Distribution Of Charged Particles Research Articles

Comparing Study on Formation of Large Discharge Currents in Atmospheric Pulse-Modulated Radio Frequency Discharges

In recent years, pulse-modulation is introduced in atmospheric radio frequency (RF) discharges to further control the discharge operation. In this article, a comparing study is performed by a 1-D fluid model to investigate the formation of large discharge currents (LDCs) in the first RF cycle during the power-on phase in an atmospheric pulse-modulated RF discharge controlled by dielectric barriers. The current–voltage characteristics and helium metastable (He*) distributions show the enhancement of a pulsed voltage on the ignition of RF discharge, which agrees well with the experimental observation. On the other hand, in a dielectric barrier discharge driven by a sinusoidal voltage of 500 MHz, double LDCs are observed in the positive and negative half-cycles, respectively, and the large pulse rise rate of applied voltage essentially influences the distribution of charged particles in the first cycle during the power-on phase. In this study, according to computational data the reverse electric field near the anode contributes greatly to the generation of LDCs in both types of discharge, and the appropriate discharge conditions are suggested to optimize the pulse-modulated RF discharges in applications.

Characteristics and Underlying Physics of Bipolar Corona Discharge of Floating Conductor

Bipolar corona discharge is the fundamental phenomenon that preoccurs in air breakdown for nongrounded objects facing a high-voltage source, which sets important bases for aircraft protection crossing thunderclouds and improvement of high-voltage switches with floating conductors, while this phenomenon has not been fully understood to date. This article proposes a bipolar corona plasma model (BCPM) based on the plasma hydrodynamic process and the chemical reactions of air discharge. The numerical analysis of the charged particle distribution matches the experimental result of the bipolar corona discharge appearance. Furthermore, the characteristics of bipolar corona discharge are described from the perspective of electric field and electron current density at the two opposite ends of the floating conductor. Results show that, at the positive end, the corona discharge has a long columnar shape in a faint light blue. While at the negative end, the corona presents a spherical shape in a stronger luminous light purple. There exists a density extremum at the position 0.03 cm away from the conductor ends in the distribution of electrons, where a low electron density zone with a concentration of 0.42 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\times \,\,10^{13}\,\,\text{m}^{-3}$ </tex-math></inline-formula> forms at the positive end, while electrons group to a high density of 2 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\times \,\,10^{16}\,\,\text{m}^{-3}$ </tex-math></inline-formula> at the negative end. The geometric length of the high-density ions zone is enlarged by 2 times at the positive end compared to the negative end. The peak electric field at the negative end is about 1.5 times stronger than the electric field at the positive end, consistent with the space charge distribution at the positive and negative ends. The unbalance of the emission and entry of electron current results in a slightly positive polarity for the floating conductor. This study can be consulted for shedding light on the underlying physics of bipolar corona discharge of floating conductors.

Synthesis and Evaluation of Finasteride-Loaded HPMC-Based Nanogels for Transdermal Delivery: A Versatile Nanoscopic Platform.

Herein, we report nanogels comprising diverse feed ratio of polymer hydroxypropyl methylcellulose (HPMC), monomer acrylic acid (AA), and cross-linker methylene bisacrylamide (MBA) fabricated for transdermal delivery of finasteride (FIN). Free radical solution polymerization method with subsequent condensation was employed for the synthesis using ammonium per sulfate (APS) and sodium hydrogen sulfite (SHS) as initiators. Carbopol-940 gel (CG) was formulated as assisting platform to deliver FIN nanogels transdermally. Developed formulations were evaluated by several in vitro, ex vivo, and in vivo parameters such as particle size and charge distribution analysis, Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), scanning electron microscopy (SEM), X-ray diffractogram (XRD), rheological testing, in vitro swelling and drug release, and ex vivo skin permeation, irritation, and toxicity assessment. The results endorsed the nanogel formation (117.3 ± 29.113 nm), and the impact of synthesizing method was signified by high yield of nanogels (≈91%). Efficient response for in vitro swelling and FIN release was revealed at pH 5.5 and 7.4. Skin irritation and toxicity assessment ensured the biocompatibility of prepared nanocomposites. On the basis of the results obtained, it can be concluded that the developed nanogels were stable with excellent drug permeation profile across skin.

