Local hydrogen recycling impact on operation of rod plasma injectors
The strong influence of hydrogen recycling on the IONOTRON-046 plasma injector operation was found. The transitions were even observed from deposition by pulsed erosion (DPE) regime of the IONOTRON operation, which characterized by strong electrode erosion into pulse implantation doping (PID) regime...
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Національний науковий центр «Харківський фізико-технічний інститут» НАН України
2002
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| Cite this: | Local hydrogen recycling impact on operation of rod plasma injectors / G.P. Glazunov, V.I. Tereshin, E.D. Volkov, A.L. Konotopskiy, J. Baranowski, M.J. Sadowski, E. Skladnik-Sadowska, J. Stanislawski, A. Wiraszka // Вопросы атомной науки и техники. — 2002. — № 4. — С. 126-128. — Бібліогр.: 5 назв. — англ. |
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Digital Library of Periodicals of National Academy of Sciences of Ukraine| _version_ | 1860235883709464576 |
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| author | Glazunov, G.P. Tereshin, V.I. Volkov, E.D. Konotopskiy, A.L. Baranowski, J. Sadowski, M.J. Skladnik-Sadowska, E. Stanislawski, J. Wiraszka, A. |
| author_facet | Glazunov, G.P. Tereshin, V.I. Volkov, E.D. Konotopskiy, A.L. Baranowski, J. Sadowski, M.J. Skladnik-Sadowska, E. Stanislawski, J. Wiraszka, A. |
| citation_txt | Local hydrogen recycling impact on operation of rod plasma injectors / G.P. Glazunov, V.I. Tereshin, E.D. Volkov, A.L. Konotopskiy, J. Baranowski, M.J. Sadowski, E. Skladnik-Sadowska, J. Stanislawski, A. Wiraszka // Вопросы атомной науки и техники. — 2002. — № 4. — С. 126-128. — Бібліогр.: 5 назв. — англ. |
| collection | DSpace DC |
| container_title | Вопросы атомной науки и техники |
| description | The strong influence of hydrogen recycling on the IONOTRON-046 plasma injector operation was found. The transitions were even observed from deposition by pulsed erosion (DPE) regime of the IONOTRON operation, which characterized by strong electrode erosion into pulse implantation doping (PID) regime with low electrode erosion. Physical mechanisms of such behavior are considered using the results of measurements of an outgassing rate from the titanium electrode rods used in IONOTRON-046 by means of mass spectrometry and thermal desorption methods, measurements of current- and voltage-waveforms, and spectroscopic studies of plasma emission. A possible practical use of the observed effects is also discussed.
|
| first_indexed | 2025-12-07T18:24:13Z |
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LOCAL HYDROGEN RECYCLING IMPACT ON OPERATION
OF ROD PLASMA INJECTORS
G.P. Glazunov, V.I. Tereshin, E.D. Volkov, A.L. Konotopskiy,
Institute of Plasma Physics of National Science Center „Kharkov Institute of
Physics&Technology”, 61108 Kharkov,Ukraine, e-mail: glazunov@ipp.kharkov.ua
J. Baranowski, M.J. Sadowski, E. Skladnik-Sadowska, J. Stanislawski, A. Wiraszka
A. Soltan Institute of Nuclear Studies, 05-400 Otwock-Swierk, Poland
The strong influence of hydrogen recycling on the IONOTRON-046 plasma injector operation was found. The
transitions were even observed from deposition by pulsed erosion (DPE) regime of the IONOTRON operation, which
characterized by strong electrode erosion into pulse implantation doping (PID) regime with low electrode erosion.
Physical mechanisms of such behavior are considered using the results of measurements of an outgassing rate from the
titanium electrode rods used in IONOTRON-046 by means of mass spectrometry and thermal desorption methods,
measurements of current- and voltage-waveforms, and spectroscopic studies of plasma emission. A possible practical
use of the observed effects is also discussed.
