Ion Number Density Research Articles

Influence of scan rate on CV Pattern: Electrical and electrochemical properties of plasticized Methylcellulose: Dextran (MC:Dex) proton conducting polymer electrolytes

Solid polymer electrolytes containing methylcellulose:dextran (MC-DEX), ammonium hexafluorophosphate (NH4PF6), and glycerol have been prepared via the solution cast method. Various techniques have been used to characterize the prepared electrolyte samples. Fourier transform infrared spectroscopy (FTIR) analysis revealed the interaction between polymers and electrolyte components. According to the electrical impedance spectroscopy (EIS), the highest conducting plasticized system achieves a conductivity of 6.71 × 10-4 S cm−1 at ambient temperature. The mobility, number density, and diffusion coefficient of ions were measured using both FTIR and EIS methods, and it was found that their values rise as the amount of glycerol increases. Polarization due to ion migration is responsible for the high value of dielectric parameters. According to transference number measurement (TNM), the transport ion (tion) is 0.92, verifying that the ions are the primary charge carriers. The electrochemical stability window of the maximum conducting plasticized system is 1.58 V, based on linear sweep voltammetry (LSV) analysis. The electrical double-layer capacitor (EDLC) device is fabricated using the highest conducting plasticized system. The cyclic voltammetry (CV) curve is roughly rectangular in shape and with no presence of Faradaic peaks with its specific capacitance of 32.69F/g at 10 mV/s.

Influence of charge carrier density, mobility and diffusivity on conductivity–temperature dependence in polyethylene oxide–based gel polymer electrolytes

Determining the transport properties of charge carriers is essential to understand the factors that affect the conductivity trend of a polymer electrolyte system. In this work, charge carrier transport parameters of polyethylene oxide–based gel polymer electrolytes were estimated from fitting the Nyquist plot with the impedance equation, derived from the equivalent circuit that consists of a resistor in series with a constant phase element. The increase in electrolyte conductivity with temperatures from 303 K to 373 K is attributed to the increase of free ions, n (TPA+ cations and I¯ anions) and not to ionic mobility, μ. The decrease in μ with temperature is associated with the increase in the Stokes drag coefficient due to increase in ion collisions. This work explains how conductivity changes with number density of ions and mobility at various temperatures.

Statistical Study of Small-scale Magnetic Holes in the Upstream Regime of the Martian Bow Shock

Abstract Small-scale magnetic holes (SSMHs) are frequently observed in the solar wind at 1 au, as well as the terrestrial current sheet and magnetosheath. These kinetic-size structures play an important role in energy dissipation and particle transportation. Here, we report the existence of SSMHs in the upstream regime of the Martian bow shock and statistically investigate these SSMHs based on 5 yr observations of the Mars Atmosphere and Volatile EvolutioN spacecraft. A total of 549 SSMHs are found, and their durations and sizes obey the lognormal distribution. The median duration is ∼0.46 s, and the median size is ∼2 ion inertial lengths. We regard an isolated SSMH or a train of SSMHs as a SSMH event. The average occurrence rate of the SSMH events is ∼0.6 event per day. The occurrence rate is much larger in the region belonging to the ion foreshock on average, suggesting that the ion foreshock is an important source of SSMHs. The occurrence of the SSMH events tends to be larger when the ion number density and the interplanetary magnetic field (IMF) strength are larger, indicating that the generation of SSMHs might be associated with ions and the IMF strength. Although their generation mechanism is still unclear, the finding of the link between the occurrence rate of the SSMH events and ion number density, as well as the IMF strength, might provide a clue to further reveal the generation mechanism of SSMHs in the solar wind or planetary foreshock.

Characteristics of Plasticized Lithium Ion Conducting Green Polymer Blend Electrolytes Based on CS: Dextran with High Energy Density and Specific Capacitance.

