Effect Of Different Plasma Parameters Research Articles

Head-on collision of ion-acoustic (modified) Korteweg–de Vries solitons in Saturn's magnetosphere plasmas with two temperature superthermal electrons

In view of the recent observations by plasma science-spacecraft-voyager and Cassini plasma spectrometer of Saturn's magnetosphere, the interaction between two counter-propagating ion-acoustic (IA) solitons is studied in an unmagnetized plasma consisting of warm adiabatic ions in addition to hot and cold electrons following kappa distribution. The head-on collision of the IA solitons is investigated using the extended Poincare–Lighthill–Kuo technique. Since this model supports both compressive and rarefactive solitons, therefore, the soliton collisions for both Korteweg–de Vries (KdV) and the modified KdV (mKdV) equations are investigated. The corresponding phase shifts after the collision for both these equations are also derived and examined. Furthermore, the effects of different plasma parameters (corresponding to Saturn's magnetosphere), including superthermality, density, and temperature on the colliding soliton profiles and their phase shifts, are examined. It is concluded that the phase shift is smaller when both hot and cold electrons are Maxwellian by comparison with the superthermal case.

Bifurcation analysis of ion-acoustic superperiodic waves in ultra-relativistic dense plasma

Abstract Bifurcation analysis of ion-acoustic solitary, periodic and superperiodic waves in ultra-relativistic quantum degenerate electron-positron-ion plasma is investigated based on Sagdeev’s pseudopotential approach. The phase plane plots for the superperiodic, periodic, and homoclinic trajectories for the dynamical system are developed. Rarefactive and compressive solitary waves are demonstrated to exist. The influence of plasma parameters on the characteristic properties of the periodic and superperiodic waves is studied. Also, the effect of different plasma parameters on the Sagdeev pseudopotential profile is investigated. The results of this study may be used to shed light on the fundamental properties of nonlinear waves in dense objects (e.g., white dwarfs and neutron stars). These results also may be beneficial in describing laboratory plasma (e.g., interaction experiments of intense laser-solid matter), and plasma applications such as microelectronic devices.

Three-Dimensional Cylindrical Dust-Acoustic Solitary Pulses in Warm Nonthermal Plasma

The nonlinear propagation of 3-D cylindrical dust-acoustic (DA) solitary waves in an unmagnetized dusty plasma system consisting of mobile adiabatic positively charged dust (PCD) grains, nonthermal ions, and electrons is investigated. The basic properties of nonlinear DA solitary structures, which exist in such a warm dusty plasma medium, are studied. The ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$3+1$</tex-math> </inline-formula> )-dimensional cylindrical Kadomstev–Petviashvili equation (cKPE) (also known as cylindrical Korteweg-de Vries (KdV) equation) is derived by using the reductive perturbation method (RPM). The possible region of the formation of solitons is shown. The effects of different plasma parameters (viz., the nonthermal parameter, the dust-to-ion temperature ratio, the ion-to-dust number density ratio, etc.) on the characteristics of the DA solitary waves are studied, and also the graphical representation of the cylindrical DA solitary structures is presented. The polarity of DA solitary waves changes with different plasma parameters (viz., the ion-to-electron temperature ratio, the nonthermality of ions and electrons, the ion-to-dust number density, etc.). These results may improve our understanding of DA solitary structures in space and laboratory plasma devices where nonthermal dusty plasma occurs.

Variable dust charge generates a special type of nonlinear structures through modified Gardner equations

AbstractNonlinear damped modified Gardner equation is derived from the dust hydrodynamic model in dusty plasma, which is collisional, unmagnetized, and has two temperature ions. An extended version of the reductive perturbation technique (RPT) is used to derive the said equations. Approximate analytical solitary wave solution is obtained for compositional parameters near the critical composition. It is found that various nonlinear structures like super periodic, superhomoclinic, and special types of nonlinear structures are emerging while an investigation is done through the system of first‐order differential equations. The effects of different plasma parameters like collisions and dust charge variables on the wave structures have been noticed. In the circumstances of nebulas, interstellar clouds, planetary magnetospheres, and cometary environments recognized by astrophysicists, Voyager spacecraft observation on the fine structure of Saturn's rings, semiconductor devices, it has been investigated that the dust charge variable modifies the super nonlinear structures significantly.

