The possible variant of pulsed RF-discharge cleaning mode of the Uragan-3m torsatron
The cleaning regime with the use of pulsed RF-discharges in hydrogen-nitrogen mixture was examined over the nitrogen concentration range from 4 at.% to 96 at.% at the same parameters of RF-generator as for pure hydrogen. The analysis of obtained preliminary data has shown that even about 2x10³ disch...
Збережено в:
| Дата: | 2005 |
|---|---|
| Автори: | , , , , , |
| Формат: | Стаття |
| Мова: | English |
| Опубліковано: |
Національний науковий центр «Харківський фізико-технічний інститут» НАН України
2005
|
| Назва видання: | Вопросы атомной науки и техники |
| Теми: | |
| Онлайн доступ: | http://dspace.nbuv.gov.ua/handle/123456789/78469 |
| Теги: |
Додати тег
Немає тегів, Будьте першим, хто поставить тег для цього запису!
|
| Назва журналу: | Digital Library of Periodicals of National Academy of Sciences of Ukraine |
| Цитувати: | The possible variant of pulsed RF-discharge cleaning mode of the Uragan-3m torsatron / G.P. Glazunov, E.D. Volkov, D.I. Baron, P.I. Konotop, A.V. Lozin, S.A. Tsybenko // Вопросы атомной науки и техники. — 2005. — № 1. — С. 33-35. — Бібліогр.: 13 назв. — англ. |
Репозитарії
Digital Library of Periodicals of National Academy of Sciences of Ukraine| id |
irk-123456789-78469 |
|---|---|
| record_format |
dspace |
| spelling |
irk-123456789-784692015-03-19T03:02:36Z The possible variant of pulsed RF-discharge cleaning mode of the Uragan-3m torsatron Glazunov, G.P. Volkov, E.D. Baron, D.I. Konotop, P.I. Lozin, A.V. Tsybenko, S.A. Magnetic confinement The cleaning regime with the use of pulsed RF-discharges in hydrogen-nitrogen mixture was examined over the nitrogen concentration range from 4 at.% to 96 at.% at the same parameters of RF-generator as for pure hydrogen. The analysis of obtained preliminary data has shown that even about 2x10³ discharge pulses in H₂-N₂₃ mixture causes drastic decrease of partial hydrogen pressure and ultimate base pressure. But, in contrast, to revert initial high hydrogen partial pressure in the U-3M torsatron vacuum chamber, it is needed more than 2x10⁴ pulsed discharges in pure hydrogen. The possible reasons of effective hydrogen removing in RF-discharges in hydrogen-nitrogen mixtures are discussed. Досліджувався режим чищення імпульсними ВЧ-розрядами в суміші водню й азоту при концентраціях азоту від 4 at. % to 96 at. % при тих же параметрах ВЧ-генератора, що і для чистого водню. Аналіз отриманих даних показав, що вже близько 2x10³ імпульсів у H₂-N₂ суміші викликає помітне зниження парціального тиску водню і граничного тиску в камері У-3М. Навпроти, щоб повернути високий парціальний тиск водню у вакуумній камері У-3М необхідно більш ніж 2x10⁴ імпульсних розрядів у чистому водні. Обговорюються можливі причини ефективного видалення водню розрядами в суміші водню й азоту. Исследовался режим чистки импульсными ВЧ-разрядами в смеси водорода и азота при концентрациях азота от 4 at.% to 96 at.% при тех же параметрах ВЧ-генератора, что и для чистого водорода. Анализ полученных данных показал, что уже около 2x10³ импульсов в H₂-N₂ смеси вызывает заметное снижение парциального давления водорода и предельного давления в камере У-3М. Напротив, чтобы вернуть высокое парциальное давление водорода в вакуумной камере У-3М необходимо более чем 2x10⁴ импульсных разрядов в чистом водороде. Обсуждаются возможные причины эффективного удаления водорода разрядами в смеси водорода и азота. 