Effect Of Ion Temperature Research Articles

Effect of screening on spectroscopic properties of Li-like ions in a plasma environment

This work presents accurate {\it ab initio} investigations of various spectroscopic properties of a few Li-like ions in presence of a plasma environment within the Debye screening potential. The coupled-cluster theory in the relativistic framework has been employed to compute ionization potentials, excitation energies, electric dipole oscillator strengths, and electric quadrupole transition probabilities of Li-like C$^{3+}$, N$^{4+}$, and O$^{5+}$ ions. The unretarded Breit interaction has been implemented to increase the accuracy of the calculations. The effects of ion density and temperature on the ionization potentials, excitation energies, electric dipole oscillator strengths, and electric quadrupole transition probabilities have been investigated in the plasma environment. It is found that the plasma screening leads to a sharp decrease in the ionization potential as the screening strength increases. With increasing strength, the oscillator strengths associated with 2$s ^{2}S_{1/2}$$\rightarrow2 p ^{2}P_{1/2, 3/2}$ transitions increase, whereas the transition probabilities associated with 3$d ^2D_{3/2, 5/2}$$\rightarrow2 s ^2S_{1/2}$ transitions decrease.

Effect of ion temperature on ion-acoustic solitary waves in a magnetized plasma in presence of superthermal electrons

Obliquely propagating ion-acoustic soliatry waves are examined in a magnetized plasma composed of kappa distributed electrons and fluid ions with finite temperature. The Sagdeev potential approach is used to study the properties of finite amplitude solitary waves. Using a quasi-neutrality condition, it is possible to reduce the set of equations to a single equation (energy integral equation), which describes the evolution of ion-acoustic solitary waves in magnetized plasmas. The temperature of warm ions affects the speed, amplitude, width, and pulse duration of solitons. Both the critical and the upper Mach numbers are increased by an increase in the ion temperature. The ion-acoustic soliton amplitude increases with the increase in superthermality of electrons. For auroral plasma parameters, the model predicts the soliton speed, amplitude, width, and pulse duration, respectively, to be in the range of (28.7–31.8) km/s, (0.18–20.1) mV/m; (590–167) m, and (20.5–5.25) ms, which are in good agreement with Viking observations.

Effect of ion temperature on ion-acoustic solitary waves in a plasma with a q-nonextensive electron velocity distribution

The effect of ion temperature on the existence of arbitrary amplitude ion-acoustic solitary waves is studied in a two component plasma in presence of a q-nonextensive velocity distributed electrons by using Sagdeev's pseudo potential technique. The range of relevent parameters for which solitons may exist is discussed. It is observed that both q, the nonextensive parameter and the ion temperature σ, play significant roles in the formation and existence of solitons.

The positive ion temperature effect in magnetized electronegative plasma sheath with two species of positive ions

The properties of a magnetized multi-component (two species of positive ions, negative ions and electrons) plasma sheath with finite positive ion temperature are studied. By using three fluid hydrodynamic model and some dimensionless variables, the ion (both lighter and heavier positive ions, and negative ions) densities, the ion (only for positive ions) velocities, and electric potential inside the sheath are investigated. In addition, the absence and presence of magnetic field and the orientation of magnetic field are considered. It is noticed that, with increase of positive ion temperature, the lighter positive ion density peaks increase only at the sheath edge and shift towards the sheath edge for both absence and presence of magnetic field. For heavier positive ions, in the absence of magnetic field, the density peaks increase at the sheath edge. But in the presence of magnetic field, the density fluctuations increase at the sheath edge. For both the cases, the density peaks shift towards the sheath edge.

Magnetic island evolution in hot ion plasmas

Effects of finite ion temperature on magnetic island evolution are studied by means of numerical simulations of a reduced set of two-fluid equations which include ion as well as electron diamagnetism in slab geometry. The polarization current is found to be almost an order of magnitude larger in hot than in cold ion plasmas, due to the strong shear of ion velocity around the separatrix of the magnetic islands. As a function of the island width, the propagation speed decreases from the electron drift velocity (for islands thinner than the Larmor radius) to values close to the guiding-center velocity (for islands of order 10 times the Larmor radius). In the latter regime, the polarization current is destabilizing (i.e., it drives magnetic island growth). This is in contrast to cold ion plasmas, where the polarization current is generally found to have a healing effect on freely propagating magnetic island.

Cylindrical or spherical dust-ion acoustic soliton in an adiabatic dusty plasma with electrons following a q-nonextensive distribution

Using the reductive perturbation technique, a cylindrical and (or) spherical Korteweg – de Vries (KdV) equation is derived for a dust-ion acoustic solitary wave (DIASW) in an unmagnetized dusty plasma, whose constituents are adiabatic ion fluid, nonextensive electrons, and negatively charged static dust particles. The solution of the modified KdV equation in nonplanar geometry is numerically analyzed. The change of the DIASW structure due to the effect of the geometry, nonextensive parameter, dust density, and ion temperature is investigated by numerical calculation of the cylindrical and (or) spherical KdV equation. It is found that both compressive and rarefactive type DIA waves are obtained depending on the plasma parameter.