Dust ion acoustic solitons and double layers in a dusty plasma with adiabatic positive dust, adiabatic positive ion species, and Cairns-distributed electrons

The propagation of dust ion acoustic solitary waves and double layers is studied in a dusty plasma with heavy adiabatic positively charged dust grains and lighter adiabatic positive ions with Cairns-distributed electrons using the arbitrary amplitude Sagdeev pseudopotential approach. The analysis of the Sagdeev pseudopotential shows that this plasma model supports the propagation of positive solitons limited by the occurrence of the ion sonic point and negative solitons limited by the occurrence of double layers. Solitons of both polarities coexist for a range of some plasma parameters. We have shown that at a critical dust-to-ion density ratio, f, at which the third derivative of the Sagdeev pseudopotential vanishes, positive and negative solitons coexist without a soliton with finite amplitude at the acoustic speed, contrary to an earlier study. This suggests that the existence of a soliton with finite amplitude at the acoustic speed is not always a pre-requisite for the coexistence of nonlinear structures of both polarities. Positive and negative solitons coexist when the electrons are strongly nonthermal, with moderate ion thermal effects. Increasing ion thermal effect shifts the coexistence region to lower values of f, and when the ion thermal effects become important, negative solitons disappear and only positive solitons survive. The effects of different plasma parameters on the characteristics of the nonlinear structures have also been discussed in detail.

Oblique propagation of nonlinear solitary structures in electron positron ion plasmas under the influence of quantizing magnetic field

We study the propagation properties of the small amplitude nonlinear ion acoustic solitary structure in dense electron-position-ion (e-p-i) plasmas. We consider an oblique propagation of the wave with respect to the applied magnetic field. The reductive perturbation technique is employed to derive the nonlinear Zakharov-Kuznetsov (ZK) equation which describes the propagation characteristics of the ion acoustic solitary wave structures in e-p-i plasmas. The effects of different plasma parameters including the positron concentration have been invesigated. These findings may be helpful to understand the small amplitude nonlinear solitary structures that exist in the dense astrophysical environments and in the intense-laser plasma interactions.

On a semiclassical model for damped dust ion-acoustic solitons with analysis of quantum electron exchange-correlation potential

The semiclassical hydrodynamic model is used to study the effect of electron exchange-correlation potential, quantum Bohm term, and degenerate pressure on the dynamics of dust ion acoustic waves by following the two-fluid theory in collisional, unmagnetized dusty plasma. For linear analysis, the dispersion relation modified by the exchange-correlation coefficient is derived. For nonlinear analysis, the standard perturbative approach is used to derive a deformed Korteweg–deVries equation with a linear damping term for finite amplitude waves. The analytical and numerical investigations in the presence of low collisional frequencies reveal the existence of compressive dissipative solitons. Considering the dense astrophysical objects, the dissipative compressive solitons are numerically investigated with the effect of different plasma parameters including collisions and exchange-correlation potential.

Experimental and Numerical Investigations of Plasma Ignition Characteristics in Gas Turbine Combustors

Reliable ignition is critical for improving the operating performance of modern combustor and gas turbines. As an alternative to the traditional spark discharge ignition, plasma assisted ignition has attracted more interest and been shown to be more effective in increasing ignition probability, accelerating kernel growth, and decreasing ignition delay time. In this paper, the operating characteristic of a typical self-designed plasma ignition system is investigated. Based on the optical experiment, the plasma jet flow feature during discharge is analyzed. Then, a detailed numerical study is carried out to investigate the effects of different plasma parameters on ignition enhancement of a one can-annular combustor used in gas turbines. The results show that plasma indeed has a good ability to expand the ignition limit and decrease the minimum ignition energy. For the studied plasma ignitor, the initial discharge kernel is not a sphere but a jet flow cone with a length of about 30 mm. Besides, the numerical comparisons indicate that the additions of plasma active species and the increases of initial energy, plasma jet flow length and discharge frequency can benefit the acceleration of kernel growth and flame propagation via thermal, kinetic and transport pathways. The present study may provide a suitable understanding of plasma assisted ignition in gas turbines and a meaningful reference to develop high performance ignition systems.

