A Study of the Gas Flow in the RF Low-Pressure Supersonic Jet Plasma Chemical System

AbstractThe low-pressure high-frequency plasma chemical vapor deposition (CVD) system was developed with non-thermal plasma process to study the Polyethylene naphthalate (PEN) surface characteristics. Plasma surface treatment by oxygen can improve the adhesive properties. A mixture of Ar and O

Download Full-text

Study on the Deposition Profile Characteristics in the Micron-Scale Trench Using Direct Simulation Monte Carlo Method

Journal of Fluids Engineering ◽

10.1115/1.2820648 ◽

1998 ◽

Vol 120 (2) ◽

pp. 296-302 ◽

Cited By ~ 5

Author(s):

Masato Ikegawa ◽

Jun’ichi Kobayashi ◽

Morihisa Maruko

Keyword(s):

Monte Carlo ◽

Monte Carlo Method ◽

Boundary Conditions ◽

Gas Flow ◽

Direct Simulation Monte Carlo ◽

Low Pressure ◽

Sputter Deposition ◽

Direct Simulation ◽

Simulation Monte Carlo ◽

Profile Characteristics

As integrated circuits are advancing toward smaller device features, step-coverage in submicron trenches and holes in thin film deposition are becoming of concern. Deposition consists of gas flow in the vapor phase and film growth in the solid phase. A deposition profile simulator using the direct simulation Monte Carlo method has been developed to investigate deposition profile characteristics on small trenches which have nearly the same dimension as the mean free path of molecules. This simulator can be applied to several deposition processes such as sputter deposition, and atmospheric- or low-pressure chemical vapor deposition. In the case of low-pressure processes such as sputter deposition, upstream boundary conditions of the trenches can be calculated by means of rarefied gas flow analysis in the reactor. The effects of upstream boundary conditions, molecular collisions, sticking coefficients, and surface migration on deposition profiles in the trenches were clarified.

Download Full-text

Behavior of Radial Incompressible Flow in Pneumatic Dimensional Control Systems

Journal of Fluids Engineering ◽

10.1115/1.1598991 ◽

2003 ◽

Vol 125 (5) ◽

pp. 843-850 ◽

Cited By ~ 2

Author(s):

G. Roy ◽

D. Vo-Ngoc ◽

D. N. Nguyen ◽

P. Florent

Keyword(s):

Gas Flow ◽

Flow Behavior ◽

Pressure Gauge ◽

Axisymmetric Flow ◽

Low Pressure ◽

Industrial Applications ◽

Nozzle Geometry ◽

Machined Surface ◽

Flow Area ◽

Simpler Algorithm

The application of pneumatic metrology to control dimensional accuracy on machined parts is based on the measurement of gas flow resistance through a restricted section formed by a jet orifice placed at a small distance away from a machined surface. The backpressure, which is sensed and indicated by a pressure gauge, is calibrated to measure dimensional variations. It has been found that in some typical industrial applications, the nozzles are subject to fouling, e.g., dirt and oil deposits accumulate on their frontal areas, thus requiring more frequent calibration of the apparatus for reliable service. In this paper, a numerical and experimental analysis of the flow behavior in the region between an injection nozzle and a flat surface is presented. The analysis is based on the steady-state axisymmetric flow of an incompressible fluid. The governing equations, coupled with the appropriate boundary conditions, are solved using the SIMPLER algorithm. Results have shown that for the standard nozzle geometry used in industrial applications, an annular low-pressure separated flow area was found to exist near the frontal surface of the nozzle. The existence of this area is believed to be the cause of the nozzle fouling problem. A study of various alternate nozzle geometries has shown that this low-pressure recirculation area can be eliminated quite readily. Well-designed chamfered, rounded, and reduced frontal area nozzles have all reduced or eliminated the separated recirculation flow area. It has been noted, however, that rounded nozzles may adversely cause a reduction in apparatus sensitivity.

Download Full-text

Diagnostics of low-pressure capacitively coupled RF discharge argon plasma

Iraqi Journal of Physics (IJP) ◽

10.30723/ijp.v13i27.266 ◽

2019 ◽

Vol 13 (27) ◽

pp. 76-82

Author(s):

Kadhim A. Aadim

Keyword(s):

Electron Temperature ◽

Electron Density ◽

Langmuir Probe ◽

Gas Flow ◽

Low Pressure ◽

Gas Pressure ◽

Rf Discharge ◽

Electrode Gap ◽

Probe Characteristic ◽

Capacitively Coupled

Low-pressure capacitively coupled RF discharge Ar plasma has been studied using Langmuir probe. The electron temperature, electron density and Debay length were calculated under different pressures and electrode gap. In this work the RF Langmuir probe is designed using 4MHz filter as compensation circuit and I-V probe characteristic have been investigated. The pressure varied from 0.07 mbar to 0.1 mbar while electrode gap varied from 2-5 cm. The plasma was generated using power supply at 4MHz frequency with power 300 W. The flowmeter is used to control Argon gas flow in the range of 600 standard cubic centimeters per minute (sccm). The electron temperature drops slowly with pressure and it's gradually decreased when expanding the electrode gap. As the gas pressure increases, the plasma density rises slightly at low gas pressure while it drops little at higher gas pressure. The electron density decreases rapidly with expand distances between electrodes.

