On phenomena in ionized gases
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- Dusty plasma structures in gas- metal vapor mixtures
- STUDY OF PROCESSES OF DUST FORMATION IN TNER ON MODEL SET OF PULSED PLASMA ACCELERATOR
- 4. References
- Effect of accumulated charge desorption in atmospheric pressure dielectric barrier discharges
- 2. Simulation model and Results
- 2. Experimental Apparatus
- Comparative analysis of properties of helium and argon atmospheric pressure plasma jets
3. Summary Pressure waves were detectable with the optical wave microphone inside the plume of plasma jets.
[1] F. Mitsugi, T. Nakamiya, Y. Sonoda, T. Kawasaki, IEEE Trans. Plasma Sci., 44 (2016) 2759. [2] F. Mitsugi, S. Kusumegi, T. Kawasaki, T. Nakamiya, Y. Sonoda, IEEE Trans. Plasma Sci., 44 (2016) 3077.
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XXXIII ICPIG, July 9-14, 2017, Estoril/Lisbon, Portugal
Dusty plasma structures in gas- metal vapor mixtures
M.K. Dosbolayev 1 , A.R. Abdirakhmanov 1 , T.S. Ramazanov 1 and S.A. Maiorov 2
IETP, al-Farabi Kazakh National University, 71, al-Farabi av., Almaty, 050040, Kazakhstan 2 Prokhorov General Physics Institute, Russian Academy of Sciences, Vavilov st. 38, Moscow, 119991, Russia merlan@physics.kz
mixtures of metal vapor and gas (Ar and He) are presented. Time characteristics (p=f(t); I=f(t)) of the gas discharge were obtained and analyzed. In addition, number of features of combustion of buffer discharge in a mixture of metal vapors and gas, and change of the properties of plasma-dust structures in it were identified.
The discharge in mixtures of metal vapor with inert gases is commonly used in various practical applications: to create pulsed atomic lasers with high temperature active element to create discharge light sources. Recently, technologies to produce nanoparticles from condensed metal vapors in different plasma environments leading to the formation of complex plasma are intensively tested. Thus, there are two types of plasma of complex composition. Firstly, discharge in mixtures of metal vapor with inert gases. In this case, during discharge metal vapors do not agglomerate, and participate in the form of individual atoms and molecules. Since the metal atoms are easily ionized compared to the atoms of the gas, it is easier to ionize gas-discharge medium. Secondly, the metal vapors, for example during cathode material sputtering, entering the discharge zone of the cathode agglomerate and become part of the plasma as individual charged nano- and micro particles. Effect of
composition of
gas on
the characteristics of the
dust formations was investigated in [1-3], where it is shown that the discharge in a mixture of different gases leads to a very significant change in the characteristics of both electronic and ionic plasma components. Moreover, the gas discharge characteristics can vary greatly even at very low concentration of impurities.
Experiments were carried out in a vertical discharge tube in classic version. The procedure of the experiment is as follows: the discharge tube is filled with homogeneous gas and the initial value of pressure is set, it is usually p≈0.17 tor. In a few minutes discharge is ignited (Fig. 1, vertical dotted line on the left). The initial value of the discharge current is set so that during combustion of discharge cathode material is sputtered. This is evidenced by increase in pressure within the tube, the process continues relatively long time until the discharge is extinguished (Fig. 1, vertical dotted line on the right). The result is formation of discharge in mixture of cathode metal vapors and gas. 0 1000 2000 3000
4000 5000
6000 0,0
0,2 0,4
0,6 0,8
1,0 1,2
p I t, s p, tor
(Ar) 0 2 4 6 8 10 12 14 16 18 I, mA Figure 1. Time characteristics of the gas discharge (p=f(t); I=f(t))
So, the dust-plasma formations in a stratified glow discharge (first striation from the cathode) in pure gas and in mixture of pure gas and metal vapor were investigated. For characteristics of structural properties of dust formations pair correlation functions were also obtained.
