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A novel optical sensor for ammonia concentration in water is demonstrated using up-conversion (UC) fluorescence intensity ratio (FIR). The sensor element consists of (i) an Er 3+ -Yb 3+ co-doped tellurite glass microsphere integrated inside a section of suspended tri-core hollow fiber (STCHF) and (ii) the pH indicator phenol red. When 980 nm pump is coupled into the microsphere, the Er 3+ ions produce green and red UC emissions. Exposure to ammonia results in a strong increase in the 560 nm absorption of the phenol red, which acts as a filter for the green emission, while the red emission is unaffected. A simple linear relation between the FIR and the ammonia aqueous concentration has been established.

Trapped ion quantum information processors as well as all competing platforms are facing a challenging task to scale up their qubit registers. Trapped ion systems typically use strong radio-frequency (r.f.) fields for confinement, which present a technological challenge in delivering the required power to miniaturized surface traps with a two-dimensional geometry. Such a geometry is desired for scaling in a large information process but is fundamentally at odds with the fact that any ions straying away from one-dimensional r.f. nulls suffer excess micromotion. We instead envision a two-dimensional array of Penning traps that will operate free from the detrimental strong r.f. fields: a repeating pattern of dc electrodes on a microfabricated trap chip with static quadrupole potentials will create an axial confinement at each trap site and in combination with a strong and homogenous magnetic field generate radial confinement. Each individual trap site would then host a single ion and would be easily reconfigurable to adjust the distance to a neighboring site to allow for tunable coupling strengths. To demonstrate the feasibility of this approach, we built an experimental apparatus that houses a micro-fabricated trap capable of creating two radially separated trapping wells inside a cryogenic vacuum chamber inserted into the bore of a 3 T superconducting magnet. We report on the first successful loading of 9 Be + ions into the trap. The results highlight our ability to successfully cool the radial motion using the radial motional mode coupling technique known as axialization.

In this paper, a novel noise adaptive moving horizon estimation (NAMHE) method is proposed to improve the accuracy of state of charge(SOC) estimation of Li-ion batteries under the unknown noise conditions. Specifically, based on the maximum likelihood principle, the unknown statistical characteristics of the noises can be estimated to modify the recurrence expression of the NAMHE. Then, the SOC estimation algorithm is designed by combining the equivalent circuit model and the proposed NAMHE. Furthermore, the convergence of the estimation error expectation is obtained for the NAMHE algorithm. Finally, the simulation results clarify that the SOC estimation error under the different unknown noise conditions can be effectively reduced by the proposed method, compared with the traditional MHE method.

Various methods have been proposed to estimate the capacity of lithium-ion batteries through constant current constant voltage charging. Existing algorithms require limiting the charging current and starting the charge from a specific low state of charge (SOC). In this paper, a capacity estimation algorithm for various initial SOC and 2 C charging currents is proposed. The proposed algorithm estimates capacity through a multilayer perceptron neural network using voltage curves measured during constant current (CC) charging, charging times, and initial SOC. Estimation accuracy was verified using two aging experiments. Estimation result shows that the Mean Absolute Error (MAE) is 0.39% and Maximum Error (ME) is 2.12%. In addition, even if there is an error in the estimated initial SOC, the capacity estimation errors are 0.85% MAE and 3.23% ME, showing robust characteristics regarding initial SOC estimate errors. The proposed algorithm is available for high charging currents and various initial SOC conditions, it and estimates capacity with high accuracy, even if there are errors in the estimated initial SOC. Owing to these advantages, the proposed algorithm can be easily implemented in actual applications.

In recent years, quantum computing has received extensive attention for its superior efficiency and application potential. For some physical architecture, one qubit can only interact with its adjacent qubits, SWAP gates are inserted to make a quantum circuit nearest neighbor compliant. The initial qubit placement algorithm in a 2D grid structure is proposed based on the constructed interaction cost metric model, and the method of dynamic grid decision is given. In order to obtain a better way of inserting SWAP gates, the gate level and circuit level interaction routing policies are put forward, and a heuristic pruning of interaction routing records is employed so as to reduce the runtime and additional quantum cost. Experimental results show that our proposed methods can achieve better performance than existing methods, and the average optimization rate of quantum cost is 21.76% and 17.23% respectively.

