Latest physics results of TJ-II flexible heliac
This paper is devoted to the presentation of the most relevant recent Physics results obtained in the TJ-II flexible heliac. Firstly ECRH modulation and plasma breakdown studies are summarised; then the particle control techniques used to obtain reproducible discharges with density under control are...
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| Опубліковано в: : | Вопросы атомной науки и техники |
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| Дата: | 2000 |
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Національний науковий центр «Харківський фізико-технічний інститут» НАН України
2000
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| Цитувати: | Latest physics results of TJ-II flexible heliac / F. Castejón, C. Alejaldre, J. Alonso, L. Almoguera, E. Ascasíbar, A. Baciero, R. Balbín, M. Blaumoser, J. Botija, B. Brañas, E. de la Cal, A. Cappa, R. Carrasco, J.R. Cepero, C. Cremy, J. Doncel, S. Eguilior, T. Estrada, A. Fernández, C. Fuentes, A. García, I. García-Cortés, J. Guasp, J. Herranz, C. Hidalgo, J.A. Jiménez, I. Kirpitchev, V. Krivenski, I. Labrador, F. Lapayese, K. Likin, Liniers, A. López-Fraguas, A. López-Sánchez, E. de la Luna, R. Martín, L. Martínez-Laso, M. Medrano, P. Méndez, K.J. McCarthy, F. Medina, B. van Milligen, M. Ochando, L. Pacios, I. Pastor, M.A. Pedrosa, A. de la Peña, A. Portas, J. Qin, L. Rodríguez-Rodrigo, A. Salas, E. Sánchez, J. Sánchez, F. Tabarés, D. Tafalla, V. Tribaldos, J. Vega, B. Zurro // Вопросы атомной науки и техники. — 2000. — № 6. — С. 3-7. — Бібліогр.: 16 назв. — англ. |
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Digital Library of Periodicals of National Academy of Sciences of Ukraine| _version_ | 1859915077435523072 |
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| author | Castejón, F. Alejaldre, C. Alonso, J. Almoguera, L. Ascasíbar, E. Baciero, A. Balbín, R. Blaumoser, M. Botija, J. Brañas, B. de la Cal, E. Cappa, A. Carrasco, R. Cepero, J.R. Cremy, C. Doncel, J. Eguilior, S. Estrada, T. Fernández, A. Fuentes, C. García, A. García-Cortés, I. Guasp, J. Herranz, J. Hidalgo, C. Jiménez, J.A. Kirpitchev, I. Krivenski, V. Labrador, I. Lapayese, F. Likin, K. Liniers, M. López-Fraguas, A. López-Sánchez, A. de la Luna, E. Martín, R. Martínez-Laso, L. Medrano, M. Méndez, P. McCarthy, K.J. Medina, F. van Milligen, B. Ochando, M. Pacios, L. Pastor, I. Pedrosa, M.A. de la Peña, A. Portas, A. Qin, J. Rodríguez-Rodrigo, L. Salas, A. Sánchez, E. Sánchez, J. Tabarés, F. Tafalla, D. Tribaldos, V. Vega, J. Zurro, B. |
| author_facet | Castejón, F. Alejaldre, C. Alonso, J. Almoguera, L. Ascasíbar, E. Baciero, A. Balbín, R. Blaumoser, M. Botija, J. Brañas, B. de la Cal, E. Cappa, A. Carrasco, R. Cepero, J.R. Cremy, C. Doncel, J. Eguilior, S. Estrada, T. Fernández, A. Fuentes, C. García, A. García-Cortés, I. Guasp, J. Herranz, J. Hidalgo, C. Jiménez, J.A. Kirpitchev, I. Krivenski, V. Labrador, I. Lapayese, F. Likin, K. Liniers, M. López-Fraguas, A. López-Sánchez, A. de la Luna, E. Martín, R. Martínez-Laso, L. Medrano, M. Méndez, P. McCarthy, K.J. Medina, F. van Milligen, B. Ochando, M. Pacios, L. Pastor, I. Pedrosa, M.A. de la Peña, A. Portas, A. Qin, J. Rodríguez-Rodrigo, L. Salas, A. Sánchez, E. Sánchez, J. Tabarés, F. Tafalla, D. Tribaldos, V. Vega, J. Zurro, B. |