QGP generation and evolution simulation of pp collision on LHC

In this paper, the generation of Quark-Gluon Plasma(QGP) in proton–proton collisions is discussed based on the thermal equilibrium theory. A partons list at the initial stage of collisions are obtained by digital sampling method, which provides a reasonable initial state for the subsequent evolution simulation. The calculation shows that the multiplicity distribution of the final charged particles obtained by this method is very similar to that of experiment or PYTHIA event generator. Thus, a new mechanism for hadron production in LHC is proposed.

Vacuum breakdown in magnetic dipole wave by 10-PW class lasers.

The vacuum breakdown by 10-PW-class lasers is studied in the optimal configuration of laser beams in the form of an m-dipole wave, which maximizes the magnetic field. Using 3D PIC simulations we calculated the threshold of vacuum breakdown, which is about 10PW. We examined in detail the dynamics of particles and identified particle trajectories which contribute the most to vacuum breakdown in such highly inhomogeneous fields. We analyzed the dynamics of the electron-positron plasma distribution on the avalanche stage. It is shown that the forming plasma structures represent concentric toroidal layers and the interplay between particle ensembles from different spatial regions favors vacuum breakdown. Based on the angular distribution of charged particles and gamma photons a way to experimentally identify the process of vacuum breakdown is proposed.

Measurement of angular and momentum distributions of charged particles within and around jets with the ATLAS detector

Studies of jet fragmentation in heavy-ion collisions can provide information about the mechanism of jet quenching inside the hot and dense QCD matter created in these collisions. These proceedings present results from measurements of charged particle yields within and around the jets in dijet, gamma+jet and Z+jet systems measured in $5.02$~TeV Pb+Pb and $pp$ collisions using the ATLAS detector at the LHC.

Resolving Space Plasma Species With Electrostatic Analyzers

Electrostatic analyzers resolve the energy-per-charge distributions of charged plasma particles. Some space plasma instruments use electrostatic analyzers among other units, such as aperture deflectors and position sensitive detectors, in order to resolve the three-dimensional energy (velocity) distribution functions of plasma particles. When these instruments do not comprise a mass analyzer unit, different species can be resolved only if there are measurable differences in their energy-per-charge distributions. This study examines the ability of single electrostatic analyzer systems in resolving co-moving plasma species with different mass-per-charge ratios. We consider examples of static plasma consisting of two species of heavy negative ions measured by a typical electrostatic analyzer design, similar to the electron spectrometer on board Cassini spacecraft. We demonstrate an appropriate modeling technique to simulate the basic features of the instrument response in the specific plasma conditions and we quantify its ability to resolve the key species as a function of the spacecraft speed and the plasma temperature. We show that for the parameter range we examine, the mass resolution increases with increasing spacecraft speed and decreasing plasma temperature. We also demonstrate how our model can analyze real measurements and drive future instrument designs.

Localized Excitation of Electromagnetic Ion Cyclotron Waves From Anisotropic Protons Filtered by Magnetic Dips

AbstractThe excitation of electrostatic and/or electromagnetic waves in the plasma universe is often associated with anisotropic velocity distributions of charged particles. In Earth's inner magnetosphere, this anisotropy can gradually develop as particles injected from the magnetotail drift around the Earth at different speeds depending on their energy and pitch angle. Here, we show that the perpendicular‐moving and bouncing ions can be separated more abruptly near the injection front. These pitch‐angle filters are localized magnetic dip structures formed by the diamagnetic behavior of the injected particles, which can trap perpendicular‐moving ions and allow bouncing ions to overtake. The resulting ion anisotropy facilitates the rapid generation of electromagnetic ion cyclotron (EMIC) waves, which in turn can largely reshape the Van Allen radiation belts. This scenario is examined by case and statistical observations, together with numerical simulations that reproduce most of the observational signatures, to support the causal relationship between magnetic dips, anisotropic ion distributions, and localized excitation of EMIC waves. Our study highlights the important roles of magnetic dips in the inner magnetospheric dynamics, as pitch‐angle filters of the injected ions and traveling hotspots of EMIC wave activities.

Pseudorapidity distribution of energy density and distribution of charged particles in different categories of the final state in pp collisions at s = 13 TeV

In this paper, we present here a detailed study of several observables as a function of pseudorapidity from several hadron production models commonly used for extended air shower simulations and compare these predictions with [Formula: see text] collisions measured by the CMS experiment at [Formula: see text] TeV. To facilitate the model/data comparisons, the pseudorapidity binning used in the energy density spectra data was also applied to the Monte Carlo analysis ([Formula: see text] and [Formula: see text]). Given that no model currently describes the full breadth of available hadronic collision data, four independent models were used in the comparison study, each with differences in the handling of soft quantum chromodynamics processes, in particular. The analysis results show that predictions from EPOS-LHC provide good agreement with the data, in contrast with the other models used in the study (QGSJETII-04, DPMJET-3.19, Sibyll2.3d). Significant modifications may be required in the rest of the model-based generators for them to provide a better description of the experimental observations.