Lithium-ion (Li-ion) batteries play a substantial role in energy storage solutions for modern-day technologies such as hand-held consumer electronics, aerospace, electric vehicles, and renewable energy systems. For Li-ion batteries, designing a high-quality battery charging algorithm is essential since it has significant influences on the performance and lifetime of Li-ion batteries. The objectives of a high-performance charger include high charging efficiency, short charging time, and long cycle life. In this paper, a model predictive control based charging algorithm is proposed, the presented technique aims to simultaneously reduce the charging time, and the temperature rise during charging. In this study, the coulomb counting method is utilized to calculate the future state-of-charge and an artificial neural network trained by experimental data is also applied to predict the future temperature rise. Comparing with the widely employed constant current-constant voltage charging method, the proposed charging technique can improve the charging time and the average temperature rise by 1.2 % and 4.13 %, respectively.

The two-step implantation of argon precursor ion (Ar+) followed by boron ion (B+) in single crystalline silicon at room temperature is discussed to activate boron implanted region by post heating at 300 followed by 400°C. The implantation of Ar+ at a dose of 6.0 × 1013 cm-2 at 70 keV with a projected range Rp(Ar) of 80 nm followed by B+ at 1.0 × 1015 cm-2 and 15 keV with Rp(B) of 62 nm caused crystalline disordered states with the effective disordered amorphous depth Aeff of 32 nm, while the post heating of 300°C for 90 min followed by 400°C for 30 min markedly decreased Aeff to 1.8 nm. The effective recrystallization by the post heating promoted activation of doped region associated with decrease in the sheet resistivity to 189 Ω/sq by the post heating. The activation ratio was estimated as 0.33 under the assumption of a hole mobility of 50 cm2/Vs in the boron implanted region.

The accurate state of charge (SoC) online estimation is a significant indicator that relates to driving ranges of electric vehicles (EV). The relationship between open circuit voltage (OCV) and SoC plays an important role in SoC estimation for lithium-ion batteries. To compare with the traditional incremental OCV (IO) test and the low current OCV (LO) test, a novel OCV test which combines IO test with LO test (CIL) is proposed in this paper. Based on the reliable parameters online identification of the dual polarization (DP) battery model, two SoC estimation algorithms are compared on the accuracy, robustness and convergence speed for the entire SoC region. Meanwhile, the comparative study of the three OCV-SoC relationships fits by the corresponding OCV tests is discussed in terms of the SoC online estimation under various temperatures. The results show that the adaptive extended Kalman filter (AEKF) algorithm can better improve the accuracy and robustness of SoC estimation than that of the extended Kalman filter (EKF) algorithm. Most importantly, the OCV-SoC relationship obtains from the CIL OCV test method is applied to the AEKF algorithm, which has higher accuracy and better statistical indices of SoC estimation, especially suitable for the low temperature.

This paper proposes a sensorless method for measuring the internal temperature of lithium-ion (Li-ion) battery cells. The method calculates the impedance phase by injecting a small AC current to the battery. Afterward, the internal temperature is determined, in real-time, by an empirical fit model that correlates the internal temperature with the impedance phase of the battery cell at a predetermined frequency. The proposed method has high accuracy at a wide range of temperatures, in general, and at high temperatures, in specific, which is vital for preventing destructive temperature rise and thermal runaway. Derivation of the method followed by experimental verification using a commercial 3.8-V/2600-mAh Samsung Li-ion battery cell at temperatures between -20°C and +50°C is presented.

Low temperature bodings of Cu by gas cluster ion beam (GCIB) irradiations with organic acid vapor were studied. GCIBs induce surface smoothing and enhancement of surface reactions without severe damage. Therefore, it is promising for the surface activated bonding (SAB). In this study, organic acid vapor is introduced during GCIB irradiation in order to assist surface oxide removal on metal films (such as Cu, Ni). From XPS study, NiO layer was selectively removed by reaction with adsorbed organic acid. Preliminary bonding experiment using this technique shows promising result for Cu-Cu bonding.

We investigate the optical properties of an array of thulium ions implanted into a lithium niobate ring resonator. We present the data showing that the ions' emission rate increases at 4K due to both cavity-induced Purcell enhancement and also array-induced cooperative coupling.

The stray charges induced on ion trap surfaces can push trapped ions away from a pseudopotential null point. This can cause the micromotion of the trapped ions that in turn results in ion heating. One of the causes of stray charges is laser scattering on dielectric surfaces. The amount of laser-induced stray charges can be related to the area of the dielectric surface exposed to the ions. In this paper, stray charges are intentionally created at various dielectric surfaces on a microfabricated ion trap chip using a laser, and the resulting ion motion is measured. The ion movements are estimated by comparing ion positions before and after laser irradiation. When the laser irradiates a dielectric surface with an area of approximately 1,750 μm2 exposed to the ion, the ion moves approximately −4.8 μm in the axial direction. When the laser irradiates another dielectric surface with an area of approximately 140 μm2 exposed to the ion, the ion moves approximately −0.6 μm. The ratio between the ion movements corresponds to the ratio between the areas of each dielectric surface directly exposed to the ion normalized to the distance between the ion and the laser-induced stray charges. The results indicate the importance of reducing the area of dielectric surfaces that are directly in the line of laser paths.