| citation_txt | Latest physics results of TJ-II flexible heliac / F. Castejón, C. Alejaldre, J. Alonso, L. Almoguera, E. Ascasíbar, A. Baciero, R. Balbín, M. Blaumoser, J. Botija, B. Brañas, E. de la Cal, A. Cappa, R. Carrasco, J.R. Cepero, C. Cremy, J. Doncel, S. Eguilior, T. Estrada, A. Fernández, C. Fuentes, A. García, I. García-Cortés, J. Guasp, J. Herranz, C. Hidalgo, J.A. Jiménez, I. Kirpitchev, V. Krivenski, I. Labrador, F. Lapayese, K. Likin, Liniers, A. López-Fraguas, A. López-Sánchez, E. de la Luna, R. Martín, L. Martínez-Laso, M. Medrano, P. Méndez, K.J. McCarthy, F. Medina, B. van Milligen, M. Ochando, L. Pacios, I. Pastor, M.A. Pedrosa, A. de la Peña, A. Portas, J. Qin, L. Rodríguez-Rodrigo, A. Salas, E. Sánchez, J. Sánchez, F. Tabarés, D. Tafalla, V. Tribaldos, J. Vega, B. Zurro // Вопросы атомной науки и техники. — 2000. — № 6. — С. 3-7. — Бібліогр.: 16 назв. — англ. |
| collection | DSpace DC |
| container_title | Вопросы атомной науки и техники |
| description | This paper is devoted to the presentation of the most relevant recent Physics results obtained in the TJ-II flexible heliac. Firstly ECRH modulation and plasma breakdown studies are summarised; then the particle control techniques used to obtain reproducible discharges with density under control are presented. Transport studies show internal heat transport barriers that reduce heat conductivity to neoclassical values, and ELM-like transport events, similar to those observed in tokamaks and in other stellarators before and during H mode transition. Evidence of ExB sheared has been observed both in the proximity of rational surfaces. Finally, a high resolution Thomsom Scattering system has shown Te and ne profile structures.
|
| first_indexed | 2025-12-07T16:04:11Z |
| format | Article |
| fulltext |
UDC 533.9
Problems of Atomic Science and Technology. 2000. № 6. Series: Plasma Physics (6). p. 3-7 3
LATEST PHYSICS RESULTS OF TJ-II FLEXIBLE HELIAC
F. Castejón, C. Alejaldre, J. Alonso, L. Almoguera, E. Ascasíbar, A. Baciero, R. Balbín,
M. Blaumoser, J. Botija, B. Brañas, E. de la Cal, A. Cappa, R. Carrasco, J. R. Cepero,
C. Cremy, J. Doncel, S. Eguilior, T. Estrada, A. Fernández, C. Fuentes, A. García, I. García-
Cortés, J. Guasp, J. Herranz, C. Hidalgo, J. A. Jiménez, I. Kirpitchev, V. Krivenski,
I. Labrador, F. Lapayese, K. Likin, M. Liniers, A. López-Fraguas, A. López-Sánchez, E. de la
Luna, R. Martín, L. Martínez-Laso, M. Medrano, P. Méndez, K.J. McCarthy, F. Medina,
B.van Milligen, M. Ochando, L. Pacios, I. Pastor, M.A. Pedrosa, A. de la Peña, A. Portas,
J.Qin, L. Rodríguez-Rodrigo, A. Salas, E. Sánchez, J. Sánchez, F. Tabarés, D. Tafalla,
V.Tribaldos, J. Vega and B. Zurro
Laboratorio Nacional de Fusión por Confinamiento Magnético
Asociación EURATOM-CIEMAT. Av. Complutense, 22. 28040 Madrid, Spain
This paper is devoted to the presentation of the most relevant recent Physics results obtained in the TJ-II flexible
heliac. Firstly ECRH modulation and plasma breakdown studies are summarised; then the particle control techniques
used to obtain reproducible discharges with density under control are presented. Transport studies show internal heat
transport barriers that reduce heat conductivity to neoclassical values, and ELM-like transport events, similar to
those observed in tokamaks and in other stellarators before and during H mode transition. Evidence of ExB sheared
has been observed both in the proximity of rational surfaces. Finally, a high resolution Thomsom Scattering system
has shown Te and ne profile structures.