Mechanism of Electric Charging of Aluminum Oxide Particles When Burning Solid Fuels

The mechanism of electrical charging of particles of aluminum oxide during the combustion of aluminized solid fuels due to the capture of ions and electrons by particles in high-temperature combustion products is considered. An analysis of the kinetics of aluminum oxide primary particles charging in the combustion zone around an aluminum particle was performed. It is shown that the charging of primary oxide particles via the capture of ions and electrons is fast. Moreover, because of the higher mobility of electrons, the particles are charged predominantly negatively. Thermionic emission is considered as an additional mechanism for the electrification of aluminum oxide particles. Because of the lack of data on the work function of the molten aluminum oxide, the parametric calculations for the primary particles electrification were performed at different values of the work function. Based on the experimental results for the electrification of oxide particles in the combustion products of aluminized solid fuels, the work function of electrons, for which the charge distribution of primary oxide particles is close to bipolar, is estimated.

Multiplicity Distribution and KNO Scaling of Charged Particles Production from pp Collisions at Different Energies

The multiplicity distribution of charged particles produced from proton–proton collisions at energies s = 2.36, 2.76, 5, 7, 8, 10, 13 and 14 TeV were studied in the present work. Furthermore, multiplicity distribution was studied in different pseudorapidity regions ∣η∣ &lt; 0.5, 1, 1.5, 2, and 2.5. KNO scaling was studied at the same pseudorapidity regions. This is valid in the pseudorapidity region ∣η∣ &lt; 0.5, but with increasing pseudorapidity, the violation increases. The influence of MPI and color reconnection in violation of KNO scaling were studied. The relation between mean multiplicity and collisions energy was explored, noted that it increases with the increasing energy of collisions.

Uncertainties in Evaluating Global Electric Circuit Interactions With Atmospheric Clouds and Aerosols, and Consequences for Radiation and Dynamics

AbstractObservations and theory relevant to evaluating the importance of the effect of Ionosphere‐Earth current density, JZ, in the global electric circuit on cloud microphysics and cloud opacity at high latitudes, with presumed consequences for surface pressure, are reviewed and updated. The day‐to‐day input variations are less than 10% of their mean values, as are the reported cloud and pressure effects, but could be indicative of more important longer‐term effects, and of neglected processes in aerosol‐cloud interactions. There is consistent evidence for responses to both externally (solar‐wind) and internally (thunderstorm and shower‐cloud) generated changes in JZ and cloud opacity. The pressure correlations show non‐stationary behavior, with changes in phase relative to that of the solar wind input and JZ variations on interdecadal timescales. These might be due to the non‐stationary nature of the solar wind, and non‐stationary aerosol populations. For modeling the cloud effects there are considerable uncertainties in the size and charge distributions of aerosol particles, droplets, and ice particles. The cloud radiative coupling with periodic solar wind inputs may nudge internal tropospheric waves into phase coherence at times when the amplitude of the solar input and the duration of the input trains exceed minimum values.

Sub-Poissonian multiplicity distributions in jets produced in hadron collisions

In this work we show that the proper analysis and interpretation of the experimental data on the multiplicity distributions of charged particles produced in jets measured in the ATLAS experiment at the LHC indicates their sub-Poissonian nature. We also show how, by using the recurrence relations and combinants of these distributions, one can obtain new and otherwise unavailable information contained in them, which may broaden our knowledge of the particle production mechanism.

Spectral tracking of energetic charged particles in wide field-of-view with miniaturized telescope MiniPIX Timepix3 1 × 2 stack