The paper relates to theoretical investigation of a breakdown mechanism in the planar gap filled with low pressure gas. The 1D1V completely kinetic model of the phenomenon is presented, based on a self-consistent solution of the Poisson equation for the electric field, and the Boltzmann kinetic equations for both electrons and singly charged ions. The simulation takes into account collision processes of impact ionization, elastic electron scattering, and resonant ion recharging. The breakdown process of a planar gap of 5 mm filled with nitrogen at a pressure of ~1 Pa and applied anode voltages of 1 and 2.5 kV is considered. The calculation has demonstrated the generation of anode-directional ion flow with mean kinetic energy nominally exceeding the applied anode voltage (multiplied by the elementary charge) due to formation of a "potential hump" at short stage of breakdown. Possibly, the described mechanism also takes place in vacuum arcs, where flows of ions with similar features are observed.

This work investigates the transient arc behavior during the anode spot mode with CuCr25 electrodes theoretically and experimentally. In the simulation, a 2D transient magneto-hydro-dynamic (MHD) model considering multi-component plasma is used to calculate the arc parameters. Then, the energy flux is obtained to calculate the anode temperature in next time step. Simulation results show that when the anode temperature is high enough, the anode vapor density increases significantly. Therefore, ions from the cathode are decelerated by the anode vapor when arriving at the ionization layer, leading to changes in the ion temperature. Then, the arc current is more likely to flow to the edge of the atom vapor area instead of the anode center. Thus, the energy flux to the anode begins to heat the area around the anode spot, leading to a more uniform anode temperature distribution and a larger anode spot. The maximum anode temperature occurs after the peak current due to the thermal inertia. Experiments using optical methods for anode temperature determination are also conducted to verify the simulation results.

In this work, the plasma initiation and development in the vacuum gap with CuCr50 cathode are investigated with a two-dimensional particle-in-cell/Monte Carlo collisional model, in which the distributions of electric field and charged particles are calculated by the Poisson’s equation and Newton’s law in the two-dimensional cylindrical coordinate respectively. Particles including electrons, neutrals and various copper ions and chromium ions are traced as super particles, and collisions between these particles are processed with Monte Carlo collisional method. Results show that the plasma quickly forms near the cathode and propagates towards the anode in a hemi-spherical shape with the external voltage applied. The space charge in the discharge features three different layers in the calculation region and results distortion in the potential distribution, which counts for the high ion velocity. Compared with the discharge in vacuum gap with pure copper cathode in the previous work, the plasma initiates and propagates faster, the neutral and plasma density are higher, the distortion of electron potential is more significant and the charged particle velocities are larger with CuCr cathode in this work.

In this paper, the formation process of single cathode spot on hydrogen titanium cathode is simulated. The influence of impregnation degree α(H content per metal atom) on the formation and development of craters was studied by the control variable method. In this model, hydrogen diffusion in the cathode is calculated, and the deformation of cathode metal is simulated by hydrodynamic model. The components considered in the model include electrons, titanium atoms, H atoms, Ti ions (Ti+, Ti2+ and Ti3+) and H+ ions. The simulation results show that the impregnation degree has a great effect on the cathode spot process. The average charge state on the pure titanium cathode is larger, while the total ion number density on the hydrogen titanium cathode is larger because of the extra hydrogen ions. Low impregnation hydrogen (impregnation degree less than 1) can reduce the surface temperature and ablation of the cathode. With the increase of impregnation degree, the proportion of titanium ions in the plasma cloud decreases gradually, resulting in the decrease of the total energy current density and the decrease of the radius and depth of cathode spots. The simulation results are broadly consistent with the work of other researchers.

