Transport and plasma control in the Tj-Ii stellarator
This paper shows the effect of 3D geometry on transport and plasma control in the TJ-II stellarator. The fuelling and impurity transport are affected due to the enhancement of neoclassical (NC) transport and subsequent onset of a radial electric field. Turbulence affects not only plasma but also n...
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Національний науковий центр «Харківський фізико-технічний інститут» НАН України
2016
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Castejón, F. 2017-03-30T16:41:51Z 2017-03-30T16:41:51Z 2016 Transport and plasma control in the Tj-Ii stellarator / F. Castejón and the TJ-II team and collaborators // Вопросы атомной науки и техники. — 2016. — № 6. — С. 9-14. — Бібліогр.: 15 назв. — англ. 1562-6016 PACS: 52.55.Hc; 52.70.-m; 52.35.-g https://nasplib.isofts.kiev.ua/handle/123456789/115226 This paper shows the effect of 3D geometry on transport and plasma control in the TJ-II stellarator. The fuelling and impurity transport are affected due to the enhancement of neoclassical (NC) transport and subsequent onset of a radial electric field. Turbulence affects not only plasma but also neutral density, with effects on the fuelling. SOL is shown to be affected by plasma edge turbulence. The properties of stability and MHD modes are also explored. The plasma flow is shown to be affected by 3/2 magnetic island. Promissing experimental results show the possibility of controlling Alfvén modes by ECRH, and magnetic configuration by rotational transform and magnetic well scans. Статья посвящена влиянию 3D-геометрии на перенос и контроль состояния плазмы в стеллараторе TJ-II. Усиление роли неоклассического переноса (НС) и возникновение радиального электрического поля влияет на результат инжекции крупинок и перенос примесей. Турбулентность оказывает влияние не только на плазму, но и на плотность нейтралов, то есть на результат инжекции крупинки. Параметры плазмы в SOL зависят от турбулентности на границе плазмы. Исследованы свойства плазмы в стабильном состоянии и при появлении МГД-колебаний. Появление острова 3/2 оказывает влияние на плазменный поток. Перспективными представляются результаты, указывающие на возможность контроля Альфвеновских мод при ЭЦР-нагреве и магнитной конфигурации изменением вращательного преобразования и величиной магнитной ямы. Стаття присвячена впливу 3D-геометрії на перенос та контроль стану плазми в стеллараторі TJ-II. Збільшення ролі неокласичного переносу (НС) і поява радіального електричного поля впливає на результат інжекції крупинок та перенос домішок. Турбулентність впливає не тільки на плазму, але й на густину нейтралів, що з’являються в результаті інжекції крупинки. Параметри плазми в SOL залежать від турбулентності на границі плазми. Вивчено властивості плазми у стабільному стані та при появі МГД- коливань. Плазмовий потік змінюється при появі острова 3/2. Здається, що результати, яки вказують на можливість контролю Альфвенівських мод при ЭЦР-нагріві та магнітної конфігурації зміною обертального перетворення і величини магнітної ями є перспективними. en Національний науковий центр «Харківський фізико-технічний інститут» НАН України Вопросы атомной науки и техники Magnetic confinement Transport and plasma control in the Tj-Ii stellarator Перенос и контроль состояния плазмы в стеллараторе Tj-Ii Перенос та контроль за станом плазми в стелараторі Tj-Ii Article published earlier |
