On phenomena in ionized gases
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- 2.2. Results and discussions
- 3. References
- Activity of catalase enzyme in P. tomentosa seeds after direct plasma treatments and treatments with plasma activated water
- 2. Results and discussion
- Growth of nano-tendril bundles on tungsten in impurity-rich helium plasmas
- 3. Results and discussion
- References
- State-by-state emission spectra fitting for non-equilibrium plasmas: OH spectra of surface barrier discharge at argon/water interface
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2. Experimental : An intense microwave plasma based low energy ion source has been developed and employed in the experiment [2]. The wetting property has been characterised by contact angle and it has been measured by sessile drop method. The surface roughness is characterised by RMS roughness which is obtained by Atomic Force Microscopy (AFM) studies.
Figure 1 shows the variation of static contact angle of de-ionised water on Cu substrates irradiated with different ion beam species. It is observed that the substrate undergoes a transition from hydrophilic to hydrophobic nature indicating a reduction in surface energy.
Fig. 1: Variation of water contact angle with fluence for different ion species It is believed that the dispersive intermolecular force between the metal atoms is perturbed by the presence of inert gas molecule. The resultant surface energy is dictated by the polarizability of the implanted species. However, for real surfaces, the definition of a static, equilibrium contact angle is not unique and the possible values of contact angles are found to lie between the advancing and receding contact angles. We found that both these angles increase with beam fluence and a nominal hysteresis is induced by this process. AFM studies reveal that nanomeric rough surfaces are developed by the irradiation process, which has very little impact on the static contact angle, however, it is responsible for the nominal hysteresis according to the Johanny- de Gennes theory [3]. The details of the analysis will be presented in the conference. 3. References [1]
P.G. de Gennes., Rev. Mod. Phys. 57, (1985) 827. [2]
A. Chowdhury and S. Bhattacharjee, J Phys. D: Appl Phys, 46, (2013) 435304.
[3] J. F. Johanny and P. G. de Gennes, J. Chem. Phys, 81, (1984), 1.
Topic number: 14 178 XXXIII ICPIG, July 9-14, 2017, Estoril/Lisbon, Portugal
Modeling of self-consistent mode formation in an electrostatic plasma lens I. Litovko 1 , A. Goncharov 2 , A. Dobrovolskiy 2 , A. Bugaev 3 , V. Gushenets 3 , E. Oks 3 1 Institute for Nuclear Research NAS of Ukraine, Kiev, Ukraine 2 Institute of Physics NAS of Ukraine, Kiev, Ukraine 3 Institute of High Current Electronics, Tomsk, Russia Here we described the modeling of self-consistent mode formation in an electrostatic plasma lens under transport through it a wide-aperture, high-current, low energy, metal-ion plasma flow produced by a cathode arc discharge. When the negative potential applied on the central cylindrical lens electrode, a radial directed stream of energetic electrons is formed. The formation of the electric potential jump near the inner surface of the cylinder has been modelled. High-energy electrons appear near the inner cylindrical surface by secondary ion-electron emission under surface bombardment by peripheral flow ions. These energetic electrons can accumulate on axis and provide a mechanism for the plasma flow focusing. It has been shown that the presence of fast electrons in the volume of the plasma lens improves the propagating ion plasma flow.
New approach for devise a novel plasma technology for elimination of micro-droplets or their reduction to the nano-scale from the dense metal ion-plasma flow formed by erosion plasma sources (vacuum arc and laser produced plasma sources), without loss of plasma production efficiency was proposed and described in [1]. This approach is based on application of the cylindrical electrostatic plasma lens configuration for introducing in a volume of propagating along the axis dense low energy ion-plasma flow convergent toward axis energetic electron beam produced self-consistently by ion-electron secondary emission from internal cylindrical surface of plasma lens central electrode (see Fig.1)
Fig.1. The scheme of model Here we are modelling the transport through an electrostatic plasma lens of a wide-aperture, high- current, low energy, metal-ion plasma flow produced by a cathodic arc discharge. The lens consists from three electrostatic ring electrodes located in a magnetic field formed by permanent magnets. Modelling parameters were closed to experimental: the lens input aperture - 80 mm, the lens length 140 mm, the outer electrodes are ground and the central electrode voltage up to -3 kV. The plasma is a copper plasma with directed ion energy 20–40 eV, and the equivalent ion current is up to several amperes depending on the potential applied to the central lens electrode. We modeled of electrical potential jump formation near the inner surface of the cylinder and appearance of self-consistent electron beam across the plasma flow. It is shown that beam is formed by double layer, appeared in a cylindrical channel of the plasma-optical system in crossed radial electrical and longitudinal magnetic fields. It is accelerated by electric potential jump. High-energy electrons appear near the inner