An experimental and theoretical study of the content of deuterium ions in the arc discharge plasma was performed for deuterated zirconium cathodes. It was found experimentally that in a high-current arc mode with a current pulse duration of several microseconds and an arc current amplitude of more than 600 A, the content of deuterium ions in the plasma can reach more than 80%, which is twice that in the cathode material. An increase in the deuterium ion content in the plasma is accompanied by an increase in the average charge of zirconium ions. Models are proposed to describe the deuterium desorption from the cathode surface and the ionization processes in the plasma of a deuterated cathode arc. The models are based on the idea that the cathode spot of a vacuum arc has a cellular (ecton) structure. The calculations performed using these models have shown that the best conditions for increasing the deuterium ion content in the arc plasma occur in the initial stage of the arc discharge. In this case, the cells of the cathode spot are located in close proximity to each other and the deuterium desorbed not only directly from the zone of operation of the spot cells but also from the hot regions of the cathode adjacent to this zone.

The new approach to explaining of ions and electrons acceleration in the vacuum arc is presented. The ion-acoustic plasma shock waves can produce the well-known shape of ion energy distribution as well as the dependence of that on the ion charge state. Experimentally measured mean ion velocities dependence on cathode material properties can be explained by ion sound shock wave dependence on "hot" electron temperature and ion mass. Experimentally measured energy distribution can be formed statistically by ion-acoustic waves with different amplitudes and velocities. In addition, the plasma turbulence can be the cause of several unexplained effects: The correspondence of ion flow peaks to strong discharge current falls can be explained by plasma turbulence rising which in turn causes abnormal plasma resistance. The Fourier spectra of ion flow law 1/f can be explained by Kolmogorov’s established turbulence spectra.

Molybdenum and Copper-Chromium samples were used as the vacuum arc cathodes in the 4-microsecond vacuum arc discharge. The pulse source was an LC-line with a quasi-rectangular pulse shape. Arc current varied from units of ampere to 125 A. Charge state distribution and the average charge state of the cathode material ions were measured via the Thomson spectrometer with automated image recording and digital data processing. It was found that the ion charge state distributions were close to the classical data at the hundred-ampere currents, and the average charge state significantly decreased with the arc current decrease for both materials. The decrease of the average charge was due to a decrease of the high-ionized ion fractions and an increase of low-ionized ion fractions (+1 and +2 for molybdenum, and +1 for copper and chromium). This effect, observed earlier only for copper cathodes, confirmed to be a feature of the plasma generation in low-current vacuum arcs on the CuCr cathodes and refractory cathodes, such as molybdenum.

The decay processes of a vacuum arc plasma after a discharge current break have been studied depending on the cathode elemental composition and the magnetic field induction. As the main methods of investigation, we used measurements of the ion current by a collector and the time-of-flight diagnostics of the mass-to-charge composition of ion fluxes from the decaying vacuum arc plasma. It is shown that the plasma generated with copper-chromium cathodes, after the vacuum arc current is interrupted, decays more slowly than when using a single-element copper cathode. The practical value of the results obtained is in the demonstration of the specific features of the decay processes in the vacuum arc plasma that develop after the discharge break in the conditions typical for operating vacuum interrupters. It is assumed that the use of copper-chromium composites as electrode materials in the presence of a magnetic field may affect the efficiency of interrupting high currents and recovery of the breakdown strength of vacuum interrupters.

This article summarizes observations on the features of the energy spectra and the charge distribution of ions in the plasma of microsecond low-current vacuum arcs in non-stationary regimes. The underlying data were obtained in the study of variations in the charge composition of ion fluxes from the plasma of a vacuum arc discharge with a quasi-rectangular current pulse. An LC line was used as a pulse generator. The analysis was carried out using a Thomson spectrometer with digital data processing. The energy spectra of the ions of the cathode material revealed ion fluxes with energies higher than typical values for the arc discharge (up to 2 keV per charge unit). It was found that the signal intensity of this component weakly depends on the discharge current. The average charge of the high-energy component is generally higher than that of conventional arc ions. In the course of research with a time-resolving gate unit, it was found that such ions are generated at the end of the discharge. Additionally, a study of the effect of spontaneous arc discharge extinction on the charge composition of ions was carried out.

This study reports progress toward realizing a high-performance Cesium (Cs)-free negative ion source, that produces negative ions using volume production in a magnetized-sheet plasma device (TPDsheet-U). Experimental observations show that the ratio of the co-extracted electron current (J EG ) and hydrogen negativeion current (J c ), J EG /J c decreases from 10 to 0.3 with a soft magnetic material plate for a magnetic filter (SMF) with thickness t = 2.0 mm at a discharge current of I d =50 A and gas pressure of P = 0.3 Pa. An SMF is a physical filter that prevents electron diffusion from the extraction region and the magnetic field control was effective in reducing the JEG/JC ratio. The J c is approximately 6 mA/cm2 at an extraction voltage (V ex ) of 10 kV, discharge current (I d ) of 80 A, gas pressure of 0.3 Pa, and external magnetic field strength of 40 mT. The current density performance of the H- ion beam, J c , was found to be approximately one-fifth of that of the negative ion source with Cs seeding in ITER-NBI.

