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1.
In the two component relativistic plasmas subject to pressure variation of adiabatic electrons and isothermal ions, both compressive and rarefactive KdV solitons are established in a quite different physical plasma model. It is desirable to define c s in a new way to substantiate the validity of the model under relativistic effects. The corresponding mathematical condition is also determined, which is a new report of this kind. It is also interesting to report that the relativistic rarefactive solitons cease to exist below some critical ion initial streaming speed v i0 for a fixed temperature α and electron streaming speed v e0. Besides, higher initial flux v i0 of ions under constant temperature is observed to generate higher speed v i at the passage of time which causes to increase (in relativistic sense) its mass diminishing thereby the growth of soliton amplitudes. 相似文献
2.
Existence of compressive relativistic solitons is established in an arbitrary ξ-direction, inclining at an angle to the direction of the weak magnetic field (ω
pi
≫ω
Bi
) in this plasma compound with ions, relativistic electrons and relativistic electron beams. It is observed that the absolute
linear growth of amplitudes of compressive solitons is due to inactive role of the weak magnetic field and the initial streaming
speeds of relativistic electrons, electron beams, and Q
b
(ion mass to electron beam mass). Besides, the small initial streaming of electrons is found to be responsible to generate
relatively high amplitude compressive solitons. The non-relativistic ions in the background plasma, but in absence of electron-beam
drift and in presence of weak magnetic field are the causing effect of interest for the smooth growth of soliton amplitudes
in this model of plasma. 相似文献
3.
In the new investigation of dust-ion acoustic (DIA) waves with negative dust charges and weakly relativistic ions and electrons in the plasma, compressive and rarefactive DIA solitons of interesting characters are established through the Korteweg-de Vries (KdV) equation. Eventually, the amplitudes of the compressive DIA solitons are found to be constant at some critical temperature ratio α c (electron to ion temperature ratio) identifying some critical dust charge Z dc . It is predicted, that the reception of dust charges by the plasma particles at the variation of temperature starts functioning to the growth of compressive soliton’s constant stage of amplitude after the state of critical α c . The identification of critical dust charge (Z dc ) which is found to be very great for solitons of constant amplitudes becomes feasible for very small dust to ion density ratio (σ). But it can be achieved, we observe, due to the relativistic increase in ion-density as in mass, which is also a salient feature of this investigation. 相似文献
4.
Dust acoustic waves are investigated in plasma system containing dynamic and streaming dust, supertherrmal electrons and ions. Linear and nonlinear studies are carried out and elaborated with the help of parameters taken for Saturn’s F-ring. An energy integral equation is obtained by using the Sagdeev potential approach, and results are displayed by solving it analytically and numerically. The dependence of nonlinear structures on κ values, the ratio of electron to dust equilibrium densities μ ed , Mach number M, and dust streaming speed v d0 have been presented. The streaming speed appears as a destructive partner for the Mach number M in the pseudoenergy equation and hence plays a dominant modifying role in the formation of nonlinear structures. It plays a destructive role for some of the solitons and works as a source, for the emergence of new solitons (region). Formation of double layers are also investigated and shown that the amplitude, width and existence of double layers structures are predominantly affected by the presence of superthermal electrons, ions, and streaming dust beam. 相似文献
5.
The Gardner equation is derived and numerically solved. This equation shows the existence of compressive and rarefactive dust-acoustic (DA) solitons with two-temperature ions beyond the K-dV (Korteweg–de Vries) limit. These may be referred to as DA Gardner solitons (DA-GSs). Here we deal with a dusty plasma, composed of negatively charged cold mobile dust fluids, inertialess Boltzmann electrons and ions with two distinctive temperatures. The basic features of the compressive and rarefactive DA solitons are identified. These solitons are found to exist beyond the K-dV limit, i.e. they exist for μ i1~μ c. Here μ i1=n i10/Z d n d0, Z d is the number of electrons residing upon the dust grain surface, and n i0 (n d0) is the lower temperature ion (dust) number density at equilibrium. These DA-GSs are completely different from the K-dV solitons, because μ c (the critical value) corresponds to vanishing of the nonlinear coefficient of the K-dV equation, and μ i1~μ c corresponds to K-dV solitons, with extremely large amplitude, for which the validity of the reductive perturbation method breaks down. It has been found that, depending on whether the parameter μ i1 is less than or greater than the critical value, the DA-GSs exhibit compression for μ i1>μ c and rarefaction for μ i1<μ c. The basic features of double layers with arbitrary amplitude are also briefly discussed, employing the pseudo-potential approach. The present investigation might be relevant to the electrostatic solitary structures observed in various cosmic dust-laden plasmas, such as supernova shells, Saturn’s F-ring, the ionopause of Halley’s comet, etc. 相似文献
6.
