Hypocycloid and epicycloid motions of aggregates consisted of one large and one small grains are experimentally observed in an rf dust plasma.The cycloid motions are regarded as combination of a primary circle and a s...Hypocycloid and epicycloid motions of aggregates consisted of one large and one small grains are experimentally observed in an rf dust plasma.The cycloid motions are regarded as combination of a primary circle and a secondary circle.Measurements with high spatiotemporal resolution show that the secondary circle is determined by the initial angle velocity of the dropped aggregate.The primary circle originates from the asymmetry of the aggregate.The small grain in the aggregate always leads the large one as they travelling,which results from the difference of the natural frequency of the two grains.Comparative experiments with regular microspheres show that the cycloid motions are distinctive features of aggregates immersed in a plasma.展开更多
The effect of ion motion in capillary-guided laser-driven plasma wake is investigated through rebuilding a two-dimensional analytical model.It is shown that laser pulse with the same power can excite more intense wake...The effect of ion motion in capillary-guided laser-driven plasma wake is investigated through rebuilding a two-dimensional analytical model.It is shown that laser pulse with the same power can excite more intense wakefield in the capillary of a smaller radius.When laser intensity exceeds a critical value,the effect of ion motion reducing the wakefield rises,which becomes significant with a decrease of capillary radius.This phenomenon can be attributed to plasma ions in smaller capillary obtaining more energy from the plasma wake.The dependence of the difference value between maximal scalar potential of wake for two cases of ion rest and ion motion on the radius of the capillary is discussed.展开更多
Hypocycloid and epicycloid motions of irregular grains （pine pollen） are observed for the first time in a dust plasma in a two-dimensional （2D） horizontal plane. These cycloid motions can be regarded as a combinat...Hypocycloid and epicycloid motions of irregular grains （pine pollen） are observed for the first time in a dust plasma in a two-dimensional （2D） horizontal plane. These cycloid motions can be regarded as a combination of a primary circle and a secondary circle. An inverse Magnus force originating from the spin of the irregular grain gives rise to the primary circle. Radial confinement resulting from the electrostatic force and the ion drag force, together with inverse Magnus force, plays an important role in the formation of the secondary circle. In addition, the cyclotron radius is seen to change periodically during the cycloid motion. Force analysis and comparison experiments have shown that the cycloid motions are distinctive features of an irregular grain immersed in a plasma.展开更多
The paper deals with calculation of the centrally symmetric and vortex forces for the momentum of a particle in the distortion tensor field from the action minimum, by analogy with the calculation of forces for a char...The paper deals with calculation of the centrally symmetric and vortex forces for the momentum of a particle in the distortion tensor field from the action minimum, by analogy with the calculation of forces for a charge in an electromagnetic field. It is demonstrated that: 1) The compensating interaction tensor corresponds to the distortion tensor in a solid. 2) The centrally symmetric force of the distortion tensor acts on the momentum as a charge, and is analogous to the Coulomb force. In a gas, it results in change in the momentum value of the molecules exponentially to some extent. The action of this force explains the high-temperature plasma in the gas. 3) The vortex force of the distortion tensor is equivalent to the Peach-Koehler force in a solid. It acts on the momentum flow, similar to the Lorentz magnetic force, and explains the vortex motions in space, in the form of “black holes”, and in the atmosphere, in the form of cyclones and anticyclones.展开更多
Based on fluid equations, we show a time-dependent self-consistent nonlinear model for void formation in magnetized dusty plasmas. The cylindrical configuration is applied to better illustrate the effects of the stati...Based on fluid equations, we show a time-dependent self-consistent nonlinear model for void formation in magnetized dusty plasmas. The cylindrical configuration is applied to better illustrate the effects of the static magnetic field, considering the azimuthal motion of the dusts. Tile nonlinear evolution of the dust void and the rotation of the dust particles are then investigated numerically. The results show that, similar to the unmagnetized one-dimensional model, the radial ion dragplays a crucial role in the evolution of the void. Moreover, the dust rotation is driven by the azimuthal ion drag force exerting on the dust. As the azimuthal component of ion velocity increases linearly with the strength of the magnetic field, tile azimuthal component of dust velocity increases synchronously. Moreover, the angular velocity gradients of the dust rotation show a sheared dust flow around the void.展开更多
Recent theoretical work on electron beam heating of magneto-active motional Plasma is presented. Power transfer from beam (plasma heating) and generated electric fields for different physical situations of linear and ...Recent theoretical work on electron beam heating of magneto-active motional Plasma is presented. Power transfer from beam (plasma heating) and generated electric fields for different physical situations of linear and nonlinear beam-plasma interaction, are studied. Based on previous works [1] [2], we shall study the effects of dusts and plasma motion () on plasma heating. Besides, the case of an inhomogeneity of beam velocity () is also considered. Taking into consideration nonlinear process, dust, plasma motion, and beam velocity inhomogeneity, are found to play a crucial role via power absorbed by the beam and the generated electric field in the system.展开更多
