scholarly journals Particle Motion in Longitudinal Waves. II Superluminal and Luminal Waves

1992 ◽  
Vol 45 (1) ◽  
pp. 21 ◽  
Author(s):  
ET Rowe
Keyword(s):  
Particle Motion ◽  
Large Amplitude ◽  
Phase Locking ◽  
Charged Particles ◽  
Phase Speed ◽  
Relativistic Effects ◽  
Longitudinal Waves ◽  
Particle Orbits ◽  
Arbitrary Amplitude ◽  
Arbitrary Energy

The motion of charged particles in superluminal and luminal longitudinal waves of arbitrary amplitude is considered in detail, including relativistic effects. In particular we discuss the ability of these waves to accelerate particles. Solutions for the particle orbits are given in both closed form and in terms of relevant expansions. The drift velocity of the particles, which describes the motion of the guiding centre, is identified. Two interesting effects are discovered: (i) the ability of large amplitude superluminal waves to drag particles along at a velocity conjugate to the wave phase speed and (ii) the existence of 'phase locking' particle orbits in the luminal case, in which particles can be accelerated to arbitrary energy.

scholarly journals Particle Motion in Longitudinal Waves. I Subluminal Waves

1992 ◽  
Vol 45 (1) ◽  
pp. 1 ◽  
Author(s):  
ET Rowe
Keyword(s):  
Electric Field ◽  
Longitudinal Wave ◽  
Drift Velocity ◽  
Particle Motion ◽  
Equations Of Motion ◽  
Phase Speed ◽  
Relativistic Energy ◽  
Longitudinal Waves ◽  
Arbitrary Phase ◽  
Particle Orbit

The classical equations of motion for a particle moving in a parallel longitudinal wave of arbitrary phase speed are discussed and the case of subluminal waves is considered in detail. Motion of both trapped and untrapped particles is explored with particular reference to the ability of a wave to accelerate particles to relativistic energy. The particle orbit is found in both closed and expanded forms, taking the electric field into account exactly. Expressions are also found for the 'drift velocity' of a particle, which is an important quantity because it is a constant of the particle motion that describes the motion of the centre of oscillation.

Large amplitude progressive interfacial waves

1979 ◽  
Vol 93 (3) ◽  
pp. 433-448 ◽  
Author(s):  
Judith Y. Holyer
Keyword(s):  
Free Surface ◽  
Surface Wave ◽  
Surface Waves ◽  
Large Amplitude ◽  
Phase Speed ◽  
Maximum Height ◽  
Interfacial Waves ◽  
Free Surface Waves ◽  
Lower Fluid ◽  
Over The Top

This paper contains a study of large amplitude, progressive interfacial waves moving between two infinite fluids of different densities. The highest wave has been calculated using the criterion that it has zero horizontal fluid velocity at the interface in a frame moving at the phase speed of the waves. For free surface waves this criterion is identical to the criterion due to Stokes, namely that there is a stagnation point at the crest of each wave. I t is found that as the density of the upper fluid increases relative to the density of the lower fluid the maximum height of the wave, for fixed wavelength, increases. The maximum height of a Boussinesq wave, which has the density almost the same above and below the interface, is 2·5 times the maximum height of a surface wave of the same wavelength. A wave with air over the top of it can be about 2% higher than the highest free surface wave. The point at which the limiting criterion is first satisfied moves from the crest for free surface waves to the point half-way between the crest and the trough for Boussinesq waves. The phase speed, momentum, energy and other wave properties are calculated for waves up to the highest using Padé approximants. For free surface waves and waves with air above the interface the maximum value of these properties occurs for waves which are lower than the highest. For Boussinesq waves and waves with the density of the upper fluid onetenth of the density of the lower fluid these properties each increase monotonically with the wave height.

Multiple Boris solvers for particle-in-cell (PIC) simulation

2021 ◽  
Author(s):  
Seiji Zenitani ◽  
Tsunehiko Kato
Keyword(s):  
Plasma Physics ◽  
Particle Motion ◽  
Charged Particles ◽  
Single Step ◽  
Pic Simulation ◽  
Particle In Cell ◽  
Step Procedure ◽  
Cell Simulation ◽  
Continuous Demand