The solution cast process is used to set up chitosan: dextran-based plasticized solid polymer electrolyte with high specific capacitance (228.62 F/g) at the 1st cycle. Fourier-transform infrared spectroscopy (FTIR) pattern revealed the interaction between polymers and electrolyte components. At ambient temperature, the highest conductive plasticized system (CDLG–3) achieves a maximum conductivity of 4.16 × 10−4 S cm−1. Using both FTIR and electrical impedance spectroscopy (EIS) methods, the mobility, number density, and diffusion coefficient of ions are measured, and they are found to rise as the amount of glycerol increases. Ions are the primary charge carriers, according to transference number measurement (TNM). According to linear sweep voltammetry (LSV), the CDLG–3 system’s electrochemical stability window is 2.2 V. In the preparation of electrical double layer capacitor devices, the CDLG–3 system was used. There are no Faradaic peaks on the cyclic voltammetry (CV) curve, which is virtually rectangular. Beyond the 20th cycle, the power density, energy density, and specific capacitance values from the galvanostatic charge–discharge are practically constant at 480 W/Kg, 8 Wh/Kg, and 60 F g−1, for 180 cycles.

Effect of relativistically degenerate electrons on linear and nonlinear structures in ion temperature gradient driven pure drift mode

Low frequency, electrostatic, pure drift mode is investigated in dense magnetized electron-ion plasma in the presence of relativistically degenerate electrons using quantum magnetohydrodynamic model (QMHD). Ions are considered as warm classical particles. Inhomogeneities in background ion density, ion temperature and external magnetic field are taken into account. In the linear regime, dispersion relation is obtained and plotted for both non-relativistic and ultra-relativistic regimes. Parametric study shows that for both non-relativistic and ultra-relativistic cases, growth rate of the wave increases by increasing, , which is the ratio of background ion temperature to density. In the nonlinear case, solitary solutions are obtained by using the functional variable method. Graphical illustrations are used to show the effect of relativistically degenerate electrons and other parameters like electron and ion number densities, magnetic field and ion temperature on nonlinear structures in both non relativistic and relativistic regimes. This work may be helpful to understand low frequency phenomena in dense inhomogeneous plasmas like neutron stars, white dwarfs and next generation lasers.

Modulational Instability of Ion-Acoustic Waves and Associated Envelope Solitons in a Multi-Component Plasma

A generalized plasma model with inertial warm ions, inertialess iso-thermal electrons, super-thermal electrons and positrons is considered to theoretically investigate the modulational instability (MI) of ion-acoustic waves (IAWs). A standard nonlinear Schrödinger equation is derived by applying the reductive perturbation method. It is observed that the stable domain of the IAWs decreases with ion temperature but increases with electron temperature. It is also found that the stable domain increases by increasing (decreasing) the electron (ion) number density. The present results will be useful in understanding the conditions for MI of IAWs which are relevant to both space and laboratory plasmas.

Obliquely propagating ion‐acoustic shock waves in a degenerate quantum plasma

AbstractA theoretical investigation has been carried out on the propagation of non‐linear ion‐acoustic shock waves (IASHWs) in a magnetized degenerate quantum plasma system composed of inertial non‐relativistic positively charged light and heavy ions, inertialess non‐relativistically or ultra‐relativistically degenerate electrons and positrons. The reductive perturbation method has been employed to derive the Burgers' equation. It has been observed that under consideration, our plasma model supports only positive potential shock structure. It is also found that the amplitude and steepness of the IASHWs have been significantly modified by the variation of ion kinematic viscosity, oblique angle, number density, and charge state of the plasma species. The results of our present investigation will be helpful for understanding the propagation of IASHWs in white dwarfs and neutron stars.