Scaling and aggregation kinetics determination of calcium carbonate using inline technique

The deposition of calcium carbonate on solid surfaces under certain conditions poses a serious problem to many industries. This scaling may lead to a lowering of heat transfer efficiency, increased energy consumption and unscheduled equipment shutdown. In order to prevent potential scaling problems it is, therefore, important to understand the mechanism of calcium carbonate deposition.This paper is an extension of previous work on the understanding of calcium carbonate crystal formation, aggregation and deposition. It describes the application of an inline technique based on Focused Beam Reflectance Measurement (FBRM) to determine the rate of calcium carbonate formation. FBRM provides a real time measurement of the dimension and number of crystals and this technique has proven to be a sensitive method with which to monitor the initial stages of the scale formation process. The effect of initial calcium ion concentration and temperature on the scaling rate has been determined, and these inline results validated from complementary offline scale measurement techniques.

Effect of finite ion temperature on arbitrary amplitude dust ion acoustic solitary waves in quantum plasma

Effect of finite ion temperature on the formation of arbitrary amplitude dust ion acoustic solitary waves in unmagnetized quantum plasma is investigated using the Sagdeev’s potential approach. It is found that the ion temperature significantly affects the region of existence and formation of dust ion acoustic solitary waves in quantum plasma. The investigation shows that the solitary structure ceases to exist when the different parameters, viz., temperature, dust density and the soliton velocity cross certain critical values. It is also found that the presence of ion temperature increases the range of wave Mach number from subsonic to supersonic regime both in presence or absence of dust particle density in unmagnetized quantum plasma.

Ion Acoustic Solitary Waves and Double-Layers in a Plasma with Nonthermal Electrons and Positrons

The effects of nonthermal electron distribution and ion temperature are incorporated in the investigation of nonlinear ion acoustic waves in a pair-ion plasma. Sagdeev pseudo- potential method which takes into account the full nonlinearity of the plasma equations is used to study solitary wave solutions. It is shown that there is a region in parameter space where both negative and positive potential can coexist. For the fixed value of nonthermal electrons, it is found that the effect of increase in ion temperature is to reduce the range of co-existence of compressive and rarefactive solitons. Particular concentration of nonthermal electrons results in disappearance of rarefactive solitons while the decrease in ion temperature, at this concentration restores the lost rarefactive solitons. Also, the existence of rarefactive double layers solitons is investigated. It is found that the nonthermal electrons and ion-temperature play significant role in determining the region of the existence of double layers.

Numerical investigation of the ion temperature effect in magnetized plasma sheath with two species of positive ions

The effect of ion temperature, magnitude of magnetic field and its orientation on a magnetized plasma sheath consisting of electrons and two species of positive ions are investigated. Using three-fluid hydrodynamic model and some dimensionless variables, the dimensionless equations are obtained and solved numerically. It is found that with the increase of the ion temperature and magnetic field strength there is a significant change in ion densities and energies in the sheath. It is also noticed that increase of magnetic field angle enhances the ion density near the sheath edge for a constant ion temperature. With increase in ion temperature and magnetic field angle, the lighter ion density near the sheath edge enhances and reverses for the heavier ion species.

Optimization of a quadrupole ion storage trap as a source for time‐of‐flight mass spectrometry

Designs of a quadrupole ion trap (QIT) as a source for time-of-flight (TOF) mass spectrometry are evaluated for mass resolution, ion trapping, and laser activation of trapped ions. Comparisons are made with the standard hyperbolic electrode ion trap geometry for TOF mass analysis in both linear and reflectron modes. A parallel-plate design for the QIT is found to give significantly improved TOF mass spectrometer performance. Effects of ion temperature, trapped ion cloud size, mass, and extraction field on mass resolution are investigated in detail by simulation of the TOF peak profiles. Mass resolution (m/Δm) values of several thousand are predicted even at room temperature with moderate extraction fields for the optimized design. The optimized design also allows larger radial ion collection size compared with the hyperbolic ion trap, without compromising the mass resolution. The proposed design of the QIT also improves the ion-laser interaction volume and photon collection efficiency for fluorescence measurements on trapped ions.

Ion front in an expanding collisionless plasma

The plasma motion near the ion front in an expanding collisionless plasma is studied. The boundary of quasineutrality, the range of application of the analytical quasineutral solution and the features of the space charge region are considered. Analytical solutions in combination with computer simulations give the quantity distributions in space and time in the analytical forms. The ion temperature effect and the electron cloud evolution are discussed.

Combined Effect of Ion Temperature and Magnetic Field on Collisionless Sheath Structure

A steady state two-fluid model has been used to study the characteristics of the collisionless plasma sheath in the presence of an external magnetic field and by taking into account both the ion temperature and the ion drift velocity at the sheath edge. The number and momentum equations of ions, the Boltzmann distribution of electrons and Poisson equations are solved numerically. The dependence of the Bohm magnetized sheath criterion to ion temperature is examined. It is shown that the ion temperature has significant effects on the sheath characteristics such as ion velocity, charged particles densities and electric potential. In the specific orientations of the magnetic field, it is found that by increasing the ion temperature, the ions do not achieve energy and the kinetic energy of the ions in the depth direction reaches the specific value at bigger distance from the plasma-sheath boundary.