<div> <div> <div> <p> Particle-in-cell (PIC) simulation has long been used in theoretical plasma physics. In PIC simulation, the Boris solver is the de-facto standard for solving particle motion, and it has been used over a half century. Meanwhile, there is a continuous demand for better particle solvers. In this contribution, we introduce a family of Boris-type schemes for integrating the motion of charged particles. We call the new solvers the multiple Boris solvers. The new solvers essentially repeat the standard two-step procedure multiple times in the Lorentz-force part, and we derive a single-step form for arbitrary subcycle number <em>n</em>. The new solvers give <em>n<sup>2</sup></em> times smaller errors, allow larger timesteps, but they are computationally affordable for moderate <em>n</em>. The multiple Boris solvers also reduce a numerical error in long-term plasma motion in a relativistic magnetized flow.</p> </div> </div> </div><p>Reference:</p><ul><li>S. Zenitani & T. N. Kato, <em>Multiple Boris integrators for particle-in-cell simulation</em>, Comput. Phys. Commun. <strong>247</strong>, 106954, doi:10.1016/j.cpc.2019.106954 (2020)</li> </ul>

scholarly journals ON EFFECTIVE ACCELERATION OF CHARGED PARTICLES IN VACUUM

2021 ◽  
pp. 39-42
Author(s):  
V.A. Buts ◽  
A.G. Zagorodny
Keyword(s):  
Wave Energy ◽  
Large Amplitude ◽  
Electromagnetic Waves ◽  
Charged Particles ◽  
Main Attention ◽  
Transverse Electromagnetic ◽  
Effective Transfer ◽  
Dynamics Of Particles

The results of studying the dynamics of particles in the fields of large-amplitude transverse electromagnetic waves are presented. The main attention is paid to the description of the found conditions, under which the effective transfer of wave energy to charged particles in vacuum is possible.

scholarly journals Can the occipital alpha-phase speed up visual detection through a real-time EEG-based brain-computer interface (BCI)?

2020 ◽  
Author(s):  
Irene Vigué-Guix ◽  
Luis Morís Fernández ◽  
Mireia Torralba Cuello ◽  
Manuela Ruzzoli ◽  
Salvador Soto-Faraco
Keyword(s):  
Real Time ◽  
Brain Computer Interface ◽  
Phase Locking ◽  
Theoretical Perspective ◽  
Reaction Times ◽  
Phase Speed ◽  
Time Estimation ◽  
Alpha Phase ◽  
Computer Interface ◽  
Α Phase

ABSTRACTElectrical brain oscillations reflect fluctuations in neural excitability. Fluctuations in the alpha band (α, 8-12 Hz) in the occipito-parietal cortex are thought to regulate sensory responses, leading to cyclic variations in visual perception. Inspired by this theory, some past and recent studies have addressed the relationship between α-phase from extra-cranial EEG and behavioural responses to visual stimuli in humans. The latest studies have used offline approaches to confirm α-gated cyclic patterns. However, a particularly relevant implication is the possibility to use this principle online for real-time neurotechnology, whereby stimuli are time-locked to specific α-phases leading to predictable outcomes in performance. Here we aimed at providing a proof-of-concept for such real-time neurotechnology. Participants performed a speeded response task to visual targets that were presented upon a real-time estimation of the α-phase via an EEG closed-loop brain-computer interface (BCI). We predicted, according to the theory, a modulation of reaction times (RTs) along the α-cycle. Our BCI system achieved reliable trial-to-trial phase-locking of stimuli to the phase of individual occipito-parietal α-oscillations. Yet, the behavioural results did not support a consistent relation between RTs and the phase of the α-cycle neither at group nor single participant levels. We must conclude that although the α-phase might play a role in perceptual decisions from a theoretical perspective, its impact on EEG-based BCI application appears negligible.

scholarly journals The Motion of Charged Dust Particles in Interplanetary Space

1980 ◽  
Vol 90 ◽  
pp. 309-310
Author(s):  
G. E. Morfill ◽  
E. Grün
Keyword(s):  
Magnetic Field ◽  
Current Sheet ◽  
Equatorial Plane ◽  
Particle Motion ◽  
Large Scale ◽  
Interplanetary Space ◽  
Dust Particles ◽  
Charged Dust ◽  
Particle Orbits ◽  
Interplanetary Plasma

The problem of electromagnetic perturbations of charged dust particle orbits in interplanetary space has been re-examined in the light of our better understanding of the large scale spatial and temporal interplanetary plasma and field topology. In the equatorial plane, the magnetic sectors, caused by the warped current sheet, produce stochastic orbit perturbations. From this a diffusive description of particle motion can be derived, provided the dust particles are sufficiently small. The effects of large unipolar magnetic field regions at high heliographic latitudes will be briefly discussed.

Sign in / Sign up

Export Citation Format

Share Document