2005 Article The possible variant of pulsed RF-discharge cleaning mode of the Uragan-3m torsatron / G.P. Glazunov, E.D. Volkov, D.I. Baron, P.I. Konotop, A.V. Lozin, S.A. Tsybenko // Вопросы атомной науки и техники. — 2005. — № 1. — С. 33-35. — Бібліогр.: 13 назв. — англ. 1562-6016 PACS: 52.40H, 52.80.Hс, 07.30.Bx http://dspace.nbuv.gov.ua/handle/123456789/78469 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 Glazunov, G.P. Volkov, E.D. Baron, D.I. Konotop, P.I. Lozin, A.V. Tsybenko, S.A. The possible variant of pulsed RF-discharge cleaning mode of the Uragan-3m torsatron Вопросы атомной науки и техники |
| description |
The cleaning regime with the use of pulsed RF-discharges in hydrogen-nitrogen mixture was examined over the nitrogen concentration range from 4 at.% to 96 at.% at the same parameters of RF-generator as for pure hydrogen. The analysis of obtained preliminary data has shown that even about 2x10³ discharge pulses in H₂-N₂₃ mixture causes drastic decrease of partial hydrogen pressure and ultimate base pressure. But, in contrast, to revert initial high hydrogen partial pressure in the U-3M torsatron vacuum chamber, it is needed more than 2x10⁴ pulsed discharges in pure hydrogen. The possible reasons of effective hydrogen removing in RF-discharges in hydrogen-nitrogen mixtures are discussed. |
| format |
Article |
| author |
Glazunov, G.P. Volkov, E.D. Baron, D.I. Konotop, P.I. Lozin, A.V. Tsybenko, S.A. |
| author_facet |
Glazunov, G.P. Volkov, E.D. Baron, D.I. Konotop, P.I. Lozin, A.V. Tsybenko, S.A. |
| author_sort |
Glazunov, G.P. |
| title |
The possible variant of pulsed RF-discharge cleaning mode of the Uragan-3m torsatron |
| title_short |
The possible variant of pulsed RF-discharge cleaning mode of the Uragan-3m torsatron |
| title_full |
The possible variant of pulsed RF-discharge cleaning mode of the Uragan-3m torsatron |
| title_fullStr |
The possible variant of pulsed RF-discharge cleaning mode of the Uragan-3m torsatron |
| title_full_unstemmed |
The possible variant of pulsed RF-discharge cleaning mode of the Uragan-3m torsatron |
| title_sort |
possible variant of pulsed rf-discharge cleaning mode of the uragan-3m torsatron |
| publisher |
Національний науковий центр «Харківський фізико-технічний інститут» НАН України |
| publishDate |
2005 |
| topic_facet |
Magnetic confinement |
| url |
http://dspace.nbuv.gov.ua/handle/123456789/78469 |
| citation_txt |
The possible variant of pulsed RF-discharge cleaning mode of the Uragan-3m torsatron / G.P. Glazunov, E.D. Volkov, D.I. Baron, P.I. Konotop, A.V. Lozin, S.A. Tsybenko // Вопросы атомной науки и техники. — 2005. — № 1. — С. 33-35. — Бібліогр.: 13 назв. — англ. |
| series |
Вопросы атомной науки и техники |
| work_keys_str_mv |
AT glazunovgp thepossiblevariantofpulsedrfdischargecleaningmodeoftheuragan3mtorsatron AT volkoved thepossiblevariantofpulsedrfdischargecleaningmodeoftheuragan3mtorsatron AT barondi thepossiblevariantofpulsedrfdischargecleaningmodeoftheuragan3mtorsatron AT konotoppi thepossiblevariantofpulsedrfdischargecleaningmodeoftheuragan3mtorsatron AT lozinav thepossiblevariantofpulsedrfdischargecleaningmodeoftheuragan3mtorsatron AT tsybenkosa thepossiblevariantofpulsedrfdischargecleaningmodeoftheuragan3mtorsatron AT glazunovgp possiblevariantofpulsedrfdischargecleaningmodeoftheuragan3mtorsatron AT volkoved possiblevariantofpulsedrfdischargecleaningmodeoftheuragan3mtorsatron AT barondi possiblevariantofpulsedrfdischargecleaningmodeoftheuragan3mtorsatron AT konotoppi possiblevariantofpulsedrfdischargecleaningmodeoftheuragan3mtorsatron AT lozinav possiblevariantofpulsedrfdischargecleaningmodeoftheuragan3mtorsatron AT tsybenkosa possiblevariantofpulsedrfdischargecleaningmodeoftheuragan3mtorsatron |
