On phenomena in ionized gases
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- Bu sahifa navigatsiya:
- References
- Luminescent spectra of noble gases and their binary mixtures under ion beam excitation
- 1. Theory and calculations
- 2. Results 2.1. Symmetric mode
- 2.2. Anti-symmetric mode
- Experimental and numerical study of a bubble plasma gas initiated by a wire explosion in a liquid
- 3. Conclusions - Perspectives
- Influence of the radial plasma non-uniformity on the etch process
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Figure 1. Reaction rates for O 2 − annihilation as a function of pressure for a stainless steel cylindrical chamber.
O 2
annihilation. No.
Reaction 1 O 2 − + O 2 (a 1 ∆ g ) → e + O 2 (X 3 Σ g − ) + O 2 (X 3 Σ g − ) 2 O 2 − + O 2 (b 1 Σ g + ) → e + O 2 (X
Σ g − ) + O 2 (X 3 Σ g − ) 3 O 2 − + O( 3 P) → O 2 (X 3 Σ g − ) + O −
4 O 2 − + O(
3 P) → e + O 3
O 2 − + O 2 + → O 2 (X 3 Σ g − ) + O
2 (X 3 Σ g − ) 6 O 2 − + O 2 + → O( 3 P) + O(
3 P) + O
2 (X 3 Σ g − ) 7 O 2 − + O + → O(
3 P) + O
2 (X 3 Σ g − ) [1] D. A. Toneli, R. S. Pessoa, M. Roberto, and J. T. Gudmundsson. J. Phys. D: Appl. Phys. 48 (2015) 325202. [2] D. A. Toneli, R. S. Pessoa, M. Roberto, and J. T. Gudmundsson. J. Phys. D: Appl. Phys. 48 (2015) 495203.
Topic number 99
XXXIII ICPIG, July 9-14, 2017, Estoril/Lisbon, Portugal
Luminescent spectra of noble gases and their binary mixtures under ion beam excitation
A.K. Amrenov, M.U. Khasenov Nazarbayev University, National Laboratory Astana, Astana, Kazakhstan
Emission spectra of noble gases and their binary mixtures were measured under heavy ion beam excitation in the range of 200-1000 nm. Lines of p-s and d-p atomic transitions prevail in the gas spectra, bands of the third continuum of Ar, Kr and Xe were observed in UV region, strong bands of heteronuclear ionic molecules were observed in Ar-Xe, Ar-Kr and Kr-Xe mixtures. The presence of impurities leads to the appearance of N 2 , N
2 + bands, KrO, ArO, XeO excimer molecules’ bands and atomic oxygen lines in the spectra. Radiation distribution among 2p-levels of atoms of noble gases was measured. Conclusions were made about mechanisms of level population in lasers on d-p transitions of noble gas atoms, 2p-1s-neon transitions.
Interest in the study of spectral-luminescent properties of low-temperature plasma excited by nuclear radiation stems to that fact that such plasma is an active medium of gas lasers with nuclear or beam pumping, scintillation detectors, as well as in spontaneous emission sources. Spectral-luminescent studies of noble gases excited by ionizing radiation began more than 50 years ago [1, 2]. The most detailed study was carried out by irradiation of dense gases with uranium fission fragments [3]. In this work, studies of spectral-luminescent characteristics of single component noble gases and binary mixtures excited by heavy ions are interesting from the standpoint of practical applications and were made under the same experimental conditions. The studies were conducted on the DC-60 accelerator [4]. Light was extracted through the quartz window located on the lid of the irradiation chamber. The spectrum of radiation was registered by compact QE65Pro and USB2000+ spectrometers; the relative spectral sensitivity of the installation was measured with the help of calibrated halogen lamp in the range of 400-1000 nm. The continuous spectra of pure gases were presented by the “third continuum” of Ar, Kr and Xe, the weak band was observed in neon in the range of 200-370 nm. Strong bands of ArXe + , ArKr + and
KrXe + heteronuclear ionic molecules were observed in the binary mixtures of gases. The radiation of impurities is presented by N 2 and N
2 + bands in helium and neon, N 2 bands in argon, KrO, ArO and XeO excimer molecules’ bands near 557 nm, atomic oxygen lines in helium, neon, and argon. 2p-1s and 3d-2p (Paschen notations) transition lines prevail in atomic spectra. Distribution of radiation intensity among atomic 2p-levels differs noticeably from the distribution of flow of the dissociative recombination of molecular ions among levels given at [5]. In less degree it is related to neon, the distribution of intensity is more uniform there. The significant part of the flow of Ar 2