| institution |
Digital Library of Periodicals of National Academy of Sciences of Ukraine |
| collection |
DSpace DC |
| title |
Transport and plasma control in the Tj-Ii stellarator |
| spellingShingle |
Transport and plasma control in the Tj-Ii stellarator Castejón, F. Magnetic confinement |
| title_short |
Transport and plasma control in the Tj-Ii stellarator |
| title_full |
Transport and plasma control in the Tj-Ii stellarator |
| title_fullStr |
Transport and plasma control in the Tj-Ii stellarator |
| title_full_unstemmed |
Transport and plasma control in the Tj-Ii stellarator |
| title_sort |
transport and plasma control in the tj-ii stellarator |
| author |
Castejón, F. |
| author_facet |
Castejón, F. |
| topic |
Magnetic confinement |
| topic_facet |
Magnetic confinement |
| publishDate |
2016 |
| language |
English |
| container_title |
Вопросы атомной науки и техники |
| publisher |
Національний науковий центр «Харківський фізико-технічний інститут» НАН України |
| format |
Article |
| title_alt |
Перенос и контроль состояния плазмы в стеллараторе Tj-Ii Перенос та контроль за станом плазми в стелараторі Tj-Ii |
| description |
This paper shows the effect of 3D geometry on transport and plasma control in the TJ-II stellarator. The fuelling
and impurity transport are affected due to the enhancement of neoclassical (NC) transport and subsequent onset of a
radial electric field. Turbulence affects not only plasma but also neutral density, with effects on the fuelling. SOL is
shown to be affected by plasma edge turbulence. The properties of stability and MHD modes are also explored. The
plasma flow is shown to be affected by 3/2 magnetic island. Promissing experimental results show the possibility of
controlling Alfvén modes by ECRH, and magnetic configuration by rotational transform and magnetic well scans.
Статья посвящена влиянию 3D-геометрии на перенос и контроль состояния плазмы в стеллараторе
TJ-II. Усиление роли неоклассического переноса (НС) и возникновение радиального электрического поля
влияет на результат инжекции крупинок и перенос примесей. Турбулентность оказывает влияние не только
на плазму, но и на плотность нейтралов, то есть на результат инжекции крупинки. Параметры плазмы в SOL
зависят от турбулентности на границе плазмы. Исследованы свойства плазмы в стабильном состоянии и при
появлении МГД-колебаний. Появление острова 3/2 оказывает влияние на плазменный поток.
Перспективными представляются результаты, указывающие на возможность контроля Альфвеновских мод
при ЭЦР-нагреве и магнитной конфигурации изменением вращательного преобразования и величиной
магнитной ямы.
Стаття присвячена впливу 3D-геометрії на перенос та контроль стану плазми в стеллараторі TJ-II.
Збільшення ролі неокласичного переносу (НС) і поява радіального електричного поля впливає на результат
інжекції крупинок та перенос домішок. Турбулентність впливає не тільки на плазму, але й на густину
нейтралів, що з’являються в результаті інжекції крупинки. Параметри плазми в SOL залежать від
турбулентності на границі плазми. Вивчено властивості плазми у стабільному стані та при появі МГД-
коливань. Плазмовий потік змінюється при появі острова 3/2. Здається, що результати, яки вказують на
можливість контролю Альфвенівських мод при ЭЦР-нагріві та магнітної конфігурації зміною обертального
перетворення і величини магнітної ями є перспективними.
