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Effects of gas pressure on plasma characteristics in dual frequency argon capacitive glow discharges at low pressure by a self-consistent fluid model

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Chinese Physics B 2017年第12期26卷 361-370页

作者：赵璐璐刘悦 Tagra Samir Key Laboratory of Materials Modification by Laser Ion and Electron Beams (Ministry of Education) School of PhysicsDalian University of Technology School of Information Science and Engineering Dalian Polytechnic University

A self-consistent fluid model for dual radio frequency argon capacitive glow discharges at low pressure is established. Numerical results are obtained by using a finite difference method to solve the model numerically, and the results are analyzed to study the effect of gas pressure on the plasma characteristics. It shows that when the gas pressure increases from 0.3 Torr （1 Torr=1.33322102 Pa） to 1.5 Torr, the cycle-averaged plasma density and the ionization rate increase; the cycle-averaged ion current densities and ion energy densities on the electrodes electrode increase; the cycle-averaged electron temperature decreases. Also, the instantaneous electron density in the powered sheath region is presented and discussed. The cycle-averaged electric field has a complex behavior with the increasing of gas pressure, and its changes take place mainly in the two sheath regions. The cycle-averaged electron pressure heating, electron ohmic heating, electron heating, and electron energy loss are all influenced by the gas pressure. Two peaks of the electron heating appear in the sheath regions and the two peaks become larger and move to electrodes as the gas pressure increases.

关键词： dual frequency gas pressure glow discharge

Shaping Stability and Temperature Field in dual frequency Electromagnetic Confinement and Shaping

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Journal of Iron and Steel Research(International) 2005年第3期12卷 14-17页

作者： SONGChang-jiang XUZhenming LIANGGao-fei SHENJun LIJian-guo ShanghaiJiaotongUniversity Shanghai200030China NorthwesternPolytechnicalUniversity Xi＇an710072China

dual frequency electromagnetic confinement and shaping (EMCS) makes it easier to adjust and control the shaping temperature field and magnetic field than single frequency EMCS. The shaping stability and temperature field of the dual frequency EMCS were investigated. The results indicate that to shape stably, the upper liquid/solid interface should be in appropriate position and the lower liquid/solid interface must be above the critical position. The current of heating induction coil and the drawing speed of sample affect the shaping temperature and its peak position, while the current of the shaping induction coil only influences the shaping temperature. During EMCS, the speed of shaped sample affects not the height of the molten metal, but the temperature of molten metal. The height of the molten metal for steady shaping was about 15 mm in the experimental conditions. Several stainless steel plate-like parts with high width to thickness ratio (≥3.5) and directional structure were obtained.

关键词： electromagnetic confinement and shaping dual frequency stainless steel directional solidification

Influence of the low-frequency source parameters on the plasma characteristics in a dual frequency capacitively coupled plasma reactor:Two dimensional simulations

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Progress in Natural Science:Materials International 2009年第6期19卷 677-684页

作者： Xiang Xu, Hao Ge, Shuai Wang, Zhongling Dai, Younian Wang , Aimin Zhu State Key Lab of Materials Modification by Electron, Ion and Laser Beams, School of Physics and Optoelectronic Technology, Dalian University of Technology, Dalian 116023, China State Key Lab of Materials Modification by Electron Ion and Laser Beams School of Physics and Optoelectronic Technology Dalian University of Technology Dalian 116023 China

A two-dimensional (2D) fluid model is presented to study the discharge of argon in a dual frequency capacitively coupled plasma (CCP) reactor. We are interested in the influence of low-frequency (LF) source parameters such as applied voltage amplitudes and low frequencies on the plasma characteristics. In this paper, the high frequency is set to 60 MHz with voltage 50 V. The simulations were carried out for low frequencies of 1, 2 and 6 MHz with LF voltage 100 V, and for LF voltages of 60, 90 and 120 V with low frequency 2 MHz. The results of 2D distributions of electric field and ion density, the ion flux impinging on the substrate and the ion energy on the powered electrode are shown. As the low frequency increases, two sources become from uncoupling to coupling. When two sources are uncoupling, the increase in LF has little impact on the plasma characteristics, but when two sources are coupling, the increase in LF decreases the uniformities of ion density and ion flux noticeably. It is also found that with the increase in LF voltage, the uniformities in the radial direction of ion density distribution and ion flux at the powered electrode decreases significantly, and the energy of ions bombarding on the powered electrode increases significantly.

关键词： dual frequency Capacitively coupled plasma Fluid simulation

2-D FLUID SIMULATION OF dual-frequency CAPACITIVELY COUPLED PLASMA

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Journal of Hydrodynamics 2009年第6期21卷 814-819页

作者： LU Yi-jia YAN Da-qiang CHEN Yao-song LTCS and College of Engineering Peking University Beijing 100871 China

dual-frequency aegon discharge at 100 m Torr is modeled with a 2-D fluid model in this study. The plate gap of the system is 20 ram, and discharges are modeled at High frequency （HF） 40 MHz, 60 MHz, 80 MHz, Low frequency （LF） 2 MHz, 5 MHz, 10 MHz, low-frequency voltage 50 V, 75 V, 100 V and high-frequency voltage 200 V, respectively. The spatial distribution of electron density and ion density and the periodic evolution of instantaneous electric potential in bulk plasma and sheath are discussed. The numerical results show that plasma density increases with HFs and LFs and LF voltage, while HFs has more effect on the density. It is concluded that improving the ratio of HFs/LFs and increasing LF voltages is a method to gain high density and high ion bombardment energy simultaneously based on the analysis of electric potential distribution.