Download Full-text

Numerical Simulation and Experimental Study on Tar Decomposition of Low-Pressure Ejection Type Burner

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.1092-1093.200 ◽

2015 ◽

Vol 1092-1093 ◽

pp. 200-206

Author(s):

De Fan Qing ◽

Mao Kui Zhu ◽

Yang Cheng Luo ◽

Ya Long Zhang ◽

Ai Rui Chen ◽

...

Keyword(s):

Numerical Simulation ◽

Flow Rate ◽

Gas Flow ◽

Low Pressure ◽

Orthogonal Test ◽

Nozzle Diameter ◽

Design Parameters ◽

Minor Effect ◽

Gas Flow Rate ◽

Tar Cracking

The tar decomposition of low-pressure ejection type burner was researched. The burner used software to simulate and analyse impact of the nozzle diameter d, the gas flow rate V and the distance of the nozzle to the wall L on tar cracking. The orthogonal test were used for design parameters d, V and L, the optimization values of these three parameters were carried out, and experimental method was used for test the numerical simulation results. Numerical simulation and experimental results showed that the greatest impact on tar cracking is the nozzle diameter d, the minor effect is the distance of the nozzle to the wall L and the weakest effect is the gas flow rate V, and when the nozzle diameter d=4 mm, the distance L=18 mm and the gas flow rate V=0.10 m3/h, the tar cracking is the most efficiency.

Download Full-text

Application of low-temperature low-pressure hydrogen plasma: treatment of artificially prepared corrosion layers

Open Chemistry ◽

10.1515/chem-2015-0045 ◽

2014 ◽

Vol 13 (1) ◽

Cited By ~ 1

Author(s):

Petra Fojtíková ◽

Lucie Řádková ◽

Drahomíra Janová ◽

František Krčma

Keyword(s):

Low Temperature ◽

Chemical Reduction ◽

Hydrogen Plasma ◽

Optical Emission ◽

Low Pressure ◽

Oh Radicals ◽

Plasma Chemical ◽

Duty Cycles ◽

Fundamental Research ◽

Pressure Hydrogen

AbstractThe aim of this work is the application of low-temperature low-pressure hydrogen plasma on artificially prepared corrosion layers, so called plasma chemical reduction. It is necessary to use samples with artificially prepared corrosion layers because it is impossible to use the real artifacts for fundamental research. The bronze was chosen as a sample material. Formation of corrosion layers on the bronze samples was carried out in concentrated hydrochloric acid vapors with the addition of sand. The radio-frequency hydrogen plasma was generated in the flowing regime at a pressure of 160 Pa. Different values of supplied power were chosen as well as different discharge modes: continuous or pulsed mode with varied duty cycles. By the combination of supplied power and mode factors, we selected two values of effective power. The process of plasma chemical reduction was monitored by optical emission spectroscopy (OES) and simultaneously, the sample temperature was measured. Rotational temperatures were calculated from OH radicals spectra. Changes in the structure and elemental composition were determined using scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDX).

Download Full-text

The Influence of Different Rim Seal Geometries on Hot-Gas Ingestion and Total Pressure Loss in a Low-Pressure Turbine

Volume 7: Turbomachinery, Parts A, B, and C ◽

10.1115/gt2010-22205 ◽

2010 ◽

Cited By ~ 6

Author(s):

P. Schuler ◽

W. Kurz ◽

K. Dullenkopf ◽

H.-J. Bauer

Keyword(s):

Pressure Loss ◽

Total Pressure ◽

Gas Flow ◽

Low Pressure ◽

Total Pressure Loss ◽

Pressure Loss Coefficient ◽

Low Pressure Turbine ◽

Hot Gas ◽

Flow Through ◽

Total Pressure Loss Coefficient

In order to prevent hot-gas ingestion into the rotating turbo machine’s inside, rim seals are used in the cavities located between stator- and rotor-disc. The sealing flow ejected through the rim seal interacts with the boundary layer of the main gas flow, thus playing a significant role in the formation of secondary flows which are a major contributor to aerodynamic losses in turbine passages. Investigations performed in the EU project MAGPI concentrate on the interaction between the sealing flow and the main gas flow and in particular on the influence of different rim seal geometries regarding the loss-mechanism in a low-pressure turbine passage. Within the CFD work reported in this paper static simulations of one typical low-pressure turbine passage were conducted containing two different rim seal geometries, respectively. The sealing flow through the rim seal had an azimuthal velocity component and its rate has been varied between 0–1% of the main gas flow. The modular design of the computational domain provided the easy exchange of the rim seal geometry without remeshing the main gas flow. This allowed assessing the appearing effects only to the change of rim seal geometry. The results of this work agree with well-known secondary flow phenomena inside a turbine passage and reveal the impact of the different rim seal geometries on hot-gas ingestion and aerodynamic losses quantified by a total pressure loss coefficient along the turbine blade. While the simple axial gap geometry suffers considerable hot-gas ingestion upstream the blade leading edge, the compound geometry implying an axial overlapping presents a more promising prevention against hot-gas ingestion. Furthermore, the effect of rim seals on the turbine passage flow field has been identified applying adequate flow visualisation techniques. As a result of the favourable conduction of sealing flow through the compound geometry, the boundary layer is less lifted by the ejected sealing flow, thus resulting in a comparatively reduced total pressure loss coefficient over the turbine blade.

Download Full-text