| first_indexed |
2025-07-06T02:33:29Z |
| last_indexed |
2025-07-06T02:33:29Z |
| _version_ |
1836863150648983552 |
| fulltext |
THE POSSIBLE VARIANT OF PULSED RF-DISCHARGE CLEANING
MODE OF THE URAGAN-3M TORSATRON
G.P. Glazunov, E.D. Volkov, D.I. Baron, P.I. Konotop, A.V. Lozin, S.A. Tsybenko
Institute of Plasma Physics of the NSC KIPT, 61108 Kharkov, Ukraine
The cleaning regime with the use of pulsed RF-discharges in hydrogen-nitrogen mixture was examined over the
nitrogen concentration range from 4 at.% to 96 at.% at the same parameters of RF-generator as for pure hydrogen. The
analysis of obtained preliminary data has shown that even about 2x103 discharge pulses in H2-N2 mixture causes drastic
decrease of partial hydrogen pressure and ultimate base pressure. But, in contrast, to revert initial high hydrogen partial
pressure in the U-3M torsatron vacuum chamber, it is needed more than 2x104 pulsed discharges in pure hydrogen. The
possible reasons of effective hydrogen removing in RF-discharges in hydrogen-nitrogen mixtures are discussed.
PACS: 52.40H, 52.80.Hс, 07.30.Bx
1. INTRODUCTION
The usual regime of pulsed RF-discharge cleaning
under wall conditioning in the Uragan-3M (U-3M)
torsatron [1, 2] includes long time plasma machine
operation at high hydrogen pressure of about 10-4 Torr.
The interaction of low temperature hydrogen plasmas
with plasma facing components (in the U-3M they are,
mainly, stainless steel housing of helical windings of
magnetic coils and TiN-coated stainless steel RF-
antennas) and the intensive molecular hydrogen flow,
passed through U-3M vacuum chamber [3], result in the
increase of hydrogen concentration on the surface and in
the bulk of the PFM and walls of vacuum chamber. As
the consequence, hydrogen partial pressure in the U-3M
vacuum chamber increases to about 5x10-7 Torr (instead
of 2-3x10-7 Torr ultimate base pressure) and desorbed
hydrogen becomes the main gas in the mass-spectrum of
residual gases. It lets to carry out plasma experiments
under sufficiently clean conditions in spite of the unbaked
variant of U-3M vacuum chamber construction.
Moreover, the possible activated state of desorbed
hydrogen similar, as it had been shown for metal hydrides
[4], could play the positive role on the initial stage of
pulsed plasma discharges. But, when the mode of
operation with low hydrogen recycling is needed, it is
necessary to revert system in the state with low hydrogen
isotope concentration in the materials and low hydrogen
partial pressure. It is possible, using rare gases during
discharge cleaning, e.g., helium or helium-oxygen
mixture [5]. Such researches are also of a great interest
from the point of view to improve methods of
minimization of hydrogen isotope contamination of
constructional materials.
2. EXPERIMENTAL RESULTS
33
As shown earlier [6-8], the small amount (about 0.5-4%)
of hydrogen admixed in N2 (or N2 admixed in H2) leads to
a significant change of discharge characteristics in high
frequency discharges and in dc glow discharges.