关键词： dual frequency CCP discharge 2-D fluid model

dual-frequency Discontinuous Space Vector Pulse Width Modulation for Five-phase Voltage Source Inverters with Harmonic Injection

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CSEE Journal of Power and Energy Systems 2021年第3期7卷 665-675页

作者： Tianyu Pu Feifei Bu Haijun Xu Wenxin Huang school of Electrical Engineering Nanjing University of Aeronautics and AstronauticsNanjing 211106China

This paper proposes a dual-frequency discontinuous space vector pulse width modulation(DFDSVPWM)for a five-phase voltage source inverter with harmonic *** this modulation,for dual-frequency voltage output and reduction of switching losses,two different zero-vector-inserted modes are flexibly employed by alternatively using two types of zero *** on the comparison with continuous SVPWM,the idea and principle of the proposed DFDSVPWM are analyzed and an example of PWM signals for one bridge is also *** switching losses analysis,the impact factors and the calculation method are investigated and the corresponding implementation is given as *** simulation and experimental results from a prototype verify the correctness and effectiveness of the proposed modulation and it has the advantages of outputting dual-frequency voltage and reducing switching losses.

关键词： Discontinuous space vector pulse width modulation dual frequency five-phase voltage source inver terharmonic injection switching losses

frequency Matching Effects on Characteristics of Bulk Plasmas and Sheaths for dual-frequency Capacitively Coupled Argon Discharges: One-Dimensional Fluid Simulation

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Plasma Science and Technology 2008年第1期10卷 57-60页

作者：王帅徐翔宋远红王友年 State Key Lab of Materials Modification by Beams Department of Physics Dalian University of Technology Dalian 116024 China

A one-dimensional fluid model is proposed to simulate the dual-frequency capacitively coupled plasma for Ar discharges. The influences of the low frequency on the plasma density, electron temperature, sheath voltage drop, and ion energy distribution at the powered electrode are investigated. The decoupling effect of the two radio-frequency sources on the plasma parameters, especially in the sheath region, is discussed in detail.

关键词： capacitively coupled plasmas dual frequency hydrodynamics sheath

dual-frequency fringe for improving measurement accuracy of three-dimensional shape measurement

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Chinese Optics Letters 2021年第10期19卷 81-87页

作者：苗自晓张启灿 Department of Opto-Electronics Sichuan UniversityChengdu 610065China

A new phase unwrapping method based on dual-frequency fringe is proposed to improve both high accuracy and large measurement range of three-dimensional shape measurement by synthesizing the projected dual-frequency fringes obtaining higher and lower *** lower-frequency one is their phase difference,which can help unwrap the wrapped phase of the higher-frequency one from their phase *** addition,the relationship between the measuring accuracy and the frequencies of the projected fringes is studied to guide the frequency selection in actual *** is found that the closer the two frequencies are,the higher the measurement accuracy will *** computer simulation and experiment results show the viability of this method.

关键词： fringe projection 3D shape measurement dual frequency phase shifting phase sum

A Novel Tunable dual-frequency Laser with Large frequency Difference

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Chinese Journal of Lasers 2002年第4期11卷 12-15页

作者：黄春宁郭辉李岩朱钧张书练 Dept. of Precision Instruments Tsinghua University The State Key Laboratory of Precision Measurement Technology and Instrument 北京 100084 Dept. of Precision Instruments Tsinghua University The State Key Laboratory of Precision Measurement Technology and Instrument 上海 100084

This paper proposed a novel tunable dual frequency laser with large frequency difference,which used LD to pump the Nd∶YAG microchip in the end surface and put the liquid pressure on the radial direction of the crystal by a pressure transporting thin film. As a result of the stress birefringence, there was a mode splitting phenomenon of the microchip laser longitudinal mode. Both theoretical analysis and experiments indicated that there is a directly proportional relation between the frequency difference and the pressure, so the tunable frequency difference could be obtained when the pressure was changed. A large frequency difference of about 3.4 GHz with linear tunable relation was achieved in the experiment,so it can be a practical light source for the absolute distance interferometry.

关键词： large frequency difference tunable dual frequency LD pumped Nd∶YAG laser

Notched Triangular Microstrip Antenna for dual-frequency Operation

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Journal of Shanghai University(English Edition) 2003年第4期7卷 375-378页

作者：江轶慧钟顺时 School of Communication and Information Engineering Shanghai University Shanghai 200072 China

A novel equilateral triangular patch with a rectangular notch etched to one radiating edge on organic magnetic substrate is proposed for dual frequency operation. Both operations of these dual frequencies arise from the perturbation of TM 10 and TM 11 mode by simply cutting a rectangular notch at the patch bottom. Simulations and experiments have shown the validity of this design. Using an organic magnetic material as the substrate, the antenna exhibits a broader bandwidth of 5.5% and 4.7% at dual-frequencies 1.56 GHz and 2.45 GHz, respectively, as well as a reduced size compared to the dual-frequency patch antennas on non-magnetic material.

关键词： triangular microstrip antenna notch dual frequency organic magnetic material.