PACS: 52.58..Lq; 52.40.Hf
1. INTRODUCTION
Hydrogen recycling process plays important role
in the operation of different fusion devices with magnetic
confinement. The particular attention is given to this
phenomenon studies including its active control, in the
frame of plasma-material interaction investigations. Also
in pulsed plasma generators, e.g. multi-rod plasma
injectors (RPI or IONOTRON type of plasma devices),
plasma accelerators, etc., which are used for various
plasma applications [1, 2], there is needed more detailed
information about such processes. The RPI devices are
equipped with two coaxial electrodes consisted of many
(up to 64) thin rods made usually of molybdenum or
titanium. Electrode rods of a RPI device are the main
plasma facing component, and, from the one hand, the
processes of a gas sorption/release by its surface can
influence the plasma machine operation and
uncontrollable change properties of modified materials.
On the other hand, by a control of the mentioned
processes, one can change (select) a required operation
regime and perform the modified materials treatment at
other conditions. So in this work some imitation
experiments were carried out to investigate the influence
of hydrogen recycling process (hereinafter we have in
view local hydrogen recycling process and local recycling
coefficient determined by hydrogen sorption/release from
RPI Ti-electrodes) on IONOTRONE-046 plasma
performances. Such information can also be useful for
understanding of physical mechanisms of hydrogen
recycling processes in fusion devices.
2. EXPERIMENTS AND RESULTS
2.1. Outgassing behavior of Ti-electrodes.
As the outgassing from material in vacuum is one of the
most important characteristics, which determines gas
sorption/release processes and ground pressure, the
measurements of outgassing rate in vacuum from the used
in IONOTRON-046 Ti-rods were carried out before
plasma experiments. A block scheme of the experimental
setup used for the outgassing investigations is similar to
that described in [3] with some modifications. The setup
comprised a thick-wall stainless-steel vacuum chamber,
which accommodated samples, a monopole mass-
spectrometer, and gauges for measurements of the
operating pressure. The vacuum chamber was connected
with a turbomolecular pump and a mechanical fore pump.
The specimens under studies were Ti-rods of 2 mm in
diameter, and 145 mm in length, which were long-time
used as external and internal electrodes in IONOTRON-
046 under nitrogen plasma operation in DPE regime. For
a comparison also investigated were virgin rods made of
pure Ti, and samples made of stainless steel rod. The
sample holder construction allowed the samples to be
heated to required temperatures up to 600°C which were
measured by the thermocouple. The experimental system
was also equipped with special hydrogen chamber to
provide hydrogen saturation of investigated rods to
required concentration.
Measurements of an outgassing rate from
investigated electrode-rods were performed by means of
the thermal-desorption and mass-spectrometry methods
[4]. Before those measurements the main vacuum
chamber was baked up for 3 hrs, at a temperature of 100 °
C. When the system was cooled down to a room
temperature, the final pressure achieved about (3-5)⋅10-8
Torr. Then the investigated rods were heated to a required
temperature with a temperature rise of about 20°/min, and
an increase in the total pressure (caused by desorbed
gases) was measured. The specific net-outgassing rate (q)
was calculated from the equation q = (p – po)S/F, where
the pumping speed S = 50 l/s, F was a surface area of the
heated sample, po was the initial pressure in vacuum
chamber before sample heating, and p was the final
pressure at given temperature value.
The mass-spectrum of the gases was registered
during the whole desorption process. It was observed that
the desorbed gases in 50-350°C range are gases with the
ratio M/Ze = 18 (H2O), 28 (CO, N2), and 44 (CO2), that is
similar to outgassing behavior of investigated earlier Mo-
rods [3]. But under heating in 300-500°C temperature
range considerable hydrogen release was observed. It
should also be noted that hydrogen release from the used
external-electrodes (cathodes) was observed lower than
126 Problems of Atomic Science and Technology. 2002. № 4. Series: Plasma Physics (7). P. 126-128
for virgin rods and hydrogen release from internal
electrodes (anodes) visibly higher than that from external
electrodes. During the heating of the Ti-electrode rods,
which were previously long-time used in the RPI device,
the outgassing more than order of value higher than that
measured for the virgin Ti-rods and stainless steel
samples (Fig.1).
Fig.1. Temperature dependencies of specific net
outgassing rate (q) from Ti-rods.
2.2. Current- and voltage-waveforms,
spectroscopic studies.