1. TJ-II DESCRIPTION
The Flexible Heliac TJ-II1 is a four period low magnetic
shear stellarator with major radius R = 1.5 m, average
minor radius a < 0.22 m, and magnetic field on axis
B0 ≤ 1.2 T. Varying the currents of the central circular
and helical coils allows one to vary the magnetic
configuration, reaching a wide interval of iota values
(iota ≈ 1.28 – 2.24) and plasma indentations and sizes
(plasma volumes ≈ 0.6 – 1.1 m3). The project was
granted EURATOM preferential support phase II in
November 89. At the end of 1996, the magnetic surfaces
mapping was successfully conducted through, giving a
good agreement between the calculated and the
measured magnetic surfaces2. [2] and the first plasma
was produced in December 1997. TJ-II started operation
in 1998 and the plasmas are created and heating by EC
waves launched by two gyrotrons, of 300 kW each, at X
mode and 2nd harmonic. Two ECRH transmission lines,
called QTL1 and QTL2, with different steering
launching capabilities (fix for QTL1 vs. poloidal and
toroidal variation in QTL2), with different power
deposition profiles and, hence, absorbed power densities
(1 in QTL1 vs. 15 W/cm3 for on-axis heating of the
narrower beam line of QTL2). Presently two Neutral
Beam Injectors (PNBI ≤ 3MW) are under installation.
Stationary plasmas during the whole gyrotron pulse (≤
0.3 s) with stored energies up to 1.3 kJ and 1.5 keV
central electron temperature are routinely achieved.
Both helium and hydrogen fuelled plasmas have been
investigated and the most recent physical results are
discussed in this paper.
2. ECRH EXPERIMENTS
A variety of experiments based on the capability of the
ECRH system can be performed. For the moment, the
results of plasma breakdown studies and power
modulation experiments are available. The system for
the TJ-II stellarator consists of two gyrotron oscillators
at 53.2 GHz, which corresponds to the second harmonic
of the electron cyclotron frequency. Each gyrotron can
deliver 300 kW of microwave power at the output
window and the pulse length is up to 1 s.
Fig.1. Power deposition profile obtained from
modulation experiments compared with ray tracing
calculations
The gyrotrons are driven by two anode modulators,
whose voltage can be modulated up to 50 kHz. Fast
modulation experiments has been performed to obtain
the power deposition profile of QTL2 line. The
modulation frequency is 5 kHz and the Fourier analysis
of ECE signal is able to register the modulation up the
3rd channel of ECE system. It is observed that the
power deposition profile is wider than the predicted by
the ray tracing calculations (see Fig. 1).
A kinetic model that takes into account the full
ionisation chain has been developed to simulate plasma
start-up by microwaves at 2nd harmonic of electron
cyclotron frequency. The model considers the particle
balance equations of the species that takes part in all the
considered processes. A good agreement between the
model predictions and the experimental data is
obtained3.
4
3. PARTICLE CONTROL AND WALL
CONDITIONING
In order to get reproducible and controlled discharges
under full ECH power injection, new gas control and
wall conditioning techniques have been implemented.
The initial procedure of wall conditioning during 1998
and 1999 campaigns was He glow discharge cleaning
(GDC) at room temperature during overnight periods
between operation days4. The main effects of this
procedure in TJ-II are to remove the hydrogen
implanted on the walls by plasma discharges and to
produce an activated surface with a typical wall
pumping behaviour. The last effect is deduced from the
decrease of the residual pressure about 10-20% after the
He GDC and from the residual gas analyser (RGA)
measurements. The improvement of the base pressure
achieved by decreasing the residual water (baking of the
chamber followed by He GDC) has had an important
effect over the reproducibility of the TJ-II discharges.
This is due to the suppression of sources of electrons
than can be accelerated during the rise of the current in
the magnetic coils. During the 1999 campaign, density
control for high ECRH injected power (higher than 300
kW) was still extremely difficult. The reason was that
He implanted on the wall during the previous GDC
conditioning was desorbed during the plasma discharge
producing uncontrolled increase of plasma density5 . As
the intensive He GDC seemed to be necessary in TJ-II in
order to have reproducible discharges, an additional
procedure for removing the implanted He from the walls
before plasma operation was required. With this aim,
during the 2000 campaign Ar GDC during ≤ 30 min.
prior to the TJ-II operation and after the overnight He
GDC was applied. The release of He atoms from the
walls by Ar bombardment has been measured. The
integration of the released fluxes during the 30 min of
the cleaning discharge yields a total amount of desorbed
He of about 1021 He-atoms corresponding to ~1 mono-
layer of the TJ-II vacuum chamber (S=75 m2). The
depletion of this He amount is enough to allow the
operation of TJ-II under high injected power and density
control by external gas puffing6. Low Z effective values
(1.5 to 2.5 in H plasmas and 3 to 4.5 in He plasmas) and
low radiated power (< 20% of injected power)7 are
typically achieved under all heating schemes applied in
the 2000 experimental campaign.