Ion temperature effects on the occurrence scattering time in dusty plasmas

The effects of ion temperature on the occurrence scattering time for the electron-dust grain collision are investigated in dusty plasmas. The Eikonal analysis is applied to obtain the scattering amplitude and occurrence scattering time for the electron-dust collision. It is found that the occurrence scattering time represents the oscillatory behavior. It is also found that the amplitude and oscillation interval of the occurrence scattering are enhanced with increasing collision energy. It is found that the ion temperature effect suppresses the occurrence scattering time in three-component dusty plasmas. It is also found that the density effect reduces the occurrence scattering time.

Effects of heavy ion temperature on low-frequency kinetic Alfvén waves

Heavy ion-electron (or proton) temperature ratio varies in a wide range in the solar and space environment. In this paper, proton and heavy ion temperatures are included in a three-fluid plasma model. For the specified parameters, low-frequency (≪ heavy ion gyrofrequency) kinetic Alfvén waves (KAWs) with sub- and super-Alfvénic speeds are found to coexist in the same plasma environment. Our results show that the temperature ratio of heavy ions to electrons can considerably affect the dispersion, propagation, and electromagnetic polarizations of the KAWs. In particular, the temperature ratio can increase the ratio of parallel to perpendicular electric fields and the normalized electric to magnetic field ratio, the variations of which are greatly different in regions with a high heavy ion temperature and with a low one. The results may help to understand the physical mechanism of some energization processes of heavy ions in the solar and space plasma environment. Effects of the ratio of electron thermal to Alfvén speeds and the heavy ion abundance on these parameters are also discussed.

Influence of arbitrarily charged dust and trapped electrons on propagation of localized dust ion-acoustic waves

A theoretical investigation is developed to study the existence, formation and basic properties of arbitrary amplitude dust ion-acoustic solitary potentials in a dusty plasma consisting of warm ions, trapped electrons and immobile negative (positive) dust particles. It is found a definite interval for the Mach number for which solitary waves exist and depend sensitively on the ion temperature and negative (positive) dust concentration. In addition, the effects of ion temperature, two oppositely charged dust species and resonant electrons on the shape of the solitary waves are also investigated extensively. For both cases of negative and positive dust grains, the effect of ion temperature is found to be destructive for the formation of localized structures. Further, the amplitude of the solitary structures decreases (increases) with the increase in the negative (positive) dust concentration.

The controlling effect of ion temperature on EMIC wave excitation and scattering

[1] The dispersion relation of parallel propagating EMIC waves is investigated in a magnetized homogeneous plasma consisting of hot H+ and He+ ions. We demonstrate that the hot plasma effects associated with He+ and H+ significantly modify the cold plasma dispersion relation, especially near ΩHe+. For plasmas with a sufficiently small fraction of warm He+ and a sufficiently dense, hot and anisotropic H+ population, the cold plasma stop band above ΩHe+ may vanish, and waves near ΩHe+ may be unstable. The maximum wavenumber for unstable L-mode waves due to the hot plasma modification is used to identify the plasma conditions required for EMIC wave scattering of MeV electrons. We conclude that relatively extreme conditions (ωpe/|Ωe| > ∼25, and H+ anisotropy >1) are required for resonance with electrons near 1 MeV, which limits such scattering only to the region just inside the plasmasphere or storm time plumes.

Dust ion-acoustic solitary waves in a dusty plasma with arbitrarily charged dust and flat-trapped electrons

The properties of arbitrary amplitude dust ion-acoustic (DIA) solitary waves (SWs) in a dusty plasma containing warm adiabatic ions, electrons following flat-topped velocity distribution, and arbitrarily (positively or negatively) charged immobile dust is studied by the pseudo-potential approach. The effects of ion temperature, resonant electrons, and dust number density are found to significantly modify the basic features of the DIA-SWs as well modify the parametric regime for the existence of compressive DIA-SWs. The pseudo-potential for small but finite amplitude limit is also analytically analyzed.

Effect of Negative Ion Parameters on Sheath Formation Criterion in Electronegative Plasmas

Using a fluid model for three types of particles, the plasma-sheath formation criterion has been analyzed in collisional electronegative plasma, and the effects of the negative ion temperature and density are examined on the positive ion transition velocity. It is shown that in the collisional sheath, there will be an allowable interval for the positive ion velocity between two upper and lower limits as the plasma-sheath formation criterion; by increasing the mean temperature of the negative charge carriers, this velocity interval decreases. To confirm the correction of the allowable interval, the plasma sheath equations are numerically solved, and the negative ion temperature effect for example, is examined on the sheath formation.

Numerical investigation of the ion temperature effects on magnetized DC plasma sheath

The properties of a magnetized plasma sheath with finite ion temperature is considered. The effects of the external magnetic field and the ion temperature on the sheath parameters are examined. It is found that by increasing the ion temperature and the magnetic field strength there is an increase in the positive space charge and the ion energy and a decrease in the sheath thickness. Furthermore, the ion temperature has a direct effect on the ion flux toward the wall.