Different experiments are run in RPI with various
working gases: hydrogen, nitrogen, etc. A spectrum of the
emitted ions depends on the injected working gas and a
time delay between the gas puffing and the application of
a high voltage pulse. The detailed description of
IONOTRON-46 device was given in Ref.[1]. In this work
RPI operated with nitrogen plasma in 28kV/16kJ regime
with delay time 200µs when so called pulsed deposition
mode (DPE) regime is realized, which is characterized by
strong electrode erosion. Such regime was of a great
interest taking into account its possible technology
applications for surface modification of materials. Of
course, the regime with low erosion, when working gas
plasma is mainly produced, also is interested for hydrogen
recycling investigations, and we are going to study it in
the next work.
Optical spectra of plasmas, produced by high-
voltage discharge between Ti-electrodes, were measured
by means of a Mechelle-900 spectrometer within the
wavelength range from 300 to 800 nm and 25 µs
exposition time duration. Measurements of the emission
spectra of nitrogen plasmas have been performed
perpendicularly to the symmetry axis of the RPI
electrodes at 10cm distance from their ends. Details of
method of spectrum measurements and analysis were
similar to that in Ref.[5]. Special attention was paid to the
Hα, NII, TiII lines.
Four kinds of experiments were carried out in the
RPI: with the use of Ti-electrodes long time operated
under nitrogen plasma RPI, with the same Ti-electrodes,
but after their mechanical cleaning and exposure to
hydrogen at pressure 2 atm. during 48 hours, Ti-
electrodes with the placing of the additional mono PdHx-
electrode (anode), Ti-electrodes after exposure in situ to
hydrogen GD plasma. The typical waveforms and spectra
for all above mentioned cases are shown in Fig.2. The
spectral lines Hα, NII, TiII intensity evolution in
dependence on the number of pulses are presented in
Figures 3, 4, 5.
3. DISCUSSION
In order to explain the described outgassing
behavior of the titanium electrode-rods, one can suggest
possible mechanisms as similar to observed earlier for
Mo-electrodes [3]. During the plasma operation regime,
electrode surfaces are cleaned by plasma discharges and
surfaces value increases due to radiation damages. As a
result, the impurity sorbing capability increases during the
time between plasma pulses and an exposure to
atmosphere (for a comparison with the virgin samples).
This impurity source can effect on RPI plasma machine
operation and especially, it can be as very important
factor for surface modification applications of RPI-
plasmas due to possible decrease of investigated sample
quality, caused by impurity release from electrode rods.
Of course, this impact becomes lower after long time
plasma machine operation and without exposure to
atmosphere. In this case other effects caused by, so called,
hydrogen recycling process can take place. Hydrogen
sorption/release by electrode material (in general case by
all materials of device) can change its properties, i.e. such
as arc ignition probability, erosion behavior, reflection
coefficient, electron emission coefficient etc., and can
lead to changing of plasma machine performances and, as
the result, to change properties of modified materials.
The observed essential hydrogen release from
used Ti-rods can be explained by high hydrogen
concentration in virgin rods. Even after long time
operation under nitrogen puffing there are high hydrogen
concentration in electrodes (it is lower in external and
higher in internal electrodes). But plasma-activated near
surface layer bulk of Ti-electrodes sorbs impurities
Fig. 2. Voltage(U)-current(I) wave-forms (A) and optical
spectra (B) of nitrogen plasma emission in IONOTRON-
127
1.00E-09
1.00E-08
1.00E-07
1.00E-06
1.00E-05
1.00E-04
1.00E-03
0 100 200 300 400 500 600 700
Temperature [ C]
O
ut
ga
ss
in
g
ra
te
, q
[T
or
r.l
/s
.c
m
]2 Used Ti-rods
Stainless steel-rods
Virgin Ti-rods
046 registered during first shots with the use of Ti (first
row)-, TiHx (second row)-, (Ti+PdHx) (third row)- and
hydrogen GD plasma treated Ti - electrodes (fourth row).
