Dynamics Of Charged Particles Research Articles

Simulation and Characterization of Micro-Discharge Phenomena Induced by Glitch Micro-Defects on an Insulated Pull Rod Surface

The reliability of GIS (gas-insulated switchgear) circuit breakers significantly depends on the condition of the insulated pull rods, with micro-defects on their surface posing a potential risk for micro-discharges and breakdown incidents. Experimentally investigating these micro-discharges is challenging due to their minute nature. This study introduces a framework to examine the linkage between micro-defects and micro-discharges, coupled with numerical simulations of the micro-discharge process in insulated pull rods afflicted by surface infiltration flaws under operational conditions. Initially, samples containing micro-defects were sectioned via water jet cutting for microstructural analysis through white light interferometry. Subsequently, a two-dimensional axisymmetric model simulating positive corona discharge from a needle to a plate electrode was employed to derive the relationship between charged particle density and the electric field in SF6 and air. Building on these observations, a micro-discharge model specific to micro-defects was developed. Comparative analysis of micro-discharge behaviors in SF6 and air for identical defect types was conducted. This research framework elucidates the discharge dynamics of charged particles in SF6 and air during micro-discharge events, shedding light on the mechanisms underpinning micro-discharges triggered by insulation rod defects.

The effects of plasma density structure on the propagation of magnetosonic waves: 1-D particle-in-cell simulations

Magnetosonic (MS) waves, i.e., ion Bernstein mode waves, are one of the common plasma waves in the Earth’s magnetosphere, which are important for regulating charged particle dynamics. How MS waves propagate in the magnetosphere is critical to understanding the global distribution of the waves, but it remains unclear. Although previous studies present that MS waves can be reflected by fine-scale density structures, the dissipation of waves by background plasma has long been neglected. In this study, we perform one-dimensional (1-D) particle-in-cell (PIC) simulations to study the propagation of MS waves through density structures, where both absorption and reflection have been included. We find that absorption is as important as reflection when considering the propagation of MS waves through density structures, and both of them are strongly dependent on the shape of density structures. Specifically, the reflectivity of MS waves is positively and negatively correlated with the height and width of density structures, respectively, while the absorptivity of MS waves has a positive correlation with both the height and width of density structures. Our study demonstrates the significance of absorption during the propagation of MS waves, which may help better understand the distribution of MS waves in the Earth’s magnetosphere.

Drift approximation by the modified Boris algorithm of charged-particle dynamics in toroidal geometry

AbstractIn this paper, we study the dynamics of charged particles under a strong magnetic field in toroidal axi-symmetric geometry. Using modulated Fourier expansions of the exact and numerical solutions, the long-term drift motion of the exact solution in toroidal geometry is derived, and the error analysis of the large-stepsize modified Boris algorithm over long time is provided. Numerical experiments are conducted to illustrate the theoretical results.

Advanced fuel fusion, phase space engineering, and structure-preserving geometric algorithms

Non-thermal advanced fuel fusion trades the requirement of a large amount of recirculating tritium in the system for that of large recirculating power. Phase space engineering technologies utilizing externally injected electromagnetic fields can be applied to meet the challenge of maintaining non-thermal particle distributions at a reasonable cost. The physical processes of the phase space engineering are studied from a theoretical and algorithmic perspective. It is emphasized that the operational space of phase space engineering is limited by the underpinning symplectic dynamics of charged particles. The phase space incompressibility according to the Liouville theorem is just one of many constraints, and Gromov's non-squeezing theorem determines the minimum footprint of the charged particles on every conjugate phase space plane. In this sense and level of sophistication, the mathematical abstraction of phase space engineering is symplectic topology. To simulate the processes of phase space engineering, such as the Maxwell demon and electromagnetic energy extraction, and to accurately calculate the minimum footprints of charged particles, recently developed structure-preserving geometric algorithms can be used. The family of algorithms conserves exactly, on discretized spacetime, symplecticity and thus incompressibility, non-squeezability, and symplectic capacities. The algorithms apply to the dynamics of charged particles under the influence of external electromagnetic fields as well as the charged particle–electromagnetic field system governed by the Vlasov–Maxwell equations.

