Effects of gas adsorbed on solid surface during gas breakdown in electron cyclotron resonance discharge

2021 ◽  
Author(s):  
Sheng Hui Fu ◽  
Zhen- Feng Ding
Keyword(s):  
Flow Rate ◽  
Gas Flow ◽  
Electron Cyclotron Resonance ◽  
Vertical Component ◽  
Plasma Source ◽  
Time Interval ◽  
Short Time Interval ◽  
Gas Flow Rate ◽  
Ecr Plasma ◽  
Long Time

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.

ECR RIE-Enhanced Low Pressure Plasma Etching of GaN/InGaN/AlGaN Heterostructures

1996 ◽  
Vol 1 ◽  
Author(s):  
Bedwyr Humphreys ◽  
Matthew Govett
Keyword(s):  
Etch Rate ◽  
Gas Flow ◽  
Electron Cyclotron Resonance ◽  
Plasma Source ◽  
Group V ◽  
Group Iii ◽  
Ecr Plasma ◽  
Selective Etch ◽  
Process Chemistry ◽  
Gas Flow Ratio

A room temperature (RT) plasma etch process has been developed to non-selectively etch GaN/InGaN/AlGaN structures, grown on sapphire substrates, using an electron cyclotron resonance (ECR) plasma source with RIE enhancement. The process chemistry chosen was Cl2/CH4 based in order to facilitate the formation of volatile etch by-products, typically to form group III halides and group V hydrides, although indium is more likely to form an organo-metallic compound as opposed to a chloride. A characteristic of this process is the very smooth sidewall features obtained and the controllability of the etch profile via ECR power, table bias and/or gas flow ratio. Typical results obtained using a RT process were etch rate above 100 nm/min., selectivity to resist mask above 30:1 and smooth anisotropic profile at low ion-energies (below 100 eV). The process etch rate showed a characteristic increase with increasing table bias (above 130 nm/min.) with only small changes in the relative etch rate of each compound (i.e. selectivity maintained at roughly 1:1), however, this etch does rely upon competing etching and deposition mechanisms and thus too large a variation in one parameter without a corresponding compensation with another leads to a rough surface and a more selective etch. The process has also been demonstrated using a metal mask (e.g. Ni) and present work is progressing onto other gas combinations and the use of high temperature electrodes.

scholarly journals Study on Effect of Structure and Propellant on Beam of ECR Ion Source

2019 ◽  
Vol 37 (6) ◽  
pp. 1095-1101
Author(s):  
Wenbin Huang ◽  
Juan Yang ◽  
Haibo Meng ◽  
Xu Xia ◽  
Yuliang Fu ◽  
...  
Keyword(s):  
Flow Rate ◽  
Gas Flow ◽  
Electron Cyclotron Resonance ◽  
Ion Beam ◽  
Ion Source ◽  
Ion Current ◽  
Gas Flow Rate ◽  
Magnetic Topology ◽  
Migration Distance ◽  
Ion Migration

To increase the ion current from the ion source is an important way to improve the performance of the electron cyclotron resonance ion thruster(ECRIT). The ion migration distance, magnetic topology and propellant have a close influence on the extracting ion beam. This influence is studied through both magnetic circuit structure calculation and experiments, by using an ion source with different gate mounting positions and magnet lengths. Experimental results show that the distribution of the ECR region will be discontinuous when the length of the magnet is too short. This will greatly reduce the performance of the ion source. To increase the length of the magnet is beneficial to the beam emission at high gas flow rate, but it reduces the beam emission at low gas flow rate. The effect of the ion migration distance on the ion beam is related to the plasma density in the ion source. When the gas flow rate is low, a longer gate mounting ring is beneficial to increase the ion current. When the gas flow rate is high, the different magnetic topology will cause the gate mounting ring which influences on the ion current. At low gas flow conditions, xenon gas can significantly improve the discharge stability of the ion source and increase the ion current. However, at high gas flow rate, the concentration effect of the neutral particles is too strong that affects the energy accumulation process of the free electrons. This would cause the decrease in the ion current.

Reduction in Microloading by High-Gas-Flow-Rate Electron Cyclotron Resonance Plasma Etching

1995 ◽  
Vol 34 (Part 1, No. 5A) ◽  
pp. 2489-2494 ◽  
Author(s):  
Naoyuki Kofuji ◽  
Kazunori Tsujimoto ◽  
Takao Kumihashi ◽  
Shin'ichi Tachi
Keyword(s):  
Flow Rate ◽  
Plasma Etching ◽  
Cyclotron Resonance ◽  
Gas Flow ◽  
Electron Cyclotron Resonance ◽  
Electron Cyclotron ◽  
Gas Flow Rate ◽  
Electron Cyclotron Resonance Plasma ◽  
Resonance Plasma

SCIENTIFIC AND ENGINEERING PRINCIPLES OF EFFICIENT FUEL USE AND ENVIRONMENTALLY FRIENDLY GAS COMBUSTION IN STOVE PLATES. PART 1. MODERN STATE-OF-THE-ART AND DIRECTIONS FOR IMPROVEMENT THE GAS BURNING IN DOMESTIC GAS COOKERS