A 3-phase a.c. arc plasma reactor with large volume plasma has been developed for the synthesis of new carbon nano-structures. One of the main characteristics of the plasma system is related to the absence of a fixed ...A 3-phase a.c. arc plasma reactor with large volume plasma has been developed for the synthesis of new carbon nano-structures. One of the main characteristics of the plasma system is related to the absence of a fixed neutral point. This gives rise to a rich and complex phenomenology related to instabilities and arc motion since the arcs are ＂burning＂ freely in the gas flow between the three electrodes. This paper is dedicated to the analysis of the behavior of such a system under typical conditions using argon and nitrogen as plasma gases. A classification of are configuration, arc commutating, arc interaction, arc motion and arc instabilities are discussed based on ultra high-speed cine camera analysis. A simple model describing the time evolution of the system is also presented and compared with the experimental measurements. The results show that an adequate control could allow the improvement of the overall system.展开更多
Steady-state plasma generated by electron cyclotron resonance （ECR） wave in the KT5D magnetized torus was studied using a fast high-resolution camera and Langmuir probes. It was found that both the discharge pattern...Steady-state plasma generated by electron cyclotron resonance （ECR） wave in the KT5D magnetized torus was studied using a fast high-resolution camera and Langmuir probes. It was found that both the discharge patterns taken by the camera and the plasma parameters measured by the probes were very sensitive to the working gas pressure and the magnetic configuration of the torus both without and with vertical fields. There existed fast vertical motion of the plasma. Tentative discussion is presented about the observed phenomena such as the bright resonance layer at a high gas pressure and the wave absorption mechanism at a low pressure. Further explanations should be found.展开更多
基金supported by National Natural Science Foundation of China(Nos.1120504411405042)+6 种基金the Natural Science Foundation of Hebei ProvinceChina(Nos.A2011201006A2012201015)the Research Foundation of Education Bureau of Hebei ProvinceChina(Nos.Y2012009ZD2015025)the Midwest Universities Comprehensive Strength Promotion Project of China
文摘Hypocycloid and epicycloid motions of aggregates consisted of one large and one small grains are experimentally observed in an rf dust plasma.The cycloid motions are regarded as combination of a primary circle and a secondary circle.Measurements with high spatiotemporal resolution show that the secondary circle is determined by the initial angle velocity of the dropped aggregate.The primary circle originates from the asymmetry of the aggregate.The small grain in the aggregate always leads the large one as they travelling,which results from the difference of the natural frequency of the two grains.Comparative experiments with regular microspheres show that the cycloid motions are distinctive features of aggregates immersed in a plasma.
基金supported by National Natural Science Foundation of China(No.11247016)the Natural Science Foundation of Jiangxi Province,China(Nos.2014ZBAB202001 and 20151BAB212010)the Science Foundation for Youths of the Jiangxi Education Committee of China(No.GJJ14224)
文摘The effect of ion motion in capillary-guided laser-driven plasma wake is investigated through rebuilding a two-dimensional analytical model.It is shown that laser pulse with the same power can excite more intense wakefield in the capillary of a smaller radius.When laser intensity exceeds a critical value,the effect of ion motion reducing the wakefield rises,which becomes significant with a decrease of capillary radius.This phenomenon can be attributed to plasma ions in smaller capillary obtaining more energy from the plasma wake.The dependence of the difference value between maximal scalar potential of wake for two cases of ion rest and ion motion on the radius of the capillary is discussed.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11205044 and 11405042)the Natural Science Foundation of Hebei Province,China(Grant Nos.A2011201006 and A2012201015)+2 种基金the Research Foundation of Education Bureau of Hebei Province,China(Grant No.Y2012009)the Program for Young Principal Investigators of Hebei Provincethe Midwest Universities Comprehensive Strength Promotion Project
文摘Hypocycloid and epicycloid motions of irregular grains （pine pollen） are observed for the first time in a dust plasma in a two-dimensional （2D） horizontal plane. These cycloid motions can be regarded as a combination of a primary circle and a secondary circle. An inverse Magnus force originating from the spin of the irregular grain gives rise to the primary circle. Radial confinement resulting from the electrostatic force and the ion drag force, together with inverse Magnus force, plays an important role in the formation of the secondary circle. In addition, the cyclotron radius is seen to change periodically during the cycloid motion. Force analysis and comparison experiments have shown that the cycloid motions are distinctive features of an irregular grain immersed in a plasma.