A highly integrated particle telescope is assembled from two MiniPIX Timepix3 detectors in stack configuration to provide time- and spectral-sensitive tracking of energetic charged particles. The telescope architecture, high granularity and per-pixel spectral response of the imaging detectors enable directional mapping of energetic charged particles in wide field-of-view (FoV) with high angular resolution (sub degree) without the need for collimators. The pixel detectors are operated in sync and readout each with separate USB 2.0 cable for integrated control and power supply. Timepix3 two per-pixel signal channels are operated in energy and time mode for detailed spectral- and time-registration of single events in each detector. Events are registered with time stamp resolution at tens of ns level between both detectors. Correlated events between both detector layers are resolved by correlated time stamp with a coincident time window <100 ns. The stack sync configuration allows to perform precise spectrometry (energy loss) and high-resolution tracking over the entire FoV. Particle-event classification is enhanced by spectral and tracking analysis of correlated events in both detectors. The sensors of the detectors can be of different semiconductor material or thickness for selective multiple energy loss ΔE1 + ΔE2 technique. Data products include detailed angular distributions of energetic charged particles with high angular resolution, time stamp, spectral response (energy loss, LET value) and enhanced particle-type resolving power of over 8 event classes. The directional response and angular resolution depend on the spacing gap between the tracker detectors. The resulting field-of-view, geometric factor and angular resolution are evaluated. Results are presented with proof-of-principle of the technique and evaluation of synchronized operation with 31 MeV protons.

To the Statistical Description of the Structure Formation in Coulomb-like Systems

A new solution to the problem of the calculation of the partition function for a Coulomb-like system is proposed. The quantum-field-theory approach is used to give a statistical description of a system of interacting particles with due regard to an arbitrary spatially inhomogeneous configuration. The formation of structures in a Coulomb-like system is analyzed and applied to thedusty plasma treatment. A necessary condition for the crystal formation in a three-dimensional system of dust particles is obtained. In the one-dimensional case, an exact solution for the spatial distribution of charged particles is presented.

Representation and modeling of charged particle distributions in tokamaks

Experimental diagnostics, analysis tools and simulations represent particle distributions in various forms and coordinates. Algorithms to manage these data are needed on platforms like the ITER Integrated Modeling & Analysis Suite (IMAS), performing tasks such as archiving, modeling, conversion and visualization. A method that accomplishes some of the required tasks for distributions of charged particles with arbitrarily large magnetic drifts in axisymmetric tokamak geometry is described here. Given a magnetic configuration, we first construct a database of guiding center orbits, which serves as a basis for representing particle distributions. The orbit database contains the geometric information needed to perform conversions between arbitrary coordinates, modeling tasks, and resonance analyses. Using that database, an imported or newly modeled distribution is mapped to an exact equilibrium, where the dimensionality is reduced to three constants of motion (CoM). The orbit weight is uniquely given when the input is a true distribution: one that measures the number of physical particles per unit of phase space volume. Less ideal inputs, such as distributions estimated without drifts, or models of particle sources, can also be processed. As an application example, we reconstruct the drift-induced features of a distribution of fusion-born alpha particles in a large tokamak, given only a birth profile, which is not a function of the alpha's CoM. Repeated back-and-forth transformations between CoM space and energy-pitch-cylinder coordinates are performed for verification and as a proof of principle for IMAS.

Jet shape and redistribution of the lost energy from jets in Pb\xa0+\xa0Pb collisions at the LHC in a multiphase transport model

Jet-medium interaction involves two important effects: jet energy loss and medium response. The search for jet-induced medium excitations is one of the hot topics in jet quenching study in relativistic nuclear collisions. In this work, we perform a systematic study on how the lost energy from hard jets evolves with the bulk medium and redistributes in the final state of heavy-ion collisions via a multi-phase transport model. In particular, the (Delta eta , Delta phi ) distribution of charged particles with respect to the jet axis and jet shape function are studied for various Pb + Pb collision centralities and for different transverse momentum intervals of charged particles. Our numerical result shows a strong enhancement of soft particles at large angles for Pb + Pb collisions relative to p + p collisions at the LHC, qualitatively consistent with recent CMS data. This indicates that a significant fraction of the lost energy from hard jets is carried by soft particles at large angles away from the jet axis.