Dynamics of charged particles in a solenoid and the accurate determination of the magnetic axis of a solenoid using measured field data.

A fundamental understanding of the theory and measurement procedures for characterizing a solenoid is crucial for making a project cost-effective and achieving the desired performance for its use in a LINAC. This paper attempts to comprehend the beam dynamics of charged particles by considering the conservation of canonical angular momentum, which can take on positive, negative, and zero values. The analytical expression to generate a parallel beam using a solenoid is derived. The effect of the final beam size on the values of a solenoid's spherical aberration coefficient and the position of the minimum beam size with respect to the focal length is studied using electron trajectories. A practical procedure to tune the above two parameters of a solenoid is demonstrated by simply modifying the demountable disks connected at each end. A mathematical model is proposed to accurately determine the axis of a solenoid and the magnetic centre using the measured magnetic field data, which is validated experimentally. Several solenoids, used in the 9.5MeV 10kW electron LINAC suitable for sterilizing medical products and food irradiation, have been characterised using this procedure.

Charged particle dynamics in an elliptically polarized electromagnetic wave and a uniform axial magnetic field

Charged particle dynamics in an elliptically polarized electromagnetic wave and a uniform axial magnetic field

A novel directly energy-preserving method for charged particle dynamics

In this paper, we apply the coordinate increment discrete gradient (CIDG) method to solve the Lorentz force system which can be written as a non-canonical Hamiltonian system. Then we can obtain a new energy-preserving CIDG-I method for the system. The CIDG-I method can combine with its adjoint method CIDG-II which is also a energy-preserving method to form a new method, namely CIDG-C method. The CIDG-C method is symmetrical and can conserve the Hamiltonian energy directly and exactly. With comparison to the well-used Boris method, numerical experiments indicate that the CIDG-C method holds advantage over the Boris method in terms of energy-conserving.

Diffusing Wave Spectroscopy Measurements of Colloidal Suspension Dynamics.

Diffusing wave spectroscopy (DWS) is used to measure the dynamics of charged silica particles between the volume fractions 0.065 ≤ ϕ ≤ 0.352 (weight percentages from 12.7 to 55.8 wt %). The short-time diffusivity averaged over the scattering vectors sampled by DWS (ϕ) decreases with an increasing concentration. An effective hard-sphere model that accounts for hydrodynamic interactions and a double-layer repulsion fits the values up to an effective volume fraction , where is the excluded shell radius normalized by the particle radius = b/a = 1.3. While DWS measurements of diffusivity are sensitive to repulsive interactions, we show that they are relatively insensitive to attraction, such as those due to secondary minima in the interaction potential or weak depletion interaction.

Nanoparticles synthesis in microwave plasmas: peculiarities and comprehensive insight

Low-pressure plasma processes are routinely used to grow, functionalize or etch materials, and thanks to some of its unique attributes, plasma has become a major player for some applications such as microelectronics. Plasma processes are however still at a research level when it comes to the synthesis and functionalization of nanoparticles. Yet plasma processes can offer a particularly suitable solution to produce nanoparticles having very peculiar features since they enable to: (i) reach particle with a variety of chemical compositions, (ii) tune the size and density of the particle cloud by acting on the transport dynamics of neutral or charged particles through a convenient setting of the thermal gradients or the electric field topology in the reactor chamber and (iii) manipulate nanoparticles and deposit them directly onto a substrate, or codeposit them along with a continuous film to produce nanocomposites or (iv) use them as a template to produce 1D materials. In this article, we present an experimental investigation of nanoparticles synthesis and dynamics in low-pressure microwave plasmas by combining time-resolved and in-situ laser extinction and scattering diagnostics, QCL absorption spectroscopy, mass spectrometry, optical emission spectroscopy and SEM along with a particle transport model. We showed for the first time the thermophoresis-driven dynamic of particle cloud in electrodless microwave plasmas. We showed that this effect is linked to particular fluctuations in the plasma composition and results in the formation of a void region in the bulk of the plasma surrounded by a particle cloud in the peripherical post-discharge. We also reveals and analyze the kinetics of precursor dissociation and molecular growth that result in the observed nanoparticle nucleation.

