Ion-acoustic solitons in an inhomogeneous multicomponent plasmawith negative ions

Ion-acoustic solitary waves are studied in an inhomogeneous multicomponent plasma by the augmentation of a K-dV equation wherein a simple form of ionization has been taken to show its interaction in changing the salient features of the soliton, as compared to those observed in a homogeneous plasma. As expected, the negative ions in the plasma bring a drastic alteration on the ion-acoustic solitons, thereby establishing a new era by showing the solitary waves to be studied by a modified K-dV equation. The emphasis has been on determining how the ionization and density gradient in the inhomogeneous plasma affect the solitons     

Ion acoustic solitons in a streaming relativistic plasma with negative ions

We analyze the effect of a nonzero streaming velocity of both positive and negative ions on the formation of solitary waves in a relativistic plasma. The thermodynamic situation is considered to be isothermal. For various values ofu _0/C andn _o/nowe obtain the variations of the amplitude and the width of the solitary wave.     

Large amplitude solitary waves in a multicomponent plasma with negative ions

When the concentration of negative ions is larger than a critical value, a small compressive pulse evolves into a subionic wave train and a large pulse develops into a solitary wave. The threshold amplitude and velocity of the solitary waves are measured and compared with predictions using the pseudopotential method.     

Ion-acoustic solitons and double-layers in a plasma consisting of positive and negative ions with non-thermal electrons

In this research paper, the authors have studied the properties of ion-acoustic solitons and double-layers in a plasma consisting of warm positive and negative ions with different concentration of masses, charged states and non-thermal electrons using small amplitude approximation. Reductive perturbation method is used to derive KdV and m-KdV equations. Existence of ion-acoustic solitons and double-layer is explored over a wide range of parameter space. The role of non-thermal electrons characterized by finite is investigated. It is observed that for a particular value of , there is a transition from compressive to rarefactive solitons. However, when is increased beyond a critical value, no double-layers are obtained. The significance of relative ion masses is also investigated.Received: 9 July 2004, Published online: 21 September 2004PACS: 52.35.-g Waves, oscillations, and instabilities in plasmas and intense beams     

Dust-acoustic solitons in quantum plasma with kappa-distributed ions

Arbitrary amplitude dust-acoustic (DA) solitary waves in an unmagnetized and collisionless quantum dusty plasma comprising cold dust particles, kappa (κ)-distributed ions and degenerate electrons are investigated. The influence of suprathermality and quantum effects on the linear dispersion relation of DA waves is investigated. Then, the effect of κ-distributed ions and degenerate electrons on the existence domain of solitons is discussed in the space of (M, f). The comparison of the existence domain for higher and lower values of κ shows that suprathermality results in propagation of solitons with lower Mach number, and the quantum effects, lead to a higher values of Mach number. The existence domain of solitons for nondegenerate κ-distributed electrons is considered for comparison with effect of degenerate electrons. Also, we found that the Sagdeev potential well becomes deeper and wider as ε _F???i decreases, as for lower κ values, the influence of quantum effects on the Sagdeev pseudopotential profile is smaller.     

Kelvin-Helmholtz instability in a plasma with negative ions

A dispersion relation for low-frequency electrostatic modes in a plasma with negative ions is derived for the case in which a velocity shear Kelvin-Helmholtz instability exists in the positive ion flow along the magnetic field. It is found that the negative ions have, generally, a destabilizing effect, as seen previously for ion-acoustic and electrostatic ion-cyclotron waves. The influence of the negative-ion-to-positive-ion mass mass ratio on the stability is also examined     

Solitons in a relativistic plasma with negative ions

The interaction of the nonlinearity and the dispersiveness causing the solitary waves is studied in a relativistic plasma with negative ions through the derivation of a nonlinear partial-differential equation known as the Korteweg-de Vries equation. The negative ions play a salient part in the existence and behavior of the solitons and could be of interest in laboratory plasmas. First, the observations are made in a nonisothermal plasma, and later the reduction to the nonisothermality of the plasma shows entirely different characteristics as compared to the solitons in the isothermal plasmas. Comparison with the various solitons is emphasized     

Reflection of modified Korteweg-de Vries solitons in a plasmahaving negative ions

The variable coefficient modified Korteweg-de Vries (mKdV) equations for incident and reflected solitons are derived and solved to study the reflection of compressive and rarefactive ion acoustic solitons at the critical density in an inhomogeneous negative ion plasma. The polarity of the incident compressive and rarefactive solitons is not altered during the reflection process. Increasing the density gradient reinforces the reflection of both compressive and rarefactive mKdV solitons, whereas enhancement of the unperturbed plasma density weakens the reflection     

Wake potential with mobile positive/negative ions in multicomponent dusty plasmas

We employ the test charge approach to calculate the electrostatic potential for a test charge in a multicomponent dusty plasma, whose constituents are the Boltzmann distributed electrons, mobile positive and negative ions, and immobile positive/negative charged dust particles. By using the modified dielectric constant of the dust-ion-acoustic (DIA) waves, the Debye screening and wake potentials are obtained. It is found that the presence of mobile negative ions significantly modify the DIA speed and the wake potential. The present results are relevant to polar mesosphere and microelectronic in the context of charged particle attraction and repulsion.     

