Ion Number Density Research Articles

Electrochemical and Ion Transport Studies of Li+ Ion-Conducting MC-Based Biopolymer Blend Electrolytes.

A facile methodology system for synthesizing solid polymer electrolytes (SPEs) based on methylcellulose, dextran, lithium perchlorate (as ionic sources), and glycerol (such as a plasticizer) (MC:Dex:LiClO4:Glycerol) has been implemented. Fourier transform infrared spectroscopy (FTIR) and two imperative electrochemical techniques, including linear sweep voltammetry (LSV) and electrical impedance spectroscopy (EIS), were performed on the films to analyze their structural and electrical properties. The FTIR spectra verify the interactions between the electrolyte components. Following this, a further calculation was performed to determine free ions (FI) and contact ion pairs (CIP) from the deconvolution of the peak associated with the anion. It is verified that the electrolyte containing the highest amount of glycerol plasticizer (MDLG3) has shown a maximum conductivity of 1.45 × 10−3 S cm−1. Moreover, for other transport parameters, the mobility (μ), number density (n), and diffusion coefficient (D) of ions were enhanced effectively. The transference number measurement (TNM) of electrons (tel) was 0.024 and 0.976 corresponding to ions (tion). One of the prepared samples (MDLG3) had 3.0 V as the voltage stability of the electrolyte.

Neutron star crust in Voigt approximation II: general formula for electron screening correction for effective shear modulus

ABSTRACT The main contribution to the effective shear modulus of neutron star crust can be calculated within Coulomb solid model and can be approximated by simple analytical expression for arbitrary (even multicomponent) composition. Here I consider correction associated with electron screening within Thomas–Fermi approximation. In particular, I demonstrate that for relativistic electrons (density ρ > 106 g cm−3) this correction can be estimated as $\delta \mu _\mathrm{eff}^\mathrm{V}= -9.4\times 10^{-4}\sum _Z n_Z Z^{7/3} e^2/a_\mathrm{e},$ where summation is taken over ion species, nZ is number density of ions with charge Ze, kTF is Thomas–Fermi screening wavenumber. Finally, ae = (4πne/3)−1/3 is electron sphere radius. Quasi-neutrality condition ne = ∑ZZnZ is assumed. This result holds true for arbitrary (even multicomponent and amorphous) matter and can be applied for neutron star crust and (dense) cores of white dwarfs. For example, the screening correction reduces shear modulus by ∼9 per cent for Z ∼ 40, which is typical for inner layers of neutron star crust.

Magnetic field topology for altering ion density in bipolar sputtering

A drastic change in the spatial ion distribution in bipolar magnetron sputtering discharge is reported upon changing the magnetic field topology. In our case, a significant increase in ion number density at certain time delays is registered when topology is changed toward the unbalanced type. A transitory torch-shaped ionization zone consequently disappears, along with the low-energy part of the ion energy distribution, due to no additional ionization in this case.

On the origin of “patchy” energy conversion in electron diffusion regions

During magnetic reconnection, field lines interconnect in electron diffusion regions (EDRs). In some EDRs, the reconnection and energy conversion rates are controlled by a steady out-of-plane electric field. In other EDRs, the energy conversion rate J→·E→′ is “patchy,” with electron-scale large-amplitude positive and negative peaks. We investigate 22 EDRs observed by NASA's Magnetospheric Multiscale mission in a wide range of conditions to determine the cause of patchy J→·E→′. The patchiness of the energy conversion is quantified and correlated with seven parameters describing various aspects of the asymptotic inflow regions that affect the structure, stability, and efficiency of reconnection. We find that (1) neither the guide field strength nor the asymmetries in the inflow ion pressure, electron pressure, nor number density are well correlated with the patchiness of the EDR energy conversion; (2) the out-of-plane axes of the 22 EDRs are typically fairly well aligned with the “preferred” axes, which bisect the time-averaged inflow magnetic fields and maximize the reconnection rate; and (3) the time-variability in the upstream magnetic field direction is best correlated with the patchiness of the EDR J→·E→′. A 3D fully kinetic simulation of reconnection with a non-uniform inflow magnetic field is analyzed; the variation in the magnetic field generates secondary X-lines, which develop to maximize the reconnection rate for the time-varying inflow magnetic field. The results suggest that magnetopause reconnection, for which the inflow magnetic field direction is often highly variable, may commonly be patchy in space, at least at the electron scale.