Higher harmonic instability of electrostatic ion cyclotron waves

Electrostatic ion cyclotron instability pertaining to the higher harmonics of proton and helium cyclotron modes is investigated in three-component magnetised plasma consisting of beam electrons, protons and doubly charged helium ions. The effect of different plasma parameters, namely, angle of propagation, number density and temperature of helium ions and electron beam speed, has been studied on the growth of proton and helium cyclotron harmonics. It is found that an increase in angle of propagation leads to the excitation of fewer harmonics of proton cyclotron waves with decreased growth rates and higher number of helium harmonics with decreased growth rates. Also, largely odd helium harmonics are excited, except for one particular case where the second harmonic also becomes unstable. The number density and temperature of ions have significant effect on the helium cyclotron instability compared to the proton cyclotron instability. Further, as the speed of electron beam is increased, the peak growth rate increases. Our results are relevant to laboratory and space plasmas where field-aligned currents exist.

Spectroscopic studies to investigate the effect of different plasma parameters on the geometrical and electronic structure of graphene

Spectroscopic studies were carried out on monolayer, trilayer, and few layers of graphene sheets to investigate the effect of plasma parameters such as the electric current, substrate temperature, and the effect of the acetylene and hydrogen gases mixture ratios on the geometrical structure, electronic and optical properties of the synthesized films. Single-, triple- and few-layer graphene sheets were deposited on copper substrates by using self-assembled direct current plasma enhanced chemical vapor deposition (DC-PECVD) reactor. The deposited graphene samples were characterized by high resolution transmission electron microscope (HRTEM), X-ray diffraction (XRD), Raman and photoluminescence (PL) spectroscopy. The results demonstrated that the number of graphene layers as well as the defects ratio of sp2 hybridization size domain have been changed notably with changing the preparation conditions, where a single layer graphene sheet was obtained at preparation conditions of H2:C2H2 ratio of 100:4 sccm, plasma electric current of 130 mA, and substrate temperature of 750 °C. The recorded PL spectrum for the single layer graphene shows one weak and broad band at 348 nm. We have recorded an exponential relation between the blue shift of the PL peak and the changing in the size domain of the sp2 hybridization.

Debye length and electric potential in magnetized nonextensive plasma

The modification of Debye length and electric potential due to the combined effects of nonextensive distribution of particles in an electron-ion plasma system, ratio of electron temperature to ion temperature, and external static magnetic field is theoretically examined. The expression for the modified Debye length is derived by solving Poisson's equation. The effects of different plasma parameters (viz., nonextensive parameters for electron and ion species, ratio of electron temperature to ion temperature, and external static magnetic field) on the modified expressions for the Debye length and electric potential are pinpointed.

EMEC instability based on kappa-Maxwellian distributed trapped electrons in auroral plasma

In space plasmas, particle distributions are often observed having high energy tails and are well fitted by kappa distribution function. However, in auroral region electrons are expected to be accelerated mainly along the magnetic field lines and one may expect Maxwellian behaviour in perpendicular direction. Therefore, in the present study propagation characteristics of electromagnetic electron cyclotron (EMEC) waves is studied by employing kappa-Maxwellian distribution function for energetic trapped electrons in auroral region. Real frequency and the growth rate expressions have been solved numerically for kappa-Maxwellian plasma and then analyzed by considering the effect of different plasma parameters for wide range of auroral altitudes. The numerical results obtained show that growth rate increases with the increase in ratio \({\omega_{pe}} / {\varOmega_{e}}\), plasma beta, temperature anisotropy \({T_{\bot}} / {T_{\parallel}}\) and trapped electron drift speed but decreases when superthermal electron population increases.

Effect of inductively coupled plasma and plasma parameters on magnetron sputtered Al-Doped ZnO highly conductive thin films at low-temperature

This work reports a detailed study on the low-temperature synthesis of highly conductive transparent Al-doped ZnO films using magnetron sputtering with the support of an inductively coupled plasma (ICP) source. It is seen that the ICP source is quite useful to provide significant ionization and excitation reactions conducive to the film growth in the magnetron plasmas. The effect of different plasma parameters on the film properties is investigated in detail. Data reveal that tailoring of vacancies of oxygen and extrinsic dopants (Al0 and Al3+) and plasma chemistry in high electron density discharges could provide simultaneous enrichment in the carriers' mobility and concentration. A plausible mechanism involving the correlation between the carrier mobility and the electron-hole interaction is realized for degenerately doped wide bandgap semiconductors.