|
| issn |
1562-6016 |
| url |
https://nasplib.isofts.kiev.ua/handle/123456789/115226 |
| citation_txt |
Transport and plasma control in the Tj-Ii stellarator / F. Castejón and the TJ-II team and collaborators // Вопросы атомной науки и техники. — 2016. — № 6. — С. 9-14. — Бібліогр.: 15 назв. — англ. |
| work_keys_str_mv |
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| first_indexed |
2025-11-26T02:59:33Z |
| last_indexed |
2025-11-26T02:59:33Z |
| _version_ |
1850609570038153216 |
| fulltext |
ISSN 1562-6016. ВАНТ. 2016. №6(106)
PROBLEMS OF ATOMIC SCIENCE AND TECHNOLOGY. 2016, № 6. Series: Plasma Physics (22) p. 9-14. 9
TRANSPORT AND PLASMA CONTROL IN THE TJ-II STELLARATOR
F. Castejón and the TJ-II team and collaborators
Laboratorio Nacional de Fusión, CIEMAT, Madrid, Spain;
Institute of Plasma Physics of the NSC KIPT, Kharkov, Ukraine;
Institute of Nuclear Fusion, RNC Kurchatov Institute, Moscow, Russia;
A.F. Ioffe Physical Technical Institute, St Petersburg, Russia;
General Physics Institute, Moscow, Russia;
IPFN, Lisbon, Portugal;
Kyoto University, Japan;
Max-Planck-Institut fur Plasmaphysik, Greifswald, Germany;
NIFS, Japan; Universidad Carlos III, Madrid, Spain;
University of California-San Diego, USA;
BIFI, Universidad de Zaragoza, Spain. SWIF, Chengdu, China
E-mail: francsico.castejon@ciemat.es
This paper shows the effect of 3D geometry on transport and plasma control in the TJ-II stellarator. The fuelling
and impurity transport are affected due to the enhancement of neoclassical (NC) transport and subsequent onset of a
radial electric field. Turbulence affects not only plasma but also neutral density, with effects on the fuelling. SOL is
shown to be affected by plasma edge turbulence. The properties of stability and MHD modes are also explored. The
plasma flow is shown to be affected by 3/2 magnetic island. Promissing experimental results show the possibility of
controlling Alfvén modes by ECRH, and magnetic configuration by rotational transform and magnetic well scans.
PACS: 52.55.Hc; 52.70.-m; 52.35.-g
INTRODUCTION
Stellarator devices are ideally suited to study the
relation between 3D magnetic topology, electric fields
and transport. This is a relevant topic not only for
stellatarors, but for tokamaks. The break of
axisymmetry implies the enhancement of NC transport,
with the subsequent onset of an ambipolar electric field,
and the strong modification of the dispersion relation of
waves in the plasma. The TJ-II heliac is used to explore
those effects in this work taking advantage of its flexible
magnetic configuration. Recent improvements in TJ-II
plasma diagnostics, including the operation of a dual
Heavy Ion Beam Probe (HIBP) and a pellet injection
system, have allowed us to get a better understanding of
plasma confinement properties. The duplication of the
HIBP system enables the measurements in two distant
toroidal planes [1].
1. IMPURITY TRANSPORT
Impurity accumulation is a key open issue in
stellarators and in more general 3D geometries.
Nevertheless, impurity accumulation is prevented in
some experiments: in the impurity hole regime in LHD
[2] and in the HDH mode in Wendelstein 7-AS [3].
Theoretical models predict that impurity transport is
affected by the variations of the first order NC electric
potential on the flux surface, Φ1, or potential
asymmetries, showing that impurity confinement can be
reduced in comparison with that of bulk ions for given
values of the potential asymmetries. Variations of Φ1
and its impact on impurities have been further studied.
A comparison across devices (TJ-II, W7-X and LHD)
have shown that [4]: the spectrum of Φ1 its coupling
with the distribution function of the impurities and the
resulting transport level is highly sensitive to the
parameters considered; the impact of Φ1 can result in a
mitigation or enhancement of the inward impurity flow.
This is clear in the LHD cases where both situations are
presented (Figs. 1 and 2). W7-X exhibits low potential
variations and impact on impurity transport. Regarding
TJ-II, Φ1 is found to be the largest at similar
collisionalities. This supports the suitability of TJ-II for
the measurement of Φ1 and study of its impact on the
impurity behaviour.
Fig. 1. Ratio eΔΦ1 /T as a function of the normalized
collision frequency
mailto:francsico.castejon@ciemat.es
10 ISSN 1562-6016. ВАНТ. 2016. №6(106)
.
Fig. 2. Radial particle flux of CVI in LHD normalized to
the density, with and without Φ1
Experimental studies searching for asymmetries
have thrown direct observations of electrostatic
potential variations within the same magnetic flux
surface [5] in TJ-II. Significant asymmetries observed in
electron-root wave-heated plasmas are reduced in ion-
root NBI-heated conditions. The observed Φ1 is of tens
of volts, in agreement with NC Monte Carlo
calculations.