Comparative analysis of charged particle distributions in [formula omitted] collisions at [formula omitted] using Monte Carlo models and fitting functions

We conducted a detailed analysis of charged particle transverse momentum distributions using multiple Monte Carlo models – Pythia, HIJING, and QGSJET – compared against experimental data from the ATLAS detector in pp collisions at s=0.9TeV. Pythia emerged as the best among the models under study in representing most of the distributions due to its comprehensive modeling of parton showers, multiparton interactions, and underlying event dynamics, while QGSJET showed good results with the data in some of the distributions only. HIJING, however, was only able to replicate reduced phase-space distributions only.To further explore the collision medium and to extract important information about collective properties, we used the Tsallis-Pareto (TP) type function and the modified Hagedorn (MH) function. The Tsallis function enabled determination of the effective temperature (Teff) and the non-extensivity parameter (n1) while the MH function provided the kinetic freeze-out temperature (T0), transverse flow velocity (<βT>), and a secondary non-extensivity parameter (n2). Our investigation revealed changes in the effective freeze-out parameters based on event conditions. The Teff and <βT> derived from the TP and MH functions respectively exhibited higher values with a tighter pT cut of >500MeV compared to a more inclusive pT cut of >100MeV. Interestingly, the values of the non-extensivity parameters—n1 for the Tsallis function and n2 for the MH function were almost identical across both the experimental data and all three Monte Carlo models. These findings offer invaluable perspectives on the dynamics of charged particles in pp collisions at s=0.9TeV.

О некоторых задачах программного управления пучком траекторий. Часть II

The paper considers the problems of macroparameter control in a linear dynamic system. In the authors’ previous paper, such problems in controlling nonlinear systems were investigated. Variations of the considered functionals and necessary optimality conditions were obtained. This paper focuses on the trajectory beam control in the linear case. In this case, the problem of beam control can be reduced to the problem of the individual trajectory control. The developed approach may be of interest in the study of charged particle dynamics in accelerating and focusing structures, as well as in the construction of the velocity field in automatic image processing.

SIMULACIÓN DE LA INYECCIÓN DE UN HAZ NEUTRO EN TOKAMAKS CONTRIANGULARIDAD POSITIVA Y NEGATIVA

In this paper the dynamics of high energy charged particles in negative and positive triangularity tokamaks is through the simulation of a neutral beam injection on analytical MHD equilibria using the exact orbit code FOCUS. It is observed that the negative triangularity configuration presents fewer losses of non-thermal particles, and an energy deposition more localized than its counterpart.

Long-term analysis of exponential integrators for charged-particle dynamics in a strong and constant magnetic field

For the charged-particle dynamics under a strong and constant magnetic field, we consider and analyze exponential integrators in this paper. We derive two kinds of exponential integrators and study their long-time behavior by using the technique of modulated Fourier expansions. It is shown that a symmetric two-stage exponential integrator and some one-stage symplectic exponential integrators approximately conserve the energy and magnetic moment of the charged-particle dynamics over long times.

Dynamics of unipolar charged particles flowing through a cylindrical tube at high number concentrations

This work provides a theoretical and non-dimensional numerical analysis of the dynamics of gas-borne unipolar charged particles flowing through a cylindrical tube at high number concentrations. It is discovered that above a threshold input particle number concentration, the concentration at the exit of the tube is nearly constant and independent of further increase in the input. Based on a maximum of 2% sensitivity of the system, the threshold input number concentration is quantified for a tube of any length more than 40 × the radius. The theoretical analysis developed in this work is used to derive correlations for the threshold input concentration and the exit concentration, as well as show that the exit particle concentration is lower than the threshold input value by a factor of 20/PD, where PD is the well-known diffusive particle penetration. The analysis demonstrates that a constant concentration can occur if and only if the ratio of non-dimensional electric particle mobility to the Gormley-Kennedy diffusion parameter is above 74, which is a hitherto unexplored regime of charged aerosol flow dynamics. It is shown that the constant concentration can occur in compact tube designs (L/R<100) as long as the mass Peclet number of the particles is high and reducing the mass Peclet number to around 10 or below makes it impossible to obtain an input-independent number concentration. It is also shown that the Reynolds number of the flow has very little effect on the charged transport dynamics, where the order of magnitude of the input-independent number concentration is not highly sensitive to the Reynolds number, provided the system remains laminar. Finally, practical examples for designing instrumentation to generate a constant concentration of charged particles are discussed.