Study on the attenuation characteristic of terahertz wave through a non-uniform magnetized plasma

In this paper, the interaction between terahertz wave and a non-uniform magnetized plasma slab is investigated. The electric field distribution in non-uniform plasma is presented and used to calculate the attenuation of the electromagnetic wave through plasma. Several types of electron density profiles are proposed and discussed. Effects of different plasma parameters (electron density, collision frequency, plasma thickness) and magnetic field amplitudes on THz wave attenuation characteristic are investigated. The transmission ratios at several typical THz signal frequencies in both unmagnetized and magnetized plasma are presented as well. These simulation results are meaningful for the flight communication.

Expansion of Titan atmosphere

Self-similar plasma expansion approach is used to solve a plasma model based on the losing phenomenon of Titan atmospheric composition. To this purpose, a set of hydrodynamic fluid equations describing a plasma consisting of two positive ions with different masses and isothermal electrons is used. With the aid of self-similar transformation, numerical solution of the fluid equations has been performed to examine the density, velocity, and potential profiles. The effects of different plasma parameters, i.e., density and temperature ratios, are studied on the expanding plasma profiles. The present investigation could be useful to recognize the ionized particles escaping from Titan atmosphere.

The effect of exchange-correlation coefficient in quantum semiconductor plasma in presence of electron-phonon collision frequency

The influence of exchange-correlation potential, quantum Bohm term, and degenerate pressure on the nature of solitary waves in a quantum semiconductor plasma is investigated. It is found that an amplitude and a width of the solitary waves change with variation of different parameters for different semiconductors. A deformed Korteweg-de Vries equation is obtained for propagation of nonlinear waves in a quantum semiconductor plasma, and the effects of different plasma parameters on the solution of the equation are also presented.

Arbitrary amplitude solitary waves in an unmagnetized quantum pair-ion plasma

Propagation of arbitrary amplitude solitary waves is investigated in an unmagnetized quantum pair-ion plasma through the usage of Sagdeev pseudopotential approach in the framework of quantum hydrodynamics model. Bohm potential is elucidated to have significant impact on the structure of solitary wave. We would like to demonstrate that the regions of stability for the solitary waves of this quantum plasma system are well determined by studying the phase portrait. Analytical calculations are employed to simplify the basic equations, which are then studied numerically. The numerical analysis of Sagdeev potential for small value of quantum diffraction parameter(H) shows that for such plasma, there exists only compressive solitons. The effect of different plasma parameters on the solitonic structure are traced .

Compressive and rarefactive dust ion-acoustic solitary waves with degenerate electron–positron–ion plasma

The nonlinear propagation of dust ion-acoustic (DIA) waves in a unmagnetized collisionless degenerate dense plasma (containing degenerate electron and positron, and classical ion fluids) has been theoretically investigated. The K-dV equation has been derived by employing the reductive perturbation method and by taking into account the effect of different plasma parameters in plasma fluid. The stationary solitary wave solution of K-dV equation is obtained, and numerically analyzed to identify the basic properties of DIA solitary structures. It has been shown that depending on plasma parametric values, the degenerate plasma under consideration supports compressive or rarefactive solitary structures. It has been also found that the effect of pressures on electrons, ions, and positrons significantly modify the basic features of solitary waves that are found to exist in such a plasma system. The relevance of our results in astrophysical objects such as white dwarfs and neutron stars, which are of scientific interest, is discussed briefly.

Dust ion acoustic solitary waves in a collisional dusty plasma with dust grains having Gaussian distribution

The influence of dust size distribution on the dust ion acoustic solitary waves in a collisional dusty plasma is investigated. It is found that dust size distribution changes the amplitude and width of a solitary wave. A critical wave number is derived for the existence of purely damping mode. A deformed Korteweg-de Vries (dKdV) equation is obtained for the propagation of weakly nonlinear dust ion acoustic solitary waves and the effect of different plasma parameters on the solution of this equation is also presented.

The Effect of Spectral Index Parameter κ on Obliquely Propagating Solitary Wave Structures in Magneto-Rotating Plasmas

Nonlinear ion-acoustic solitary wave structures in collisionless, non-relativistic, homogenous, magneto-rotating plasma, in which the electron species follow the kappa distribution function, are studied. The Korteweg-de Vries (KdV) equation is derived by using the reductive perturbation method, and the effects of different plasma parameters on the obliquely propagating nonlinear solitary wave structures in the magneto-rotating plasma are presented. It is noticed that the spectral index parameter κ significantly modifies the nonlinear wave structure.