[1]
S.A. Maiorov, T.S. Ramazanov, K.N. Dzhumagulova, A.N. Jumabekov, M.K. Dosbolayev. Physics of Plasmas 15 (2008) 093701. [2]
Maiorov, S.K. Kodanova, M.K. Dosbolayev and E.B. Zhankarashev, Contrib. Plasma Phys. 51, (2011) 505-508.
[3] M.K. Dosbolayev, A.U. Utegenov, T.S. Ramazanov, and T.T. Daniyarov, Contrib. Plasma Phys. 53, (2013), 426 –431.
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XXXIII ICPIG, July 9-14, 2017, Estoril/Lisbon, Portugal
Topic number
M.K. Dosbolayev 1 , A.B. Tazhen 1 , A.U. Utegenov 1 , T.S. Ramazanov 1
1 IETP, al-Farabi Kazakh National University, 71, al-Farabi av., Almaty, 050040, Kazakhstan
In this work the results of the experimental investigation of dust formation after interaction of pulsed plasma flow with candidate material of thermonuclear reactor in PPA-30 are presented. Via Raman spectrometer it was revealed, that after interaction of plasma, the surface structure of graphite target becomes amorphous. Also in this experimental work, the materials with fractal surface as in tokamaks, which was appeared by the erosion, were obtained.
Since the eighties of the last century, an interest in the creation of controlled thermonuclear fusion reactors with magnetic confinement has been actively developing for domestic and industrial using. Due to this, tokamak is the most perspective device for its implementation. It is known, that the main
problem of
realization of
controlled thermonuclear fusion is the dust formation, which appears after interaction pulsed plasma flow with the components of reactor, placed inside the vacuum chamber. It has been established that the dust microparticles form layers in the form of films, which can be carried out of the chamber and, thus, be distributed in other systems of the reactor. Thereby, the accumulation of dust and precipitation of film in the volume of reactor play a negative role. First of all, it leads to instability of combustion of high temperature plasma and nucleation of breakdowns, secondly, to the
capture and
accumulation of tritium, which is a problem for safe of reactor operation and its economy [1]. Composition of particles includes materials of the first wall and other internal elements of structure, which are typically graphite, titanium, tungsten, beryllium and steel.
The experiments were performed on a plasma accelerator PPA-30. Device consists of two coaxial electrodes, separated by an insulator. To investigate the dust formation after irradiation of the material with pulsed plasma flow, graphite plate was used. After the collision with the target of plasma flow, formed dust particles collected by separate container for further analysis (Figure 1). Analysis showed that the structure of obtained particles has a rough surface and the particle size varies in the range ~ 10- 45 micron. According to the Raman spectrum [2] it was revealed that the
graphite surface
is an
inhomogeneous. The Raman spectrum of the defective area of the sample, which is characterized by an increase in the peak intensity of D, the total broadening of the peaks and the peak offset G in the high frequency region with a value of 1595 cm -1
suggests a certain degree of amorphous structure.
Figure 1. Principle schematic of the model experimental set-up. 1-system of electrodes, 2-plasma flow, 3-graphite plate, 4-container of separate.
Experimental results of study of processes of the dust formation on model set in IETP KazNU are shown. According to the results of synergetic analysis of erosion products, it was found that after interacting with pulsed plasma flow, the target surface becomes amorphous, which indicated the increasing of D peak in the Raman spectrum of the irradiated target.
[1]
J.C. Flanagan, M. Sertoli, M. Bacharis et al. Plasma physics and controlled fusion. 57 (2015) 014037. [2]
Introductory Raman Spectroscopy. Second Edition. Elsevier (2003).
214 XXXIII ICPIG, July 9-14, 2017, Estoril/Lisbon, Portugal
Effect of accumulated charge desorption in atmospheric pressure dielectric barrier discharges
H. Akashi and T. Yoshinaga UP
P Dept. of App. Phys., National Defense Academy, Yokosuka, Japan P
Recently, atmospheric dielectric barrier discharges are widely applied to various fields, such as ozone generation, surface modification and so on. In dielectric barrier discharges, there are many parameters which affect to plasma significantly, so less attentions on interaction between plasma and dielectric surfaces. In the present paper, desorption of accumulated charges on dielectric surfaces is considered in atmospheric pressure dielectric barrier discharges using two dimensional fluid model. It is found that the waveforms of discharge current and voltage are similar to the results of no desorption case, however, electrons and ions in the vicinity of the dielectrics significantly increase with consideration of desorption, such as low secondary electron emission condition.