This paper contains the results of the high- current vacuum arc study. Plasma ions scatter diagrams were obtained. A current pulse with a duration of 15 μs and with a maximum of 6 μs was used to produce the arc. Also, in this work, plasma flow was studied at 3 different distances from the plasma source. From the obtained results, it can be assumed that nonlinear solitary waves exist in the plasma.

A high efficiency and low crosstalk SiN grating coupler was demonstrated for trapped ion qubit manipulation. By optimizing a chirped double-etch grating with inverse design, a diffraction efficiency of 98.0 % was achieved for 729 nm. Additionally, an ellipse-shaped beam resulted in a low crosstalk of -36 dB assuming 7.07 µm neighboring ion spacing.

Pseudospark (PS) sourced beams have unique features of high-current density and self-focusing by the ion channel. This paper presents the characteristics of the PS-sourced beam from PIC simulations, as well as the potential of the PS-sourced beam for driving a THz extended interaction oscillator (EIO) operating at 350 GHz.

Using ion milling, the evolution of defect structure of Molecular Beam Epitaxy (MBE)-grown HgCdTe (MCT) has been followed from the time of the milling down to the full relaxation of defects induced by the treatment. It was found that in the case of ion-milled HgCdTe stored at the room temperature, the relaxation process stops only after several months. The idea of the work was to present possibly most comprehensive pattern of the nature and dynamics of defects in MCT heterostructures fabricated with MBE. Selected publications illustrate full examination methodology, which was applied in an attempt to use ion milling for revealing the defect structure of MBE-grown HgCdTe.

The methodology of determination of a glow discharge's heating efficiency dependence on process conditions and mode parameters while diffusion welding is provided in current work. It is established that the samples heating during diffusion welding in a glow discharge is provided by two heating sources: bombardment of their surfaces by accelerated in the near-cathode region gas ions as well as heat transfer from plasma of positive discharge column, which can reaches of 20 to 50% of total discharge's energy.

Complex plasma systems are of much interest as they permit micron sized dust particles to form stable and unstable structures. These structures can be used as probes to gain insight into the parameters of the plasma system [1] . The dust particle interaction with the ions flowing towards a negative lower electrode creates an ion wake field, which is difficult to measure experimentally. This wake field affects the charge on the dust grains, as well as the electric field and ion flow speed. Using a one-dimensional,seven-particle dust chain confined in a glass box placed on the lower electrode of a Gaseous Electronics Conference rf cell, the ion wake field along with the dust charge and electric field inside the plasma environment can be investigated.

A simple deuterium DC glow discharge was employed to study the production of densely packed deuterium clusters with high binding energies in palladium. The incident ions create damage cascades leading to the production of defects such as vacancies, dislocations, and voids. These defects trap interstitial deuterons with binding energies dependent on the trap’s geometry and volume. 1 Varying fluences of incident ions were used (1E18 ions/cm 2 , 1E19 ions/cm 2 , and 1E20 ions/cm 2 ) and incident energies dependent on cathode bias (-0.75 kV, -0.875 kV, and -1.0 kV). Thermal Desorption Spectroscopy (TDS) was used to estimate the clusters’ trapping energies. 2 There appeared to be a deuterium trapping limit dependent on defect concentration where once a distinct defect density was met any further damage was counterproductive in deuterium trapping. The condition that produced the most trapped deuterium was -0.75 kV in 1 Torr deuterium with a fluence of 1E18 ions/cm 2 . Some samples were observed under SEM and TEM. The results showed surface pit and blister formations which grew in concentration as the fluence increased. Beneath the surface formations, cross-section images showed large voids and holes in the material with cracks at grain boundaries. TEM images displayed the resulting damage structure which extended ~250 nm into the cathode for a sample at 1.0 Torr and -1.0 kV. A proposal is that as the damage concentration increased, these voids grew to such an extent that they formed the blisters and eventually ruptured.