4. TRANSPORT AND TURBULENCE STUDIES
Electron heat diffusivity, obtained from power
modulation experiments and power balance analysis, is
about 4 m2/s in the plasma core region and increases
when approaching the plasma boundary region8.
Measurements of electron temperature profiles using
electron cyclotron emission (ECE) and Thomson
scattering diagnostics have shown evidence of internal
heat transport barriers in the TJ-II stellarator, as
illustrated in Fig. 2.a. Transport analysis shows a
reduction in transport coefficients to a transport rate
consistent with neoclassical predictions based on Monte
Carlo simulations9 (see Fig. 2.b). The cause of the
observed confinement enhancement could be that ripple
trapped electrons pumped out by ECRH may create a
sheared electric field and ExB decorrelation effects
could diminish the turbulent transport. Indeed, non-
Maxwellian features have been observed in electron
distribution functions over the 1-5 keV energy range,
which could be related to an ECRH induced
deformation of the distribution function.
a
0
2
4
6
8
10
0 0.05 0.1 0.15 0.2
X
e
(m 2
/s
)
reff (m)
b
Fig. 2. a: Thomson scattering (electron temperatre
and density) profiles of helium plasmas with 300 kW
injected power and different electron density. ECE
temperature profile (open squares in the top box) is
displayed for the low density case in which the ITB
appears; b: Electron heat diffusivities for a
discharge with a transport barrier (presents a
minimum) and one without barrier.
5
Fig. 3. Radial profile of ion temperature for the
100_44_64 configuration with 300 kW heating power
Charge exchange (CX) neutral particle energy spectra
have been measured with a 5-channel spectrometer in
hydrogen plasmas with line electron densities of 0.5-1.2
x 1019 m-3 and injected power P=200-600 kW.
Measurements were done near to the perpendicular
velocity distribution. The slope in the spectrum in the
range of energies 100-200 eV provides an ion
temperature, Ti, of 50-70 eV, whereas the same analysis
for fast atoms with energies above 250 eV provides a
temperature of 90 - 120 eV. The analyser scans a
poloidal cross section along a vertical line and is placed
in the cross section with the highest magnetic ripple,
ensuring that charge exchange analyser measures mainly
ion energy distribution of trapped particles. Radial Ti (r)
profile has been measured in the 100_44_64
configuration (central iota 1.551) and is shown in Fig. 3.
It can be fitted by the expression: Ti (r) = Ti (0) * [1-
r4]2.8.
ELM-like transport events have been measured in
plasmas with stored energies of about 1 kJ. The plasma
develops bursts of magnetic activity (observed in the
Mirnov coils), followed by a large spike in the Ha
signal10, as shown in Fig. 4. The electron temperature
measured by the ECE system shows a pivot point at the
plasma radius r ≈ 0.6 (where the temperature is in the
range of 100-200 eV). As a consequence, the electron
temperature profile flattens at this plasma position. This
flattening is due to an increase by a factor 2 of the
electron thermal diffusivity, caused by the triggering of
the ELM instability. These events are localised at the
pressure gradient region suggesting the possible role of
resistive ballooning instabilities. Edge parameters
(electron density and temperature) have been
investigated for a fixed magnetic configuration (named
100_40_63, with rotational transform at axis 1.509) in
both, H and He plasmas by means of He and Li atomic
beams and Langmuir probes11, as shown in Fig. 5.
Density and power scans have been conducted. No
significant differences in electron temperatures near the
last closed flux surface (LCFS) are seen as the power is
changed. In most cases, a high insensitivity of edge
characteristics to the operational parameters has been
found, such as constant edge density for central density
scan and constant edge temperatures for the power scan.
