Behaviour features of the radiative losses of the torsatron U – 3M plasma
The total bolometrically measured plasma radiation losses on the RF heating power were found. The results of measurements demonstrate a nonmonotonic dependence of radiation losses on RF power. Namely, at low RF power levels (80...170 kW) the total radiation losses raised with increasing the RF pow...
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Національний науковий центр «Харківський фізико-технічний інститут» НАН України
2006
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| Цитувати: | Behaviour features of the radiative losses of the torsatron U – 3M plasma / V.D. Kotsubanov, A.E. Kulaga, I.K. Nikolskij, V.K. Pashnev, S.A. Tsybenko // Вопросы атомной науки и техники. — 2006. — № 6. — С. 56-58. — Бібліогр.: 7 назв. — англ. |
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irk-123456789-817802015-05-21T03:02:17Z Behaviour features of the radiative losses of the torsatron U – 3M plasma Kotsubanov, V.D. Kulaga, A.E. Nikolskij, I.K. Pashnev, V.K. Tsybenko, S.A. Magnetic confinement The total bolometrically measured plasma radiation losses on the RF heating power were found. The results of measurements demonstrate a nonmonotonic dependence of radiation losses on RF power. Namely, at low RF power levels (80...170 kW) the total radiation losses raised with increasing the RF power. However, the total radiation losses decreased sharply when RF power exceeded 200 kW (down to ≈20 kW at 240 kW of RF power). Simultaneously, the intensity of impurity lines fell down significantly, whereas the average electron temperature (found from ECE measurement) did increase. The authors consider that screening properties of periphery plasma give reasons for above experimental facts. На торсатроне “У-3М” проведены измерения зависимости общих радиационных потерь от уровня вводимой в плазму ВЧ-мощности. Измерения показали немонотонную зависимость величины радиационных потерь от уровня вводимой ВЧ-мощности. При вводимой ВЧ-мощности на уровне 80...170 кВт величина радиационных потерь пропорционально возрастает. Доля радиационных потерь резко падает (до ~10% от вводимой ВЧ мощности) когда ВЧ-мощность достигает ≥200 кВт. Одновременно (более чем на порядок) уменьшаются интенсивности примесных линий, в то время как электронная температура в области удержания продолжает расти (ЭЦР радиометр). Авторы полагают, что объяснением приведенных выше экспериментальных фактов могут быть экранирующие свойства магнитной конфигурации торсатрона. На торсатроні “У-3М” проведені вимірювання залежності загальних радіаційних втрат від рівня введеної у плазму ВЧ-потужності. Виміри показали немонотонну залежність радіаційних втрат від рівня ВЧ-потужності. При введеній ВЧ-потужності на рівні 80...170 кВт доля радіаційних втрат пропорційно зростає. Доля радіаційних втрат різко зменшується (до ~10% від рівня ВЧ-потужності) коли введена ВЧ-потужність досягає рівня ≥200 кВт. Одночасно (більше ніж на порядок) зменшується інтенсивність ліній домішок, в той же час електронна температура продовжує зростати (ЕЦР радіометр). Автори вважають, що поясненням наведених вище експериментальних фактів можуть бути екрануючі властивості магнітної конфігурації торсатрону. 2006 Article Behaviour features of the radiative losses of the torsatron U – 3M plasma / V.D. Kotsubanov, A.E. Kulaga, I.K. Nikolskij, V.K. Pashnev, S.A. Tsybenko // Вопросы атомной науки и техники. — 2006. — № 6. — С. 56-58. — Бібліогр.: 7 назв. — англ. 1562-6016 PACS: 52.55.Hc http://dspace.nbuv.gov.ua/handle/123456789/81780 en Вопросы атомной науки и техники Національний науковий центр «Харківський фізико-технічний інститут» НАН України |
| institution |
Digital Library of Periodicals of National Academy of Sciences of Ukraine |
| collection |
DSpace DC |
| language |
English |
| topic |
Magnetic confinement Magnetic confinement |
| spellingShingle |
Magnetic confinement Magnetic confinement Kotsubanov, V.D. Kulaga, A.E. Nikolskij, I.K. Pashnev, V.K. Tsybenko, S.A. Behaviour features of the radiative losses of the torsatron U – 3M plasma Вопросы атомной науки и техники |
| description |
The total bolometrically measured plasma radiation losses on the RF heating power were found. The results of
measurements demonstrate a nonmonotonic dependence of radiation losses on RF power. Namely, at low RF power
levels (80...170 kW) the total radiation losses raised with increasing the RF power. However, the total radiation losses
