Clarification on Polarity of Bipolar Electric Field Solitary Structures in Space Plasmas with Satellite Observation

The bipolar electric field solitary(EFS)structures observed frequently in space plasmas by satellites have two different polarities,first positive electric field peak then negative(i.e.,positive/negative)and first negative then positive peak(i.e.,negative/positive).We provide the physical explanation on the polarity of observed bipolar EFS structures with an electrostatic ion fluid model.The results show that if initial electric field𝐸E_(0)>0,the polarity of the bipolar EFS structure will be positive/negative;and if𝐸E_(0)<0,the polarity of the bipolar EFS structure will be negative/positive.However,for a fixed polarity of the EFS,either positive/negative or negative/positive,if the satellite is located at the positive side of the EFS,the observed polarity should be positive/negative,if the satellite is located at the negative side of the EFS,the observed polarity should be negative/positive.Therefore,we provide a method to clarify the natural polarity of the EFS with observed polarity by satellites.Our results are significant to understand the physical process in space plasma with the satellite observation.

Effect on Landau damping rates for a non-Maxwellian distribution function consisting of two electron populations

In many physical situations where a laser or electron beam passes through a dense plasma,hot low-density electron populations can be generated,resulting in a particle distribution function consisting of a dense cold population and a small hot population.Presence of such low-density electron distributions can alter the wave damping rate.A kinetic model is employed to study the Landau damping of Langmuir waves when a small hot electron population is present in the dense cold electron population with non-Maxwellian distribution functions.Departure of plasma from Maxwellian distributions significantly alters the damping rates as compared to the Maxwellian plasma.Strong damping is found for highly nonMaxwellian distributions as well as plasmas with a higher density and hot electron population.Existence of weak damping is also established when the distribution contains broadened flat tops at the low energies or tends to be Maxwellian.These results may be applied in both experimental and space physics regimes.

Nonlinear Landau damping of high frequency waves in non-Maxwellian plasmas

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.

Dust-Lower-Hybrid Surface Waves in Classical and Degenerate Plasmas

The dispersion relation for general dust low frequency electrostatic surface waves propagating on an interface between a magnetized dusty plasma region and a vacuum is derived by using specular reflection boundary conditions both in classical and quantum regimes. The frequency limit ωωci ωce is considered and the dispersion relation for the Dust-Lower-Hybrid Surface Waves(DLHSW's) is derived for both classical and quantum plasma half-space and analyzed numerically. It is shown that the wave behavior changes as the quantum nature of the problem is considered.