Therefore, before experiments in the U-3M some imitating
examinations had been carried out in abnormal glow
discharge plasmas of an axial configuration [9], when
hydrogen came through hot Pd-cathode into nitrogen
plasma, and in mirror Penning discharge plasmas in DSM-
1 device [10]. The current-voltage characteristics were
measured with and without hydrogen admixture (≈ 1-8
at.%). In the case of glow discharge plasmas it had been
founded really strong influence of hydrogen admixture to
nitrogen on discharge current (as seen in Fig.1, discharge
current at the same voltage for H2-N2 mixture is in 5-8
times higher than for pure nitrogen). In the contrary, in
the case of Penning discharges it had not been founded of
significant influence of the hydrogen admixture in the
working gas (nitrogen) on voltage-current plasma
performances (Fig.2). A similar situation was observed for
discharges when nitrogen was admixed in hydrogen. Such
behavior can be explained by the fact that the plasma
column of Penning discharge due to magnetic field has no
direct contact with the wall surface, so surface reactions
influencing recombination rate do not play an essential
Fig. 1. I-V characteristics for abnormal GD in pure
nitrogen and in nitrogen with hydrogen admixture
.
Fig.2. Current-voltage characteristics for N2- and (N2 +
1%H2) – Penning discharges at pressure 0.266Pa.
role. It has to be noted only, that discharge current
instability takes place in Penning discharges during of a
few minutes on an initial stage of discharge caused by
impurity flow from cathodes. In this time discharge
current decreased on 30-50% from the current value in the
initial stage of discharge.
According to estimations made in [10], it could be
about 75 % impurity content (mainly H2O, CO, CO2,) on
the initial stage of discharges, if to suppose only one
impurity monolayer on cathodes surfaces before
discharge. So really, on the initial stage, the discharge
characteristics are presented for mixture of gases. The
second fact needed to be noted is the essential ultimate
pressure improvement, observed after pure nitrogen
throughput and discharge cleaning in nitrogen of Penning
discharge device DSM-1, which long time worked with
hydrogen work gas before.
In this work the cleaning regime of U-3M with the
use of pulsed RF-discharges in hydrogen-nitrogen
mixtures was examined under the nitrogen concentrations
4 at.% and 96 at.% at the same parameters as for pure
hydrogen: 1 pulse per 6 seconds, RF input power was
about 50 kW, discharge duration was 60 ms, the
stationary magnetic field was varied from 250Gs to 270
Gs. The comparison measurements of plasma density,
voltage-current characteristics of Langmuir probe, current
and voltage of RF-antenna, mass-spectra were made in
discharges at the different nitrogen concentration and in
pure hydrogen. It is seen in Fig.3 that plasma density
decreases with nitrogen concentration increase, and the
essential rise of the antenna voltage is observed (Fig. 4).
Note, that at this time the breakdown voltages for H2-N2
mixtures were essentially lower than for pure hydrogen.
To provide the increase of plasma density and low
antenna voltage one can using of the raising of the
magnetic field value from 250 Gs (pure hydrogen) to 270
Gs and what is more (for H2-N2 mixtures).
Fig.3. Plasma density vs nitrogen concentration in
hydrogen under different magnetic fields.
At the same time voltage-current characteristics of
Langmuir probe are near for both the pure hydrogen and
mixtures (Fig.5). This fact confirms that in the case of the
magnetic confined plasmas there are not essential
influence of the surface recombination reactions, as it was
observed for Penning discharges [10].
It is seen in Fig.6 that even about 2-5x103 discharge
pulses in H2-N2 mixture causes drastic decrease of partial
hydrogen pressure. It should be noted that ultimate base
pressure also decreased from 2.5x10-7 Torr to 1.5x10-7
Torr. But, in contrast, to revert initial high hydrogen
partial pressure in the U-3M vacuum chamber, it is
needed more than 2x104 pulsed discharges in pure
hydrogen. What could be the reasons of such hydrogen
effective removing?
Fig.4. Influence of magnetic field on RF antenna voltage
for different nitrogen admixtures: - 250Gs, - 270Gs
Fig.5. I-V characteristics of Langmuir probe under
cleaning discharges in pure hydrogen (closed squares),
in (4%N2+96%H2)-mixture (open triangles) and in
(96%N2+4%H2) mixture (open squares).