The study of electron acoustic waves (EAWs) have gain importance in the past many years because of their presence in various plasma systems such as astrophysical/ space plasmas 1 . These waves are formed due to presence of two distinct electron components at different temperatures in plasma. Depending upon the temperature difference, the cold electrons become inertial and hot electrons provide the necessary pressure to develop the restoring force for the EAWs to exist likewise the ion acoustic waves (IAWs) in electron-ion plasma where the inertia is provided by the massive ions and the inertialess electrons provide the restoring force. Moreover, in the dynamics of EAWs, the ions are assumed to form only a stationary background because of their larger dynamical time scale as compared to that of electrons. Numerous investigations have already been done to examine the properties of linear and nonlinear EAWs with the presence of electron beam 2 . A Korteweg–de Vries(KdV) equation is derive d for a plasma comprised of cool background electrons , cool inertial electron beam with superthermal κ-distributed electro ns. It has been analysed that inclusion of electron beam can alter the properties of electron acoustic solitary waves, but can only produce negative polarity solitary structures. The present work may be useful to explore and understand the characteristics of non-linear wave structures observed in several astrophysical and space plasma environments such as polar cap boundary layer (PCBL) region and Earth’s magnetosphere.

Relativistic weakly collisional plasmas describe a variety of astrophysical and terrestrial plasmas, ranging from relativistic outflows from active galactic nuclei to high power microwave and magnetically insulated transmission lines. In many such systems, high fidelity kinetic models are computationally infeasible due large dynamical scales and long dynamical times. Conversely, most fluid based models such as magnetohydrodynamics (MHD) miss many relevant aspects of plasma behavior. Between these two models, two fluid methods – where the electrons and ions are evolved as separate, coupled fluids – capture many of the plasma physics of a kinetic code while remaining computational tractable for large systems.

Radioactivity induced in material irradiated by accelerated deuterons has been investigated in experiments conducted using a unique configuration of dense plasma focus (DPF) driven by the Hawk pulsed-power generator at the Naval Research Laboratory. The high inductance (607 nH) and associated high voltage (640 kV) and fast rise time (1.2 µs) of Hawk are unusual for a DPF driver, as is the initialization of the DPF using local mass injection rather than a conventional neutral gas fill. The local mass injection involves injecting transient neutral gas and plasma into a vacuum chamber at prescribed locations just prior to application of the main current pulse that drives the DPF. Evidence of ions accelerated to energies over an order of magnitude higher than the applied generator voltage has been observed in ion multi-pinhole images obtained with absorbers of varying thickness and in neutron time-of-flight detector signals. In this work an aluminum plate was positioned for irradiation by accelerated deuterons escaping the plasma during the DPF pulse. Following irradiation, a NaI(Tl) detector was used to record the energy spectrum and decay rate of the radioactivity induced in the plate. At the same time, an x-ray/γ-ray sensitive image plate placed in contact with the irradiated plate was used to record the spatial distribution of that radioactivity. The measurements showed γ-ray spectra and half-lives consistent with induced 27 Al(d,p) 28 Al and 12 C(d,n) 13 N reactions in the aluminum and from carbon impurities in the chamber. The induced radioactivity was concentrated at the center of the plate, which was located on the axis of the machine during irradiation.

Ion recombination in the gas phase plays an important role in plasma science and chemistry that is closely related to various applications in combustion and materials processing. Due to the lack of robust theoretical models of three body ion recombination, this project intends to develop a Langevin dynamics-based ion recombination rate constant model that is applicable for a broad pressure and temperature range combination taking into account the effect of ionic structure (especially for polyatomic ions). At high pressures, Langevin Dynamics is commonly considered to be efficient model for ion-neutral gas interactions and the implementation of LD enables the trajectory analysis and obtaining the ensemble averaged estimates of the of ion recombination rate constant. Ion recombination or mutual neutralization is modeled within the framework of classical physics and thus does not explicitly model the quantum nature of electron transfer kinetics from the anion to the cation. We hypothesized that electron transfer takes place with near certainty when two atoms (one part of the cation and the other part of the anion) when their separation is less than or equal to σ - distance σ between two atoms at which the potential energy (due to van der Waals or polarization interaction) between the ions is zero. The comparison with experimental data 1 – 5 for several ion pairs reveals an agreement of ±50% with most of the tested ion pairs. At low pressure end, a good agreement is observed as well between ion pairs that consist of polyatomic ions.

Scale-invariant breathing oscillations are observed in similar magnetron discharges via fully kinetic particle-in-cell/Monte Carlo collision simulations. The similarity law (SL) is verified over a scale from magnetron discharges to microdischarges. Breathing oscillations are suppressed at higher pressure p and enhanced at stronger magnetic fields B. In other words, the plasma oscillations appear and intensify a s the similarity invariant B / p increases. Meanwhile, the electron mobility approaches the ion mobility, and an appreciable time-averaged potential drops outside the sheath. Reducing B / p or pd , the breathing oscillations are suppressed due to the increase in wavelength or the decrease in characteristic scale of discharge. With the onset and development of breathing oscillations, the electron energization mechanism shifts from sheath energization to Ohmic heating in the ionization region. The characteristics of breathing oscillations and the transition of electron energization mechanism are scale-invariant under similar discharge conditions due to the electron kinetic invariance. The results of this study contribute to a more comprehensive understanding of the operation of magnetron discharges.