Continuous-stage adapted exponential methods for charged-particle dynamics with arbitrary magnetic fields

Continuous-stage adapted exponential methods for charged-particle dynamics with arbitrary magnetic fields

On charged particle dynamics near flat solid surface

The motion of a non-relativistic charged particle near flat solid surface at small sliding angles is examined within the formalism of the effective potential composed by interaction of a particle with surface atoms and excited plasmons. As known, the presence of curvature in a solid surface can result in forming a set of discrete quantum states for a particle in the potential well of interaction with the surface.In this work we demonstrate that, at the glancing to flat-surface motion of fast charged particles, small channeling oscillations can be also observed for some special conditions. It is shown that the effective interaction potential represents a shallow well capable to hold a particle in a bound state. We succeeded to analytically determine the energy levels of a particle in such a potential well, as well as the critical angle for a particle to be trapped, in terms of known critical angle of channeling in crystals and a newly proposed function for simplification.

Charged particles motion and quasiperiodic oscillation in Simpson–Visser spacetime in the presence of external magnetic fields

The present work is devoted to the study of the dynamics of charged particles around Simpson–Visser black holes (with the length parameter lle 2) and wormholes (l>2) immersed in an external asymptotically uniform magnetic field. To do this, first, we solve the Maxwell equation for 4-potentials of the electromagnetic field and show that the difference between the numerical solution and Wald’s solution is small enough to neglect it, which may allow us to use the solution obtained by Wald. We also study fundamental frequencies of in the vertical and radial oscillations of charged particles around circular stable orbits around the magnetized black hole. The effects of the magnetic interaction and length parameters on the fundamental frequencies. We investigate the quasiperiodic oscillations (QPOs) around the black hole in relativistic precession and epicyclic resonance models. It is also shown that the combined effects of magnetic interaction for negatively charged particles and length parameters can mimic the spacetime effects of the Schwarzschild black hole compensating for their effects, as well as the spin of rotating Kerr black holes. The distance between an orbit where a QPO is generated with the ratio of upper and lower frequencies 3: 2 and innermost stable circular orbits is also studied. It is found that the QPO orbits are very close to ISCO in the RP model at l<2. This implies that the obtained result helps to determine the ISCO around black holes. We also study the applications of observed QPOs around stellar-mass black holes in microquasars and supermassive black holes.

Dynamics of ultrarelativistic charged particles with strong radiation reaction. II. Entry into Aristotelian equilibrium

Dynamics of ultrarelativistic charged particles with strong radiation reaction. II. Entry into Aristotelian equilibrium

Dynamics of ultrarelativistic charged particles with strong radiation reaction. I. Aristotelian equilibrium state

Dynamics of ultrarelativistic charged particles with strong radiation reaction. I. Aristotelian equilibrium state

Physics informed neural network for charged particles surrounded by conductive boundaries

Molecular dynamics of charged particles in porous conductive media have received considerable attention in recent years due to their application in cutting-edge technologies such as batteries and supercapacitors. Due to the presence of long-range electrical interactions, induced charges present at the boundary, and the influence of boundary conditions, the simulation of these systems is more challenging than the simulation of typical molecular dynamic systems. Simulating these kinds of systems typically involves using a numerical solver to solve the Poisson equation, which is a very time-consuming procedure. Recently, Physics-Informed Neural Networks (PINNs) have been introduced as an alternative to numerical solutions of PDEs. In this paper, we present a new PINN-based model for predicting the potential of point-charged particles surrounded by conductive walls. As a result of the proposed PINN model, the mean square error is less than 7% and R^{2} score is more than 90% for the corresponding example simulation. Results have been compared with typical neural networks and random forest as standard machine learning algorithms. The R^{2} score of the random forest model was 70%, and a standard neural network could not be trained well.