between plasma pulses and under atmosphere exposure,
therefore we do not observed any influence of hydrogen
in rods on device operation under nitrogen puffing (first
row in Fig.2). Note, that it is the evidence for the fact that
electrode-rod bulk has not been heated to high
temperature under plasma impact. The mechanical
cleaning of Ti-electrodes and their exposure to hydrogen
at pressure 2 atm. leads to cardinal changes in nitrogen
plasma regime of the IONOTRON device caused by a
transition from low hydrogen recycling coefficient to high
hydrogen recycling coefficient (second row in Fig.2). The
similar effect with some specificity was also observed,
when one hydrogen saturated PdH0.55-electrode was
placed in multi-Ti-rods system (third row in Fig.2) or
when Ti-rods were treated in situ by GD hydrogen plasma
of ≈300eV ion energy during 1 hour (fourth row in Fig.2)
If to suggest that spectral line intensity is
proportionate to concentration of element in plasma
column, one can see in Figures 4, 5, 6 that hydrogen
release from electrodes leads to the transition from
deposition by pulsed erosion (DPE) regime which
characterized by strong electrode erosion into pulse
implantation doping (PID) regime low electrode erosion.
Fig. 3. Evolution of Hα, line intensity vs. number of shot
for different state of electrodes (high/low hydrogen
recycling coefficient).
As seen in Fig. 3, 4, 5, under the use of TiHx -and
(Ti+PdHx) – electrode systems the Hα-line intensity is
highest possible during the first shots due to high
hydrogen release from the nearest surface layer bulk of
the rods. Palladium has high hydrogen mobility even at
the moderate temperatures. So only one Pd-rod in
electrode system provides Hα-line intensity increase
during first pulse more than 64 hydrogen saturated Ti-
rods. At the same time Ti-line intensities are the lowest
(Fig.4). It means the lowest erosion of Ti-electrodes and
that the transition from one operation mode (DPE) to
another (PID) is realized due to high hydrogen recycling
(additional gas puffing) along whole length of electrodes.
After a few pulses (after about ten shots for TiHx rods)
hydrogen concentration in the nearest surface layer bulk
of Ti-rods (or in Pd-rod) decreases and the operation
regime reverts to the state of DPE mode (Fig.7). So the
modification of local hydrogen recycling coefficient in
the range of multi-rod electrode system could be as an
original method to change operation regime of rod plasma
injectors that could be useful, e.g., for surface
Fig. 4. Evolution of TiII and NII lines vs. number of shot
for discharges with TiHx-electrodes.
modification experiments. In the case of the basic
investigation of hydrogen isotope plasmas such method
can provide the additional purity and improvement of
plasma characteristics.
4. CONCLUSION
The main results of the described study can be
summarized as follows. Changing of hydrogen recycling
coefficient in the range of electrode system can lead to the
transitions from deposition by pulsed erosion regime of
the IONOTRON device operation, which characterized by
strong electrode erosion, into pulse implantation doping
regime with low electrode erosion. Such method could be
used, e. g., in material modification experiments and in
basic plasma investigations.
The specific net-outgassing rate of Ti rods,
which were used in the nitrogen plasma pulse operation
regime of the IONOTRON, was about one order
magnitude higher than for the virgin Ti rods. The
favorable reason of such outgassing behavior could be an
enhancing of rod impurity sorbing capability under/after
plasma irradiation. At the same time considerable
hydrogen release at high temperature was observed from
the used Ti-rods due to high hydrogen concentration in
virgin Ti-rods.
These results are of importance for applications
of IONOTRON-type devices in basic plasma studies and
material engineering. It can also be useful for
understanding of hydrogen recycling processes in fusion
machines.
ACKNOWLEDGEMENT
The described study was performed within the frame of
Polish-Ukrainian Scientific Cooperation Program
supported by the Polish and Ukrainian governments
REFERENCES
[1] J. Langner, et al., Nukleonika, 45/3 (2000) 193-197.
[2] V.I. Tereshin. 2nd National Symposium PLASMA’95 “Research and
applications of plasmas”, Warsaw, Poland, June 26-28, 1995, v.2.
Invited papers, p.87-94.
[3] G.P. Glazunov, et al., Proc. of the Intern. Symp. PLASMA-2001
“Reasearch and Applications of Plasmas”, Warsaw, September 19-21,
2001, P8-8, p.216
128
0 2 4 6 8 10
500
1000
1500
2000
2500
Ti
Ti+PdHx
TiHx
In
te
ns
ity
o
f H
-a
lp
ha
li
ne
[a
.u
.]
