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Modulation of the plasma uniformity by coil and dielectric window structures in an inductively coupled plasma

Plasma Science and Technology 2021年第9期23卷 111-122页

作者： Xiaoyan SUN Yuru ZHANG Jing YE Younian WANG Jianxin HE Textile and Garment Industry of Research In stitute Zhongyuan University of Tech no logyZhengzhou 450007.People's Republic of China Key Laboratory of Materials Modification by Laser Ion and Electron Beams(Ministry of Education)School of PhysicsDalian University of TechnologyDalian 116024People's Republic of China School of Textiles Zhongyuan University of Technology.Zhengzhou 450007People's Republic of China

The effects of coil and dielectric window structures on the plasma distribution are examined in a cylindrically symmetric planar inductively coupled plasma(ICP).A two-dimensional(2 D)fluid model is employed to investigate the design issues of ICP source for *** the gradient coil structure is applied at 400 W and 20 mTorr,the ionization rate caused by the power deposition decreases at the reactor center as compared to that in a reactor with a planar coil above the planar dielectric window,and a rather uniform plasma is ***,for the vertical coil geometry,all the coils move to the position of the outermost coil,and the peaks of the power deposition and ionization rate appear at the radial edge of the *** this case,the plasma density is characterized by an edge-high ***,it is observed that the plasma uniformity is improved by increasing the source power under a gas pressure of 20 mTorr and becomes better when the gas pressure increases to 30 mTorr with the source power being fixed at400 W in the gradient coil configuration,but the uniformity of plasma worsens with the rising source power or pressure due to the strong localization in the vertical coil ***,when the discharge is sustained in a reactor with a stepped dielectric window at r=0.135 m,the best plasma uniformity is obtained at 400 W and 20 m Torr because the ionization rate is enhanced at the outermost coil,and the dielectric window at r=0.135 m blocks the diffusion of plasma towards the *** addition,higher source power and lower gas pressure produce more uniform plasma for the designs with a stepped window near the symmetry *** the dielectric window is stepped at r=0.135 m,the non-uniformity of plasma initially decreases and then increases with the increase in source power or gas *** the dielectric window is stepped at the radial edge of the chamber,the plasma uniformity is improved by increasing the source power and gas pressure due t

关键词： fluid simulation gradient coil vertical coil stepped dielectric window plasma uniformity

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simulation of the plasticizing behavior of composite modified doublebase(CMDB)propellant in grooved calendar based on adaptive grid technology

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Defence Technology（防务技术） 2021年第6期17卷 1954-1966页

作者： Su-wei Wang Xiu-duo Song Zong-kai Wu Lei Xiao Guang-pu Zhang Yu-bing Hu Ga-zi Hao Wei Jiang Feng-qi Zhao National Special Superfine Powder Engineering Research Center of China School of Chemistry and Chemical EngineeringNanjing University of Science and TechnologyNanjing210094China Xi'an Modern Chemistry Research Institute Xi'an710065China

The frequent occurrence of safety accidents during the calendering process is caused by the flammable and explosive properties of composite modified double-base(CMDB)*** of process parameters with the aid of fluid simulation technology could effectively ensure the safety of the calendering *** improve the accuracy of the simulation results,material parameters and model structure were corrected based on actual conditions,and adaptive grid technology was applied in the local mesh *** addition,the rheological behavior,motion trajectories and heat transfer mechanisms of CMDB propellant slurry were studied with different gaps,rotational rates and temperatures of two *** results indicated that the refined mesh could significantly improve the contour clarity of boundaries and simulate the characteristics of CMDB propellant slurry reflux movement caused by the convergent flow near the *** with the gap,the increased rotational rate of roller could promote the reflux movement and intensify the shear flow of slurry inside the flow region by viscous shear ***,under the synergistic effect of contact heat transfer as well as convective heat exchange,heat accumulated near the outlet and diffused along the reflux movement,which led to the countercurrent heat dissipation behavior of CMDB propellant *** plasticizing mechanism of slurry and the safety of calendering under different conditions were explored,which provided theoretical guidance and reference data for the optimization of calendering process *** on the simulation results,the safety of the CMDB propellant calendering process could be significantly improved with a few tests conducted during a short research and development cycle.