decreased sharply when RF power exceeded 200 kW (down to ≈20 kW at 240 kW of RF power). Simultaneously, the
intensity of impurity lines fell down significantly, whereas the average electron temperature (found from ECE
measurement) did increase. The authors consider that screening properties of periphery plasma give reasons for above
experimental facts. |
| format |
Article |
| author |
Kotsubanov, V.D. Kulaga, A.E. Nikolskij, I.K. Pashnev, V.K. Tsybenko, S.A. |
| author_facet |
Kotsubanov, V.D. Kulaga, A.E. Nikolskij, I.K. Pashnev, V.K. Tsybenko, S.A. |
| author_sort |
Kotsubanov, V.D. |
| title |
Behaviour features of the radiative losses of the torsatron U – 3M plasma |
| title_short |
Behaviour features of the radiative losses of the torsatron U – 3M plasma |
| title_full |
Behaviour features of the radiative losses of the torsatron U – 3M plasma |
| title_fullStr |
Behaviour features of the radiative losses of the torsatron U – 3M plasma |
| title_full_unstemmed |
Behaviour features of the radiative losses of the torsatron U – 3M plasma |
| title_sort |
behaviour features of the radiative losses of the torsatron u – 3m plasma |
| publisher |
Національний науковий центр «Харківський фізико-технічний інститут» НАН України |
| publishDate |
2006 |
| topic_facet |
Magnetic confinement |
| url |
http://dspace.nbuv.gov.ua/handle/123456789/81780 |
| citation_txt |
Behaviour features of the radiative losses of the torsatron U – 3M plasma / V.D. Kotsubanov, A.E. Kulaga, I.K. Nikolskij,
V.K. Pashnev, S.A. Tsybenko
// Вопросы атомной науки и техники. — 2006. — № 6. — С. 56-58. — Бібліогр.: 7 назв. — англ. |
| series |
Вопросы атомной науки и техники |
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AT kotsubanovvd behaviourfeaturesoftheradiativelossesofthetorsatronu3mplasma AT kulagaae behaviourfeaturesoftheradiativelossesofthetorsatronu3mplasma AT nikolskijik behaviourfeaturesoftheradiativelossesofthetorsatronu3mplasma AT pashnevvk behaviourfeaturesoftheradiativelossesofthetorsatronu3mplasma AT tsybenkosa behaviourfeaturesoftheradiativelossesofthetorsatronu3mplasma |
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2025-07-06T07:14:42Z |
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2025-07-06T07:14:42Z |
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| fulltext |
BEHAVIOUR FEATURES OF THE RADIATIVE LOSSES
OF THE TORSATRON U – 3M PLASMA
V.D. Kotsubanov, A.E. Kulaga, I.K. Nikolskij,
V.K. Pashnev, S.A. Tsybenko
Institute of Plasma Physic, NSC KIPT, Akademicheskaya Str.1, 61108, Kharkov, Ukraine,
e – mail: kotsubanov@ kipt.kharkov.ua
The total bolometrically measured plasma radiation losses on the RF heating power were found. The results of
measurements demonstrate a nonmonotonic dependence of radiation losses on RF power. Namely, at low RF power
levels (80...170 kW) the total radiation losses raised with increasing the RF power. However, the total radiation losses
decreased sharply when RF power exceeded 200 kW (down to ≈20 kW at 240 kW of RF power). Simultaneously, the
intensity of impurity lines fell down significantly, whereas the average electron temperature (found from ECE
measurement) did increase. The authors consider that screening properties of periphery plasma give reasons for above
experimental facts.
PACS: 52.55.Hc
1. INTRODUCTION
One of the peculiarities of the U – 3M torsatron with
the magnetic system disposed inside of a large vacuum
volume, is the existence of a natural divertor, which is the
essential part of the magnetic configuration. This
circumstance creates specific conditions when measure
the energy radiative losses by bolometer.
When the bolometric sensor localized in the space
between helical windings at the too long distance from the
confining volume (excluding the shadowing of the
bolometer directional diagram), there is the possibility
that it receives the charged particles from the divertor
fluxes or from background plasma. In this case the sensor
signal is defined not only by the radiative flux and by
neutral particles, but by some part of the charged particle
flux also.
Ta
king into account mentioned above, we designed the
compact bolometer sensor, having the high resistance
against electromagnetic hashes and permitting to position
it at the inner surface of the magnetic winding casing. The
sensor measures the total radiative losses and has the
reception angle near to 2π (2π – bolometer) [1,2].
In this report we present the results of measurement
of the total radiative losses of the torsatron U – 3M
plasma as function of the RF heating power.