Fig. 3. Long Range correlation (LRC) of potential
Significant progress has been made regarding the
understanding of empirical actuators, such as ECRH
heating, to avoid core impurity accumulation. These
results were obtained using the two HIBP systems
located at two different toroidal ports separated by 90
0
.
Experiments with combined NBI and ECR heating have
shown direct experimental evidence of the influence of
ECRH on turbulent mechanisms, increasing both the
level of fluctuation and the amplitude of Long-Range-
Correlations (LRC), as a proxy of Zonal Flows (ZFs) for
potential fluctuations (Fig. 3) but not for density and
poloidal magnetic fluctuations (not shown). Whereas
ECRH influences the level of fluctuations in a wide
range of plasma densities, ECRH induced reversal of
the NC Er has been observed only in low-density
plasmas.
2. PLASMA FUELLING AND NEUTRAL
DYNAMICS
Core density control is a critical issue on the path
towards the development of steady- state scenarios in
3-D devices. First core plasma fuelling experiments,
using a cryogenic pellet injector system have been
performed in TJ-II, which has enabled particle fuelling
and transport experiments [6].
Fig. 4. Electron density and temperature profiles before
the pellet injection (BI, #39063), immediately after the
pellet injection (AI, #39062), and long after the pellet
injection (LAI, #39065)
A small pellet is injected at an intermediate radial
position and density evolution is measured with
Thomson Scattering and interferometry. A density
increase due to ablation is initially observed outside the
core moving inwards and reducing with time. Finally,
we observe a core density increase after the complete
ablation of the pellet, a phenomenon that has been
described using NC simulations with DKES code
(Fig. 4). This phenomenon, if extensible to other helical
devices, is of prime relevance: it would mean that
pellets that do not reach the magnetic axis may still be
able to mitigate core density depletion.
Pellet injection has been used also to perturb the
plasma equilibrium potential and to study the
subsequent relaxation. A sudden perturbation of the
plasma equilibrium is induced by the injection of a
cryogenic hydrogen pellet in the TJ-II stellarator,
followed by a damped oscillation in the electrostatic
potential, which is observed for the first time [7]. The
ISSN 1562-6016. ВАНТ. 2016. №6(106) 11
waveform of the relaxation is consistent with the
gyrokinetic (GK) theory.
Usually, fuelling simulations assume a cloud
distribution of neutrals, given by the puffing
characteristics. Here, we explore the possible response
of neutrals to plasma turbulence, which could modify
fuelling properties. With this aim, the helium line-ratio
technique was applied with a spectroscopic high-speed
camera set-up looking to the emission of helium puffed
close to the separatrix. In this way, we obtain the two-
dimensional image of the edge plasma electron density
with a few millimetres spatial resolution and exposure
times down to 15 μs. This technique allows us to
measure the turbulent coherent electron density-
structure of Blobs that have been compared with the raw
helium emission. The differences between plasma
density and raw emission structures can gives insight on
the neutral distribution, showing indications of thermal
neutrals react to the plasma fluctuations becoming also
turbulent at frequencies of 10…100 kHz, with
dimensions of one to several centimetres. The
responsible mechanism to bring neutrals spatially and
temporally inhomogeneous would be the turbulent local
electron impact ionization by the plasma Blobs and
Holes [8]. This can substantially modify the fuelling
properties.
Another key topic for fuelling is whether anomalous
transport driven at the plasma edge influences the
scrape-off layer (SOL) width. Experiments in the TJ-II
Stellarator and have found that the SOL density profile
is affected by the structure of edge radial electric fields
and fluctuations. It is concluded that SOL profiles are
coupled with edge plasma parameters.