Fig. 4. Time traces of: (a) Ha signal, (b) Mirnov coil
signal and (c) ECE signals at four radial positions
showing ELM-like activity in TJ-II shot #2156
However, a systematic broadening of edge profiles with
P/ne has been observed. Scrape off layer (SOL) particle
e-folding lengths have been also recorded, allowing the
evaluation of diffusion coefficients (D) and global
particle confinement times (tp) under the assumption of
no strong asymmetries. D values of the order of DBohm
and tp values ranging from 14 to 3 ms have been
obtained. A clear degradation of particle confinement
with injected power has been found, together with
indications of confinement enhancement with density.
TJ-II has a large value of edge magnetic ripple (about
35% for the standard configuration). As a consequence
relatively large fractions of trapped particles and
enhanced energy and particle losses should be expected
in the plasma boundary region12. This fact may explain
the particularly low densities and temperatures observed
in the plasma boundary. Experimental evidence of ExB
sheared flows linked to rational surfaces has been
obtained in the plasma edge region of the TJ-II for
different magnetic configurations13. The presence of the
4/2 rational surface, predicted by vacuum magnetic field
calculations, can be detected by two clear footprints, as
shown in Fig. 6: the flattening in the edge profiles and
the modification in the root mean squared (rms) of
floating potential fluctuations. The measured correlation
time of fluctuations (10 ms) turns out to be comparable
to the inverse of the ExB decorrelation rate, suggesting
the possible role of rational surfaces to access high
confinement regimes. The resulting ExB sheared flows
associated to rational surfaces would depend on the
competition between mechanisms driving flows (i.e.
6
Reynolds stress, ambipolar electric field due to ion-
electron fluxes differences) and damping flow processes
(i.e. magnetic viscosity).
Fig. 5. Edge density profiles measured measured by
means of Li atomic beam in He (top) and H (bottom)
plasmas. The numbers inside the boxes indicate, for
each profile, the ECRH heating power (in kW) and the
line average density (in units of 1019 m-3), respectively
In order to investigate transport characteristics close to
instability thresholds, the radial profile of ion saturation
current and floating potential and their fluctuations has
been measured in magnetic configurations with the same
rotational transform (iota (a) ≈ 1.8), but whose magnetic
well ranges from 0.2 % to 2 %. The level of fluctuations
at the plasma boundary increases in the plasma
configuration with magnetic hill in the plasma edge. The
increase in the fluctuation level is due to fluctuations in
the frequency range (1-30 kHz). Interestingly, the
breaking point in the frequency spectra (i.e. 1/f region)
is directly related with the level of fluctuations. These
experimental results show the important role of
magnetic well in stabilising pressure gradient
instabilities in the TJ-II stellarator and open the
possibility of investigating the properties of turbulent
transport in the proximity of instability thresholds14.
5. PROFILE STRUCTURES IN TJ-II
Fine structures are found in the TJ-II electron
temperature and density profiles15 (see Fig. 7), when
they are measured using a high spatial resolution
Thomson scattering system. These structures consist in
peaks and valleys superimposed to a smooth average.
Fig. 6. Effects of the 4/2 rational surface in the plasma
edge region. Top to bottom: Radial profiles of the ion
saturation current, the floating potential and the r.m.s.
of the floating potential
Some irregularities remain in an ensemble average of 15
reproducible discharges with similar macroscopic
parameters like line density, central temperature, and
plasma current. They are found in all the magnetic
configurations explored in plasmas heated by electron
cyclotron waves. Their possible origin is under study,
but three lines of though are considered. Firstly, the
effects related to magnetic topology of the device,
namely iota profile and resonant surfaces. The fact that
some features in the profiles survive to an ensemble
average of the series of reproducible discharges would
reinforce this theory. However, in order to extract clear
conclusions about whether or not the rational surfaces,
even the high order ones, have any influence on the
profiles, a detailed knowledge of the plasma current
profile is needed. Secondly, the structures can be
another manifestation of the wide band plasma
turbulence detected by other diagnostics, like Mirnov
coils and ECE system. Finally, kinetic effects induced
by high power density microwaves seem to be able to
enhance the structure amplitude.