cylindrical surface by secondary ion-electron emission at this surface bombardment by peripheral flow ions. Electrons are magnetized and ions are not magnetized. The electron mobility across a magnetic field is strongly suppressed. The electron movement along magnetic field is free up to region of electric potential jump. Under these conditions the magnetic field lines are equipotential up to region of electric potential jump. Thus, the magnetic field lines are equipotential inside flow. Then in space, filled with plasma, the electrical field is created, the form of which is approximately similar the structure of magnetic field lines. Because the electrons of the flow are magnetized, they in the field of the short coil are displaced to its axis, damping expansion of the flow due to electric field of plasma flow polarization. Thus, with increase of magnetic field the near axis density of flow increases. It is shown the energetic electrons accumulate on axis and provide ion focusing. Note that they can also provide additional energy pumping into system for reducing the micro- droplet component in the dense, low-temperature, metal plasma. [1] A. A. Goncharov, Rev. Sci. Instrum., 87 (2016), 02B901
Topic number 5 179
XXXIII ICPIG, July 9-14, 2017, Estoril/Lisbon, Portugal
Activity of catalase enzyme in P. tomentosa seeds after direct plasma treatments and treatments with plasma activated water
N. Puač P 1 P , N. Škoro 1 P , K. Spasić P 1 , S. Živković P 2 P , M. Milutinović 2 , V. Šašić 2 , G. Malović P 1
Z.Lj. Petrović 1,3
P 1 P
P
P
Belgrade, Serbia 3 Serbian Academy of Sciences and Arts, Knez Mihailova 35, 11000 Belgrade, Serbia
In this abstract we report on influence of direct and indirect plasma treatments on catalase enzyme activity in Paulownia tomentosa seeds. The direct treatment of the seeds was performed in low- pressure RF plasma system for different treatment times. After treatments these seeds were imbibed with distilled water. The other set of P. tomentosa seeds was imbibed with plasma activated water (PAW). PAW was produced by using atmospheric pressure plasma source in treatments with different durations. Seeds from both sets were exposed to the same conditions and after 5 days activity of catalase enzyme was measured. In comparison to the control sample, differences in the activity was observed both regarding direct and PAW treated seeds and regarding duration of treatments.
Non-equilibrium low and atmospheric pressure plasmas can be efficiently used in stimulation of seed growth, increase of germination percentage and decontamination, breaking of dormancy or increase in the length of seed sprout. We have developed several low pressure and atmospheric pressure plasma systems for treatment of seeds and plant cells [1-3]. Here we will present the results obtained in treatments of Paulownia tomentosa seeds by non- equilibrium plasma that operates at low and atmospheric pressures. We have determined the germination percentage and activity of catalase enzyme for all treated samples and compared it to the control samples.
Low pressure plasma treatments of seeds were performed in the cylindrically shaped RF plasma system that operates at 13.56 MHz reactor. The seeds were then imbibed with distilled water. Unlike low pressure plasma treatments where seeds were in direct contact with plasma, in case of atmospheric pressure plasma treatments we have treated distilled water (PAW) which was then used for imbibition of seeds. After the imbibition process seeds were exposed to red light for 5 min. In Figure 1 we show activity of catalyse enzyme 5 days after imbibition of water. The catalase activity for the treated samples is increased comparing to the untreated sample. This is in accordance with the observed increase in germination percentages obtained for this samples.
Figure 1. The activity of the catalase enzyme obtained by using native page. Data was obtained five days after the imbibition of water (distilled). This work was supported by the MESTD of Serbia projects III41011 and ON171037.
[1] N. Puač, Z.Lj. Petrović, S. Živković, Z. Giba, D. Grubišić and A.R. Đorđević, Plasma Processes and Polymers, Wiley-VCH Verlag GmbH & Co. (2005). [2] N. Puač, Z.Lj. Petrović, G. Malović, A. Đorđević, S. Živković, Z. Giba and D. Grubišić, J. Phys. D:Appl. Phys. 39 (2006) 3514-3519. [3] N. Puač, S. Živković, N. Selaković, M. Milutinović, J. Boljević, G. Malović and Z.Lj. Petrović, Appl. Phys. Lett. 104(21) (2014) 214106.
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XXXIII ICPIG, July 9-14, 2017, Estoril/Lisbon, Portugal Growth of nano-tendril bundles on tungsten in impurity-rich helium plasmas D. Hwangbo 1 , S. Kajita 2 , S. Kawaguchi 1 , H. Tanaka 1 , N. Ohno 1
Tungsten samples were irradiated with helium plasma which contains impurity gases to investigate the effect of impurity ions on the morphology changes under the sputtering dominant regime. The surfaces of the samples after irradiation were not uniform and the isolated nano-tendril bundles were found on the surfaces when the incident ion energy was higher than the threshold energy of sputtering by He ions. The size of the nano-tendril bundles were several tens m and this was unexpectedly huge considering the sputtering effect under several hundreds eV of the incident ion energy. This result suggests that the impurity ions may work as an important source to form the isolated nano-tendril bundles.