Properties of ion acoustic solitons head-on collision in an ultracold neutral plasma composed of ion fluid and non-Maxwellian electron distributions are investigated. For this purpose, the extended Poincare-Lighthill-Kuo (PLK) method is employed to derive coupled Kortweg-de Vries (KdV) equations describing the system. The nonlinear evolution equations for the colliding solitons and corresponding phase shifts are investigated both analytically and numerically. It is found that the polarity of the colliding solitons strongly depends on the type of the non-Maxwellian distribution (via nonthermal or superthermal electron distributions). Especially the phase shift due to solitons collision is strongly influenced by the non-Maxwellian distribution. A new critical nonthermal parameter β c , characterizing the nonthermal electron distribution, and which is not present for superthermal particle distributions, allows the existence of double polarity of the solitons. The phase shift increases below β c for compressive solitons, but it decreases above β c for rarefactive soliton. For superthermal distribution the phase shift increases rapidly for low spectral index κ, whereas for higher values of κ, the phase shift decreases smoothly and becomes nearly stable for κ>10. Around β c and small values of κ, the deviation from the Maxwellian state is strongest, and therefore the phase shift has unexpected behavior due to the presence of more energetic electrons that are represented by the non-Maxwellian distributions. The nonlinear structure, as reported here, could be useful for controlling the solitons that may be created in future ultracold neutral plasma experiments. 相似文献
7.
Extreme ultraviolet (EUV) resonance fluorescence of the (0,v″) bands of the c′41Σu+→X1Σg+ and the (1,v″) bands of the b′ 1Σu+→X1Σg+ transitions of N2 has been observed by photon excitation of N2 in the vicinity of 95.8 nm. The integrated fluorescence intensities of the c′4→X (0,v″) emission become saturated at N2 pressures higher than ∼0.16 mTorr. The emission features in the spectral region between 105 and 130 nm become progressively significant as the N2 pressure is increased. The (1,v″) progression for v″ up to 11 of the b′→X transition and two progressions of the Lyman-Birge-Hopfield (LBH) system have been identified. The multiple scattering processes apparently cause significant reduction in the c′4→X (0,0) emission rates. The present results may be useful in the explanation of the weak c′4→X (0,0) fluorescence as well as the significant c′4→X (0,v″) features in the dayglow of the Earth observed by the Far Ultraviolet Spectroscopic Explorer. 相似文献
8.
Malay Kumar Ghorui Ganesh Mondal Prasanta Chatterjee 《Astrophysics and Space Science》2013,346(1):191-201
Nonlinear propagation of two dimensional dust-acoustic solitary waves in a magnetized quantum dusty plasma whose constituents are electrons, ions, and negatively charged heavy dust particles are investigated using quantum hydrodynamic model. The Zakharov-Kuznetsov (ZK) equation is derived by using reductive perturbation technique (RPT). The higher order inhomogeneous ZK-type differential equation is obtained for the correction to ZK- soliton. The dynamical equation for dressed soliton is solved by using renormalization method. The effects of obliqueness (l x ) of the wave vector, magnetic field strength (B 0), quantum parameter for ions (H i ), soliton velocity (θ) and Fermi temperature ratio (σ) on amplitudes and widths of the ZK-soliton and as well as of the dressed soliton are investigated. The conditions for the validity of the higher order correction are described. Suitable parameter ranges for the existence of compressive and rarefactive dressed solitons are also discussed. 相似文献
9.
Nonlinear propagation of dust-acoustic waves in an unmagnetized dusty plasma consisting of negatively charged mobile dust, nonextensive ions following nonextensive q-distribution and two distinct temperature superthermal electrons following superthermal kappa distribution each, is investigated by employing lower and higher order nonlinear equations, namely the Korteweg-de-Vries (K-dV), the modified Korteweg-de-Vries (mK-dV) and the Gardner equations. The characteristic features of the hump (positive potential) and dip (negative potential) shaped dust-acoustic (DA) Gardner solitons are found to exist beyond the K-dV limit. The effects of two superthermal temperature electrons and ions nonextensivity on the basic characteristics of DA K-dV, mK-dV and Gardner solitons have also been investigated. It has been found that the DA Gardner solitons exhibit either negative or positive potential solitons only for q<q c where, q c is the critical value of the nonextensive parameter q. The possible applications of our results in understanding the localized nonlinear electrostatic structures existing in solar atmosphere, Saturn’s magnetosphere etc. (where the tails of the high energetic particles at different temperatures follow power-law like distribution) are also briefly discussed. 相似文献
10.