Chemical reactivity transfer from gas-phase plasmas to liquid can be significantly enhanced when a plasma interacts with small liquid micro-droplets as opposed to bulk liquid. In this contribution, the role of • OH as well as non- • OH driven chemistry on the degradation of an organic compound (formate) by activation of water micro-droplets by atmospheric pressure diffuse RF glow plasmas in He and different gas admixtures (Ar, H 2 , O 2 , H 2 O) is explored. Using detailed gas-phase plasma diagnostics, droplet characterization and ex situ chemical analysis of the plasma- treated droplets, the effect of short-lived species such as O • , H • and • OH, O 2 ( a ), electrons/ions, and metastable atoms of He and Ar is quantified. With increasing droplet residence time, the formate decomposition increases in electronegative plasmas (He/H 2 O He/Ar/H 2 O, He/O 2 ), with a maximum of ~70% within ~15 ms, while an inverse trend is observed in electropositive plasmas (He, He/H 2 , He/Ar), with >75% degradation within ~5 ms.

The deuterium-fill Dense Plasma Focus (DPF) is a Z-pinch configuration that produces energetic ions, X-rays, and neutrons from a high-temperature and high-density plasma pinch. There have been limited studies that consider the impact of the insulator length on the resulting pinch quality and neutron production. Experiments were conducted on a 4.4 kJ (250 kA, 21 kV) Mather type DPF 1 with laser probing diagnostics and a Be-activation detector for three different insulator sleeve lengths. Here, we report the results of experiments to optimize the neutron yield as a function of insulator sleeve length and fill pressure. The results show that the insulator length plays an important role in the dynamics, including pinch timing and neutron yield: increasing the insulator length reduces the effective anode length and thus affects the optimal fill pressure.

The PlasmaKristall-4 (PK-4) experiment on the International Space Station (ISS) has been widely used to study collective behavior and self-organization of dust grains immersed in a plasma environment under microgravity conditions. Recently it has been shown that the PK-4 BU, a ground-based replica of the PK-4, supports the presence of inhomogeneous features related to ionization waves moving through the positive column on the microsecond timescale 1 . Plasma conditions within the ionization waves, such as plasma density and electric fields, have been shown to vary by up to an order of magnitude from background values. Previous investigations of dust dynamics within the PK-4 environment have focused on time-averaged plasma conditions, assuming a homogeneous environment. Given the importance of plasma density and electric fields for dust self-organization, it is important to understand the impact of their observed variability. Here results will be presented from an N-body simulation which models dust and ion dynamics, employing initial boundary conditions derived from a 2D particle-in-cell with Monte Carlo collisions (PIC/MCC) simulation of the observed ionization waves.

Chemistry evolution in transient plasma or fireball systems in air comprised of multiple elements is extremely complex, owing to numerous ionic, atomic, and molecular species present, overlapping spectral lines, and the gas-phase oxidation. Although plasma chemistry is widely studied for analytical and material detection applications, tracking the chemical evolution from atoms and ions to diatoms, polyatoms, and larger molecules, nanoparticles, and agglomerates in a multi-component system remains largely unexplored.

A coordinated experimental-simulation study was carried out to explore the relationship between plasma conditions and ion angular energy distributions incident on a DC glow discharge cathode. Langmuir probe measurements of the Electron Energy Distribution Functions (EEDF) validated a COMSOL simulation’s accuracy which confirmed the proper methodology for reproducing discharge dynamics. 1 The simulation was a coupling between COMSOL’s Plasma module and Boltzmann Equation, Two-Term Approximation module allowing for accurate calculations of the Townsend coefficients. Proper Townsend coefficients are necessary to represent the kinetics of DC discharges with low ionization fractions and species mobility that are highly dependent on the electric field, e.g., ions transiting the plasma sheath. The EEDFs were measured along the cathode dark space and negative glow regions using the Druyvesteyn method. 2 After the trend of EEDFs were validated, the model was expanded to extract ion angular energy distributions in conditions where measuring plasma properties became no longer feasible.