Numerical Evaluation on the Propagation of Non-breakdown Streamer in Natural Ester under Negative Lightning Impulse Voltage via Shadowgraph Imaging

A modified shadowgraph imaging setup equipped with a high-speed camera is utilized to achieve a numerical evaluation of temperature, number densities of molecules, ions and electrons to the refractive-index of negative non-breakdown streamer in rapeseed insulating oil for revealing the dynamics of streamer propagation. The non-breakdown streamer is found reaching fairly high speed of 3.01-4.66 km/s during 0-1.7 μs. The following 10 μs is dominated by streamer propagation with the grayscale decreasing continuously for the entire streamer. The dissipation is identified starting at ca. 11.7 μs in the stem region while the head of streamer remaining further propagation. This is followed by a dissipation expansion from the stem to the head regions. The double-unsaturated triglycerides are evidenced as the main ionization components in the non-breakdown streamer, which aid to identify the temperature variations, instead of electrons, positive ions, or dissociation of molecules, contribute mainly to the refractive index drop of the streamer. The mapping for the temperature distribution of streamer is resultantly possible and provides the insight to ascertain the inhomogeneous migration of electrons the kinetic superiority for the streamer evolution dynamics.

Dynamical Coupling Between the Low‐Latitude Lower Thermosphere and Ionosphere via the Nonmigrating Diurnal Tide as Revealed by Concurrent Satellite Observations and Numerical Modeling

AbstractThe diurnal eastward‐propagating tide with zonal wavenumber 3 (DE3) is an important tidal component due to its ability to effectively couple the ionosphere‐thermosphere with the tropical troposphere. In this work, we present the first results of a prominent zonal wavenumber‐4 (WN4) structure in the low‐latitude ionosphere observed by the Scintillation Observations and Response of The Ionosphere to Electrodynamics (SORTIE) CubeSat mission during May 27–June 5, 2020. Least squares analyses of concurrent in situ ion number density measurements from the SORTIE and the Ionospheric Connection Explorer satellites near 420 and 590 km show this pronounced WN4 to be driven by DE3. Thermosphere Ionosphere Mesosphere Energetics Dynamics Sounding of the Atmosphere using Broad band Emission Radiometry temperatures and Specified‐Dynamics Whole Atmosphere Community Climate Model with thermosphere and ionosphere eXtension output demonstrate that the ionospheric WN4 structure is driven by DE3 propagating from the lower thermosphere.

Two typical collective behaviors of the heavy ions expanding in cold plasma with ambient magnetic field

We have numerically studied the evolution of heavy ions that expand in a cold background plasma at a large scale. Two typical collective behaviors of the heavy ions are identified with the conditions where only the traversing heavy ions' initial total mass is different. Our work has demonstrated that a difference in the initial total mass of the moving heavy ions is able to induce completely different collective behaviors of the plasma. The simulation is performed via the hybrid model in which the ions and electrons are treated as classical particles and mass-less fluids, respectively. Due to the imbalance of the electric and magnetic force on the heavy ions, these particles will evolve into different collective patterns eventually. These patterns manifest a rather different stopping behavior of the moving ions and an opposite drifting direction of the electron fluid at the rim of the expanding plasma. Further numerical and analytical calculations show that the imbalance depends not only on the number densities of the plasma ions but also on the spatial variations of the magnetic fields. Our work reveals that the collective behavior of the heavy ions is highly non-linear, and the non-linearity is able to induce different phenomena in the evolution of the system at a large scale.

Numerical investigation on the influence of metal particles on the characteristics of a high-current vacuum arc

In the arc-burning process of a high-current vacuum arc (HCVA), the metal particles (MPs) splashed from the active anode will have a significant influence on the plasma characteristics of the arc column. In this paper, the influence of varying MPs on the characteristics of HCVA are studied by establishing a HCVA model containing single or multiple MPs. The simulation results show that when the MPs vaporized metal vapor (MV) enters the interelectrode region and once the arc column plasma cannot ionize all atoms immediately, the ionization layer and the neutral atom vapor area (NAVA) will be formed in the adjacent region of the MPs. When the MP diameter and temperature increase, the number of vaporized metal atoms increases, so that the influence range of MV increases, and the area of ionization layer and the NAVA increases. In addition, when the arc current increases or the MPs are closer to the cathode surface, the greater the ion number density and ion pressure around the MPs are, the stronger the compression on the MV will be, resulting in the decrease of the area of ionization layer and the neutral atom vapor, and the increase of the net ionization rate of the ion number density. When multiple MPs exist in the interelectrode region at the same time, the MV from the MPs will affect each other. In the central region of multiple MPs, the density of MV becomes the largest, while the net ionization rate of ion number density is distributed in the periphery region of the MP group.