Fig.6. Time evolution of hydrogen concentration in the
vacuum chamber of the Uragan-3M torsatron, as
measured by IPDO-1 mass-spectrometer.
There are the main three kinds of outgassing surfaces
in the U-3M, which specify a vacuum conditions:
stainless steel walls of the U-3M vacuum chamber and
plasma unfacing surfaces of stainless steel housing of
helical windings, plasma facing surfaces of stainless steel
housing of helical windings, and TiN-coated stainless
steel RF-antennas. For the first, the essential role can play
an intensive molecular nitrogen flow, passed through U-
3M vacuum chamber under the pressure of discharge
cleaning regime similar to effect of essential decrease of
TiN and stainless steel outgassing after hydrogen
throughflow presented in [3, 11]. It is well known [12]
that the interaction between nitrogen and a stainless steel
surface is negligible and the exposure to N2 atmosphere
makes possible to short time of pumpdown and to
improve an ultimate pressure including hydrogen partial
pressure. For the plasma facing surfaces of the U-3M
34
35
components, behind of nitrogen throughflow, the
important role can play interactions of adsorbed particles
with neutrals (the production of H and N atoms radically
increases in mixtures [12]) and different radicals
NH(NH+), NH2(NH2
+ ). In such conditions the removal of
adsorbed hydrogen could be more effective. And, at last,
what about TiN-coated surfaces of the RF-antennas. It
had been shown in the previous work [13] that long time
work of TiN-coated surfaces under exposure to hydrogen
plasmas can lead to drastic changes in the TiN outgassing
behavior. It is caused by the possibility of selective
sputtering of the TiN surface, and the Ti enrichment of
the coating nearest surface layer. Titanium, in its turn,
activaly adsorbs hydrogen and impurities. So, after the
work over a long period of time under hydrogen plasma
impact, the TiN-coated RF-antennas could change into
significant source of hydrogen and, after exposure to air,
of impurities, too. In this situation the exposure of TiN-
coated surfaces to nitrogen plasmas or to plasmas of N2-
H2 mixtures could not only to clean these surfaces, but to
repair the faulty parts of antennas forming titanium nitride
instead of titanium. Of course, to choose the optimal
characteristics of RF-discharge cleaning in the U-3M and
to shed light on the real mechanisms of wall conditioning
under cleaning in N2-H2 mixtures, the additional
experiments are needed.
3. CONCLUSION
It had been shown that short time wall conditioning of
the U-3M torsatron by RF-discharge cleaning in N2-H2
mixtures had resulted in essential decrease of hydrogen
partial pressure and in improvement of the base ultimate
pressure. Such variant of RF-dischage cleaning mode
could be used, but additional experiments are needed
before, to choose the optimal discharge characteristics and
to understand in detail the real mechanisms of the N2-H2
mixed plasma interactions with surfaces of the U-3M
torsatron components.
REFERENCES
[1] O.M. Shvets et al. // Proc. of the 4th Int. Symposium on the
Heating in Toroidal Plasmas, March 21-28, 1984, Roma, Italy.
v.1, 1984, p.513-528.
[2] E.D.Volkov et al. // Proc. of the Int. Conf. on Phenomena
in Ionized Gases, July, 11-16, 1999, Warsaw, Poland,
Contributed papers. v.1, 1999, p.205-206.
[3] G.P.Glazunov, et al.//VIII Ukrainian Conference and School
on Plasma Physics and Controlled Fusion, Alushta (Crimea),
September 11-16, 2000, Book of Abstracts. Kharkov, NSC
KIPT, p. 26.
[4] A.V. Basteyev et al. Activation of Hydrogen and Hydric
Energy Resources. Kiev: “Naykova Dumka”. 1993.
[5] J.N. Brooks et al. // J. Nucl. Mater. v. 241-243, 1997, p.294-
298.
[6] F.M. Dias et al. // Proc. of the Int. Conf. On Phenomena in
Ionized Gases, Warsaw, Poland, July 11-16, 1999. Contributed
papers. v. 1, p. 151-152.
