The dispersion of Langmuir wave(LW)in an unmagnetized collisionless plasma with regularized Kappa distributed electrons is investigated from the kinetic theory.The frequency and damping rate of LW are analyzed for the...The dispersion of Langmuir wave(LW)in an unmagnetized collisionless plasma with regularized Kappa distributed electrons is investigated from the kinetic theory.The frequency and damping rate of LW are analyzed for the parameters relating to the source region of a typeⅢsolar radio burst.It is found that the linear behavior of LW is greatly modified by the suprathermal indexκand the exponential cutoff parameterα.In the regionκ<1.5,the damping rate of LW will be much larger than the one with Maxwellian distributed electrons.Hence,the nonlinear process of LW in lowκregion may exhibit different properties in comparison with the one in largeκregion.展开更多
This treatise analyzes the coupled nonlinear system of the model for the ion sound and Langmuir waves.The modified(G'/G)-expansion procedure is utilized to raise new closed-form wave solutions.Those solutions are ...This treatise analyzes the coupled nonlinear system of the model for the ion sound and Langmuir waves.The modified(G'/G)-expansion procedure is utilized to raise new closed-form wave solutions.Those solutions are investigated through hyperbolic,trigonometric and rational function.The graphical design makes the dynamics of the equations noticeable.It provides the mathematical foundation in diverse sectors of underwater acoustics,electromagnetic wave propagation,design of specific optoelectronic devices and physics quantum mechanics.Herein,we concluded that the studied approach is advanced,meaningful and significant in implementing many solutions of several nonlinear partial differential equations occurring in applied sciences.展开更多
一般认为,Langmuir波(LW)转换为电磁波是太阳Ⅲ型射电爆的产生机制。由电子束流不稳定性可以很容易地激发LW,正向LW和反向LW的相互作用被认为是产生Ⅲ型爆二次谐波的原因,但反向LW的色散方程和产生机制尚未得到充分研究。通过粒子(Parti...一般认为,Langmuir波(LW)转换为电磁波是太阳Ⅲ型射电爆的产生机制。由电子束流不稳定性可以很容易地激发LW,正向LW和反向LW的相互作用被认为是产生Ⅲ型爆二次谐波的原因,但反向LW的色散方程和产生机制尚未得到充分研究。通过粒子(Particle In Cell,PIC)模拟研究了反向LW的产生机制,发现反向LW不能由电子束流直接激发,其能量基本上是由正向LW散射得到的。然而,电子束流对正向LW的二次谐波有直接放大作用。展开更多
Space plasmas often possess non-Maxwellian distribution functions which have a significant effect on the plasma waves. When a laser or electron beam passes through a dense plasma, hot low density electron populations ...Space plasmas often possess non-Maxwellian distribution functions which have a significant effect on the plasma waves. When a laser or electron beam passes through a dense plasma, hot low density electron populations can be generated to alter the wave damping/growth rate. In this paper, we present theoretical analysis of the nonlinear Landau damping for Langmuir waves in a plasma where two electron populations are found. The results show a marked difference between the Maxwellian and non-Maxwellian instantaneous damping rates when we employ a non-Maxwellian distribution function called the generalized （r, q） distribution function, which is the generalized form of the kappa and Maxwellian distribution functions. In the limiting case of r = 0 and q→∞, it reduces to the classical Maxwellian distribution function, and when r = 0 and q→k ＋1, it reduces to the kappa distribution function.展开更多
Effect of Langmuir circulation （LC） on upper ocean mixing is investigated by a two-way wave-current coupled model. The model is coupled of the ocean circulation model ROMS （regional ocean modeling system） to the s...Effect of Langmuir circulation （LC） on upper ocean mixing is investigated by a two-way wave-current coupled model. The model is coupled of the ocean circulation model ROMS （regional ocean modeling system） to the surface wave model SWAN （simulating waves nearshore） via the model-coupling toolkit. The LC already certified its importance by many one-dimensional （1D） research