To ensure the uniformity of plasma generated by the ion source in the neutral beam system, a large-area high-current ion source with multi-drivers is designed in the neutral beam system1. When these drivers are simultaneously supplied with alternating current work at the same time, there may be mutual coupling and interference between themselves2,3 due to the small distance between them (about 10 cm), which results in an asymmetric distribution of the RF magnetic field in the driver, thereby affects the normal operation of the RF ion source. In this study, a three-dimensional numerical simulation model of the 2-drivers of the radio frequency ion source was established. The electromagnetic induction between the two drivers was simulated and analyzed via this three-dimensional model. Under different distances, the distribution of the magnetic field in the driver without input which induced by the driver with input is analyzed. This research will provide theoretical support for the distribution of CRAFT's RF negative ion source drivers.

High resolution K-shell emission from Ni solid and near solid density nanowire arrays was measured at the ALEPH laser facility using a newly commissioned high resolution x-ray spectrometer. The spectrometer consists of a spherically bent Ge crystal coupled to a CCD. The targets were irradiated with high contrast laser pulses using the 400nm second harmonic beamline which operates at highly relativistic intensities, ao ~ 20. The ion and electron density of the plasmas were varied using arrays of 100nm diameter nanowire arrays with different wire spacings which varied from 7% of solid density to 24%. This parametrizes the collisional and radiative properties of the plasma as well as the temperature. The time integrated, high resolution K-shell spectra, coupled with moderate resolution, time resolved x ray emission reveal that the lower density nanowire arrays reach higher temperatures and radiate for longer durations of time (~25 ps) whereas the higher density nanowire arrays radiate for less than 10 ps, converging with the x-ray emission of the solid density Ni foil. Overall, the x-ray yield of the lower density nanowire arrays exceeds that of the solid density foil by a factor of ~5x. In contrast to this, the average charge state of the solid density foils is greater than that of the nanowire arrays due to the larger collisional ionization rates which occur at solid density. The experimental results will be compared to detailed transient atomic physics computations coupled with radiative hydrodynamic simulations with initial conditions provided by three-dimensional particle in cell simulations.

Multipactor discharges are widely observed in rf accelerators, high power microwave transmission and space-based communication systems [1] - [2] . Understanding the fundamental physics of the transit multipactor and ionization breakdown is important. In this work, a novel multilayer-structured discharge (MSD) is reported in multipactor-coexisting plasma ionization breakdown by fully kinetic particle-in-cell (PIC) simulations [3] - [7] . The observed multilayer structure is originated by the response of ions to the electric field. It is found that the electron diffusion and multipactor discharge near the surface produce two electric fields in opposite directions towards and away from the dielectric surface, respectively. Thus, ions are gathered to form a locally high density profile, which is followed by the electron density. Furthermore, the relatively stronger restoring field induced by the multipactor discharge drives the ions away from the surface, and the locally high electron density diffuses away from the surface, resulting in a local electric field also away from the surface, which drives the ion density peak to propagate towards the bulk plasma. Such a process is periodically repeated, and finally, a MSD is formed, and propagate into bulk region.

It was generally assumed that the magnetron sputtering discharge is maintained by the sheath acceleration of secondary electrons, emitted from the cathode target upon ion impact, as described by the well-known Thornton equation, which originally was formulated to give the minimum required voltage to sustain the discharge [1] . However, it has been demonstrated recently that Ohmic heating of electrons outside the cathode sheath is roughly of the same order as heating due to acceleration across the sheath in dc magnetron sputtering (dcMS) discharges [2] . When operated as high power impulse magnetron sputtering (HiPIMS) discharge Ohmic heating of the plasma electrons is found to dominate over sheath acceleration by typically an order of magnitude [3] . In HiPIMS discharge a high density plasma is created by applying high power pulses at low frequency and low duty cycle to a magnetron sputtering device. Here we discuss the large discharge currents, the discharge current composition at the target surface, and the electron energy distribution [4] in HiPIMS discharges. We discuss the role of self-sputter (SS-) recycling and working gas recycling within the discharge. We find that above a critical current density J crit ≈ 0.2 A/cm 2 , a combination of self-sputter recycling and working gas-recycling is the general case [5] . For high self-sputter yields, the discharges become dominated by SS-recycling, and contains only a few energetic secondary electrons. For low self-sputter yields, the discharges operated above J crit are dominated by working gas recycling, and secondary electrons play a more important role. We explore a discharge with Al target which develops almost pure self-sputter recycling, a discharge with Ti target that exhibits a mix of self-sputter recycling and working gas-recycling [6] , and discharges with graphite target and a reactive Ar/O 2 gas mixture with poisoned target where working gas-recycling dominates [7] .