[7] V. Kudrle et al. // Proc. of the Int. Conf. on Phenomena in
Ionized Gases, Warsaw, Poland, July 11-16, 1999. Contributed
papers. v. 1, p. 167-168.
[8] N. Sasaki et al. // Proc. of the Int. Conf. On Phenomena in
Ionized Gases, Warsaw, Poland, July 11-16, 1999. Contributed
papers. v. 3, p. 21-22.
[9] G.P.Glazunov. // Int. J. Hydrogen Energy. (22). 1997, No.
2/3, p. 263-268.
[10] G. P. Glazunov et al. // Physica Scripta. 2003, vol. T103, p.
89-92.
[11] G.P. Glazunov et al. // Proc. of the 4th International
Symposium “Vacuum technologies and equipment”, April 23-
27, 2001, Kharkov, Ukraine. v. 1, 2001, p.26-27.
[12] R. Erlandson. J. Vac. // Sci. Technol. 1981, v. 19(3), p. 748-
753.
[13] G.P. Glazunov et al. // J. Nucl. Mater. 2001, v. 290-293, p.
266-270.
ВОЗМОЖНЫЙ ВАРИАНТ РЕЖИМА ЧИСТКИ ТОРСАТРОНА УРАГАН-3М
ИМПУЛЬСНЫМИ ВЫСОКОЧАСТОТНЫМИ РАЗРЯДАМИ
Г.П. Глазунов, Е.Д. Волков, Д.И. Барон, П.И. Конотоп,А.В. Лозин, С.А. Цыбенко
Исследовался режим чистки импульсными ВЧ-разрядами в смеси водорода и азота при концентрациях азота
от 4 at.% to 96 at.% при тех же параметрах ВЧ-генератора, что и для чистого водорода. Анализ полученных
данных показал, что уже около 2x103 импульсов в H2-N2 смеси вызывает заметное снижение парциального
давления водорода и предельного давления в камере У-3М. Напротив, чтобы вернуть высокое парциальное
давление водорода в вакуумной камере У-3М необходимо более чем 2x104 импульсных разрядов в чистом
водороде. Обсуждаются возможные причины эффективного удаления водорода разрядами в смеси водорода и
азота
МОЖЛИВИЙ ВАРІАНТ РЕЖИМУ ЧИЩЕННЯ ТОРСАТРОНА УРАГАН-3М
ІМПУЛЬСНИМИ ВИСОКОЧАСТОТНИМИ РОЗРЯДАМИ
Г.П. Глазунов, Є.Д. Волков, Д.І. Барон, П.И. Конотоп, А.В. Лозін, С.А. Цибенко
Досліджувався режим чищення імпульсними ВЧ-розрядами в суміші водню й азоту при концентраціях
азоту від 4 at. % to 96 at. % при тих же параметрах ВЧ-генератора, що і для чистого водню. Аналіз отриманих
даних показав, що вже близько 2x103 імпульсів у H2-N2 суміші викликає помітне зниження парціального тиску
водню і граничного тиску в камері У-3М. Навпроти, щоб повернути високий парціальний тиск водню у
вакуумній камері У-3М необхідно більш ніж 2x104 імпульсних розрядів у чистому водні. Обговорюються
можливі причини ефективного видалення водню розрядами в суміші водню й азоту.
Institute of Plasma Physics of the NSC KIPT, 61108 Kharkov,
The cleaning regime with the use of pulsed RF-discharges in
The usual regime of pulsed RF-discharge cleaning under wall
In this work the cleaning regime of U-3M with the use of pul
At the same time voltage-current characteristics of Langmuir
It is seen in Fig.6 that even about 2-5x103 discharge pulses
Fig.5. I-V characteristics of Langmuir probe under cleaning
REFERENCES
Исследовался режим чистки импульсными ВЧ-разрядами в смеси в
Досліджувався режим чищення імпульсними ВЧ-розрядами в суміш
|