scholarly journals Self-Organization of Charged Particles in an Electric Field

2021 ◽  
pp. 46-62
Author(s):  
William J. B. Oldham Jr.
Keyword(s):  
Electric Field ◽  
Electric Fields ◽  
Charged Particles ◽  
Opposite Polarity ◽  
Self Organization ◽  
Constant Field ◽  
Particle Interactions ◽  
Small Systems ◽  
System States ◽  
Final System

Self-organization in small systems of particles with simple dynamic laws has been simulated. The purpose of this work was to investigate self-organization in small systems of charged particles under the influence of an electric field where we could follow individual particles. There are positively and negatively charged particles. The intention is to look for pattern formation as the system evolves. Three electric fields and the particle-to-particle interactions were utilized to provide the forces. The three electric fields were a constant field, a ramp field, and an oscillatory field. The final system states for various electric fields are presented. For the two kinds of particles simulated, like particles have a repulsive force, while unlike particles have an attractive force. Initially, the particles are randomly distributed in a two dimensional square bounded region, and then allowed to dynamically interact for a number of iterations. Using the inverse square law force, modified at short distances, most cases resulted in equilibrium with the particles of opposite polarity paired up. Since this was a state of equilibrium no more movement occurred. The results of the experiments are presented in graphical format. The main conclusions are that this model can be used to study small dynamic systems, and that the presence of an external electric field does not significantly modify the final configuration but hastens the development of the equilibrium state.

scholarly journals A Study of Self-Organization in Small Systems with Simple Dynamics

2020 ◽  
pp. 39-59
Author(s):  
William J. B. Oldham ◽  
James Rejcek
Keyword(s):  
Dynamic Systems ◽  
Opposite Polarity ◽  
Repulsive Force ◽  
Self Organization ◽  
Two Dimensional ◽  
System State ◽  
Small Systems ◽  
Final System ◽  
Individual Particles ◽  
Number Of Iterations

Self-organization in small systems of particles with simple dynamic laws has been simulated.  The purpose of this work is to investigate self-organization in small systems where we could follow individual particles.  The intention is to look for pattern formation as the system evolves.  For the two kinds of systems studied, the motion and the final system state for various dynamic iterations are presented.  In the first system design, two kinds of particles are simulated.  Like particles have a repulsive force, while unlike particles have an attractive force.  Initially, the particles are randomly distributed in a two dimensional square bounded region, and then allowed to dynamically interact for a number of iterations.  In experiment 1 the particles have different polarity.  Using the inverse square law force, modified at short distances, most cases resulted in equilibrium with the particles of opposite polarity paired up. Since this was a state of equilibrium no more movement occurred.  In the second experiment, there are two groups of particles initially separated by a boundary.  The particles on each side of the boundary are further divided into two groups referred to as strong or weak particles.  In this experiment the resulting patterns were clusters of particles. The forces among all of the particles can be varied to study the configurations that result from the dynamics.  The results of the experiments are presented in graphical format.  The main conclusion is that this model can be used to study small dynamic systems.

scholarly journals Ionization Waves Enhance the Production of X-rays during Streamer Collisions

Atmosphere ◽  
2021 ◽  
Vol 12 (9) ◽  
pp. 1101
Author(s):  
Vernon Cooray ◽  
Gerald Cooray ◽  
Marcos Rubinstein ◽  
Farhad Rachidi
Keyword(s):  
Experimental Data ◽  
Electric Field ◽  
Electric Fields ◽  
Time Synchronization ◽  
Field Enhancement ◽  
Opposite Polarity ◽  
X Rays ◽  
Weakly Conducting ◽  
Ionization Waves ◽  
Discharge Gap

Experimental data show that in laboratory sparks, X-rays are produced in time synchronization with the meeting of streamers of opposite polarity just before the final breakdown of the discharge gap. It has been suggested that the electric field enhancement created during the collision of streamers could provide the necessary conditions for electron acceleration, even though some of the theoretical studies show that the duration of the electric field is not long enough to do so. The experimental data on laboratory discharges show that. when streamers of opposite polarity meet each other, a potential or ionization wave that renders the streamer channels conducting is initiated. This paper shows that these ionization waves that convert the discharge channels from weakly conducting to highly conducting are associated with electric fields large enough to accelerate electrons to relativistic energies.

scholarly journals Using Wavelet Transform To Extract Frequency Content In Electric Field Radiated By Unusual Lightning Activity