dissociative recombination refers to the 2p 9
level in argon, while about half of the radiation refers to 2p 2 level. The half of radiation occurs from 2p 5 level in xenon, there is only 4% of the flow of Xe 2 + ion recombination at this level. Apparently, population of atomic 2p-levels of noble gases happens in cascade transitions from d-levels [6, 7], and the dissociative recombination of molecular ions with electrons is not the major process in population of 2p atomic levels of noble gases. Table 1. Emission intensity distribution (in percentage) on the 2p levels of Xe in xenon and Ar-Xe, He-Xe with 1% of Xe and 0.8 kPa total pressure P, kPa
2p 5
2p 6
2p 7
2p 8
2p 9
2p 10
0.27 56.0
8.0 4.3
16.8 7.4
6.4 0.53
47.2 8.6
4.4 19.8
7.6 11.3
0.81 41.6
9.1 3.6
23.0 7.9
13.7 Ar-Xe
3.8 9.4
10.5 3.5
4.8 66.9
He-Xe 1.2
42.7 1.4
11.7 9.1
33.4 References [1] W.R. Bennett, Ann. Phys. 18 (1962) 367- 420. [2] R.J. De Young, W.R. Weaver, J. Opt. Soc. Am. 70 (1980) 500–506. [3] V.V. Gorbunov et al., Proceedings of RFNC- VNIIEF, (2004) 148-185 (in Russian). [4] B. Gikal et al., Physics of Particls and Nuclei Letters, 5 (2008) 642–644. [5] V.A. Ivanov, Soviet Physics Uspekhi, 35 (1992) 17-36. [6] M.U. Khasenov, Laser and Particle Beams, 32 (2014) 501-508. [7] S.P. Mel’nikov et al., Lasers with Nuclear Pumping. Springer (2015). Topic 13 umb13er 100
XXXIII ICPIG, July 9-14, 2017, Estoril/Lisbon, Portugal
Mode conversion characteristics of the electrostatic hybrid waves in a magnetized plasma slab
M.-J. Lee P 1 P , U G. Jung UP 1 P , Y.-D. Jung P 2 P
P 1 P
P
P
Kyunggi-Do 15588, Republic of Korea
Mode conversion characteristics of electrostatic hybrid surface waves due to the magnetic field orientation in a magnetized plasma slab have been investigated. The dispersion relations for the symmetric and anti-symmetric modes of hybrid surface waves are derived for two different magnetic field configurations: parallel and perpendicular. For the parallel magnetic field configuration, we have found that the symmetric mode propagates as upper-and lower-hybrid waves. However, the hybrid characteristics disappear and two non-hybrid waves are produced for the anti-symmetric mode. For the perpendicular magnetic field configuration, however, the anti-symmetric mode propagates as the upper-and lower-hybrid waves and the symmetric mode produces two non-hybrid branches of waves.
We consider a magnetized dusty plasma slab with the sharp boundaries at 0
and x L such that the characteristic length of plasma is much greater than the scale length of the inhomogeneity. Then, the specular reflection condition can be used as the boundary condition for the study of surface waves [1,2]. This boundary condition yields the dispersion equation for electrostatic surface waves propagating in the
direction in an isotropic plasma slab represented by [3] 2 1 1 1 0 ( , ) 1 ik L ik L l dk k e k k e
where is the wave frequency, ( )
k k and ( ) z k k are the x- and z-components of the wave vector k, respectively,
component of the plasma dielectric permittivity. When the parallel magnetic field 0 0
B
z is
applied to the boundary surfaces, the longitudinal plasma dielectric permittivity in dusty plasma for , ,
cd ci ce kv is obtained as follows [22]: 2
2 2 2 2 ,||
2 2 2 2 2 2 ( , , ) 1 pe x pe z pi pd l x z ce k k k k k k
where
1 2 4 p n q m is the plasma frequency of species ( = e, i, d for electron, ion and dusty grain, respectively) and 0
q B m c is the
cyclotron frequency of species
0 c q B m c . Then the integral equation can be performed to derive the dispersion relation for the surface waves in the magnetized plasma slab.
1 2 2 2 2 2 2 2 2 2 2 1 1 1 tanh 0 2
pi pd pe pi pd ce z F k L 2.2. Anti-symmetric mode
1 2 2 2 2 2 2 2 2 2 2 1 1 1 coth 0 2
pi pd pe pi pd ce z F k L
[1] A. F. Alexandrov, L. S. Bogdankevich, and A. A. Rukhadze, Principles of Plasma Electrodynamics (Springer, Berlin, 1984). [2] Yu M. Aliev, H. Schlüter, and A. Shivarova, Guided-Wave-Produced Plasmas (Springer, Berlin, 2000).