and mechanism analysis work. This work focuses on inducing LC＇s effect in a three-dimensional （3-D） model and applying it to real field modeling. In ROMS, the Mellor-Yamada turbulence closure mixing scheme is modified by including LC＇s effect. The SWAN imports bathymetry, free surface and current information from the ROMS while exports signifi- cant wave parameters to the ROMS for Stokes wave computing every 6 s. This coupled model is applied to the South China Sea （SCS） during September 2008 cruise. The results show that LC increasing turbulence and deepening mixed layer depth （MLD） at order of O （10 m） in most of the areas, especially in the north part of SCS where most of our measurements operated. The coupled model further includes wave break- ing which will brings more energy into water. When LC works together with wave breaking, more energy is transferred into deep layer and accelerates the MLD deepening. In the north part of the SCS, their effects are more obvious. This is consistent with big wind event in the area of the Zhujiang River Delta. The shallow water depth as another reason makes them easy to influence the ocean mixing as well.展开更多
A new three-dimensional numerical model is derived through a wave average on the primitive N-S equations, in which both the＂Coriolis-Stokes forcing＂ and the＂Stokes-Vortex force＂ are considered. Three ideal experim...A new three-dimensional numerical model is derived through a wave average on the primitive N-S equations, in which both the＂Coriolis-Stokes forcing＂ and the＂Stokes-Vortex force＂ are considered. Three ideal experiments are run using the new model applied to the Princeton ocean model （POM）. Numerical results show that surface waves play an important role on the mixing of the upper ocean. The mixed layer is enhanced when wave effect is considered in conjunction with small Langmuir numbers. Both surface wave breaking and Stokes production can strengthen the turbulent mixing near the surface. However, the influence of wave breaking is limited to a thin layer, but Stokes drift can affect the whole mixed layer. Furthermore, the vertical mixing coefficients clearly rise in the mixed layer, and the upper ocean mixed layer is deepened especially in the Antarctic Circumpolar Current when the model is applied to global simulations. It indicates that the surface gravity waves are indispensable in enhancing the mixing in the upper ocean, and should be accounted for in ocean general circulation models.展开更多
文摘The dispersion of Langmuir wave(LW)in an unmagnetized collisionless plasma with regularized Kappa distributed electrons is investigated from the kinetic theory.The frequency and damping rate of LW are analyzed for the parameters relating to the source region of a typeⅢsolar radio burst.It is found that the linear behavior of LW is greatly modified by the suprathermal indexκand the exponential cutoff parameterα.In the regionκ<1.5,the damping rate of LW will be much larger than the one with Maxwellian distributed electrons.Hence,the nonlinear process of LW in lowκregion may exhibit different properties in comparison with the one in largeκregion.
文摘This treatise analyzes the coupled nonlinear system of the model for the ion sound and Langmuir waves.The modified(G'/G)-expansion procedure is utilized to raise new closed-form wave solutions.Those solutions are investigated through hyperbolic,trigonometric and rational function.The graphical design makes the dynamics of the equations noticeable.It provides the mathematical foundation in diverse sectors of underwater acoustics,electromagnetic wave propagation,design of specific optoelectronic devices and physics quantum mechanics.Herein,we concluded that the studied approach is advanced,meaningful and significant in implementing many solutions of several nonlinear partial differential equations occurring in applied sciences.