Investigation of number density, temperature, and kinetic energy of nanosecond laser-induced Zr plasma species for self-generated electric and magnetic fields in axial expansion of plume

The number density, temperature, and kinetic energy of laser-induced Zr plasma species have been evaluated experimentally under ultra-high vacuum conditions as a function of 1 to 4 cm axial distances of the plume at laser irradiances ranging from 4.5 to 11.7 G W c m − 2 . Zr plasma parameters have been evaluated using time-of-flight (ToF) measurements by using a Faraday cup (FC) as a diagnostic technique. The amplitudes of the signals as well as the number density and temperature are strongly dependent upon laser irradiance and axial distances. With increasing laser irradiance the laser-induced plasma (LIP) parameters show an increasing trend. The increasing trend of the plasma parameters along with increasing laser irradiance is attributed to an enhanced energy deposition per atom, which is responsible for an enhanced ablation rate, surface temperature, and ablation/shock pressures. However, a decreasing trend is obtained with increasing axial distances, which is explainable based on adiabatic expansion, cooling, and recombination losses. The LIP electron and ion number densities vary from 3.13 × 1 0 13 to 6.81 × 1 0 13 c m − 3 and 1.84 × 1 0 13 to 4.41 × 1 0 13 c m − 3 , respectively. The electron temperature varies from 1.54 to 125 eV, whereas the kinetic energy of the ions varies from 1.2 to 34 keV. The maxima of Zr plasma parameters are achieved away from the target surface. In order to correlate the charge particle distribution and their energies with self-generated electric and magnetic fields (SGEMFs), the measurements have been performed by employing electric and magnetic probes, respectively. The signal profiles of the SGEMFs reveal the quadrupolar distribution, which is attributed to two oppositely generated dipoles whose contribution is strongly dependent upon axial distances and laser irradiances. The strength of both SGEMFs shows an increasing trend with increasing laser irradiance, and a decreasing trend is obtained with increasing probe-target distance. For overall plume axial expansion, the LIP electric and magnetic fields vary from 30 to 3140 V/m and 0.2 to 0.4 T, respectively. Similar trends of the SGEMFs and the axial gradients of the electron-ion number density confirm the quadrupolar structure of plasma, which corresponds to the electron-ion charge separation. This charge separation is due to the spatially evolved number density and temperature gradients in the plasma. Their correlation and optimization will be helpful for using LIP as a powerful source of electric and magnetic fields in ion acceleration and inertial confinement fusion.

The first molecules in the intergalactic medium and halos of the Dark Ages and Cosmic Dawn

We study the formation and destruction of the first molecules at the epochs of the Dark Ages and Cosmic Dawn to evaluate the luminosity of the protogalaxy clumps (halos) in the molecular lines. The cosmological recombination is described using the RecFast model of an effective three-level atom, while the chemistry of the molecules is examined using the relevant basic kinetic equations. We then studied the effect of collisional and radiative excitation of molecules on the intensity of molecular emission in both warm and hot halos. Using the Planck data on the reionization of the intergalactic medium at z ∼ 6−8, we evaluated the upper limits of the light energy density for four models of thermal light from the first sources that appeared in the Cosmic Dawn epoch. Assuming that in the halos, the light energy density may essentially be even higher, we estimated the impact of the light from the first sources (the first light) on the formation and destruction of the first molecules in them as well as between them. We show that the molecules H2 and HD are destroyed by photodissociation processes shortly before the full reionization in the inter-halo medium, in the medium of both types of halos and for all models of the first light. At the same time, the number density of helium hydride ions, HeH+, shows essentially more complicated dependences on the kinetic temperature of halos and the models of the first light. These features characterizing the abundance of molecules also determine the intensity of the halos luminescence during their evolution. Furthermore, we calculated the evolution of the brightness temperature of the individual halo in the rotational lines of H2, HD and HeH+ molecules relative to the temperature of the cosmic microwave background at redshifts corresponding to the Dark Ages and Cosmic Dawn epochs. It does not exceed the microkelvin, but its detection may be an important source of information about the physical processes taking place at the beginning of the formation of the first stars and galaxies at the epochs of the Dark Ages and Cosmic Dawn.