It is known that surface morphology changes occur on tungsten (W), one of the most promising candidates of divertor plate material in nuclear fusion devices, when exposed to helium (He) plasmas: nanostructures, so-called fuzz, are formed [1]. The growth mechanisms of the fuzz have been argued in several ways: surface migration by viscoelastic model [2] or adatom diffusion [3], or growth and burst of He bubbles under the surface [4]. It has been known that fuzz growth is affected with sputtering by impurity ions in He plasmas [5]. Here we examine the effect of impurity ions on the morphology changes on the W surfaces when the incident ion energy is higher than the threshold of He ions, It is demonstrated unexpected formation of nano-tendril bundles(NTBs) in impurity-rich He plasma irradiation is introduced. 2. Experimental setup Experiments were performed in the linear divertor plasma simulator NAGDIS-II. He plasmas were produced in DC arc discharge with the typical electron density and temperature of ~1 × 10 19 m -2 and
~5 eV, respectively. W samples were installed in the He plasma and biased negatively via a bipolar power supply to control the incident ion energy. The ion flux was in the range of 0.8 - 2 × 10 22 m
s -1 . To compare the effect of sputtering by impurities, two different discharge conditions were set up by opening/closing the moving valve of turbo molecular pump near the end target of NAGDIS-II. By closing the valve, background pressure was changed from ~6 × 10 -7 to ~2 × 10 -6 Torr, meaning that the impurity level increased by factor of three. He gas flow was fixed in the range of 150-160 sccm. 3. Results and discussion After the plasma irradiation with high impurity level condition, although the surfaces of samples were not covered with fuzz, isolated nano-tendril bundles were formed on the surfaces. As shown in Fig. 1, the sizes of the NTBs were over several tens m, which was unexpectedly huge considering the present condition, such as 500 eV of incident ion energy. The remaining surface where the NTBs were not formed had no fuzz or tiny loops grown. Similar bundles were fabricated with the addition of RF modulation of the ion energy [6]. This result suggests NTBs can also be fabricated without ion energy modulation in the impurity-rich He plasmas. Figure 1. SEM micrograph of nano-tendril bundle with incident ion energy 500 eV.
[1] S. Kajita et al., Nucl. Fusion 49 (2009) 095005. [2] S.I. Kracheninnikov Phys. Src. T145 (2011) 014040.
[3] D. Trufanov et al., Phys. Procedia 71 (2015) 20. [4] A.M. Ito et al., Nucl. Fusion 55 (2015) 73013. [5] T.J. Petty et al., Nucl. Fusion 55 (2015) 093033. [6] K.B. Woller et al., 26 th IAEA FEC, MPT/P5-26, Kyoto, Japan, 2015. Topic number : 3 181
XXXIII ICPIG, July 9-14, 2017, Estoril/Lisbon, Portugal 6
State-by-state emission spectra fitting for non-equilibrium plasmas: OH spectra of surface barrier discharge at argon/water interface
J. Voráč, U P. Synek UP P , V. Procházka P P , T. Hoder
P Department of Physical Electronics, Faculty of Science, Masaryk University, Kotlářská 2, Brno, Czech Republic
A novel method of state-by-state fitting of OH(A 2 Σ + →X 2 Π) spectra is introduced and applied to a
special case of surface dielectric barrier discharge (DBD) in contact with water level. The resulting
Boltzmann plot revealed three groups of OH(A 2 Σ + ) ₋ hot group , cold group , and group influenced by
isoenergetic vibrational energy transfer OH(A 2
Σ + , v ’=1→ v’ =0). The state-by-state fitting is incorporated
in the massiveOES software package and available for free to the scientific community. The linearity of
the problem ensures low computational demands ₋ the whole fit for one spectrum takes few seconds on a
usual office computer. The Boltzmann plot was extensively analysed, the three groups were decoupled
and the of OH production pathways were investigated.
Figure: The population distribution of OH(A 2 Σ + ) rotational states and two-exponential fit. The corresponding temperatures are K and
K.
40 0 T rot low = 3
± 3
800 50 T rot high = 7
± 5
Recently, the interest in discharges in contact with
water increased enormously [1]. Often, the
discharges are ignited in a noble gas and the atoms
and water fragments are the only available spectral
signature. In such cases, the spectrum of hydroxyl
radical (OH) may seem attractive for neutral gas
thermometry. This contribution brings an extensive
analysis of OH(A 2 Σ + →X 2 Π) spectrum obtained on
special case of kHz driven surface DBD in contact
with water. As other groups, we have observed a
spectrum that may be interpreted as a superposition
of emission from several groups of OH. We have
distinguished three groups - cold group , best
observable for low N ’ quantum numbers, hot group ,
best observable for higher N’ quantum numbers and
the
third group influenced by isoenergetic
vibrational energetic transfer
OH(A 2 Σ + ,
’=1→
v’ =0), best observable for 9 ≤ N ’≤ 13. The
unusual accuracy of our Boltzmann plot (see the
figure) was enabled by the novel method of
state-by-state fitting. This approach combines
spectral simulation and traditional Boltzmann
construction procedure. A synthetic spectrum is
simulated for each rovibronic upper state, including
the instrumental broadening and matched with the
measurement. Best-fitting linear combination is then
searched for. This functionality was incorporated to
the massiveOES software package [2,3,4]. Download 9.74 Mb. Do'stlaringiz bilan baham: 
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