关键词： Composite modified double base propellant Calendering process fluid simulation Vortex flow0

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Adaptive step-size forward advection method for aerosol process simulation

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International Journal of Digital Earth 2023年第1期16卷 937-964页

作者： Yuang Wu Shuo Liu Bowen Shu Weichao Sun Sheng Wang Hongyang Zhang Chenchen Chen Aerospace Information Research Institute Chinese Academy of ScienceBeijingPeople’s Republic of China University of Chinese Academy of Sciences BeijingPeople’s Republic of China School of Electronic Electrical and Communication EngineeringUniversity of Chinese Academy of SciencesBeijingPeople’s Republic of China

Outdoor aerosol processes are often associated with disasters and diseases,which threaten human life and *** aerosols are afluid system affected by meteorological conditions and three-dimensional complex *** variable wind speed and direction and complex terrain boundary conditions make simulating advection processes *** on incompressibleflow conditions,we designed an adaptive time step algorithm for forward advection for the rapid simulation of aerosol *** method is based on thefirst-order forward semi-Lagrangian advection method with unconditional mass ***-order truncated error coefficient function theory generates an adaptive time step to control the accuracy of forward *** aerosol simulation experiments in two small outdoor scenes were designed,and the effects of the traditional backward advection and forwardfixed step methods were compared with the algorithm in this *** proposed simulation method showed improved accuracy compared with the other two methods in experimental scenarios;moreover,compared with those of the traditional backward method,the computation time was significantly reduced and the conservation of mass was significantly ***,the proposed method is a fast simulation method for outdoor aerosol numerical *** POLICY *** first-order forward semi-Lagrangian method,which requires no iteration and less computation and offers unconditional conservation,was used..The law of truncation error coefficient of thefirst-order forward method was studied and an adaptive step algorithm was designed..Full-size real aerosol experiments in small-scale complex outdoor scenes were conducted for verification and comparison of simulation effects.

关键词： Virtual geographical environments aerosol prediction finite difference method fluid simulation adaptive algorithms

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Augmented Flow simulation Based on Tight Coupling Between Video Reconstruction and Eulerian Models

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Journal of Computer Science & Technology 2018年第3期33卷 452-462页

作者： Feng-Yu Li Chang-Bo Wang Hong Qin Hong-Yan Quan School of Computer Science and Software Engineering East China Normal University Shanghai 200062 China Department of Computer Science State University of New York at Stony Brook NY 11794-4400 U.S.A

Hybrid approaches such as combining video data with pure physics-based simulation have been popular in the recent decade for computer graphics. The key motivation is to clearly retain salient advantages from both data-driven method and model-centric numerical simulation, while overcoming certain difficulties of both. The Eulerian method, which has been widely employed in flow simulation, stores variables such as velocity and density on regular Cartesian grids, thereby it could be associated with （volumetric） video data on the same domain. This paper proposes a novel method for flow simulation, which is tightly coupling video-based reconstruction with physically-based simulation and making use of meaningful physical attributes during re-simulation. First, we reconstruct the density field from a single-view video. Second, we estimate the velocity field using the reconstructed density field as prior. In the iterative process, the pressure projection can be treated as a physical constraint and the results of each step are corrected by obtained velocity field in the Eulerian framework. Third, we use the reconstructed density field and velocity field to guide the Eulerian simulation with anticipated new results. Through the guidance of video data, we can produce new flows that closely match with the real scene exhibited in data acquisition. Moreover, in the multigrid Eulerian simulation, we can generate new visual effects which cannot be created from raw video acquisition, with a goal of easily producing many more visually interesting results and respecting true physical attributes at the same time. We demonstrate salient advantages of our hybrid method with a variety of animation examples.

