scholarly journals Observation of Axial Neutral-Gas Flow Reversal in an ECR Plasma

2019 ◽  
Vol 14 (0) ◽  
pp. 1201066-1201066
Author(s):  
Emika ABE ◽  
Kenichiro TERASAKA ◽  
Shinji YOSHIMURA ◽  
Mitsutoshi ARAMAKI ◽  
Masayoshi Y. TANAKA
Author(s):  
Ming Zheng ◽  
Siddhartha Banerjee ◽  
Xiaohong Xu ◽  
Usman Asad ◽  
Xiaoye Han ◽  
...  

Empirical and theoretical studies are made between the inlet and central heating schemes in a flow reversal embedment of diesel aftertreatment converters in order to investigate the influences of gas flow, heat transfer, chemical reaction, oxygen concentration, and substrate properties. The periodic flow reversal converter is found effective to treat engine exhausts that are difficult to cope with conventional unidirectional flow converters. However, the previous work indicates that the exhaust temperature from modern diesel engines is commonly insufficient to sustain a high conversion or regeneration rate and thus supplemental heating techniques are commonly applied. A technique of fuelling at the central region of a flow-reversal embedment is found more energy-efficient to raise the temperature of the catalytic flow-bed and therefore to drastically reduce the supplemental heating to the substrate. An effective fuel delivery technique has been tested to improve the fuel dispersion of the central fuel delivery strategy at various engine-out exhaust temperatures, compositions, and flow rates.


Author(s):  
Александр Юрьевич Шемахин ◽  
Виктор Семенович Желтухин ◽  
Евгений Юрьевич Шемахин

Для моделирования процессов в ВЧ-плазме пониженного давления с продувом газа разработана гибридная математическая модель при числах Кнудсена - для несущего газа. Модель включает начально-краевую задачу для кинетического уравнения Больцмана, описывающего функцию распределения несущего нейтрального газа, краевые задачи для уравнения неразрывности электронной, ионной и метастабильной компонент, уравнения сохранения энергии электронов, для ВЧ-уравнений Максвелла в форме телеграфных уравнений и уравнения Пуассона для потенциальной составляющей поля. Приводятся результаты расчета электрической напряженности, концентрации электронов, ионов и метастабилей, потенциальной составляющей электромагнитного поля в цилиндрической вакуумной камере. A hybrid mathematical model for the Knudsen numbers - for the carrier gas has been developed to simulate processes in a low pressure RF plasma with gas flow. The model includes an initial boundary value problem for the kinetic Boltzmann equation describing the distribution function of the carrier neutral gas, boundary value problems for the continuity equation of the electronic, ionic and metastable components, the electron energy conservation equations, for Maxwell’s RF equations in the form of telegraphic equations and the Poisson equation for the potential part of field. The results of the calculation of the electric intensity, the concentration of electrons, iones and metastables, the potential component of the electromagnetic field in a cylindrical vacuum chamber are presented.


Author(s):  
Е. Sigarev ◽  
G. Kryachko ◽  
A. Dovzhenko ◽  
Yu. Lobanov ◽  
A. Pohvalitiy

The results studies influence physicochemical properties and thickness cover slag, formed during ladle desulfurization pig iron by blowing a mixture of lime and magnesium, features formation a breaker on the surface bath and the level of metal losses with emissions outside ladle from this zone are presented. The necessity creating conditions for ensuring height breaker, which would not exceed thickness slag layer on the surface bath, has been substantiated. Using results of the high-temperature simulation blowing the cast iron melt with a neutral gas supplied through the nozzles tips stationary and rotating submersible lances, features development of counter waves and metal splashes in the absence and during formation slag cover with thickness of 30—80 mm on the surface bath are determined. The features change in the height and area breakers are determined depending on the gas flow rate for blowing bath and thickness slag. Based on the analysis results low-temperature modeling bath blowing, scientific ideas about the combined effect of the bath blowing intensity, speed of rotation submerged lance and thickness slag layer on the diameter bubbling zone, gas saturation of the bath and features wave formation on its surface in the slag-free zone were further developed (so-called «eye»). The nature relationship between length of the gas jet from lance nozzle, diameter «eye», and geometric parameters breaker has been established. It is shown that dependence profile breaker on speed of rotation lance and thickness slag layer is nonlinear. So, blowing bath through tip of a rotating lance with one nozzle at 240 rpm. with a gas flow rate of 2.2 l/min. creates conditions for raising top breaker to a height that is 33 % higher than the current thickness slag layer and contributes to the intensification formation of waves and bursts on the surface bath. With a decrease in the gas flow rate to 1.0 l/min., Under other unchanged conditions, height breaker is already 2/3 of the height slag layer, and as thickness slag decreases proportionally decreases. The smallest, recorded in the experiments, relative height breaker was 33.3% of the slag thickness at a lance rotation speed in the range of 90—120 rpm. Mathematical models are proposed that are suitable for calculating height breakers depending on the thickness slag layer, speed of rotation lance and intensity of gas injection into the bath. Taking into account established mutually opposite effect thickness of the cover slag layer and speed of rotation submerged lance on the «eye» area and height of the breaker, it is advisable to continue search for ways to improve design tip submerged lance and slag mode of ladle desulfurization.