3. INNOVATIVE POWER EXHAUST
SCENARIOS AND PFCs
Novel solutions for plasma facing components based
on the use of liquid metals like Li and SnLi alloys have
been developed. The TJ-II program on liquid metals
addresses fundamental issues like the self-screening
effect of liquid Li driven by evaporation to protect
plasma-facing components against huge heat loads and
tritium inventory control, using recently installed Li and
SnLi liquid limiters (LLL). Biasing of Li limiters with
respect to carbon ones has evidenced the important role
of the secondary electron emission of plasma-exposed
surfaces in the development of enhanced confinement
modes. Very recently, LiSn alloys have been exposed to
TJ-II plasmas in a Capillary Porous System (CPS). The
evolution Zeff during the discharge shows that the
influx of impurities in the plasma is very small. The
main results obtained are:
- H retention values of ~ 0.01 % H/(Sn+Li) at T<
450º C were deduced from Thermal Desorption
Spectroscopy (TDS) at the laboratory in agreement with
previous reports and in situ TDS in TJ-II.
- Insertion of a LiSn sample into the edge of TJ-II
does not lead any significant perturbation of the plasma
parameters. Zeff values typically below 1.5 and very
low Prad/Pin values (< 2 %) were deduced.
- Conversely, plasma operation became impossible if
the alloy is directly deposited on the SS support.
- Only Li emission was detected. No traces of Sn
were detected by visible and UV spectroscopy.
- H recycling did not evolve with temperature.
These results provide good perspectives for use of
LiSn alloys as a PFC in a Reactor.
As a further example of the beneficial effect of Li
coating, we achieved plasma start up in TJ-II under
lithium coated walls using only NBI, without the help of
any other external power supply. This has been
achieved despite the large shine through in the phase of
plasma creation.
4. PLASMA STABILITY STUDIES
Experiments on TJ-II have shown that stability at
high beta values is better than predicted by Mercier
criterion linear stability analyses. One of the
possibilities offered by TJ-II flexibility is to change the
magnetic well keeping the same rotational transform
profile. It has been shown that a reduction of magnetic
well has a direct impact on fluctuations without
reducing plasma confinement drastically [9]. In fact,
confinement time depends more on NC effects and on
the size of the configuration (Fig. 5) than on magnetic
well. This result suggests that Mercier stability
calculations are missing some stabilization mechanisms,
which could be explained by self-organization
mechanisms involving transport and gradients. The
effect of the magnetic well scan on electromagnetic
modes has also been studied, showing consequences on
the onset of Geodesic Acoustic Modes (GAMs) and on
the Alfvén Eigenmode (AE) properties [10], as will be
shown in Section 7.
Fig. 5. Energy confinement times for three values of the
plasma density and the values of the magnetic well.
Those configurations with negative magnetic value
should be unstable
GAMs are relevant for confinement, given their
interaction with broadband turbulence and fast particles,
and they are expected to be strongly damped in TJ-II.
The latter reason implies that GAMs must be driven
steadily to overcome the damping [11]. In the former
case, energetic ions can act as a driver, giving rise to
EGAMs. On top of this driver, EGAMs have been also
identified with fast electrons acting as a driver in TJ-II
plasmas [12].
12 ISSN 1562-6016. ВАНТ. 2016. №6(106)
5. MOMENTUM TRANSPORT
TJ-II has provided clear evidence that three-
dimensional magnetic structures have a significant
impact on plasma confinement and L-H transitions. We
have performed experiments on the effect of magnetic
islands on the plasma perpendicular flow and density
turbulence. Doppler reflectometry have been used to
study the plasma flow in Ohmically induced magnetic
configuration scans, which changed the rotational
transform profile and the location of the rational values
of the rotational transform [13]. A characteristic
signature of the 3/2 magnetic island as it crosses the
Doppler reflectometer measurement position is clearly
detected, showing a modulation in the perpendicular
flow that changes twice its direction. The perpendicular
flow reverses at the centre of the magnetic island and a
flow shear develops at the island boundaries. An
example is shown in Fig. 6, where the 3/2 magnetic
island, in its way from the plasma centre to the plasma
edge, crosses the Doppler reflectometer measurement
region, showing a change in the turbulence (b), a
inversion in the flux (c) when the net plasma current is
about -5 kA (d). These observations could explain the
link between magnetic islands and transport barriers in
fusion devices.