Recently, atmospheric dielectric barrier
discharges (DBDs) are widely applied to various fields, such as ozone generation, decomposition of toxics, surface modification, medical sterilization and so on. However, in dielectric barrier discharges, there are many parameters which affect to plasma significantly, such as dielectric materials and its thicknesses, geometries of electrodes, gas, gas pressure and gas mixtures, applied voltage waveforms, and so on. Less attentions on the interaction between plasma and dielectric surfaces and have been almost neglected. Golubovskii et al [1], simulated Atmospheric Pressure Townsend Discharges (APTG) using one dimensional fluid model. Recently, Itoh et al [2] also mentioned about desorption from dielectrics in DBDs. In the present paper, desorption of accumulated charges on dielectric surfaces is considered in atmospheric pressure dielectric barrier discharges using two dimensional fluid model [3,4] and the effect of desorption on DBD has been discussed.
The present simulation model is the same as ref.[3,4]. 7.5kV and 200kHz sinusoidal voltage is applied to 760Torr Oxygen gas. Boundary condition at x=0, 0.6cm is periodical. And charges are accumulated on the dielectric surfaces. In the present paper, desorption from dielectric is considered. Figure 1 shows the one cycle averaged spatial distributions of electron densities w/o and w/ the desorption effect. As shown in the figure*(a), electrons are locally generated and each high density regions consist of 5 filaments (streamers). However, with the considering desorption, high electron density regions are formed widely in x direction in the vicinity of the dielectrics. In the case of w/o desorption, electrons are recombine with ions on the dielectrics, but distributed on the dielectrics uniformly. In the case of w/ desorption, the accumulated electrons uniformly distributed on the dielectrics desorb gradually into the discharge space. As a result, total electron density in the discharge space becomes higher than conventional model. And only two kinds of streamers can be obtained with consideration of desorption case in spite of three without consideration of desorption case.
[1] Y.B.Golubovskii, et al, J.Phys. D: Appl.Phys. Vol.35, pp.751-761 (2002) [2] H.Itoh et al, ESCAMPIG XXIII, Bratislava, Slovakia, p.192 (2016) [3] G.Takahashi and H.Akashi, IEEJ Trans. FM, Vol.131, No.3, pp.205-210 (2011) (in Japanese) [4] G.Takahashi and H.Akashi, IEEE Trans. PS, Vol.39, No.11, pp.234-235 (2011)
Topic number 10 0.00 0.10
0.20 0.30
0.40 0.50
0.60 0.20
0.15 0.10
0.05 0.00
x (cm) y (cm
) 0.0e+000
1.5e+011 3.0e+011
electron density(cm-3) 0.00
0.10 0.20
0.30 0.40
0.50 0.60
0.20 0.15
0.10 0.05
0.00 x (cm)
y (cm ) 0.0e+000 1.5e+011 3.0e+011
electron density (cm-3) Fig.1. Spatial distributions of electron density (one cycle average). (a) without consideration of desorption. (b) with consideration of desorption. (a) (b) 215
XXXIII ICPIG, July 9-14, 2017, Estoril/Lisbon, Portugal
Investigation of compositions in plasma-irradiated buffer evoking TRP-channel mediated calcium response
S. Sasaki P 1 P , Y. Zheng P1 1 P , M. Kanzaki P 2
, T. Kaneko 1
P
P
P
P
Although plasma medicine is a rapidly emerging field and medical applications using non-equilibrium atmospheric pressure plasma are promising, the interaction mechanism between the plasmas and living cells remains unclear. In order to enhance understandings of the interaction, we focused on transient receptor potential (TRP) channel(s) on cell membrane as biological targets of APP-produced reactive species and investigated the concentrations of hydrogen peroxide (H 2 O 2 ) and
the potency of the reactive species for evoking calcium responses through TRP channel. The results suggest that the precursor(s) of H 2 O
may be responsible for the APP-induced TRP-channel-mediated calcium responses.