7
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Fig. 7. Electron temperature and density profiles in
TJ-II
Measurement of the wave number spectra in fusion
devices is difficult due to the fact that spatially resolved
information is required. A comparative study of the
wave number spectra obtained using both a high-
resolution Thomson scattering system (core plasma
region) and Langmuir probes (edge region) is under
way. The (radial) wave number spectra show a
remarkable similarity in shape, which does not appear to
depend significantly on either measuring technique,
plasma region or plasma conditions. Specifically, the
wave number spectra obtained from Thomson scattering
are similar to wave number spectra obtained in various
devices using different techniques, indicating that the
detailed structure observed in the density and
temperature16
Fig. 8. Wave number spectra of Temperature profile
structures for 20 accumulated shots
References
1C. Alejaldre et al., Plasma Phys. Control. Fusion 41
(1999) B109
2 E. Ascasíbar et al., J. Plasma Fusion Res. SERIES 1,
(1998) 183-186
3 A. Cappa et al., “Plasma breakdown by ECRH at 2nd
harmonic in TJ-II”, submitted to Nuclear Fusion.
4F.L. Tabarés et al., J. Nucl. Mater. 266-269 (1999)
1273-1278
5 D. Tafalla et al., Wall conditioning and density control
in TJ-II stellarator, Proc. 14th Int. Conf. on Plasma
Surface Interactions, Rosenheim, Germany 2000. To
appear in J. Nucl. Mater.
6 K. J. McCarthy et al., Impurity behaviour studies in the
TJ-II Stellarator, Proc. 27th EPS Conf. on Controlled
Fusion and Plasma Physics, Budapest 2000. To appear.
7 E. Ascasíbar et al., Magnetic configuration dependence
of the plasma energy content in TJ-II stellarator, Proc.
27th EPS Conf. on Controlled Fusion and Plasma
Physics, Budapest 2000. To appear.
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plasmas, Proc. 12th IAEA International Stellarator
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ROM)
9 F. Castejón et al., Internal heat transport barriers in TJ-
II flexible heliac, submitted to Nuclear Fusion.
10 I. García-Cortés et al., ELM-like transport events in
TJ-II stellarator, to be published in Nuclear Fusion.
11 F.L. Tabarés et al., Edge transport characterisation of
hydrogen and helium plasmas in the TJ-II stellarator,
Proc. 27th EPS Conf. on Controlled Fusion and Plasma
Physics, Budapest 2000. To appear.
12 V. Tribaldos, Monte Carlo computations of
neoclassical transport in TJ-II stellarator, Submitted to
Physics of Plasmas..
13 C. Hidalgo et al., Generation of sheared poloidal
flows via Reynold stress and transport barrier physics,
Plasma Phys. Control. Fusion 42 (2000) A153. M.A.
Pedrosa et al., Edge fluctuations and transport in the TJ-
II stellarator, Proc. 27th EPS Conf. on Controlled
Fusion and Plasma Physics, Budapest 2000. To appear.
14 C. Hidalgo et al., Properties of turbulent transport in
the proximity of instability thresholds, Submitted for
publication to EU-US TTF 2000
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plasmas, accepted for publication in Physical Review
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| id | nasplib_isofts_kiev_ua-123456789-78490 |
| institution | Digital Library of Periodicals of National Academy of Sciences of Ukraine |
| issn | 1562-6016 |
| language | English |
| last_indexed | 2025-12-07T16:04:11Z |
| publishDate | 2000 |
| publisher | Національний науковий центр «Харківський фізико-технічний інститут» НАН України |
| record_format | dspace |