3
Influence of the 3/2 magnePc island on perpendicular flow
The change in the flow
measured in the Pme
interval t 1140 - 1170 ms,
represents a characterisPc
signature of the magnePc
island as it crosses the DR
measurement posiPon
Fig. 6. Time evolution of line density (a), spectrograms
of turbulence measured by DR (b) perpendicular flows
measured by DR (c) and plasma current (d)
6. CONTROLLING FAST ION
CONFINEMENT
The study and control of AEs is basic in plasma
devices given the influence of these modes on fast ion
confinement. Here we explore several mechanisms to
control and mitigate AEs. The HIBP diagnostic is
capable to measure simultaneously the oscillations of
plasma electric potential, density and poloidal magnetic
field and the Mirnov coils can measure the magnetic
fluctuations.
Fig. 7. Evolution with spectrogram with iota, which
varies with time in a single discharge. Chirping appears
always for the same values of iota
First of all, ECRH was applied on NBI-heated
discharges of TJ-II. A change from steady to chirping
frequency or even to a mitigation of the AEs was
observed [14]. As the ECRH power increases (power
scan from 80 to 225 kW), the amplitude of produced
chirping AE mode increases while the bursts periodicity
becomes more regular. HIBP measurements show that
the chirping mode has a ballooning structure in plasma
potential but an anti-ballooning structure in Bpol.
Beyond ECRH, configuration scan appears as another
tool for AE control. Fig. 7 shows the time traces of the
evolution of the mode spectrum as the rotational
transform varies during the configuration scan. The
chirping appears always for the same values of
rotational transform (marked with stripes) [15]. On top
of the rotational transform, we explore the effect of the
magnetic scan on AEs, which opens new ways to
control such modes and, hence, their effect on fast ion
confinement.
The importance of distinguishing chirping from
steady behaviour relies on the different effect of the
mode on fast ion confinement. We use the fast neutral
flux, measured by the Compact Neutral Particle
Analyser (CNPA), as a proxy for the fast ion density, so
the larger the CNPA flux the larger the fast ion
concentration. Hence, we can compare the fast ion
confinement of different experiments by comparing the
CNPA spectra: in case that the fast ion source is the
same, the larger the fast neutral spectrum the larger the
fast ion confinement. Fig. 8 shows that the CNPA
spectra for three cases: steady, chirping and mitigated
AEs. It is seen that the confinement is better in the cases
with chirping and mitigated AE than in the one with
steady AE.
We have also investigated the influence of magnetic
ISSN 1562-6016. ВАНТ. 2016. №6(106) 13
well on AEs properties, taking advantage of the TJ-II
flexibility. We have found a strong influence of this
parameter on AEs on both, frequency, mode number
and amplitude of the mode. The complexity of
dispersion relation in TJ-II provokes such a strong
change in the mode properties. In particular, it is
observed that the frequency of the destabilised modes is
decreasing with the magnetic well, which allows one to
change the population of resonant ions: the lower the
magnetic well the lower the frequency for similar
plasma densities. One expects that the energy of the
resonant ions is lower in the case of lower AE
frequencies.
Fig. 8. shows that the CNPA spectra for three cases:
steady, chirping and mitigated AEs, demonstrating a
better confinement for the chirping case
CONCLUSIONS
The influence of 3D geometry on confinement
physics has been explored taking advantage of the TJ-II
flexibility. The break of axisymmetry causes that NC
transport is not automatically ambipolar, giving rise to
the onset of a radial electric field, which has strong
influence on particle transport and fuelling. The first
order NC theory predicts the existence of asymmetries
on the magnetic surfaces, which have been observed
experimentally in TJ-II, and can have strong influence
on impurity transport form both NC and turbulent
approaches.
