Temperature of impurity ions in a RF heated plasma of the U-3M torsatron as measured by means of the Doppler spectrometry
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| Zitieren: | Temperature of impurity ions in a RF heated plasma of the U-3M torsatron as measured by means of the Doppler spectrometry / V.G. Konovalov, V.N. Bondarenko, A.N. Shapoval, A.S. Slavny, V.S. Voitsenya, E.D. Volkov // Вопросы атомной науки и техники. — 2002. — № 4. — С. 53-55. — Бібліогр.: 6 назв. — англ. |
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irk-123456789-802462015-04-15T03:02:06Z Temperature of impurity ions in a RF heated plasma of the U-3M torsatron as measured by means of the Doppler spectrometry Konovalov, V.G. Bondarenko, V.N. Shapoval, A.N. Slavny, A.S. Voitsenya, V.S. Volkov, E.D. Magnetic confinement 2002 Article Temperature of impurity ions in a RF heated plasma of the U-3M torsatron as measured by means of the Doppler spectrometry / V.G. Konovalov, V.N. Bondarenko, A.N. Shapoval, A.S. Slavny, V.S. Voitsenya, E.D. Volkov // Вопросы атомной науки и техники. — 2002. — № 4. — С. 53-55. — Бібліогр.: 6 назв. — англ. 1562-6016 PACS: 52.55.Hc; 52.70.Kz http://dspace.nbuv.gov.ua/handle/123456789/80246 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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Magnetic confinement Magnetic confinement |
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Magnetic confinement Magnetic confinement Konovalov, V.G. Bondarenko, V.N. Shapoval, A.N. Slavny, A.S. Voitsenya, V.S. Volkov, E.D. Temperature of impurity ions in a RF heated plasma of the U-3M torsatron as measured by means of the Doppler spectrometry Вопросы атомной науки и техники |
| format |
Article |
| author |
Konovalov, V.G. Bondarenko, V.N. Shapoval, A.N. Slavny, A.S. Voitsenya, V.S. Volkov, E.D. |
| author_facet |
Konovalov, V.G. Bondarenko, V.N. Shapoval, A.N. Slavny, A.S. Voitsenya, V.S. Volkov, E.D. |
| author_sort |
Konovalov, V.G. |
| title |
Temperature of impurity ions in a RF heated plasma of the U-3M torsatron as measured by means of the Doppler spectrometry |
| title_short |
Temperature of impurity ions in a RF heated plasma of the U-3M torsatron as measured by means of the Doppler spectrometry |
| title_full |
Temperature of impurity ions in a RF heated plasma of the U-3M torsatron as measured by means of the Doppler spectrometry |
| title_fullStr |
Temperature of impurity ions in a RF heated plasma of the U-3M torsatron as measured by means of the Doppler spectrometry |
| title_full_unstemmed |
Temperature of impurity ions in a RF heated plasma of the U-3M torsatron as measured by means of the Doppler spectrometry |
| title_sort |
temperature of impurity ions in a rf heated plasma of the u-3m torsatron as measured by means of the doppler spectrometry |
| publisher |
Національний науковий центр «Харківський фізико-технічний інститут» НАН України |
| publishDate |
2002 |
| topic_facet |
Magnetic confinement |
| url |
http://dspace.nbuv.gov.ua/handle/123456789/80246 |
| citation_txt |
Temperature of impurity ions in a RF heated plasma of the U-3M torsatron as measured by means of the Doppler spectrometry / V.G. Konovalov, V.N. Bondarenko, A.N. Shapoval, A.S. Slavny, V.S. Voitsenya, E.D. Volkov // Вопросы атомной науки и техники. — 2002. — № 4. — С. 53-55. — Бібліогр.: 6 назв. — англ. |
| series |
Вопросы атомной науки и техники |
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2025-07-06T04:12:52Z |
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2025-07-06T04:12:52Z |
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1836869404074180608 |
| fulltext |
TEMPERATURE OF IMPURITY IONS IN A RF HEATED PLASMA OF THE
U-3M TORSATRON AS MEASURED BY MEANS OF THE DOPPLER
SPECTROMETRY
V.G.Konovalov, V.N.Bondarenko, A.N.Shapoval, A.S.Slavny, V.S.Voitsenya, E.D.Volkov
Institute of Plasma Physics, NSC KIPT, 61108 Kharkov, Ukraine
PACS: 52.55.Hc; 52.70.Kz
1. INTRODUCTION
The spectroscopic methods of measurements of ion
temperature, Ti, are routinely used in magnetic fusion
experiments. However some strong requirements must be
satisfied as for the quality of spectroscopic equipment and
reproducibility of plasma parameters when spectral line
profile is obtained shot by shot. Besides, the radial
location of ions of the given ionization state in the plasma
volume should be known. The correctness of Ti
measurement results has to be controlled by comparing
them with temperature Ti of the main plasma ion
component (H+, D+) by calculation of energy balance for
impurity ions. Important is also the requirement to
estimate the role of other possible mechanisms of
broadening of the impurity ion line profiles.