[21] H. J. Lee and Y. K. Lim, J. Korean Phys. Soc. 50, 1056 (2007). 101
XXXIII ICPIG, July 9-14, 2017, Estoril/Lisbon, Portugal
Experimental and numerical study of a bubble plasma gas initiated by a wire explosion in a liquid
Z. Laforest, U J.-J. Gonzalez, P. Freton
Applications, using electrical arc in liquid, increase with the use of pulsed energy of microseconds or nanoseconds. Some observed phenomena are common to those applications like the presence of a gas bubble surrounding the discharge. In order to understand the different mechanisms driving the bubble behavior, a numerical and an experimentation studies with a longer pulse of energy around 10ms were developed. The experimental results show an expansion and then a collapse of this bubble during the discharge. These observations linked to simulation results suggest some similitudes with the literature, such as the heating of the liquid and the gas by the discharge and a rise of pressure during the expansion of the bubble.
Electrical arcs in liquids have many applications such as electrohydraulic discharges in water [1], nanostructures synthesis in
various aqueous
solutions [2] or oil circuit breakers [3]. Although the conditions on time and energy discharges are different for each of those applications, a gas bubble surrounds the arc. The aim of this work is to understand the mechanisms and phenomena driving the gas bubble with experimental and numerical approaches. The experimental setup is composed of an electrical alimentation, a reactor and measurements. The electrical alimentation enables to generate a 10ms pulse current of a few kA. The reactor contains two tungsten plane electrodes of 1.6mm diameter immersed in the liquid. The area between the two electrodes is observed by a fast camera. In the same time, the electric discharge characteristics are measured by current and voltage probes. A numerical model is also proposed to support the experimental results. The Fluent ANSYS software is chosen [4]. The VOF (Volume-Of- Fluids) model is adopted and completed with the change phase Lee’s model [4].
The experimental setup allows to change some parameters such as the inter-contact gap, the injected energy
and power
or the
liquid environment. For example, a case in water liquid can be studied with a distance between the two electrodes of 3mm initially linked by a copper fuse wire of 100µm. The delivered energy for the electrical arc is 1kJ during 10ms. As other author observations [1-3][5], a gas bubble containing the electrical arc is observed. The simulation results show a global rise of the temperature as in Burakov et al. work [2] due to Joule effect and of the pressure as in Chen et al. work [1]. In our theoretical case, the central temperature and pressure can reach respectively 16kK and 15bars inside the bubble. Consequently, these characteristics lead to the bubble expand. When the injected energy is not sufficient, the gas is cooled and the pressure decreases. So after one phase of expansion, the bubble quickly collapses. This dynamic is also noted by others authors using different experimental conditions [3] like a shorter time of discharge [5].
An experimental setup and a theoretical model are developed to study the plasma bubble behavior in a liquid. In order to be able to discuss the bubble dynamic a parametric study is made changing the distance between the two electrodes, the nature of the liquid, the apply energy. All these results will be presented and discussed.
[1] W. Chen, O. Maurel, C. LaBorderie, T. Reess, A. DeFerron, M. Matallah, G. Pijaudier- Cabot, A. Jacques, F. Rey-Bethbeder, Heat Mass Transfer 50, 673 (2014).
[2] V.S. Burakov, E.A. Nevar, M.I. Nedel'ko, N. V. Tarasenko, Russ. J. Gen. Chem. 85, 1222 (2015). [3] J. Slepian, T. E. Browne,
[4] Ansys Inc. PDF Documentation, 15.0, http://148.204.81.206/Ansys/readme.html (2013). [5] A. Claverie, J. Deroy, M. Boustie, G. Avrillaud, A. Chuvatin, E. Mazanchenki, G. Demol, B. Dramane, Rev. Sci. Instrum. 85, 063701 (2014). 102
XXXIII ICPIG, July 9-14, 2017, Estoril/Lisbon, Portugal
Influence of the radial plasma non-uniformity on the etch process
V. Georgieva P , U S. Tinck UP , A. Bogaerts PP
Research Group PLASMANT, Department of Chemistry, University of Antwerp, Antwerp, Belgium
SF 6 /O 2 plasmas sustained in an inductively-coupled plasma (ICP) reactor are simulated by a hybrid model. An additional model based on the Monte Carlo method is used to simulate the Si etch rate and profiles. Extensive gas-phase and surface chemistry sets are developed. The reactive species fluxes control the deposition rate of the passivation SO x F
layer and the chemical etching, while the ion energy and angular distributions control the physical sputtering. It is found that the reactive species fluxes decrease, the ion energy range contracts and the ion angular distribution becomes wider, away from the wafer centre. The present research investigates the effect of the spatial variation in the plasma properties on the etch rate and profile.
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