Bio-Based Plasticized PVA Based Polymer Blend Electrolytes for Energy Storage EDLC Devices: Ion Transport Parameters and Electrochemical Properties.

This report shows a simple solution cast methodology to prepare plasticized polyvinyl alcohol (PVA)/methylcellulose (MC)-ammonium iodide (NH4I) electrolyte at room temperature. The maximum conducting membrane has a conductivity of 3.21 × 10−3 S/cm. It is shown that the number density, mobility and diffusion coefficient of ions are enhanced by increasing the glycerol. A number of electric and electrochemical properties of the electrolyte—impedance, dielectric properties, transference numbers, potential window, energy density, specific capacitance (Cs) and power density—were determined. From the determined electric and electrochemical properties, it is shown that PVA: MC-NH4I proton conducting polymer electrolyte (PE) is adequate for utilization in energy storage device (ESD). The decrease of charge transfer resistance with increasing plasticizer was observed from Bode plot. The analysis of dielectric properties has indicated that the plasticizer is a novel approach to increase the number of charge carriers. The electron and ion transference numbers were found. From the linear sweep voltammetry (LSV) response, the breakdown voltage of the electrolyte is determined. From Galvanostatic charge-discharge (GCD) measurement, the calculated Cs values are found to drop with increasing the number of cycles. The increment of internal resistance is shown by equivalent series resistance (ESR) plot. The energy and power density were studied over 250 cycles that results to the value of 5.38–3.59 Wh/kg and 757.58–347.22 W/kg, respectively.

Torch Simulator: An analytical model for rapid prediction of inductively coupled plasma parameters

In this study, a novel analytical model has been developed to predict the parameters of the radio-frequency (RF) inductively coupled plasma (ICP), including axial temperature, electron number density, ion number density, ionization percentage, neutral atom number density, and robustness. The developed model has been implemented in a MATLAB app. The core element of Torch Simulator is a mathematical model which is highly accurate in predicting the temperature of plasma for the Fassel torch. In this simulator, the results of a computational fluid dynamics (CFD) model have been used to train the model with respect to the functions that describe the induction zone's size and position. The Torch Simulator can predict the ICPs parameters within a few seconds allowing the ICPs to be easily simulated, analyzed, and optimized. The results of the simulator are also compared with the results of a detailed CFD simulation as well as experimental measurements. It is shown that there is good agreement between the predictions of the Torch Simulator and the available data.

Two‐dimensional drift solitary structures in inhomogeneous magnetized OH ion plasmas with generalized (r, q) distributed electrons

AbstractIn this paper, the effect of generalized (r, q) distributed electrons on the linear and nonlinear coupling of drift and ion acoustic waves in a nonuniform plasma containing Hydrogen and Oxygen ions is investigated. In the linear regime, it is observed that increasing the percentage of flat‐topped (i.e. r > 0) electrons enhances the frequency of the coupled drift‐ion acoustic waves, whereas the increasing values of the spectral index q mitigates it. In the nonlinear regime, one‐ and two‐dimensional Korteweg de Vries‐like and Kadomtsev‐Petviashvili‐like equations are derived and their solutions are plotted for different ratios of ion number densities and for different values of double spectral indices r and q of the generalized distribution of electrons. It is found that only rarefactive structures exist for two‐dimensional solitons, however, both rarefactive and compressive structures are observed for the one‐dimensional case. The limiting cases of kappa and Maxwellian distributions are also discussed and their comparison with the generalized (r, q) distribution is thoroughly investigated. Spatial scales for the formation of rarefactive and compressive solitary structures are also discussed with reference to the changing electron distribution functions. The possible applications of the present study are also spelled out with special reference to space plasmas.