Interaction of ion-acoustic solitons for multi-dimensional Zakharov Kuznetsov equation in Van Allen radiation belts

The propagation of nonlinear ion-acoustic waves (IAWs) in a magnetoplasma having superthermal inertialess electrons and inertial warm adiabatic ions is examined. In this regard, Zakharov Kuznetsov (ZK) equation is derived in order to investigate the characteristics of the ion-acoustic solitons (IASs) in the small but finite amplitude limit. Using the Hirota bilinear method, both single and two-solitons solutions of the two and three-dimensional ZK equations are obtained. According to the parameters of Van Allen radiation belts, the effects of superthermality, magnetic field, ion number density, and the ion temperature on the profile of both single and two-solitons are explored. The estimates of the spatial extent of the interaction of solitons in the outer radiation belts are also given.

Ion-acoustic multisolitons in pair-ion plasmas containing degenerate electrons: overtaking collisions at critical compositions

Overtaking collisions of ion-acoustic (IA) solitons are examined in an unmagnetized pair-ion plasma containing degenerate electrons. A Korteweg-de Vries (KdV) equation governing nonlinear IA solitons in such a degenerate plasma model is obtained. At critical compositions, the nonlinear coefficient of the KdV equation vanishes. Therefore, a modified KdV (mKdV) equation describing nonlinear IA solitons in the degenerate plasma model has been derived by extending the analytic analysis to this critical case. Hirota’s bilinear method has been applied to obtain the multisolitons solution and their corresponding phase shifts in these two situations. For an in-depth analysis, we investigated the dynamics of two solitons of the same polarity and opposite polarities resulting from the overtaking collision for discrete times. In particular, the phase shifts are obtained for the first time at critical components in degenerate plasmas. In these two cases, it is found that the magnitude of the phase shifts due to the overtaking interaction of two solitons increases with increasing the negative ion-to-positive ion number density ratio. The present study may help explain the properties of nonlinear waves in white dwarfs that support the propagation of solitons.

Glycerol as an efficient plasticizer to increase the DC conductivity and improve the ion transport parameters in biopolymer based electrolytes: XRD, FTIR and EIS studies

In the current work Plasticized sodium ion conducting solid polymer electrolytes (SPEs) based on polyvinyl alcohol: methylcellulose (PVA: MC) and sodium iodide (NaI) as the electrolytic salt are fabricated. The SPE films are created using a renowned solution casting procedure, and the results of the experiments are provided. The development of polymers-salt complexes is supported by the Fourier-transform infrared transform (FTIR) analysis. The degrees of crystallinity of the polymers are noticeably decreased as a result of the glycerol plasticizer, according to X-ray diffraction test. The sample inserted with 40 wt% glycerol has the maximum ionic conductivity, according to electrical impedance spectroscopy (EIS). Electrical equivalence circuits (EEC) are used to explore the electrolytes circuit components. For the highest conducting electrolyte, the number density ( n ), mobility (µ), and diffusion coefficient (D) of ions are found to be 2 × 10 21 , 1.79 × 10 −6 , and 4.59 × 10 −8 , respectively. A high dispersion of the real component of dielectric permittivity at a lower frequency are used to infer the space charge influence induced by stainless-still (SS) electrodes. The tangent loss spectra show that the bouncing chance per unit time decreases as the glycerol concentration rises.