Properties of propagation of large amplitude dust ion-acoustic solitary waves and double layers are investigated in electron-positron-ion plasma with highly charged negative dust. Sagdeev pseudopotential method has been used to derive the energy balance equation. The expression for the critical Mach number (lower/upper limit) for the existence of solitary structures has also been derived. The Sagdeev pseudopotential is a function of numbers of physical parameters such as ion temperature (σ), positron density (δ p ), dust density (δ d ) and electron to positron temperature ratio (β). These parameters significantly influence the properties of the solitary structures and double layers. Further it is found that both polarity (compressive and rarefactive) solitons and negative potential double layers are observed. 相似文献
11.
A theoretical investigation has been made on the Dust ion-acoustic (DIA) Gardner solitons (GSs) and double layers (DLs) in electronegative plasma consisting of inertial positive and negative ions, super-thermal (kappa distributed) electrons, and negatively charged static dust. The standard reductive perturbation method is employed to derive the Korteweg-de Vries (K-dV), modified K-dV (mK-dV), and standard Gardner equations, which admits solitary waves (SWs) and DLs solutions. It have been found that GSs and DLs exist for α around its critical value α c , where α c is the value of α corresponding to the vanishing of the nonlinear coefficient of the K-dV equation. The parametric regimes for the existence of both the positive as well as negative SWs and negative DLs are obtained. The basic features of DIA SWs and DLs are analyzed and it has been found that the polarity, speed, height, thickness of such DIA SWs and DLs structures, are significantly modified due to the presence of two types of ions and spectral index (κ) of super-thermal electrons. It has also been found that the characteristics of DIA GSs and DLs, are different from that of the K-dV solitons and mK-dV solitons. The relevance of our results to different interstellar space plasma situations are discussed. 相似文献
12.
Jianfei Tang Dejin Wu Guoqing Zhao Ling Chen Chengming Tan 《Astrophysics and Space Science》2014,353(1):131-135
Langmuir waves (LWs), which are believed to play a crucial role in the plasma emission of solar radio bursts, can be excited by streaming instability of energetic electron beams. However, solar hard X-ray observations imply that the energetic flare electrons usually have a power-law energy distribution with a lower energy cutoff. In this paper, we investigate LWs driven by the power-law electrons. The results show that power-law electrons with the steepness cutoff behavior can excite LWs effectively because of the population inversion distribution below the cutoff energy (E c ). The growth rate of LWs increases with the steepness index (δ) and decreases with the power-law index (α). The wave number of the fastest growing LWs (kλ D ), decreases with the characteristic velocity of the power-law electrons ( \(v_{c}=\sqrt{2E_{c}/m_{e}}\) ) and increases with the thermal velocity of ambient electrons (v T ). This can be helpful for us to understand better the physics of LWs and the dynamics of energetic electron beams in space and astrophysical plasmas. 相似文献
13.
The dispersion equation for hydromagnetic surface waves along a plasma-plasma interface has been solved as a function of the compressibility factor c
1/v
A1, where c
1 and v
A1 are the acoustic and Alfvén wave speed in one of the medium, for general wave propagation direction. Both slow and fast magnetosonic surface waves can exist. The nature and existence of these waves depends on the values of c
1/v
A1 and , the angle of wave propagation. For low- plasmas only fast mode exists. The slow mode does not propagate below a critical value of c
1. When c
1 the phase velocity of the slow wave tend to the Alfvén surface wave velocity in the incompressible media and for large the phase velocity of the fast wave approaches this value. The phase velocity of the slow wave increases whereas for the fast wave it decreases with increase in the angle . 相似文献
14.
V. N. Sazonov 《Astrophysics and Space Science》1972,19(1):25-45
The degree of circular polarizationp c is calculated for two models of a source of synchrotron radiation:
- A source with an inhomogeneous magnetic field and isotropic angular distribution of the electrons with respect to the magnetic field;
- A source with a homogeneous magnetic field and anisotropic angular distribution of the electrons in which the anisotropy of angular distribution substantially increases with the electron energy.
15.
Existence of both subsonic and supersonic compressive solitons of interesting characters is established in this magnetized plasma model with non relativistic ions and relativistic electrons. The small supersonic range for the generation of compressive solitons is shown to confine near the vicinity of the direction of the magnetic field. It is predicted that the relativistic variation of electron’s mass is responsible for the expansion of Sagdeev potential to result increase in soliton’s amplitude and decrease in its width. 相似文献
16.