Multi‐dimensional instability of electrostatic solitary waves in a warm multi‐ion dust plasma

AbstractStudy of dust ion acoustic waves in a magnetized dusty plasmas composed of negatively or positively charged static dust, positive and negative ions, as well as kappa distribution electrons is presented. The Zakharov–Kuznetsov (ZK) equation is derived via reductive perturbation technique. The solitary wave solution of ZK equation is given and the multi‐dimensional instability of these solitary waves is investigated via small k perturbation method. The instability criterion and growth rate relying on obliqueness, superthermality, positive ion thermal pressure, relative ion number density, magnetic field strength, and direction cosines are discussed for five cases. The results are beneficial to understand different nonlinear characteristics of unstable electrostatic disturbances in laboratory and space plasmas.

Dust-acoustic wave electrostatic and self-gravitational potentials in an opposite polarity dusty plasma system

An opposite polarity dusty plasma system (containing inertial positive as well as negative dust species and inertialess singly charged ion species) is considered. The nature of the electrostatic and self-gravitational potential structures (associated with the dust-acoustic waves) is identified by the numerical analysis of two coupled second-order nonlinear differential equations. The latter are Poisson’s equations for electrostatic and self-gravitational potentials, where the positive and negative dust number densities (determined from their continuity and momentum equations) and the ion number density (determined from the Boltzmann law) are substituted. It is observed that the plasma system under consideration supports the dust-acoustic solitary structures associated with the positive as well as negative self-gravitational potentials but only with the positive electrostatic potential. The basic features of the electrostatic and self-gravitational solitary potential structures are studied. It is also found that the amplitude of the electrostatic and self-gravitational solitary potential structures decreases with the increase in the positive dust number density. The effects of other different dusty plasma parameters on these solitary potential structures are also identified. The applications of this investigation in some space and laboratory dusty plasma systems are pinpointed.

The Study of Plasticized Sodium Ion Conducting Polymer Blend Electrolyte Membranes Based on Chitosan/Dextran Biopolymers: Ion Transport, Structural, Morphological and Potential Stability.

The polymer electrolyte system of chitosan/dextran-NaTf with various glycerol concentrations is prepared in this study. The electrical impedance spectroscopy (EIS) study shows that the addition of glycerol increases the ionic conductivity of the electrolyte at room temperature. The highest conducting plasticized electrolyte shows the maximum DC ionic conductivity of 6.10 × 10−5 S/cm. Field emission scanning electron microscopy (FESEM) is used to investigate the effect of plasticizer on film morphology. The interaction between the electrolyte components is confirmed from the existence of the O–H, C–H, carboxamide, and amine groups. The XRD study is used to determine the degree of crystallinity. The transport parameters of number density (n), ionic mobility (µ), and diffusion coefficient (D) of ions are determined using the percentage of free ions, due to the asymmetric vibration (υas(SO3)) and symmetric vibration (υs(SO3)) bands. The dielectric property and relaxation time are proved the non-Debye behavior of the electrolyte system. This behavior model is further verified by the existence of the incomplete semicircle arc from the Argand plot. Transference numbers of ion (tion) and electron (te) for the highest conducting plasticized electrolyte are identified to be 0.988 and 0.012, respectively, confirming that the ions are the dominant charge carriers. The tion value are used to further examine the contribution of ions in the values of the diffusion coefficient and mobility of ions. Linear sweep voltammetry (LSV) shows the potential window for the electrolyte is 2.55 V, indicating it to be a promising electrolyte for application in electrochemical energy storage devices.