The goal of this paper is to determine the plasma ion
temperature using data on profiles of spectral lines of
intrinsic impurity, i.e., carbon ions (lines CV 227.1 nm
and CIII 229.6 nm) in the plasma confinement volume of
U-3M torsatron and to compare these results with data of
Ti measurements based on the energy distribution of
charge exchange atoms (CXA) obtained by neutral
particle analyzer (NPA).
2. EXPERIMENTAL CONDITIONS AND
RESULTS
The experiments were carried out on the fusion device
Uragan-3M (U-3M) which is a l=3, 9 magnetic field period
torsatron with major radius 100 cm and mean plasma
radius 12.5 cm. The hydrogen plasma was produced and
maintained during ~50 ms by RF fields in the frequency
range ω≤ωci corresponding to a multimode Alfven
resonance regime. The spectroscopical measurements were
provided for the following conditions: toroidal magnetic
field 0.7T, PRF ≤ 240kW, mean plasma density ~1⋅1018 m-3.
Fig.1 shows the relative positions of diagnostic ports
Fig.1 Disposition of diagnostic channels.
relating the present work: 1. NPAII – for measuring CXA
fluxes, i.e., the H+ ion energy distribution along the toroidal
direction with the line of sight passing near the RF antenna;
2. NPA⊥ for measuring the CXA flux in vertical direction
was positioned at ~90° from the RF antenna along the
toroidal direction; 3. Spectroscopy for measuring the chord
distributions of different spectral lines in vertical direction
of the cross section (DD), where plasma column is
symmetrical relatively the central plane of U–3M;
4. Spectroscopy along the toroidal direction of the plasma
confinement volume.
For spectroscopy measurement of ion temperature the C4+
and C2+ ions were used. The potentials of excitation of
these ions differ very strongly each other what gives chance
to obtain some data on the Ti radial distribution. During
these experiments, the spectral range chosen for spectral
measurements, was practically free of other spectral lines.
Problems of Atomic Science and Technology. 2002. № 4. Series: Plasma Physics (7). P. 53-55 51
Fig.2. Time behaviors of RF power supplied to antenna
and integrated along lines of sight: the plasma density ne
and spectral line intensities of indicated lines.
In Fig.2 the waveforms are shown for RF power
supplied to antenna and integrated along the line of sight:
the plasma density ne and spectral line intensities of carbon
and hydrogen lines. The chord distributions of intensities of
these lines in the D-D cross-section are presented in Fig. 3.
Fig. 3. Chord distributions of intensities of lines in the D-D
cross-section.
The technique of obtaining the radial distribution of line
intensities from measured chord distribution is minutely
described in [5]. It is seen that the chord profile of CV
radiation was limited by size 14-15 cm, CIII radiation – 24-
25 cm and Hα radiation – 26-27 cm. The intensities of
indicated lines of carbon ions in a poloidal cross section
were not enough for measuring the line profiles if one takes
into account the requirements on the widths of entrance and
exit slits of the spectrometer in use. Therefore for line
profile measurements we used the port for the tangent
plasma observation. With this, the center of the observation
line was antipode to the position of the RF antenna center
(Fig.1) and according to geometry of measurements, the
volume of observation was 5-6 cm in diameter. For the
spectrometer MDR-23 with grating 1200 lines per mm the
inverse linear dispersion was 1.3 nm/mm in the first order,
but to work with better resolution we used the 3rd order of
the spectrum. The total number of points on the line
contour was ~30 (obtained shot by shot). The instrumental
contour was measured by means of Hg lamp (line 253.6
nm) operating in a cold regime and its halfwidth was ≈
0.015 nm what corresponds to the “instrumental
temperature” ~8 eV (for carbon). The contribution of
Zeeman and Stark effects into broadening of indicated
carbon lines may not be taken into account, [1,2].
The probable Doppler width of spectral line contours
were estimated with taking into account the previously
obtained NPA data, [3,4].
Fig.4. Energy distribution of H+ ions obtained by NPAII.