Sheath characteristics in multi-component plasma with negative ions

Properties of steady state ion sheath formed in front of a negatively biased metal plate under the influence of negative ions have been investigated in collisionless argon/SF₆ plasma. This experiment is carried out at a fixed discharge voltage and fixed filament heating power. In this experiment, the decrement in plasma pre-sheath potential drop as well as positive ion drift velocity toward the plate is experimentally recorded in the presence of negative ions. It is also found that the plasma positive ion density and plasma electron temperature decrease in the presence of negative ions. These factors attribute to the decrease of ion current toward the plate. Hence the usual ion sheath expands. Article presented at the International Conference on the Frontiers of Plasma Physics and Technology, 9–14 December 2002, Bangalore, India.     

Ion-acoustic wave in relativistic nonisothermal plasma with negative ions

We study solitary wave formation in a nonisothermal plasma with negative ions. When the ions are considered to be relativistic. The variations of the amplitude, width, and the phase velocity are obtained explicitly with respect to the ratio of the ion densities and the streaming velocity.     

The role of negative ions in experiments with complex plasma

The influence of negative ions on the state of an rf gas-discharge dusty (complex) plasma containing electronegative gaseous impurities was investigated. A simple one-dimensional argon-discharge model allowing for the impurity-induced plasmachemical reactions was taken as an example to show that the addition of even a minor amount of molecular oxygen changes appreciably the plasma composition and plasma transport properties, as well as the microparticle charges. In turn, these changes have a strong effect on the microparticle force balance and on the formation of various dusty structures in the discharge.     

Separation of ions on the front of a shock wave in a multicomponent plasma

The structure of a shock wave propagating in a plasma with two types of ions has been studied within the model of multifluid hydrodynamics based on the 13-moment system of Grad’s equations. Although the averaged dynamics of the shock front coincides with the single-component variant of the average-ion model, its structure is different at a noticeable difference between charge-to-mass ratios of different ions, demonstrating their separation on the shock front. For the problem of inertial confinement fusion, the range of parameters for which such a separation is important, as well as physical processes determining the two-component structure of the shock front, has been established.     

KdV-type solitons in multicomponent relativistic plasmas

A reductive perturbation technique is used to derive modified Korteweg-deVries (KdV) equations with different degrees of isothermality in a plasma, in order to study the existence and behavior of ion-acoustic solitary wave propagation ingoing in a multicomponent relativistic plasma. The solutions of the KdV equations are obtained. It is found that the presence of multiple ions and electrons in the relativistic plasma causes a different behavior regarding the formation of solitons in plasmas.     

Cylindrical and spherical electron-acoustic Gardner solitons and double layers in a two-electron-temperature plasma with nonthermal ions

Cylindrical and spherical Gardner solitons (GSs) and double layers (DLs) in a two-electron-temperature plasma system (containing cold electrons, hot electrons obeying a Boltzmann distribution, and hot ions obeying a nonthermal distribution) are studied by employing the reductive perturbation method. The modified Gardner equation describing the nonlinear propagation of the electron-acoustic (EA) waves is derived, and its nonplanar GS and DL solutions are numerically analyzed. The parametric regimes for the existence of GSs, which are associated with both positive and negative potential, and DLs which are associated with positive potential, are obtained. The basic features of nonplanar EA GSs, and DLs, which are found to be different from planar ones, are also identified. The implications of our results in space and laboratory plasmas are briefly discussed.     

Observation of diverging cylindrical solitons excited with a probe

Ion acoustic solitons are excited using a large cylindrical probe enclosed in an insulator. Their speed is smaller than that of plane or converging solitons and their width increases as they travel away from the probe.     

Ion acoustic solitons in a relativistic warm plasma with densitygradient

Modified Korteweg-deVries equation (mK-dV), which governs the behavior of ion acoustic solitons in a relativistic warm plasma with density gradient, is derived. The electron inertia is also taken into account which is important when the streaming ions are present in the plasma. A solution of the mK-dV equation is obtained for the constant density gradient. When the ion acoustic soliton propagates into the lower plasma density region, its amplitude and energy increase, but the width decreases; the same is the case for the stronger density gradients     

Observation of the emission of positive and negative ions in triple and quadruple collisions in a solid under bombardment with keV argon ions

Particles that leave a solid as a result of several consecutive binary collisions are detected in the energy spectra of positive and negative ions emitted upon the irradiation of C, Si, Ge, and In targets with 2-to 5-keV Ar⁺ ions. The appearance of a spectral structure due to the sequence of three and four collisions in the solid can be attributed to the selective role of the surface, which is similar to the channeling effect in crystals.     

Oblique magneto-acoustic solitons in a rotating plasma

Weakly nonlinear magneto-acoustic waves propagating at an arbitrary angle to the external magnetic field in a rotating plasma are considered. A model equation (Ostrovsky's equation with positive dispersion) is derived from a set of basic magneto-hydrodynamic equations. Stationary solutions of this equation are obtained numerically and analyzed in detail theoretically. These include solitary-type solutions (solitons with monotonic and oscillating tails), complex multisolitons (bound states of coupled single solitons), as well as periodic waves. We emphasize that the positive dispersion, in contrast to the negative one, gives rise to solitary waves within the framework of Ostrovsky's equation.     

Parameters of a multicomponent laser-induced plasma

Technical Physics - We report on the results of analysis of parameters of a laser-induced plasma, which were obtained using emission diagnostics of a laser torch plasma from a CuInSe2...