关键词： video reconstruction velocity estimation fluid simulation volume modeling and re-simulation

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Discontinuity of mode transition and hysteresis in hydrogen inductively coupled plasma via a fluid model

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Chinese Physics B 2015年第11期24卷 296-302页

作者：徐会静赵书霞高飞张钰如李雪春王友年 Key Laboratory of Materials Modification by Laser Ion and Electron Beams (Ministry of Education)School of Physics and Optoelectronic Technology Dalian University of Technology

A new type of two-dimensional self-consistent fluid model that couples an equivalent circuit module is used to in- vestigate the mode transition characteristics and hysteresis in hydrogen inductively coupled plasmas at different pressures, by varying the series capacitance of the matching box. The variations of the electron density, temperature, and the circuit electrical properties are presented. As cycling the matching capacitance, at high pressure both the discontinuity and hysteresis appear for the plasma parameters and the transferred impedances of both the inductive and capacitive discharge components, while at low pressure only the discontinuity is seen. The simulations predict that the sheath plays a determi- native role on the presence of discontinuity and hysteresis at high pressure, by influencing the inductive coupling efficiency of applied power. Moreover, the values of the plasma transferred impedances at different pressures are compared, and the larger plasma inductance at low pressure due to less collision frequency, as analyzed, is the reason why the hysteresis is not seen at low pressure, even with a wider sheath. Besides, the behaviors of the coil voltage and current parameters during the mode transitions are investigated. They both increase （decrease） at the E to H （H to E） mode transition, indicating an improved （worsened） inductive power coupling efficiency.

关键词： inductively coupled plasmas mode transition hysteresis fluid simulation

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Influence of dielectric materials on uniformity of large-area capacitively coupled plasmas for N_2/Ar discharges

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Chinese Physics B 2016年第10期25卷 244-251页

作者：梁英爽张钰如王友年 School of Physics and Optoelectronic Technology Dalian University of Technology

The effect of the dielectric ring on the plasma radial uniformity is numerically investigated in the practical 450-mm capacitively coupled plasma reactor by a two-dimensional self-consistent fluid model. The simulations were performed for N2/Ar discharges at the pressure of 300 Pa, and the frequency of 13.56 MHz. In the practical plasma treatment process,the wafer is always surrounded by a dielectric ring, which is less studied. In this paper, the plasma characteristics are systematically investigated by changing the properties of the dielectric ring, i.e., the relative permittivity, the thickness and the length. The results indicate that the plasma parameters strongly depend on the properties of the dielectric ring. As the ratio of the thickness to the relative permittivity of the dielectric ring increases, the electric field at the wafer edge becomes weaker due to the stronger surface charging effect. This gives rise to the lower N~+ ion density, flux and N atom density at the wafer edge. Thus the homogeneous plasma density is obtained by selecting optimal dielectric ring relative permittivity and thickness. In addition, we also find that the length of the dielectric ring should be as short as possible to avoid the discontinuity of the dielectric materials, and thus obtain the large area uniform plasma.

关键词： capacitive N_2/Ar discharge fluid simulation dielectric materials plasma radial uniformity

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Spatially adaptive long-term semi-Lagrangian method for accurate velocity advection

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Computational Visual Media 2018年第3期4卷 223-230页

作者： Takahiro Sato Christopher Batty Takeo Igarashi Ryoichi Ando The University of Tokyo Tokyo Japan University of Waterloo Waterloo Canada. National Institute of Informatics Japan.

We introduce a new advection scheme for fluid *** main contribution is the use of long-term temporal changes in pressure to extend the commonly used semi-Lagrangian scheme further back along the time *** algorithm starts by tracing sample points along a trajectory following the velocity field backwards in time for many *** this backtracing process,the pressure gradient along the path is integrated to correct the velocity of the current time *** show that our method effectively suppresses numerical diffusion,retains small-scale vorticity,and provides better long-term kinetic energy preservation.