PACIAE 2.2.1: An updated issue of the parton and hadron cascade model PACIAE 2.2

The parton and hadron cascade model PACIAE 2.2 (cf. Yan et al. (2018) [11]) has been upgraded to the new issue of PACIAE 2.2.1 with the chiral magnetic effect (CME). The charge correlation parameter, γss and γos, which is typically used to “detect” the CME, is calculated by PACIAE 2.2.1 in Au+Au and Pb+Pb collisions, and the result is consistent with the STAR and ALICE data. As an example, PACIAE 2.2.1 model is employed to mimic the pseudorapidity distribution (dNch/dη) and transverse momentum spectra (pT) of charged particles in non-central Au+Au collisions at RHIC energy and Pb+Pb collisions at LHC energy. The chiral magnetic effect is found to partly affect the final-state basic observables in relativistic nuclear collisions. By this new issue a more realistic dynamical evolution of relativistic nuclear collisions can be depicted. Program summaryProgram Title: PACIAE version 2.2.1CPC Library link to program files:https://doi.org/10.17632/w3g68dj4d9.3Code Ocean capsule:https://codeocean.com/capsule/3695338Licensing provisions: CC By 4.0Programming language: FORTRAN 77 or GFORTRANJournal reference of previous version: Comput. Phys. Comm. 224 (2018) 417Does the new version supersede the previous version?: No.Reasons for the new version: In order that PACIAE 2.2.1 model is now able to simulate the CME-related physics and a more realistic dynamical evolution scenario in the relativistic nucleus-nucleus collisions.Summary of revisions: In PACIAE 2.2.1 model the chiral magnetic effect is introduced. The CME-induced charge separation mechanism [7] into the initial partonic states is artificially added by switching py values for a fraction f of the downward moving partons with those of the corresponding upward moving antipartons.Nature of problem: PACIAE is based on PYTHIA, where it has no any mechanisms to generate the chiral magnetic effect (CME). The CME is a novel transport phenomenon arising from the interaction between quantum anomalies and strong magnetic fields in the ultra-relativistic nuclear collisions. Charge separation is an important consequence of the CME. In order to depict the CME, the corresponding upgrade about introducing a global charge separation scheme into the initial partonic states is highly required.Solution method: The global CME-induced charge separation mechanism [7] into the initial partonic states is introduced by switching py values for a fraction f of the downward moving partons with those of the corresponding upward moving antipartons.Additional comments including restrictions and unusual features: PACIAE 2.2.1 has three versions of PACIAE 2.2.1a, 2.2.1b, and 2.2.1c. PACIAE 2.2.1a is for the elementary collision (here no upgraded from PACIAE 2.2a). PACIAE 2.2.1b and PACIAE 2.2.1c are for the nucleus-nucleus collision of A + A with input file of usu.dat. PACIAE 2.2.1b and PACIAE 2.2.1c are similar in the physical contents but are different in the topological structure [8].•Using the attached input file of usux.dat to run 1000 events for the s = 200 GeV Non Single Diffractive pp collision by PACIAE 2.2.1a takes ≈0.5 min.•Using the attached input file of usu.dat to run 10 events for the 35%-45% non-central Au+Au collisions at sNN = 200 GeV by PACIAE 2.2.1b takes ≈6 min.•Using the attached input file of usu.dat to run 10 events for the 35%-45% non-central Au+Au collisions at sNN = 200 GeV by PACIAE 2.2.1c takes ≈8 min.

Влияние формы электродов на оптическое излучение плазмы кототкодугового разряда высокого давления в ксеноне

A short-arc high-pressure xenon discharge with a thoriated tungsten cathode (this is the reason for the presence of thorium atoms in the discharge gap) is investigated depending on the shape of the electrode surface. Based on the previously developed model, the electrokinetic characteristics and optical radiation of the plasma are calculated. It is shown that the shape of the electrode surface (the shape of the anode surface is considered in more detail) strongly affects, first of all, the electric field in the discharge gap, which, in turn, determines the plasma temperature and the spatial distributions of thorium atoms and charged particles (thorium and xenon ions). The resulting change in the electrokinetic characteristics significantly affects the optical radiation of the plasma, allowing the choice of the shape of the electrode surface to obtain the prevalence of radiation in the ultraviolet, visible, or infrared regions of the spectrum.

Rapidity-dependent charge-dependent flow, global polarisation and chiral magnetic effect in heavy ion collisions

An extremely strong magnetic field (as strong as 1015 T) is created in the off-central heavy-ion collisions by the spectator protons which "miss" the collisions, flying past each other rather than colliding. The magnetic field is interesting to be studied as it is expected to leave distinct imprints in the distribution of final state charged particles. In addition, novel QCD phenomena are anticipated to emerge with the presence of a strong magnetic field and the formation of charge-parity violating domains inside the medium produced in heavy-ion collisions. The aim of this article is to review two methods utilised by the experimental searches to probe the early magnetic field: the directed flow of charged hadrons (and heavy-flavour hadrons D0 and ¯D0) and the global polarisation of Λ and ¯Λ hyperons. Furthermore, this article is also dedicated to review the searches for one of the novel QCD phenomena, the chiral magnetic effect, at the LHC and RHIC.