| spelling | Castejón, F. Alejaldre, C. Alonso, J. Almoguera, L. Ascasíbar, E. Baciero, A. Balbín, R. Blaumoser, M. Botija, J. Brañas, B. de la Cal, E. Cappa, A. Carrasco, R. Cepero, J.R. Cremy, C. Doncel, J. Eguilior, S. Estrada, T. Fernández, A. Fuentes, C. García, A. García-Cortés, I. Guasp, J. Herranz, J. Hidalgo, C. Jiménez, J.A. Kirpitchev, I. Krivenski, V. Labrador, I. Lapayese, F. Likin, K. Liniers, M. López-Fraguas, A. López-Sánchez, A. de la Luna, E. Martín, R. Martínez-Laso, L. Medrano, M. Méndez, P. McCarthy, K.J. Medina, F. van Milligen, B. Ochando, M. Pacios, L. Pastor, I. Pedrosa, M.A. de la Peña, A. Portas, A. Qin, J. Rodríguez-Rodrigo, L. Salas, A. Sánchez, E. Sánchez, J. Tabarés, F. Tafalla, D. Tribaldos, V. Vega, J. Zurro, B. 2015-03-18T15:42:24Z 2015-03-18T15:42:24Z 2000 Latest physics results of TJ-II flexible heliac / F. Castejón, C. Alejaldre, J. Alonso, L. Almoguera, E. Ascasíbar, A. Baciero, R. Balbín, M. Blaumoser, J. Botija, B. Brañas, E. de la Cal, A. Cappa, R. Carrasco, J.R. Cepero, C. Cremy, J. Doncel, S. Eguilior, T. Estrada, A. Fernández, C. Fuentes, A. García, I. García-Cortés, J. Guasp, J. Herranz, C. Hidalgo, J.A. Jiménez, I. Kirpitchev, V. Krivenski, I. Labrador, F. Lapayese, K. Likin, Liniers, A. López-Fraguas, A. López-Sánchez, E. de la Luna, R. Martín, L. Martínez-Laso, M. Medrano, P. Méndez, K.J. McCarthy, F. Medina, B. van Milligen, M. Ochando, L. Pacios, I. Pastor, M.A. Pedrosa, A. de la Peña, A. Portas, J. Qin, L. Rodríguez-Rodrigo, A. Salas, E. Sánchez, J. Sánchez, F. Tabarés, D. Tafalla, V. Tribaldos, J. Vega, B. Zurro // Вопросы атомной науки и техники. — 2000. — № 6. — С. 3-7. — Бібліогр.: 16 назв. — англ. 1562-6016 https://nasplib.isofts.kiev.ua/handle/123456789/78490 533.9 This paper is devoted to the presentation of the most relevant recent Physics results obtained in the TJ-II flexible heliac. Firstly ECRH modulation and plasma breakdown studies are summarised; then the particle control techniques used to obtain reproducible discharges with density under control are presented. Transport studies show internal heat transport barriers that reduce heat conductivity to neoclassical values, and ELM-like transport events, similar to those observed in tokamaks and in other stellarators before and during H mode transition. Evidence of ExB sheared has been observed both in the proximity of rational surfaces. Finally, a high resolution Thomsom Scattering system has shown Te and ne profile structures. en Національний науковий центр «Харківський фізико-технічний інститут» НАН України Вопросы атомной науки и техники Magnetic confinement Latest physics results of TJ-II flexible heliac Article published earlier |
| spellingShingle | Latest physics results of TJ-II flexible heliac Castejón, F. Alejaldre, C. Alonso, J. Almoguera, L. Ascasíbar, E. Baciero, A. Balbín, R. Blaumoser, M. Botija, J. Brañas, B. de la Cal, E. Cappa, A. Carrasco, R. Cepero, J.R. Cremy, C. Doncel, J. Eguilior, S. Estrada, T. Fernández, A. Fuentes, C. García, A. García-Cortés, I. Guasp, J. Herranz, J. Hidalgo, C. Jiménez, J.A. Kirpitchev, I. Krivenski, V. Labrador, I. Lapayese, F. Likin, K. Liniers, M. López-Fraguas, A. López-Sánchez, A. de la Luna, E. Martín, R. Martínez-Laso, L. Medrano, M. Méndez, P. McCarthy, K.J. Medina, F. van Milligen, B. Ochando, M. Pacios, L. Pastor, I. Pedrosa, M.A. de la Peña, A. Portas, A. Qin, J. Rodríguez-Rodrigo, L. Salas, A. Sánchez, E. Sánchez, J. Tabarés, F. Tafalla, D. Tribaldos, V. Vega, J. Zurro, B. Magnetic confinement |
| title | Latest physics results of TJ-II flexible heliac |
| title_full | Latest physics results of TJ-II flexible heliac |
| title_fullStr | Latest physics results of TJ-II flexible heliac |
| title_full_unstemmed | Latest physics results of TJ-II flexible heliac |
| title_short | Latest physics results of TJ-II flexible heliac |
| title_sort | latest physics results of tj-ii flexible heliac |
| topic | Magnetic confinement |
| topic_facet | Magnetic confinement |
| url | https://nasplib.isofts.kiev.ua/handle/123456789/78490 |
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