Author(s):  
Sheng Hui Fu ◽  
Zhen- Feng Ding

Abstract The microwave breakdown power (Pwb) in an ECR plasma source was not merely determined by pressure (gas flow rate), but found to vary with the time interval between two successive breakdowns. The measured Pwb dropped rapidly from a high value at a short time interval to a low level at a long time interval. The obtained dependence of Pwb on pressure (gas flow rate) exhibited distinct features: the normal monotonicity and abnormal non-monotonicity at the short and long time intervals, respectively. The effective zone in the antenna’s surface bombarded by hot electrons heated in the ECR layer was validated by (1) masking the antenna with a film having a variable radius; (2) calculating the distribution of the vertical component of the microwave electric field with respect to the static magnetic field; (3) imaging glows of transient breakdown discharges with a fast camera. The reduction in Pwb was mainly attributed to the enhanced emission of δ-electrons from the gas-adsorbed antenna under the bombardment of energetic electrons coming from the ECR layer.. The correlation between the dynamic gas coverage and the coefficient emission of δ-electrons was established to understand the abnormal ECR breakdown features.


1997 ◽  
Vol 467 ◽  
Author(s):  
J. P. Conde ◽  
V. Chu ◽  
F. Giorgis ◽  
C. F. Pirrt ◽  
S. Arekat

ABSTRACTHydrogenated amorphous silicon-carbon alloys are prepared using electron-cyclotron resonance (ECR) plasma-enhanced chemical vapor deposition. Hydrogen is introduced into the source resonance cavity as an excitation gas. Silane is introduced in the main chamber in the vicinity of the plasma stream, whereas the carbon source gases, methane or ethylene, are introduced either with the silane or with the hydrogen as excitation gases. The effect of the type of carbon-source gas, excitation gas mixture and silane-to-carbon source gas flow ratio on the deposition rate, bandgap, subgap density of states, spin density and hydrogen evolution are studied.


1996 ◽  
Vol 150 ◽  
pp. 35-38 ◽  
Author(s):  
Bo Å. S. Gustafson ◽  
Susan M. Lederer

The local cloud in which the Sun is embedded participates in a general flow from the direction of the Sco-Cen association (Weaver, 1979) while the Sun is moving in the direction of Hercules. The relative motion is well determined by the neutral gas flow (Cox and Reynolds, 1987). A prominent cone of gravitationally focused neutral helium indicates the downwind direction to within ±3°. The average flow speed outside the solar system, 26 km/s, is determined to within ±1 km/s. Measurements from the Ulysses spacecraft (Witte et al., 1993) confirmed this flow. Since interstellar matter contains dust as well as gas, efforts have been made to detect the dust flow through the solar system. However, until recently these efforts have been unsuccessful and modeling of the flow has been controversial.


2014 ◽  
Vol 926-930 ◽  
pp. 1627-1631
Author(s):  
Wei Feng Zou ◽  
Bo Lan

The paper uses computational fluid dynamics software FLUENT to build a single-channel numerical simulation model of the mine ventilation gas Thermal Flow-Reversal Reactor (TFRR). Combining with the analysis of orthogonal test, the influences that four factors (Initial temperature distribution, Ventilation gas flow velocity, Volume fraction of methane, Exchange period) act on reactor performance is investigated. An optimal operation condition is proposed by the establishment of the priority sequence of these four factors.


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