2. EXPERIMENTAL DEVICE. BOLOMETERS
The U – 3M device [3] is l=3 torsatron with 9 periods
of the helical magnetic field. The major tore radius is 100
cm, the inner radius of the casings of the helical windings
is 19cm. Magnetic system together with the support frame
are disposed inside the vacuum chamber of ~70 m3
volume. The chamber is evacuated up to 10-7 Torr. Plasma
is created by RF method resonance excitation of the ion
cyclotron waves at the frequency 8.4 MHz. The confining
magnetic field on the axis of device is B =0.7 T. The
maximal power, supplied to the plasma in described
experiments was of 240 kW.
One of the cross sections of magnetic configuration,
defined as D-section, is presented in fig. 1, where 1 – is
the plasma volume, limited by an outermost magnetic
surface. The region 2 is the ergodic layer [4], where the
line of force perform 1...100 turns around the major axis,
before leaving the plasma volume. As follows from
results of calculations [4] and from experiment [5], the
thickness of ergodic layer changes from 2 to 6 cm, in
dependence of azimuthal angle.
Fig. 1. Cross section of the U – 3M magnetic
configuration
U – 3M torsatron bolometric system consists of 4
sensors, disposed on the plasma facing surfaces of the
magnetic winding casings. Toroidal angles of the sensor
disposition with respect to RF – antenna were from 20˚ to
180˚. The point of the sensor disposition in D – section is
shown in fig 1 (3). Magnetic field in the point of sensor
disposition is ~1.0 T.
The time resolution of the bolometers is ~1 ms. The
lower limit of the registered power density is 20 mW/cm2
on the surface of the sensor element. The transmission
56 Problems of Atomic Science and Technology. 2006. № 6. Series: Plasma Physics (12), p. 56-58
band of the bolometric channel electronics equals to
~2∙103 Hz.
3. EXPERIMENTAL RESULTS
The experimental dependence of the radiative plasma
losses as a function of the RF power input is presented in
fig 2. Because the radiative losses do change during the
heating pulse (e.g., fig. 3), along the vertical axis of the
graph in fig. 2 we put the value of the energy of radiative
losses normalized to the RF power input (E).
Fig 2. Normalize dependences radiative losses
per pulse on the applied RF power
Fig 3. shows the temporal dependences of the
radiative loss power (P) for three levels of RF power: 1 –
80 kW, 2 – 170 kW, and 3 – 240 kW.
As it is seen from the pictures, for the relative low
levels of the applied power (80...170 kW) the total
radiative losses increase significantly with the RF power.
In this power interval the total radiative losses were about
40...50% of the RF power input.
Fig 3. Temporal behaviour of radiative losses at
three
levels of RF power
The radiative losses decreased sharply when applied
RF power exceeds ≈ 200kW. In this case the part of
radiative losses dropped to ~10% of the RF power.
Simultaneously the following effects are observed:
1. Decreasing (more than factor ten) the intensity of
the light impurity (C+2, O+2 ) spectral lines.
2. Decreasing the average electron density from
3.6∙1012 cm-3 by 1.6∙1012 cm-3.
3. Increasing up to 80 eV of the electron temperature
in the ergodic layer region. At that Te in the central part of
confining volume increased up to 600 eV (measured by
ECR radiometer).
4. DISCUSSIONS
The abovementioned experimental results may be
explained by decreasing ne in the confining volume, when
the RF power is increased [6]. Fig. 4 shows the
dependences of the average electron density (<ne>) and
radiative losses (at 30 ms after discharge start) as a
function of the RF power. It is seen from fig. 4 that there
is no simple proportionality between the time behavior of
radiative losses and electron density. Electron density
remains almost constant, when RF power changed from
80 to 170 kW. In this case the maximal level of the
radiative losses increased from 40 to 76 kW.
Fig 4. Dependences of the average electron density and
radiative losses level from RF power:
1 – radiative losses level, 2- electron density
More adequately the majority of the experimental
data may be explained by the divertor properties of the
ergodic layer of the magnetic configuration U – 3M
device (fig. 1). When the levels of RF power are lower,
the periphery of plasma column remains cold, and the
degree of ionization is low enough. In this case the
impurities desorbed from the inner surfaces of the
magnetic winding casings, can practically freely penetrate
57
through the ergodic layer, undergoing ionization in the
plasma confinement volume.
When the level of the RF power is increased, Te of
the plasma periphery begins to increase too, reaching
80 eV in ergodic layer, when the RF power level
increases up to 240 kW.
Taking into account that the density of hydrogen
molecules is (3…4)∙1011cm-3, we estimate the ne in the
ergodic layer is ne ≈ 8∙1011 cm-3. The velocities of the
desorbed radicals CH or OH type can be taken as
≈ 8∙104 cm∙s-1. Then the mean free path of such molecules
for ionization in the ergodic layer is of the order of 1 cm.