文摘The paper deals with calculation of the centrally symmetric and vortex forces for the momentum of a particle in the distortion tensor field from the action minimum, by analogy with the calculation of forces for a charge in an electromagnetic field. It is demonstrated that: 1) The compensating interaction tensor corresponds to the distortion tensor in a solid. 2) The centrally symmetric force of the distortion tensor acts on the momentum as a charge, and is analogous to the Coulomb force. In a gas, it results in change in the momentum value of the molecules exponentially to some extent. The action of this force explains the high-temperature plasma in the gas. 3) The vortex force of the distortion tensor is equivalent to the Peach-Koehler force in a solid. It acts on the momentum flow, similar to the Lorentz magnetic force, and explains the vortex motions in space, in the form of “black holes”, and in the atmosphere, in the form of cyclones and anticyclones.
基金Supported by the Program for Innovation Research of Science in Harbin Institute of Technology under Grant No A201413
文摘Based on fluid equations, we show a time-dependent self-consistent nonlinear model for void formation in magnetized dusty plasmas. The cylindrical configuration is applied to better illustrate the effects of the static magnetic field, considering the azimuthal motion of the dusts. Tile nonlinear evolution of the dust void and the rotation of the dust particles are then investigated numerically. The results show that, similar to the unmagnetized one-dimensional model, the radial ion dragplays a crucial role in the evolution of the void. Moreover, the dust rotation is driven by the azimuthal ion drag force exerting on the dust. As the azimuthal component of ion velocity increases linearly with the strength of the magnetic field, tile azimuthal component of dust velocity increases synchronously. Moreover, the angular velocity gradients of the dust rotation show a sheared dust flow around the void.
文摘Recent theoretical work on electron beam heating of magneto-active motional Plasma is presented. Power transfer from beam (plasma heating) and generated electric fields for different physical situations of linear and nonlinear beam-plasma interaction, are studied. Based on previous works [1] [2], we shall study the effects of dusts and plasma motion () on plasma heating. Besides, the case of an inhomogeneity of beam velocity () is also considered. Taking into consideration nonlinear process, dust, plasma motion, and beam velocity inhomogeneity, are found to play a crucial role via power absorbed by the beam and the generated electric field in the system.
基金supported by National Natural Science Foundation of China (No. 10375065)Anhui Natural Science Foundation (03045102)+1 种基金Europeam Commission projects NanoComp HPRN-CR-2000-0037PlasmaCarb G5RD-CT-1999-00173
文摘A 3-phase a.c. arc plasma reactor with large volume plasma has been developed for the synthesis of new carbon nano-structures. One of the main characteristics of the plasma system is related to the absence of a fixed neutral point. This gives rise to a rich and complex phenomenology related to instabilities and arc motion since the arcs are ＂burning＂ freely in the gas flow between the three electrodes. This paper is dedicated to the analysis of the behavior of such a system under typical conditions using argon and nitrogen as plasma gases. A classification of are configuration, arc commutating, arc interaction, arc motion and arc instabilities are discussed based on ultra high-speed cine camera analysis. A simple model describing the time evolution of the system is also presented and compared with the experimental measurements. The results show that an adequate control could allow the improvement of the overall system.
基金the National Science Foundation of China (Nos.10235010,10335060)Funds from the Ministry of Educationthe Academy of Science of China
文摘Steady-state plasma generated by electron cyclotron resonance （ECR） wave in the KT5D magnetized torus was studied using a fast high-resolution camera and Langmuir probes. It was found that both the discharge patterns taken by the camera and the plasma parameters measured by the probes were very sensitive to the working gas pressure and the magnetic configuration of the torus both without and with vertical fields. There existed fast vertical motion of the plasma. Tentative discussion is presented about the observed phenomena such as the bright resonance layer at a high gas pressure and the wave absorption mechanism at a low pressure. Further explanations should be found.