Plasma medicine is a rapidly emerging field, and a number of researchers have reported innovative applications of non-equilibrium atmospheric pressure plasma (APP) [1, 2]. While the fact that reactive species are key components of APP in the plasma medical treatment is now widely accepted, the interaction mechanism between the reactive species and living cells remains unclear. Because the first contact of the species with cells is considered to be just the membrane lipids or the membrane proteins, we have intensively investigated the APP-induced changes in cell membrane transports. Thus, we experimentally showed that unclassified reactive species in APP-irradiated solution can trigger physiologically relevant Ca 2+ influx through transient receptor potential (TRP) channel(s) on cell membrane [3]. However, it is still challenging to specify the key species and the key member of TRP family. Therefore, we tried to measure the APP-produced reactive species and the induced calcium response through TRP channels.
APP was generated using low frequency (LF) (frequency: 8 - 10 kHz, voltage: 5 - 12 kV) with Helium gas flow, which was exposed to the biological buffer. The plasma-irradiated solution was put on a hot plate (37°C) for a retention time t r , and
added to mouse fibroblast cells 3T3-L1 (indirect plasma irradiation) or added to hydrogen peroxide monitoring probe. Real-time changes in the amount of the intracellular calcium ion concentration ([Ca 2+
i ) were obtained using a calcium indicator fluo 4 and a confocal microscope.
3. Experimental Results and Discussion Figure 1 shows that (a) the concentration of hydrogen peroxide (H 2 O 2 ) in plasma-irradiated solution at varying t
and (b)time course of changes in the average [Ca 2+ ] i of 3T3-L1 cells stimulated with plasma-irradiated solution at t
= 30 s, 300 s, and 600 s. The concentration of H 2 O 2 increased but the production rate decreased with time after APP irradiation, which indicating that APP-irradiated solution gradually lost the capacity to produce the precursor of H 2 O
with time. As t r increased, the APP-induced increase in [Ca 2+ ] i was lower. These results suggest that the precursor(s) of H 2 O 2 is
responsible for the APP-induced calcium response. In the presentation, I will show the result on the mechanism of not only calcium responses but also other membrane transports evoked by APP irradiation.
[1] G. Fridman, et al., Plasma Process. Polym. 5 (2008) 503. [2] S. Sasaki, et al.: J. Phys. D: Appl. Phys. 49 (2016) 334002.
[3] S. Sasaki, et al., Sci. Rep. 6 (2016) 25728. 17
(a) (b) Fig. 1. (a) The concentration of hydrogen peroxide (C H2O2 ) in
plasma-irradiated solution at varying t r and (b)time course of changes in the average [Ca 2+ ] i of 3T3-L1 cells stimulated with plasma-irradiated
solution at t r = 30 s, 300 s, and 600 s. 0 100 200 300 400 500 600 0 10 20 30 40 50 t r (s) C H 2 O 2 ( μ M) 216
XXXIII ICPIG, July 9-14, 2017, Estoril/Lisbon, Portugal
Comparative analysis of properties of helium and argon atmospheric pressure plasma jets
Y.А. Ussenov 1,2 , A.S. Pazyl 1 , A.K. Akildinova 1 , M.K. Dosbolayev 1,3 , M.T. Gabdullin 1 ,
T. T. Daniyarov 1 , T.S. Ramazanov 1,3
1 Al-Farabi Kazakh National University, NNLOT, Al-Farabi, 71, 050040, Almaty 2 Institute of applied science and information technologies, Shashkina, 40/48, 050038, Almaty 3 Al-Farabi Kazakh National University, IETP, Al-Farabi, 71, 050040, Almaty
This paper presents the results of studies of the structure, electrical, optical properties and temperature of the atmospheric pressure plasma jet in noble gases, such as helium and argon. The length and shape of the plasma jet at different gas flow rates and values of high voltage on the discharge electrodes were compared. Dynamic and static current-voltage characteristics on the basis of the oscillograms were also analyzed. Discharge spectra were obtained by optical emission spectroscopy method and compared for He and Ar gases. Temperature of treating surface (cupper plate) measured by thermocouple at different values of gas flow rate.
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