It was admitted in [5], that ergodic layer thickness (in
dependence on the azimuthal angle) varies from 2 to
6 cm. Such length is enough for effective screening of the
confining volume from mentioned impurities. Obviously,
the screening effect of the ergodic layer has to depend on
the level of RF power input and on the value of impurity
influx. Namely, the too large flux of impurities can lead
to the decrease of the electron temperature at the plasma
periphery.
The experimental data of fig. 3 qualitatively support
such explanation.
5. CONCLUSIONS
1. The assumption about screening properties of the
ergodic layer do most completely explain the
experimental data, mentioned above.
2. The screening effect of the magnetic configuration
increases with increasing the RF power.
3. The growth of the screening properties occurs
faster in the 180...240kW interval of the heating power.
It is worthy to note, that the screening properties of
the periphery plasma in magnetic configuration of U-3M
torsatron were firstly experimentally demonstrated in [7].
In that wor, it has been showen, that up to 70% of the
carbon atoms injected into the plasma by the laser
ablation, were diverted.
REFERENCES
1. V.I. Kovalenko, V.D. Kotsubanov, I.K. Nikolsky et
al.// Bulletin of Kharkov Univesity. Ser. “Physical.
Nuclei, particles, fields”. 2005, 1(26), p. 96 – 98 (in
Russian).
2. S. Besshou, S. Morimoto et al. // Nuclear Fusion. 1986,
v. 26, № 1, p. 114 -117.
3. V.V. Bakaev, S.P. Bondarenko, V.V. Bronnikov et al.//
Plasma Physic and Contr. Nucl. Fusion. 1984, v. 2,
p. 397- 407.
4. V.E. Bykov, Yu.K. Kuznetsov, O.S. Pavlitchenko et
al.// A Collection of Papers Presented at the IAEA
Technical Committee Meeting. Garching, Germany. 1993.
p. 391- 396.
5. V.E. Bykov, V.S. Voitsenya, V.E. Volkov et al.//
Problems of Atomic Science and Technology, Series
”Thermonuclear fusion” (3). 1990, p. 12 – 31.
6. V.V. Chechkin, L.I. Grigor’eva, E.L. Sorokovoi et al.//
Nuclear Fusion. 2003, v. 43, p. 1175 – 1182.
7. V.D. Berezhnyi E.D. Volkov, V.D. Kotsubanov,
I.K. Nikolsky et al.: Preprint. Kharkov: NSC KIPT,
KhFTI 1 – 23,1989.
ОСОБЕННОСТИ ПОВЕДЕНИЯ РАДИАЦИОННЫХ ПОТЕРЬ
ПЛАЗМЫ ТОРСАТРОНА “У-3М”
В.Д. Коцубанов, А.Е. Кулага, И.К. Никольский,
В.К. Пашнев, С.А. Цыбенко
На торсатроне “У-3М” проведены измерения зависимости общих радиационных потерь от уровня
вводимой в плазму ВЧ-мощности. Измерения показали немонотонную зависимость величины радиационных
потерь от уровня вводимой ВЧ-мощности. При вводимой ВЧ-мощности на уровне 80...170 кВт величина
радиационных потерь пропорционально возрастает. Доля радиационных потерь резко падает (до ~10% от
вводимой ВЧ мощности) когда ВЧ-мощность достигает ≥200 кВт. Одновременно (более чем на порядок)
уменьшаются интенсивности примесных линий, в то время как электронная температура в области удержания
продолжает расти (ЭЦР радиометр). Авторы полагают, что объяснением приведенных выше
экспериментальных фактов могут быть экранирующие свойства магнитной конфигурации торсатрона.
ОСОБЛИВОСТІ ПОВЕДІНКИ РАДІАЦІЙНИХ ВТРАТ
ПЛАЗМИ ТОРСАТРОНУ “У-3 М”
В.Д. Коцубанов, А.Є. Кулага, І.К. Нікольський,
В.К. Пашнєв, С.A. Цибенко
На торсатроні “У-3М” проведені вимірювання залежності загальних радіаційних втрат від рівня введеної у
плазму ВЧ-потужності. Виміри показали немонотонну залежність радіаційних втрат від рівня ВЧ-потужності.
При введеній ВЧ-потужності на рівні 80...170 кВт доля радіаційних втрат пропорційно зростає. Доля
радіаційних втрат різко зменшується (до ~10% від рівня ВЧ-потужності) коли введена ВЧ-потужність досягає
58
рівня ≥200 кВт. Одночасно (більше ніж на порядок) зменшується інтенсивність ліній домішок, в той же час
електронна температура продовжує зростати (ЕЦР радіометр). Автори вважають, що поясненням наведених
вище експериментальних фактів можуть бути екрануючі властивості магнітної конфігурації торсатрону.
59
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