We have shown core depletion density can be
overcome by injecting a pellet, even it is ablated before
reaching the plasma centre. Pellet injection has also
allowed us to obtain for the first time a direct
observation of the electric field relaxation, with good
agreement with GK simulations. Another important
characteristic of the fuelling in TJ-II is the structure of
the neutrals that reflect the blobs that are found in
density turbulence. The coupling of the edge plasma
parameters with SOL density profiles has also influence
on fuelling as has been explored here. As the fuelling
experiments demonstrate, the plasma wall interaction in
TJ-II depends strongly on the 3D geometry and makes
TJ-II a well-suited laboratory to explore innovative
solutions for plasma facing components based on the
use of liquid metals like Li and SnLi alloys.
The 3D geometry has also strong effects on plasma
stability and turbulence. We have obtained stable
plasmas in theoretically Mercier-unstable
configurations. EGAMs driven by fast ions and also by
fast electrons are also detected and studied in TJ-II.
The plasma flow is affected by the magnetic island,
as can be directly measured by Doppler reflectometry.
The dispersion relation of AEs is also affected by the
3D geometry. In particular, we have shown that the
magnetic well is a governing parameter of the frequency
of the mode: the larger the well, the higher the
frequency. The rotational transform plays a key role in
the AEs properties: we have found the rotational
transform windows in which the mode presents a
chirping nature (without ECRH, used before for AE
control) and the ones in which its frequency varies
steadily, following plasma current and density. This
poses the magnetic configuration as another important
knob for controlling AEs and, hence, fast ion
confinement, beyond ECRH.
ACKNOWLEDGEMENTS
This work has been carried out within the
framework of the EUROfusion Consortium and has
received funding from the Euratom research and
training programme 2014-2018 under grant agreement
No 633053. The views and opinions expressed herein
do not necessarily reflect those of the European
Comission.
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Article received 19.10.2016
ПЕРЕНОС И КОНТРОЛЬ СОСТОЯНИЯ ПЛАЗМЫ В СТЕЛЛАРАТОРЕ TJ-II
F. Castejón and the TJ-II team and collaborators
Статья посвящена влиянию 3D-геометрии на перенос и контроль состояния плазмы в стеллараторе
TJ-II. Усиление роли неоклассического переноса (НС) и возникновение радиального электрического поля
влияет на результат инжекции крупинок и перенос примесей. Турбулентность оказывает влияние не только
на плазму, но и на плотность нейтралов, то есть на результат инжекции крупинки. Параметры плазмы в SOL
зависят от турбулентности на границе плазмы. Исследованы свойства плазмы в стабильном состоянии и при
появлении МГД-колебаний. Появление острова 3/2 оказывает влияние на плазменный поток.
Перспективными представляются результаты, указывающие на возможность контроля Альфвеновских мод
при ЭЦР-нагреве и магнитной конфигурации изменением вращательного преобразования и величиной
магнитной ямы.
ПЕРЕНОС ТА КОНТРОЛЬ ЗА СТАНОМ ПЛАЗМИ В СТЕЛАРАТОРІ TJ-II
F. Castejón and the TJ-II team and collaborators
Стаття присвячена впливу 3D-геометрії на перенос та контроль стану плазми в стеллараторі TJ-II.
Збільшення ролі неокласичного переносу (НС) і поява радіального електричного поля впливає на результат
інжекції крупинок та перенос домішок. Турбулентність впливає не тільки на плазму, але й на густину
нейтралів, що з’являються в результаті інжекції крупинки. Параметри плазми в SOL залежать від
турбулентності на границі плазми. Вивчено властивості плазми у стабільному стані та при появі МГД-
коливань. Плазмовий потік змінюється при появі острова 3/2. Здається, що результати, яки вказують на
можливість контролю Альфвенівських мод при ЭЦР-нагріві та магнітної конфігурації зміною обертального
перетворення і величини магнітної ями є перспективними.
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