Molecular Understanding of Charge Storage in MoS2 Supercapacitors with Ionic Liquids

Owing to high electrical conductivity and ability to reversibly host a variety of inserted ions, 2D metallic molybdenum disulfide (1T‐MoS2) has demonstrated promising energy storage performance when used as a supercapacitor electrode. However, its charge storage mechanism is still not fully understood, in particular, how the interlayer spacing of 1T‐MoS2 would affect its capacitive performance. In this work, molecular dynamics simulations of 1T‐MoS2 with interlayer spacing ranging from 0.615 to 1.615 nm have been performed to investigate the resulting charge storage capacity in ionic liquids. Simulations reveal a camel‐like capacitance‐potential relation, and MoS2 with an interlayer spacing of 1.115 nm has the highest volumetric and gravimetric capacitance of 118 F cm−3 and 42 F g−1, respectively. Although ions in MoS2 with an interlayer spacing of 1.115 nm diffuse much faster than with interlayer spacings of 1.365 and 1.615 nm, the MoS2 with larger interlayer spacing has a much faster‐charging process. Our analyses reveal that the ion number density and its charging speed, as well as ion motion paths, have significant impacts on the charging response. This work helps to understand how the interlayer spacing affects the interlayer ion structures and the capacitive performance of MoS2, which is important for revealing the charge storage mechanism and designing MoS2 supercapacitor.

Characteristics of non-Maxwellian magnetized sheath with secondary electron emission

In this paper, the effects of non-Maxwellian distribution of electrons on the characteristics of magnetized plasma sheath with secondary electron emission are investigated by using a magnetic fluid model of one-dimensional velocity and three-dimensional space. The velocity of electrons follows the non-extensive distribution, and the ions are magnetized in a magnetic field with a certain tilt angle relative to the wall. The effects of the non-extensive electron distribution parameter <i>q</i> and the magnetic field strength and angle on the Bohm criterion, the floating wall potential, the secondary electron number density at the sheath edge, the sheath thickness and the ion velocity are studied by establishing the self-consistent equations. When the electron velocity distribution deviates from the Maxwellian distribution, the results show that as the <i>q</i>-parameter increases, the value of the Bohm criterion decreases, the floating wall potential increases, the number of secondary electrons at the sheath increases, the sheath thickness decreases, the number density of ions and electrons decline faster, the number density of ions near the wall is higher, and the velocities of the ions in the three directions are all reduced. In addition, as the magnetic field strength increases, the sheath thickness decreases, and the number density of ions and electrons in the sheath area decrease rapidly; the larger the magnetic field angle, the more significant the influences of the parameter <i>q</i> on the wall potential and the sheath thickness are, while the velocity component of the ion in the <i>x</i>-direction decreases with the increase of the magnetic field angle, but in the case of super-extensive distribution (<i>q</i> < 1), the velocity change near the wall presents an opposite trend, the increase of magnetic field angle causes wall velocity to increase; when it is close to Maxwellian distribution (<i>q</i> → 1), the velocity near the wall does not depend on the change of the magnetic field angle and basically tends to be identical; in the case of sub-extensive distribution (<i>q</i> > 1), the velocity near the wall decreases with the magnetic field angle increasing.

Distribution of Electrons and Ions Near an Absorbing Spherical Body in a Nonequilibrium Plasma

The applicability of the collision kinetic model of point sinks, viz., the linearized theory of screening of the electric field produced by a charged dust particle, based on the Vlasov equations for electrons and ions in a nonequilibrium plasma, which are supplemented with collision terms in the Bhatnagar–Gross–Crook form and effective point sinks to dust particle, is analyzed. The criterion for the applicability of the collision kinetic model of point sinks is the smallness of the deviation of the electron and ion number densities near an absorbing spherical body from unperturbed values. The distributions of electron and ion number densities obtained using the collision kinetic model of point sinks and the orbit motion limited approach are compared. It is shown that the latter approach is applicable only in the low-pressure limit, and upon an increase in pressure, the Coulomb asymptotics of the potential, which is proportional to the frequency electron and ion collisions with neutral atoms (molecules), renders the orbit motion limited approach inapplicable for calculating the ion distribution. It is established that the domain of applicability of the collision kinetic model of point sinks is close to the applicability domain of the Debye–Huckel theory.