Number of shot
0 2 4 6 8 10
0
1000
2000
3000
4000
5000
6000
7000
TiΙ Ι 430.79
TiΙ 455.54
TiΙ Ι 439.5
NΙ Ι Ι 464.06
NΙ Ι 404.13
In
te
ns
ity
o
f l
in
es
/
[a
.u
.]
Number of shot
[4] G.P. Glazunov, et al., J. Nuclear Materials. 290-293 (2001) 266-270.
[5] J. Baranowski, E. Skladnik-Sadowska, K. Czaus, M.J. Sadowski.
NUCLEONIKA, (2002) to be published.
129
Local HYDROGEN RECYCLING IMPACT ON OPERATION
OF ROD PLASMA INJECTORS
A. Soltan Institute of Nuclear Studies, 05-400 Otwock-Swierk, Poland
1. Introduction
References
|
| id | nasplib_isofts_kiev_ua-123456789-80323 |
| institution | Digital Library of Periodicals of National Academy of Sciences of Ukraine |
| issn | 1562-6016 |
| language | English |
| last_indexed | 2025-12-07T18:24:13Z |
| publishDate | 2002 |
| publisher | Національний науковий центр «Харківський фізико-технічний інститут» НАН України |
| record_format | dspace |
| spelling | Glazunov, G.P. Tereshin, V.I. Volkov, E.D. Konotopskiy, A.L. Baranowski, J. Sadowski, M.J. Skladnik-Sadowska, E. Stanislawski, J. Wiraszka, A. 2015-04-14T18:27:52Z 2015-04-14T18:27:52Z 2002 Local hydrogen recycling impact on operation of rod plasma injectors / G.P. Glazunov, V.I. Tereshin, E.D. Volkov, A.L. Konotopskiy, J. Baranowski, M.J. Sadowski, E. Skladnik-Sadowska, J. Stanislawski, A. Wiraszka // Вопросы атомной науки и техники. — 2002. — № 4. — С. 126-128. — Бібліогр.: 5 назв. — англ. 1562-6016 PACS: 52.58..Lq; 52.40.Hf https://nasplib.isofts.kiev.ua/handle/123456789/80323 The strong influence of hydrogen recycling on the IONOTRON-046 plasma injector operation was found. The transitions were even observed from deposition by pulsed erosion (DPE) regime of the IONOTRON operation, which characterized by strong electrode erosion into pulse implantation doping (PID) regime with low electrode erosion. Physical mechanisms of such behavior are considered using the results of measurements of an outgassing rate from the titanium electrode rods used in IONOTRON-046 by means of mass spectrometry and thermal desorption methods, measurements of current- and voltage-waveforms, and spectroscopic studies of plasma emission. A possible practical use of the observed effects is also discussed. The described study was performed within the frame of Polish-Ukrainian Scientific Cooperation Program supported by the Polish and Ukrainian governments. en Національний науковий центр «Харківський фізико-технічний інститут» НАН України Вопросы атомной науки и техники Plasma dynamics and plasma-wall interaction Local hydrogen recycling impact on operation of rod plasma injectors Article published earlier |
| spellingShingle | Local hydrogen recycling impact on operation of rod plasma injectors Glazunov, G.P. Tereshin, V.I. Volkov, E.D. Konotopskiy, A.L. Baranowski, J. Sadowski, M.J. Skladnik-Sadowska, E. Stanislawski, J. Wiraszka, A. Plasma dynamics and plasma-wall interaction |
| title | Local hydrogen recycling impact on operation of rod plasma injectors |
| title_full | Local hydrogen recycling impact on operation of rod plasma injectors |
| title_fullStr | Local hydrogen recycling impact on operation of rod plasma injectors |
| title_full_unstemmed | Local hydrogen recycling impact on operation of rod plasma injectors |
| title_short | Local hydrogen recycling impact on operation of rod plasma injectors |
| title_sort | local hydrogen recycling impact on operation of rod plasma injectors |
| topic | Plasma dynamics and plasma-wall interaction |
| topic_facet | Plasma dynamics and plasma-wall interaction |
| url | https://nasplib.isofts.kiev.ua/handle/123456789/80323 |
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