2021 ◽  
Vol 14 (14) ◽  
pp. 62-67
Author(s):  
Suraj Neupane ◽  
Shriram Sharma ◽  
Puja Sharma
Keyword(s):  
Wavelet Transform ◽  
Electric Field ◽  
Electric Fields ◽  
Time Domain ◽  
Opposite Polarity ◽  
Frequency Content ◽  
Field Change ◽  
Polarity Field ◽  
Main Activity ◽  
Domain Information

In this frequency spectrum electric fields radiated by the unusual lightning activities have been computed using the wavelet transform technique. The unusual lightning activities have very recently been identified activities and are very poorly understood among the lightning community. As the electric fields are very recently identified and are measured in time domain, to the best of our knowledge, their frequency content has not been studied as of today. To understand the physics of the discharge mechanism of such events, the frequency domain information plays a significant role. In order to extract frequency domain information from the time domain electric field signatures the wavelet transform technique has been employed. For the purpose, the electric field pertinent to the unusual activity, has been divided into two parts namely main activity and the preceding opposite polarity field change.  From the computation, it is found that the opposite-polarity field change radiates energy in the spectral range of 2 kHz to 173 kHz whereas, the main activity predominantly radiates in the frequency range 2 kHz to 162 kHz. Such a wider spectral range that the unusual activities radiate have not been reported for the other known activities such as positive and negative return strokes. Evidently, the unusual events have some unique origin of discharge unlike the known activities. Further, as the unusual events were noticed in the temperate region (Uppsala, Sweden) and Sub-tropical climatic zone (Kathmandu, Nepal), it should have some common source of origin between two regions.

scholarly journals Relation between magnetic fields and electric currents in plasmas

2005 ◽  
Vol 23 (7) ◽  
pp. 2589-2597 ◽  
Author(s):  
V. M. Vasyliunas
Keyword(s):  
Electric Field ◽  
Time Scales ◽  
Electric Fields ◽  
Spatial Scales ◽  
Charged Particles ◽  
Displacement Current ◽  
Plasma Dynamics ◽  
Electric Fields And Currents ◽  
The One ◽  
The Magnetic Field

Abstract. Maxwell's equations allow the magnetic field B to be calculated if the electric current density J is assumed to be completely known as a function of space and time. The charged particles that constitute the current, however, are subject to Newton's laws as well, and J can be changed by forces acting on charged particles. Particularly in plasmas, where the concentration of charged particles is high, the effect of the electromagnetic field calculated from a given J on J itself cannot be ignored. Whereas in ordinary laboratory physics one is accustomed to take J as primary and B as derived from J, it is often asserted that in plasmas B should be viewed as primary and J as derived from B simply as (c/4π)∇×B. Here I investigate the relation between ∇×B and J in the same terms and by the same method as previously applied to the MHD relation between the electric field and the plasma bulk flow vmv2001: assume that one but not the other is present initially, and calculate what happens. The result is that, for configurations with spatial scales much larger than the electron inertial length λe, a given ∇×B produces the corresponding J, while a given J does not produce any ∇×B but disappears instead. The reason for this can be understood by noting that ∇×B≠4π/c)J implies a time-varying electric field (displacement current) which acts to change both terms (in order to bring them toward equality); the changes in the two terms, however, proceed on different time scales, light travel time for B and electron plasma period for J, and clearly the term changing much more slowly is the one that survives. (By definition, the two time scales are equal at λe.) On larger scales, the evolution of B (and hence also of ∇×B) is governed by ∇×E, with E determined by plasma dynamics via the generalized Ohm's law; as illustrative simple examples, I discuss the formation of magnetic drift currents in the magnetosphere and of Pedersen and Hall currents in the ionosphere. Keywords. Ionosphere (Electric fields and currents) – Magnetospheric physics (Magnetosphere-ionosphere interactions) – Space plasma physics (Kinetic and MHD theory)

Dielectrophoresis of Nanoparticles

2004 ◽  
Author(s):  
Arun Thankamony John Kadaksham ◽  
Pushpendra Singh ◽  
Nadine Aubry
Keyword(s):  
Brownian Motion ◽  
Electric Field ◽  
Electric Fields ◽  
Numerical Scheme ◽  
Relative Magnitude ◽  
Hydrodynamic Forces ◽  
Uniform Electric Field ◽  
Particle Interactions ◽  
Particle Trajectories ◽  
Random Manner