3-D Dynamic Simulation of the Initial Expansion Process of Vacuum Arc Plasma in DC Interruption

This work investigates the dynamic characteristics of vacuum arc in the initial expansion process of a direct current (dc) circuit breaker. Based on the commercial cup-type axial magnetic field (AMF) contact, a 3-D transient magnetohydrodynamic (MHD) model is established. In the model, transient equations are used to study the transient characteristics of the vacuum arc. The effect of magnetic field hysteresis is also considered in the method. The dynamic mesh technique is adopted to simulate the electrode separation, which can make the simulation results more accurate. The simulation results show that, during the initial expansion process, with the increase in the current, the arc gradually expands in the electrode gap. The ion pressure, ion number density, axial current density, and energy flux density to the anode gradually decrease. Ion rotation can be observed under the influence of the magnetic field, and the rotation speed will increase with the increase in the current. Two different arc ignition positions are also compared. The result shows that igniting the arc at the contact center is more helpful to the success of the interruption of the dc circuit breaker. The appearance of the arc predicted by the model is consistent with the experimental results.

On positively charged dust in the coma of comet 67P

ABSTRACT Moment analysis of ion spectrograms measured by the Ion Composition Analyser (ICA) in the coma of comet 67P typically produces an ion number density estimate markedly lower than the number density of free electrons as measured by the Mutual Impedance Probe and the dual Langmuir Probe. While there are good reasons to distrust the ion density moment estimate in these circumstances, the issue cannot yet be considered fully understood and it is of interest to see whether any natural non-instrumental cause is possible. An obvious such cause would be whether a significant fraction of the positive charge density resides in positively charged dust grains that are not measured by the ICA. Here, we show that this scenario is highly unlikely, even near perihelion where photoemission is the strongest. In our semi-analytical grain charging model, we balance the current contributions to grains of photoelectron emission and electron attachment so as to find the expected charge state for a grain of a given radius. The charge state is affected by the ambient electron number density, the electron temperature, and the heliocentric distance. While at times the bulk of the dust population around comet 67P could be charged positive, dust charging, including photoelectron emission, should have a negligible influence on the overall ionization balance in the cometary coma simply because the dust particles are not ubiquitous enough.

Electro-responsive electrorheological effect and dielectric spectra analysis of topological self-crosslinked poly(ionic liquid)s

By changing the amount of vinylimidazole grafted on phenyl ring, we designed and prepared a series of topological self-crosslinked poly(ionic liquid)s (TS-PILs) with different number of spacer arms by free radical polymerization. The influences of the number of spacer arms on the electrorheological (ER) effect of TS-PILs in insulating carrier liquid were studied by rheological test under electric stimulus and the influence mechanism was analyzed by broadband dielectric spectroscopy. It was found that the ER effect of TS-PILs containing organic counterion bis(trifluoromethane sulfonylimide) (TFSI-) increased with the increase of the number of spacer arms. Broadband dielectric spectra analysis showed that the increased ER effect with the number of spacer arms was attributed to the increase of interfacial polarization strength and the decrease of electrode polarization with the number of spacer arms. Activation energy analysis indicated that increasing the number of spacer arms could promote ion pair dissociation and ion number density but inhibit long-range movement of ions, which was responsible for the increase of interfacial polarization strength and the decrease of electrode polarization. The results provided a guidance insight for the design and preparation of high-performance crosslinked PIL-based ER materials.

Investigation of the confinement of high energy non-neutral proton beam in a bent magnetic mirror

By using the particle-in-cell (PIC) simulation method, we studied how the proton beam is confined in a bent magnetic mirror. It is found that the loss rate of the charged particles in a bent mirror is less than that in the axi-symmetric mirror. For a special bent mirror with the deflection angle of the coils α = 45°, it is found that the loss rate reaches maximum value at certain ion number density where the ion electrostatic oscillation frequency is equal to the ion cyclotron frequency. In addition, the loss rate is irrelevant to the direction of the proton beam. Our results may be helpful to devise a mirror. In order to obtain the least loss rate, we may choose an appropriate deflection angle, and have to avoid a certain ion number density at which the ion electrostatic oscillation frequency is equal to the ion cyclotron frequency.

Elucidating Curvature-Capacitance Relationships in Carbon-Based Supercapacitors.