关键词： fluid simulation advection method ofcharacteristics spatially adaptive inte-gration interpolation error correction

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Visual simulation of clouds

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Visual Informatics 2017年第1期1卷 1-8页

作者： Yoshinori Dobashi Kei Iwasaki Yonghao Yue Tomoyuki Nishita Hokkaido University/UEI Research Japan Wakayama University/UEI Research Japan The University of Tokyo Japan UEI Research/Hiroshima Shudo University Japan

Clouds play an important role when synthesizing realistic images of outdoor *** realistic display of clouds is therefore one of the important research topics in computer *** order to display realistic clouds,we need methods for modeling,rendering,and animating clouds *** is also important to control the shapes and appearances of clouds to create certain visual *** this paper,we explain our efforts and research results to meet such requirements,together with related researches on the visual simulation of clouds.

关键词： Clouds Procedural modeling Image-based modeling fluid simulation Feedback control Genetic algorithms

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A Simplified Approach of Open Boundary Conditions for the Smoothed Particle Hydrodynamics Method

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Computer Modeling in Engineering & Sciences 2021年第11期129卷 425-442页

作者： Thanh Tien Bui Yoshihisa Fujita Susumu Nakata Graduate School of Information Science and Engineering Ritsumeikan UniversityShiga525-8577Japan College of Information Science and Engineering Ritsumeikan UniversityShiga525-8577Japan

In this paper,we propose a simplified approach of open boundary conditions for particle-based fluid simulations using the weakly compressible smoothed-particle hydrodynamics(SPH)*** this scheme,the values of the inflow/outflow particles are calculated as fluid particles or imposed desired values to ensure the appropriate evolution of the flow field instead of using a renormalization process involving the fluid *** concentrate on handling the generation of new inflow particles using several simple approaches that contribute to the flow field *** advantages of theδ^(+).-SPH scheme,specifically the particle shifting technique,were successfully applied to correct the position,velocity,and pressure terms of the ***,unexpected errors were removed and tensile instabilities of the particles were *** proposed technique is validated for several benchmark test cases,and the tests show that the results match the reference solutions well.A viscous open-channel flow is used to demonstrate the stability of the flow field during the computational *** on this stability,we compress the computational domain to a lower resolution in a second test case while preserving the accuracy of the *** over a backward-facing step is used to highlight the challenges of inflow boundary conditions with prescribed or non-prescribed *** developed technique is well suited to the wall boundaries and the evolution of the flow *** results demonstrate the robustness and versatility of the proposed technique for a variety of simulations.

关键词： fluid simulation smoothed particle hydrodynamics open boundaries

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simulation of free-surface flow using a boundless grid

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Science China(Information Sciences) 2013年第3期56卷 38-47页

作者： WANG ChangBo ZHANG Qiang KONG FanLong Software Engineering Institute East China Normal University Shanghai Key Laboratory of Trustworthy Computing East China Normal University

Physically based fluid simulation in recent years has been successful for small-scale fluids such as liquid in a cubic ***,for boundless free-surface flow of large scale and irregular area,there is a critical trade-off between simulation efficiency and accuracy because of the restriction of the traditional regular computational *** paper introduces boundless computational grids based on hierarchical runlength encoding to simulate large-scale free-surface *** first modeled the free-surface flow with a lattice Boltzmann method,and calculated the surface curvature in the update *** then introduced an effective method with which to calculate the surface curvature according to the surface tension so that the surface detail was enhanced,and obtained the curvature of each surface effectively as it was ***,we dynamically compressed and indexed the computational cells with the improved hierarchical run-length encoding algorithm,so that the grid expands dynamically according to the fluid flow and the computational resources used were proportional to the volume of the *** fluids in different situations were simulated *** proposed method makes the best of the computational resources to perform the simulation with high resolution,and dynamically allocates resources so that the fluid can expand in random directions without boundaries,which is suited to the simulation of large-scale visual scenes.

关键词： fluid simulation free surface boundless grid hierarchical run-length encoding computing resource

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