A numerical scheme based on the distributed Lagrange multiplier method (DLM) is used to study the motion of nano sized particles of dielectric suspensions subjected to uniform and nonuniform electric fields. Particles are subjected to both electrostatic and hydrodynamic forces, as well as Brownian motion. The results of the simulations presented in this paper show that in the case of uniform electric fields the evolution of the particle structures depends on the ratio of electrostatic particle-particle interactions and Brownian forces. For solids fraction of the order 0.01, when this ratio is of the order of a hundred or more particles form stable chains and columns whereas when this ratio is of the order ten the particles are distributed in a random manner. For the non uniform electric field cases considered in this paper, the relative magnitude of Brownian forces is in the range such that it does not influence the eventual collection of particles by dielectrophoresis and the particular locations where the particles are collected. However, Brownian motion is observed to influence the transient particle trajectories. The deviation of the particle trajectories compared to those determined by the electrostatic and hydrodynamic forces alone is characterized by the ratio of Brownian and dielectrophoretic forces.

scholarly journals Response of equatorial ionosphere to episodes of asymmetric ring current activity

1997 ◽  
Vol 15 (10) ◽  
pp. 1316-1323 ◽  
Author(s):  
J. H. Sastri ◽  
M. A. Abdu ◽  
J. H. A. Sobral
Keyword(s):  
Electric Field ◽  
Electric Fields ◽  
Ring Current ◽  
Opposite Polarity ◽  
Equatorial Region ◽  
Local Times ◽  
High Time Resolution ◽  
Plasma Drift ◽  
F Region ◽  
Current Events

Abstract. We present the characteristics of the response of equatorial ionospheric zonal electric field and F-region plasma density to the asymmetric ring current intensifications that occurred in succession on 16 December 1991, corresponding to the STEP/EITS-2 campaign period. The study is based on high-time- resolution (1-min) data of asymmetic ring current indices, ASY(H/D) and F-region vertical plasma drift, Vz measurements at Kodaikanal (10.25°N; 77.5°E; dip 4°), India and quarter-hourly ionosonde data of Fortaleza (4°S; 322°E; dip –9°), Brazil. It is shown that short-lived disturbances in F-layer vertical plasma drift, Vz and height (h'F/hpF2) indicative of westward and eastward electric fields prevail simultaneously in the dusk (18–21 LT) and predawn (02–05 LT) sectors, respectively, in association with the decay phase of asymmetic ring current events. Electric fields of opposite polarity do also seem to manifest at these local times, particularly in the early-morning sector in conjunction with the intensification of the asymmetric ring current. At a given location, electric field disturbances associated with individual asymmetric ring current events are thus bipolar in nature, with fields of opposite polarity during the growth and decay phases. The nature and polarity structure of the observed electric field disturbances are in agreement with the theoretical/model predictions of prompt penetration of high-latitude electric fields to the equatorial region.

scholarly journals On the effect of concentration on the spectra luminous gase

1920 ◽  
Vol 98 (691) ◽  
pp. 255-260 ◽  
Keyword(s):  
Electric Field ◽  
Electric Fields ◽  
Charged Particles ◽  
Sodium Atom ◽  
Reliable Data ◽  
Bunsen Flame ◽  
Qualitative And Quantitative ◽  
Spark Discharges ◽  
Close Proximity ◽  
Chemical Character

It is now more than forty years since Lockyer made the remarkable observation that in the spectra of electric spark discharges in mixtures of nitrogen and oxygen, the nitrogen lines were narrow and the oxygen lines broad when the oxygen was present in excess, and in the same way the oxygen lines were narrow and the nitrogen lines broad when the nitrogen was in excess. Although Lockyer put this discovery to practical use in order to make accurate measurements of the wave-lengths of the lines, it seems to have been relegated since to the numerous phenomena in spectroscopy which defy an explanation. Effects akin to this are by no means uncommon. It has long been known that the widths of spectrum lines from flames containing sodium or lithium are greatly affected by the concentration of these substances in the flame. Lord Rayleigh remarks, in connection with the behaviour of the D lines of sodium in the Bunsen flame, “Is there no distinction in kind between encounters first of two sodium atoms and secondly of one sodium atom and an atom, say, of nitrogen ? The behaviour of soda dames shows that there is. Otherwise it seems impossible to explain the great effect of relatively very small additions of soda in presence of large quantities of other gases. The phenomena suggest that the failure of the least coloured dames to give so high an interference as is calculated from Doppler’s principle may be due to encounters with other gases, but that the rapid falling off when the supply of soda is increased is due to something special. This might be of a quasi­ chemical character, e.g., to temporary associations of atoms, or again to vibrators in close proximity putting one another out of tune.” Since these words were written our knowledge of the circumstances which govern the widths of broadened spectrum lines under certain specified conditions has materially increased. Stark’s suggestion,‡ that the broadening of the lines in the spectra of condensed spark discharges is intimately connected with the resolution of the lines into components by the electric field, has been fully confirmed, and it has been shown that in the case of hydrogen and helium the broadening observed under these conditions can be accounted for satisfactorily and completely by the resolution of the lines by the electric fields of neighbouring charged particles on the radiating atoms. The electrical resolution of the lines of hydrogen and helium has been examined by a number of observers, and reliable data, both qualitative and quantitative, are available; in the case of other elements, though considerable progress has been made, our information is less complete, but it is known that for a given electric field the resolution of the lines of heavier atoms such as sodium is very small in comparison with that of the hydrogen or helium lines. It is difficult, therefore, to account for the behaviour of the lines of sodium and many other lines of heavy elements which broaden easily to an extent which seems quite out of proportion to their electrical resolution.