Sanjay Sarkar 《Astrophysics and Space Science》2014,349(1):245-253
Dust-ion-acoustic (DIA) waves in an unmagnetized dusty plasma system consisting of inertial ions, negatively charged immobile dust, and superthermal (kappa distributed) electrons with two distinct temperatures are investigated both numerically and analytically by deriving Korteweg–de Vries (K-dV), modified K-dV (mK-dV), and Gardner equations along with its double layers (DLs) solutions using the reductive perturbation technique. The basic features of the DIA Gardner solitons (GSs) as well as DLs are studied, and an analytical comparison among K-dV, mK-dV, and GSs are also observed. The parametric regimes for the existence of both the positive as well as negative SWs and negative DLs are obtained. It is observed that superthermal electrons with two distinct temperatures significantly affect on the basic properties of the DIA solitary waves and DLs; and depending on the parameter μ c (the critical value of relative electron number density μ e1), the DIA K-dV and Gardner solitons exhibit both compressive and rarefactive structures, whereas the mK-dV solitons support only compressive structures and DLs support only the rarefactive structures. The present investigation can be very effective for understanding and studying various astrophysical plasma environments (viz. Saturn magnetosphere, pulsar magnetosphere, etc.). 相似文献
17.
The occurrence at a heliocentric distance of 1 AU of alpha particle streaming velocities larger than proton streaming velocities,v
/v
p
>1 (Ogilvie, 1975) is investigated on the basis of the theory suggesting the existence in the solar wind of an accelerating force acting preferentially on the alpha particles.Accurate solution of the three-fluid model equations for the quiet solar wind indicates that anecessary andsufficient condition for (v
/v
p
)1 AU>1 is the presence of a relativelyweak accelerating forceacting in a limited region in the vicinity of 1 AU. If the force is effectiveonly at small heliocentric distances, the alpha particle streaming velocity excess vanishes at distances less than 1 AU, because of the (equalization) action of the dynamical friction force. 相似文献
18.
We analyze the propagation features of synchrotron radiation of a charge moving with a gyrating helix trajectory (3-dimensional) in a magnetoplasma. We found that a new factor (1+ cot ) should be included into the relevant spectrum radiation formulae and the usual relativistic factor has to be modified as
, ifv <v
g
, the radiative energy are more concentrated along the velocity of the moving charge; but ifv>v
g, the direction of maximum energy cone deviates from the direction of the moving charge. 相似文献
19.
Gardner solitons (GSs) and double layers (DLs) of dust ion acoustic (DIA) waves in an electronegative plasma (composed of inertial positive and negative ions, Maxwellian cold electrons, non-thermal hot electrons, and negatively charged static dust) are studied. The reductive perturbation method is employed to derive the Korteweg-de Vries (K-dV), modified K-dV, and standard Gardner equations, which admits solitary wave and DLs solutions for σ around its critical value σ c (where σ c is the value of σ corresponding to the vanishing of the nonlinear coefficient of the K-dV equation). The parametric regimes for the existence of the GSs and DLs, are obtained. The basic features of DIA GSs and DLs (associated with negative structure only) are analyzed. It has been found that the characteristics of DIA GSs and DLs, are different from that of the K-dV solitons and mK-dV (mixed K-dV) solitons. The implications of our results to different space and laboratory plasma situations are discussed. 相似文献
20.
The electrostatic shocks and solitons are studied in weakly relativistic and collisional electron-positron-ion plasmas occurring
in polar regions of pulsar. The plasma system is composed of relativistically streaming electrons, positrons while ions are
taken to be stationary. Dissipative effects in the system are due to collision phenomena among the constituents of relativistic
plasma. Nonlinear dynamics of the dissipation and dispersion dominated relativistic plasma systems are governed by Korteweg-de
Vries Burger (KdVB) and Korteweg-de Vries (KdV) equations respectively. Numerical results, exploring the effects of plasma
parameters on the profile of nonlinear waves are expedited graphically for illustration. Positron to electron temperature
ratio plays the role of a decisive parameter. It is noticed that compressive shocks and solitons evolve in the system if the
positron to electron temperature ratio is less than a critical value. However, there exists a threshold value of positron
to electron temperature ratio beyond which the system supports the rarefactive shocks and solitons. The results may have importance
in the relativistic plasmas of pulsar magnetosphere. 相似文献