Nanoscale surface curvatures, either convex or concave, strongly influence the charging behavior of supercapacitors. Rationalizing individual influences of electrode atoms to the capacitance is possible by interpreting distinct elements of the charge-charge covariance matrix derived from individual charge variations of the electrode atoms. An ionic liquid solvated in acetonitrile and confined between two electrodes, each consisting of three undulated graphene layers, serves as a demonstrator to illustrate pronounced and nontrivial features of the capacitance with respect to the electrode curvature. In addition, the applied voltage determines whether a convex or concave surface contributes to increased capacitance. While at lower voltages capacitance variations are in general correlated with ion number density variations in the double layer formed in the concave region of the electrode, for certain electrode designs a surprisingly strong contribution of the convex part to the differential capacitance is found both at higher and lower voltages.

Results of plasma radiative compression investigation in the PF-24 device operated with D2, Ar and (100%-x)D2+x%Ar mixtures obtained using the 5-phase Lee model code

The article presents new results for plasma radiative compression in high-current discharges in the z-pinch configuration. The results are based on the 113 discharges performed in the plasma-focus PF-24 device operated with D2, Ar and (100%-x)D2+xAr mixtures, with Ar pressure fractions x ≈ 3–60% (mole fractions). The constant initial total pressure is about 2.9 mbar and the constant initial pressure of Ar is 1.2 mbar. Each experimental discharge was simulated individually using the 5-phase Lee model code to carry out the fitting procedure of the total discharge current waveform. The results from these 113 computed discharges fitted to the corresponding 113 experimental discharges show that the increase of the effective atomic number of the gas mixture increases the probability of occurrence of plasma radiative compression phenomenon. Relatively weak radiative compression was found for part of the discharges in 15–60% range of Ar mole fractions and in Ar, while the stronger radiative compression occurred for part of discharges in Ar only. This is because there was too little total x-ray line radiation emission during the equilibrium pinch lifetime related to the very small amount of swept up mass and the low current flow through pinched plasma, represented by the decreasing values of model parameters as the Ar mole fraction increases. The results show that the main pinch parameters influencing the occurrence and strength of radiative compression are: total x-ray line emission yield, effective atomic number, initial pinch radius, initial pinch ion number density and initial pinch ion/electron temperature.

Electrorheology and dielectric polarization of backbone, pendant and cross-linked poly(ionic liquid)s

Backbone, pendant and cross-linked poly(ionic liquid) (PIL) particles with the same ion pair and similar ion number density have been prepared and the electro-responsive electrorheological (ER) effect of their suspensions in insulating carrier liquid has been comparably studied by rheology and dielectric spectroscopy. It has found that the ER effect of cross-linked PILs is strongest and that of backbone PILs is weakest. Dielectric spectrum analysis has showed that the difference of ER effect is mainly due to the difference in the ion leakage and effective interfacial polarization of PIL particles under electric fields. Although the backbone PILs have the largest interfacial polarization strength, its ion leakage conductance is also largest and this results in its weakest ER effect. The cross-linked PILs well restrains the ion leakage conductance and the ER effect is largely enhanced. The difference in ion leakage conductance and ER effect is further related to the difference of PIL matrix structure according to X-ray diffraction characterization. This study clarified the influence of matrix structure on ER effect and dielectric polarization of PILs and provided a guidance for the design of PIL ER materials.

Correlation of Pinch Properties with Minimum Pinch Radius in UNU/ICTP PFF for Different Pressure of Argon Gas

In this present work, numerical experiments are performed using the Lee code to examine the correlation of minimum pinch radius(rmin) with pinch energy density(PED),ion number density (Ni),induced voltage(Vmax), total radiation power (Prad),and Joule heating power (Pjoule)in UNU/ICTP PFF device when using argon gas at different pressure. The computed results show that at the optimum pressure of 1.0 Torr argon, PED (338 × 109Jm-3), Ni (123 × 1023/m3), Vmax (245 kV), Pjoule(114.48 × 108W),and Prad (173 × 108W) reach to their maximum values whilst the rmin reaches to its lowest value of 0.01 cm. At this optimum condition, the strong radiation cooling effect is found and the excess (Pjoule-Prad) in radiative power of -58.51× 108W(negative singe indicates the energy going out from pinch plasma) which is sufficiently enough to cause the radiative collapse in heavier argon pinch plasma. Hence, the excess radiation power would be another reason for the occurrence of radiative collapse beside the critical (Pease-Braginskii) current. The variation nature of pinch properties of this studies are compared with those of PF1000 plasma focus device that makes the consistent of the present research work.