In Fig.4 the energy distribution of H+ ions obtained by
NPAII are presented (note, that results of NPA⊥
measurement are very much similar). These data indicate
that there are three groups of H+ ions in the confined
plasma with “temperatures” equal to: T1≅70eV, T2≅300eV
Fig. 5. Equipartition time for C4+ and C2+ ions in the
background H+ plasma.
and T3≅500eV. The estimated relative composition of
every this component is: n1≈85-90%, n2≈6-12%, n3≈4-6%.
However, for the temperature of impurity ions to
correspond to the H+ ion temperature, the particle life time
has to be much longer than the equipartition time. Thus, the
life time of H+ ions, τp≅1.5÷2 ms, found by measuring Hα
line intensity, has to be compared with the equipartition
time [6] for both, C4+ and C2+ ions, in a wide energy of H+
ions, comparable with “temperatures” shown in Fig. 5.
From data of this figure one can conclude that the
favorable conditions for correct Ti measurements are
fulfilled for C4+ ion component, and measurements of ion
temperature by use of the CIII line can also be correct for
Ti(H+)≤100eV. The results of measurements of the CV
and CIII line contours are shown in Fig.6 (note, that these
data are obtained by integration along the line of sight). In
Fig. 6a the experimental points are presented together
with a Gaussian fitting contour of the same halfwidth as
the experimental halfwidth. It is evident that at the wings
there is a very big difference of measured points and the
fitting curve. However, if the experimental contour is
depictured as a sum of two Gaussian profiles with different
54
200 400 600
0
4
8
12
16
Temperature of H+ ions, eV
τ eq
, m
s
CV
CIII
0 2000 4000
4
8
12
16
.
ln
(1
/E
1
/ 2
*d
n/
dE
)
E,eV
504eV
300eV
76eV
halfwidth, much better fitting to the experimental profile
can be obtained, as Fig. 6b demonstrates.
Such a presentation indicates that in the plasma
confinement volume there are two groups of C4+ ions with
energy distribution corresponding to temperatures ~40 eV
and ~300 eV. This result is in good qualitative agreement
with measurements by the NPA method. In contrast,
contour of the C2+ ion line is reasonably depicted by only
one Gaussian curve. The halfwidth of this contour
corresponds to the temperature value ~30 eV, Fig.6c.
The “temperature” of H atoms found from Hά line width
was estimated as ~2ev without accounting other
broadening factors. This value is in accordance with
typical data for the energy of Franck - Condon H atoms.
3. SUMMARY
1. The spectroscopic data on ion temperature from
measurement of CV 227nm line structure showed the
existence of double-energy distributions of C4+ ions. This is
in a quite good agreement with results of NPA data for
energy distribution of the main plasma component (H+
ions).
2. To our regret, the intensity of CIII and CV lines was
not enough to provide similar measurements in the D-D
cross section and thus to obtain the information on radial
distribution of Ti. Such measurements are planned to be
provided in the next campaign when plasma parameters ne,
Te will be sufficient for this.
REFERENCES
[1] S.E.Frish. Opticheskie spectry atomov. Moscow,
1963, p.41 (in Russian).
[2] Hans R. Griem. Plasma spectroscopy. Moscow, 1969,
p.77 (in Russian).
[3] Volkov E. D., Arsen’ev A. K., et al. Generation of
fast particles in RF discharge plasma in the Uragan-3M
torsatron, Proc. 25th EPS Conf. Control. Fusion Plasma
Physics. Prague. 1998, 22C, p.455.
[4] V.V.Chechkin, et al. Plasma flow asymmetries in the
natural helical divertor of an l = 3 torsatron and their
relation to particle losses. Nucl. Fusion, 42 (2002) p.192.
[5] Bondarenko V.N. et al. Investigation of radial
distributions of spectral line radiation emissivities in
torsatron “Uragan-3M”. These Proceedings.
[6] L. Spitzer. Physics of Fully Ionized Gases.
Moscow, 1965, p.179 (in Russian).
Fig. 6a. Experimental points together with a Gaussian
fitting contour.
Fig. 6b Two Gaussian profiles fit with different halfwidth
of every component.
Fig.6c. Calculated contour of the C2+ ion line
and the experimental points.
55
229,65 229,70 229,75
0,0
0,5
1,0
CIII
N
or
m
. I
nt
en
si
ty
Wavelength, nm
227,025 227,100 227,175
0,0
0,5
1,0
N
or
m
. I
nt
en
si
ty
Ti~300eV
Ti~40eV
Wavelength, nm
227,025 227,100 227,175
0,0
0,5
1,0
N
or
m
. i
nt
en
si
ty
Wavelength, nm
V.G.Konovalov, V.N.Bondarenko, A.N.Shapoval, A.S.Slavny, V.S.Voitsenya, E.D.Volkov
REFERENCES
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