scholarly journals No light at the end of the tunnel

2021 ◽  
Vol 75 (5) ◽  
Author(s):  
H. R. Reiss
Keyword(s):  
Charged Particle ◽  
Electric Field ◽  
Electric Fields ◽  
Quantum Tunneling ◽  
Laser Field ◽  
Laser Light ◽  
Particle Interactions ◽  
Propagation Property ◽  
Tunneling Model ◽  
Low Frequencies

Abstract The tunneling model for laser-induced processes implies the replacement of the propagating field of a laser by an oscillatory electric field. The view of the electric field as the primary influence in charged particle interactions fails for laser processes where the propagation property is important. Electric fields lack several quintessential laser-field properties that become dominant at high intensities and/or low frequencies. Quantum tunneling is not a concept generally suited to laser light. Conversely, laser criteria do not apply to electric-field phenomena like Sauter–Schwinger pair production in the vacuum, contrary to a widespread assumption. Graphic abstract

scholarly journals MOVEMENT OF CHARGED PARTICLES IN MAGNETIC AND NONUNIFORM STOCHASTIC ELECTRIC FIELDS

2021 ◽  
pp. 112-117
Author(s):  
N.A. Azarenkov ◽  
A.D. Chibisov ◽  
D.V. Chibisov
Keyword(s):  
Electric Field ◽  
Electric Fields ◽  
Cyclotron Frequency ◽  
Charged Particles ◽  
Planck Equation ◽  
Homogeneous Magnetic Field ◽  
Equation Of Motion ◽  
Stochastic Field ◽  
Characteristic Oscillation ◽  
Diffusion Motion

The equation of motion of charged plasma particles in a homogeneous magnetic field and in an inhomogeneous stochastic electric field with a characteristic oscillation frequency much lower than the electron cyclotron frequency and much higher than the ion cyclotron frequency is solved. The diffusion motion, as well as the drift of ions and guiding center of electrons, due to the inhomogeneity of the stochastic electric field, is considered. The obtained values of the diffusion coefficient and drift velocity are used in the Fokker-Planck equation to determine the stationary distribution of the plasma density due to the effect of an inhomogeneous stochastic field.

Tuning the Electric Field Response of MOFs by Rotatable Dipolar Linkers

2019 ◽  
Author(s):  
Johannes P. Dürholt ◽  
Babak Farhadi Jahromi ◽  
Rochus Schmid
Keyword(s):  
Electric Field ◽  
Electric Fields ◽  
Structural Changes ◽  
Dielectric Behavior ◽  
Two Dimensions ◽  
Dielectric Constants ◽  
Electric Response ◽  
Dipole Strength ◽  
Metal Organic ◽  
Dynamics Simulations

Recently the possibility of using electric fields as a further stimulus to trigger structural changes in metal-organic frameworks (MOFs) has been investigated. In general, rotatable groups or other types of mechanical motion can be driven by electric fields. In this study we demonstrate how the electric response of MOFs can be tuned by adding rotatable dipolar linkers, generating a material that exhibits paralectric behavior in two dimensions and dielectric behavior in one dimension. The suitability of four different methods to compute the relative permittivity κ by means of molecular dynamics simulations was validated. The dependency of the permittivity on temperature T and dipole strength μ was determined. It was found that the herein investigated systems exhibit a high degree of tunability and substantially larger dielectric constants as expected for MOFs in general. The temperature dependency of κ obeys the Curie-Weiss law. In addition, the influence of dipolar linkers on the electric field induced breathing behavior was investigated. With increasing dipole moment, lower field strength are required to trigger the contraction. These investigations set the stage for an application of such systems as dielectric sensors, order-disorder ferroelectrics or any scenario where movable dipolar fragments respond to external electric fields.

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