Validation of the use of THEMIS-B and THEMIS-C as a near-Earth solar wind monitor

Two THEMIS (Time History of Events and Macroscale Interactions during Substorms) spacecraft, B and C, began orbiting the Moon in 2011 and have since provided routine measurements of the plasma conditions in the lunar orbit. In this study, we systematically compare these measurements in near-Earth space with solar wind measurements obtained from the Lagrangian 1 (L1) point and propagated to the Earth, including measurements in the OMNI database and from the Wind spacecraft. A statistical comparison between THEMIS data and data from the OMNI database from September 2011 to December 2017 showed that the <em>Y</em> and <em>Z</em> components of the magnetic field and the flow speed are generally consistent between the two data sets. The ion number density and the dynamic pressure measured by THEMIS in near-Earth space are lower than those in the OMNI database, suggesting possible variation in the solar wind environment while propagating from the L1 point to near-Earth space. We further show two examples in which near-Earth solar wind measurements are applied in calculating the magnetopause location and in quantifying the magnetic field response to interplanetary shocks. Both examples suggest that using solar wind data from near-Earth space achieves better results than using solar wind data from the L1 point. These results provide validation of THEMIS-B and THEMIS-C as an alternative monitor of the near-Earth solar wind environment.

Propagation characteristics of (2 + 1) dimensional dust acoustic solitary waves in hot dusty plasma

The propagation characteristics of (2 + 1) dimensional nonlinear dust acoustic solitary wave in an unmagnetized hot dusty plasma composed of dust particles, electrons and nonthermal ions are studied in the paper. Firstly, the Kadomtsev-Petviashvili (KP) equation, which is used to describe the (2 + 1) dimensional nonlinear dust acoustic solitary wave, is derived by the reduced perturbation method, and the phase diagram and the Sagdeev potential equation of the system are obtained by using the traveling wave solution method. Then, the effects of different parameters in the hot dusty plasma system on the nonlinear coefficient, dispersion coefficient of the KP equation, system phase diagrams, Sagdeev potential function and the solitary wave solution in isothermal and adiabatic states are discussed by using numerical simulation and analysis method of mathematical software. Finally, the results show that the mass of dust particles, temperature, number density and distribution state of electrons and nonthermal ions have important effects on the amplitude, width and waveform of the nonlinear dust acoustic solitary wave under isothermal and adiabatic conditions.

Temporal studies of titanium ionised density fraction in reactive HiPIMS with nitrogen admixture

Temporal evolutions of the ground state number densities of titanium atoms and ions and the ionised density fraction during pulse on-time are experimentally investigated for the high-power impulse magnetron sputtering process in an Ar and Ar/N2 atmosphere. For the study, two distinct pulses with the same pulse length at a constant average power but different pulse off-times were selected. In both conditions, four representative points within the hysteresis curve were chosen, and the time evolutions of sputtered species densities were investigated in both the target and the substrate regions. At the pulse beginning, a high density of residual particles sputtered during the previous pulse is present in both studied regions. In the target region, in conditions of longer pulse off-time and thus higher peak discharge current, 95% of sputtered particles are ionised in metallic, transition and compound regimes. With shorter pulse off-time conditions, and thus a lower peak discharge current, the ionised density fraction is the lowest in the metallic regime; in the transition and compound regimes, it exceeds 80%. In the substrate region, the temporal evolution of sputtered species densities differs from that obtained in the target region. After the pulse ignition, titanium atoms and ions remaining near the substrate from the previous pulse are pushed away. In the metallic regime, the sputtered atoms refill the substrate region already during the pulse on-time in both the low- and high-current conditions. In the high-current conditions, the titanium ions arrive at the substrate together with the sputtered atoms; however, in the low-current conditions, the titanium ion density decreases during the pulse on-time, and the titanium ions arrive later during the pulse off-time. In the transition and compound regimes, both densities steadily decrease during the pulse on-time and the titanium atoms and ions arrive at the substrate during the pulse off-time.