
compared with MSE measurements in Fig. 4 for the
time instant 250 ms. The simulated electron temperature
profile at the same time is presented in Fig. 5.
2. PERIODIC GAS PUFFING IN T-10
The experiments with periodic gas puffing have
proved to be a powerful tool for plasma diffusion
investigation [5]. The new series of T-10 experiments
was carried out in 2011 in Ohmic discharges with
BT = 2.4 T, current Ip = 200 kA and densities ⎯ne = 1.7,
2.5 and 3.5×1019 m-3, and for ⎯ne = 2.5×1019 m-3 with
Ip = 130, 200 and 300 kA [6]. Periodic D2 puffing was
made though piezoelectric valve in the stationary stage
of the discharge with modulation periods of T = 60 and
90 ms.
Fig. 4. Profiles of plasma values at t=250 ms for NBI-
heated shot #24433. Notations: pbiN, pbeN (MW/m3s) –
NBI power input to ions and electrons, jBS, jOH –
bootstrap and Ohmic currents (MA/m2), CNHR, CNSA -
Hirshman and Sauter-Angioni conductivities (μΩ*m);
other notations as in Fig. 1
Fig. 5. Modeled electron temperature profile for NBI-
heated pulse vs measurements
Fig. 6. The modulation of plasma chord density
(interferometer signals)
The modulation of chord density signal is clearly seen
over the whole plasma cross section (Fig. 6).
The attempt to explain the experimental spatial
distribution of modulation amplitudes and phases by
means of simple diffusion model with constant in time
diffusion coefficient and pinch velocity failed in the
case of higher densities, so a complex model with
periodic variation of parameters has to be constructed.
However, the usual version of the CPTM with constant
in time coefficients has demonstrated the capability to
meet the experimental profiles of modulation amplitude
and phase shift as presented in Fig. 7.
The gas puffing was simulated by 1 % modulation of
wall cold neutrals influx and antiphased modulation of
electron temperature and density boundary values.
600 700 800 900
0,0
0,2
0,4
0,6
0,8
1,0
21 cm
12.6 cm
4.2 cm
-4.2 cm
-12.6 cm
-21 cm
Δ
(n
e
l),
a
.u
.
time, ms
T-10
98 ISSN 1562-6016. ВАНТ. 2013. №1(83)
-20 0 20
0
1
2
3 ne=2.5*1019m-3; Ip=200 kA
T=60 ms
T=90 ms
A
m
pl
itu
de
r, cm
(a)
-20 0 20
100
200
300
Ph
as
e,
d
eg
re
es
r, cm
(b)
Fig. 7. Relative chord densities modulation amplitudes
(a) and phase shifts (b) profiles for two modulation
periods T°=°60 And 90 ms. Points are measurements,
curves are CPTM modeling
The runs reveal strong dependencies of observed
modulation amplitudes and phases on the ratio of
temperature and density boundary disturbances.
Namely, amplitudes and phases agree with experiment,
when the relative value of the boundary temperature
modulation is about twice the density one. It should be
mentioned that the excess of temperature disturbances
over the density ones was observed experimentally for
the average plasma density under consideration.
CONCLUSIONS
The comparison of modeling results with TS, CXRS
and MSE measurements for both Ohmic and NBI-
heated MAST discharges confirmed the adaptability of
neoclassical conductivity in this case. This conclusion is
somewhat different from the results of previous work on
this topic [4]; one of the possible reasons might be the
different representation of plasma boundary in the
codes. Particular form of neoclassical conductivity
(Hirshman or Sauter-Angioni expression) has a weak
effect upon the safety factor profile and other values.
The analysis of periodic gas puffing experiments in
T-10 demonstrated the capability of the usual version of
the CPTM to meet the experimental profiles of the
chord density modulation amplitudes and phase shifts.
ACKNOWLEDGEMENTS
The authors thank D. Keeling for discussion. The
work is supported by Rosatom contract
H.4x.45.90.12.1023, Rosnauka contracts
16.518.11.7004 and NSh 5044.2012.2, and by
Consultancy Agreement with UKAEA 3000160385.
REFERENCES
1. Yu.N. Dnestrovskij et al. // Nucl. Fusion. 1995, v. 35,
p. 1047.
2. S.P. Hirshman, R.J. Hawryluk, B. Birge // Nucl.
Fusion. 1977, v. 17, p. 611.
3. O. Sauter, C. Angioni, and Y.R. Lin-Liu // Phys.
Plasmas. 1999, v. 6, p. 2834.
4. D. Keeling et al. // 38-th EPS Conf. on Plasma
Physics. 2011, Rep. 05.130.
5. V.A. Vershkov, N.L. Vasin, V.А. Zhuravlev // Fizika
Plazmy. 1984, v. 10, p. 1125 (in Russian).
6. M.A. Borisov et al. // 38-th EPS Conf. on Plasma
Physics. 2011, Rep. 05.127.
Article received 19.10.12
МОДЕЛИРОВАНИЕ НЕКОТОРЫХ НЕСТАЦИОНАРНЫХ ПРОЦЕССОВ В ПЛАЗМЕ ТОКАМАКОВ
М.А. Борисов, С.В. Черкасов, А.В. Данилов, Ю.Н. Днестровский, А.Ю. Днестровский, А. Филд,
С.Е. Лысенко, Х. Мейер, В.А. Вершков
Представлены результаты моделирования импульсов из двух серий экспериментов на двух разных
токамаках, существенно отличающихся геометрическими параметрами. Первая серия включает два
импульса с нарастанием тока сферического токамака MAST, а вторая – несколько импульсов Т-10 с
периодическим газонапуском. Моделирование осуществлялось с помощью кода ASTRA в рамках
транспортной модели канонических профилей (ТМКП).
МОДЕЛЮВАННЯ ДЕЯКИХ НЕСТАЦІОНАРНИХ ПРОЦЕСІВ У ПЛАЗМІ ТОКАМАКІВ
М.А. Борисов, С.В. Черкасов, А.В. Данилов, Ю.М. Дністровський, А.Ю. Дністровський, А. Філд,
С.Є. Лисенко, Х. Мейер, В.А. Вершков
Представлені результати моделювання імпульсів з двох серій експериментів на двох різних токамаках,
що істотно відрізняються геометричними параметрами. Перша серія включає два імпульси з наростанням
струму сферичного токамака МАST, а друга – декілька імпульсів Т-10 з періодичним газонапуском.
Моделювання здійснювалося за допомогою коду ASTRA в рамках транспортної моделі канонічних профілів
(ТМКП).
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