文摘一般认为,Langmuir波(LW)转换为电磁波是太阳Ⅲ型射电爆的产生机制。由电子束流不稳定性可以很容易地激发LW,正向LW和反向LW的相互作用被认为是产生Ⅲ型爆二次谐波的原因,但反向LW的色散方程和产生机制尚未得到充分研究。通过粒子(Particle In Cell,PIC)模拟研究了反向LW的产生机制,发现反向LW不能由电子束流直接激发,其能量基本上是由正向LW散射得到的。然而,电子束流对正向LW的二次谐波有直接放大作用。
基金Project supported by the Pakistan Science Foundation Project No.PSF/Res/P-GCU/Phys.(143)the National Natural Science Foundation of China(Grant Nos.41074114 and 41274146)the Specialized Research Fund for State Key Laboratories of China
文摘Space plasmas often possess non-Maxwellian distribution functions which have a significant effect on the plasma waves. When a laser or electron beam passes through a dense plasma, hot low density electron populations can be generated to alter the wave damping/growth rate. In this paper, we present theoretical analysis of the nonlinear Landau damping for Langmuir waves in a plasma where two electron populations are found. The results show a marked difference between the Maxwellian and non-Maxwellian instantaneous damping rates when we employ a non-Maxwellian distribution function called the generalized （r, q） distribution function, which is the generalized form of the kappa and Maxwellian distribution functions. In the limiting case of r = 0 and q→∞, it reduces to the classical Maxwellian distribution function, and when r = 0 and q→k ＋1, it reduces to the kappa distribution function.
基金the National Basic Research Program of China under contract Nos 2011CB403501 and 2012CB417402the Open Research Foundation for the State Key Laboratory of Satellite Ocean Environment Dynamics,Second Institute of Oceanography,State Oceanic Administration under contract No. SOED1210the Fund for Creative Research Groups by NSFC under contract No. 41121064
文摘Effect of Langmuir circulation （LC） on upper ocean mixing is investigated by a two-way wave-current coupled model. The model is coupled of the ocean circulation model ROMS （regional ocean modeling system） to the surface wave model SWAN （simulating waves nearshore） via the model-coupling toolkit. The LC already certified its importance by many one-dimensional （1D） research and mechanism analysis work. This work focuses on inducing LC＇s effect in a three-dimensional （3-D） model and applying it to real field modeling. In ROMS, the Mellor-Yamada turbulence closure mixing scheme is modified by including LC＇s effect. The SWAN imports bathymetry, free surface and current information from the ROMS while exports signifi- cant wave parameters to the ROMS for Stokes wave computing every 6 s. This coupled model is applied to the South China Sea （SCS） during September 2008 cruise. The results show that LC increasing turbulence and deepening mixed layer depth （MLD） at order of O （10 m） in most of the areas, especially in the north part of SCS where most of our measurements operated. The coupled model further includes wave break- ing which will brings more energy into water. When LC works together with wave breaking, more energy is transferred into deep layer and accelerates the MLD deepening. In the north part of the SCS, their effects are more obvious. This is consistent with big wind event in the area of the Zhujiang River Delta. The shallow water depth as another reason makes them easy to influence the ocean mixing as well.
基金The Open Fund of the Shandong Province Key Laboratory of Ocean Engineering,Ocean University of China(Fundamental Research Funds for the Central Universities)under contract No.201362045the Open Fund of the Key Laboratory of Digital Ocean,State Oceanic Administration of China under contract No.KLDO201406
文摘A new three-dimensional numerical model is derived through a wave average on the primitive N-S equations, in which both the＂Coriolis-Stokes forcing＂ and the＂Stokes-Vortex force＂ are considered. Three ideal experiments are run using the new model applied to the Princeton ocean model （POM）. Numerical results show that surface waves play an important role on the mixing of the upper ocean. The mixed layer is enhanced when wave effect is considered in conjunction with small Langmuir numbers. Both surface wave breaking and Stokes production can strengthen the turbulent mixing near the surface. However, the influence of wave breaking is limited to a thin layer, but Stokes drift can affect the whole mixed layer. Furthermore, the vertical mixing coefficients clearly rise in the mixed layer, and the upper ocean mixed layer is deepened especially in the Antarctic Circumpolar Current when the model is applied to global simulations. It indicates that the surface gravity waves are indispensable in enhancing the mixing in the upper ocean, and should be accounted for in ocean general circulation models.