2017 ◽  
pp. 3-18 ◽  
Author(s):  
B.S. Soroka ◽  
V.V. Horupa
Keyword(s):  
Natural Gas ◽  
Flow Rate ◽  
Gas Flow ◽  
Renewable Energy Sources ◽  
Combustion Process ◽  
Orifice Diameter ◽  
Firing Process ◽  
Gas Flow Rate ◽  
Gas Combustion ◽  
Gas Stoves

Natural gas NG consumption in industry and energy of Ukraine, in recent years falls down as a result of the crisis in the country’s economy, to a certain extent due to the introduction of renewable energy sources along with alternative technologies, while in the utility sector the consumption of fuel gas flow rate enhancing because of an increase the number of consumers. The natural gas is mostly using by domestic purpose for heating of premises and for cooking. These items of the gas utilization in Ukraine are already exceeding the NG consumption in industry. Cooking is proceeding directly in the living quarters, those usually do not meet the requirements of the Ukrainian norms DBN for the ventilation procedures. NG use in household gas stoves is of great importance from the standpoint of controlling the emissions of harmful components of combustion products along with maintenance the satisfactory energy efficiency characteristics of NG using. The main environment pollutants when burning the natural gas in gas stoves are including the nitrogen oxides NOx (to a greater extent — highly toxic NO2 component), carbon oxide CO, formaldehyde CH2O as well as hydrocarbons (unburned UHC and polyaromatic PAH). An overview of environmental documents to control CO and NOx emissions in comparison with the proper norms by USA, EU, Russian Federation, Australia and China, has been completed. The modern designs of the burners for gas stoves are considered along with defining the main characteristics: heat power, the natural gas flow rate, diameter of gas orifice, diameter and spacing the firing openings and other parameters. The modern physical and chemical principles of gas combustion by means of atmospheric ejection burners of gas cookers have been analyzed from the standpoints of combustion process stabilization and of ensuring the stability of flares. Among the factors of the firing process destabilization within the framework of analysis above mentioned, the following forms of unstable combustion/flame unstabilities have been considered: flashback, blow out or flame lifting, and the appearance of flame yellow tips. Bibl. 37, Fig. 11, Tab. 7.

On the Influence of Fluctuating Flow Rate Upon the Performance and Behaviour of Isothermal Reacting Systems

1998 ◽  
Vol 63 (6) ◽  
pp. 881-898
Author(s):  
Otakar Trnka ◽  
Miloslav Hartman
Keyword(s):  
Flow Rate ◽  
Gas Flow ◽  
Fluidized Bed Reactor ◽  
Computational Techniques ◽  
Continuous Stirred Tank Reactor ◽  
Gas Flow Rate ◽  
Solid Reaction ◽  
Continuous Stirred Tank ◽  
And Performance ◽  
Reacting Systems

Three simple computational techniques are proposed and employed to demonstrate the effect of fluctuating flow rate of feed on the behaviour and performance of an isothermal, continuous stirred tank reactor (CSTR). A fluidized bed reactor (FBR), in which a non-catalytic gas-solid reaction occurs, is also considered. The influence of amplitude and frequency of gas flow rate fluctuations on reactant concentrations at the exit of the CSTR is shown in four different situations.

scholarly journals Investigation on influences of loose gas on gas-solid flows in a circulating fluidized bed (CFB) reactor using full-loop numerical simulation

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Pengju Huo ◽  
Xiaohong Li ◽  
Yang Liu ◽  
Haiying Qi
Keyword(s):  
Numerical Simulation ◽  
Flow Rate ◽  
Gas Flow ◽  
Circulating Fluidized Bed ◽  
Separation Efficiency ◽  
Circulation Rate ◽  
Solid Mass ◽  
Gas Flow Rate ◽  
Gas Leakage ◽  
Mass Circulation

AbstractThe influences of loose gas on gas-solid flows in a large-scale circulating fluidized bed (CFB) gasification reactor were investigated using full-loop numerical simulation. The two-fluid model was coupled with the QC-energy minimization in multi-scale theory (EMMS) gas-solid drag model to simulate the fluidization in the CFB reactor. Effects of the loose gas flow rate, Q, on the solid mass circulation rate and the cyclone separation efficiency were analyzed. The study found different effects depending on Q: First, the particles in the loop seal and the standpipe tended to become more densely packed with decreasing loose gas flow rate, leading to the reduction in the overall circulation rate. The minimum Q that can affect the solid mass circulation rate is about 2.5% of the fluidized gas flow rate. Second, the sealing gas capability of the particles is enhanced as the loose gas flow rate decreases, which reduces the gas leakage into the cyclones and improves their separation efficiency. The best loose gas flow rates are equal to 2.5% of the fluidized gas flow rate at the various supply positions. In addition, the cyclone separation efficiency is correlated with the gas leakage to predict the separation efficiency during industrial operation.

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