Localization of intense electromagnetic waves in plasmas

2008 ◽  
Vol 366 (1871) ◽  
pp. 1757-1769 ◽  
Author(s):  
Padma Kant Shukla ◽  
Bengt Eliasson
Keyword(s):  
Electromagnetic Waves ◽  
Laser Light ◽  
Electron Distribution Function ◽  
Intense Laser ◽  
Electron Hole ◽  
Temperature Plasma ◽  
Numerical Studies ◽  
Cold Component ◽  
Electron Holes ◽  
The Stability

We present theoretical and numerical studies of the interaction between relativistically intense laser light and a two-temperature plasma consisting of one relativistically hot and one cold component of electrons. Such plasmas are frequently encountered in intense laser–plasma experiments where collisionless heating via Raman instabilities leads to a high-energetic tail in the electron distribution function. The electromagnetic waves (EMWs) are governed by the Maxwell equations, and the plasma is governed by the relativistic Vlasov and hydrodynamic equations. Owing to the interaction between the laser light and the plasma, we can have trapping of electrons in the intense wakefield of the laser pulse and the formation of relativistic electron holes (REHs) in which laser light is trapped. Such electron holes are characterized by a non-Maxwellian distribution of electrons where we have trapped and free electron populations. We present a model for the interaction between laser light and REHs, and computer simulations that show the stability and dynamics of the coupled electron hole and EMW envelopes.

scholarly journals The dynamics of electron and ion holes in a collisionless plasma

2005 ◽  
Vol 12 (2) ◽  
pp. 269-289 ◽  
Author(s):  
B. Eliasson ◽  
P. K. Shukla
Keyword(s):  
Electromagnetic Waves ◽  
Collisionless Plasma ◽  
Negative Ion ◽  
Electron Hole ◽  
Langmuir Waves ◽  
Ion Density ◽  
Relativistic Mass ◽  
Numerical Studies ◽  
Electron Holes ◽  
Mass Increase

Abstract. We present a review of recent analytical and numerical studies of the dynamics of electron and ion holes in a collisionless plasma. The new results are based on the class of analytic solutions which were found by Schamel more than three decades ago, and which here work as initial conditions to numerical simulations of the dynamics of ion and electron holes and their interaction with radiation and the background plasma. Our analytic and numerical studies reveal that ion holes in an electron-ion plasma can trap Langmuir waves, due the local electron density depletion associated with the negative ion hole potential. Since the scale-length of the ion holes are on a relatively small Debye scale, the trapped Langmuir waves are Landau damped. We also find that colliding ion holes accelerate electron streams by the negative ion hole potentials, and that these streams of electrons excite Langmuir waves due to a streaming instability. In our Vlasov simulation of two colliding ion holes, the holes survive the collision and after the collision, the electron distribution becomes flat-topped between the two ion holes due to the ion hole potentials which work as potential barriers for low-energy electrons. Our study of the dynamics between electron holes and the ion background reveals that standing electron holes can be accelerated by the self-created ion cavity owing to the positive electron hole potential. Vlasov simulations show that electron holes are repelled by ion density minima and attracted by ion density maxima. We also present an extension of Schamel's theory to relativistically hot plasmas, where the relativistic mass increase of the accelerated electrons have a dramatic effect on the electron hole, with an increase in the electron hole potential and in the width of the electron hole. A study of the interaction between electromagnetic waves with relativistic electron holes shows that electromagnetic waves can be both linearly and nonlinearly trapped in the electron hole, which widens further due to the relativistic mass increase and ponderomotive force in the oscillating electromagnetic field. The results of our simulations could be helpful to understand the nonlinear dynamics of electron and ion holes in space and laboratory plasmas.

Electron holes in the Earth's magnetotail current sheet: role of magnetic field gradients and electron anisotropy

2020 ◽  
Author(s):  
Pavel Shustov ◽  
Ilya Kuzichev ◽  
Ivan Vasko ◽  
Anton Artemyev ◽  
Anatoliy Petrukovich
Keyword(s):  
Magnetic Field ◽  
Current Sheet ◽  
Magnetic Field Gradient ◽  
Electron Distribution Function ◽  
Inhomogeneous Magnetic Field ◽  
Field Configuration ◽  
Slow Electron ◽  
Electron Hole ◽  
Field Lines ◽  
Electron Holes

<p>Electron holes are nonlinear electrostatic structures that are often observed in the vicinity of the magnetotail energy release regions, e.g. magnetic reconnection. In this work we develop 1.5D Vlasov code simulations of the electron hole dynamics in the magnetic field configuration typical of the current sheet of the Earth's magnetotail. We consider the propagation of electron holes along magnetic field lines in the inhomogeneous magnetic field of the current sheet with realistically anisotropic electron distribution function. We demonstrate that electron holes generated near the equatorial plane of the current sheet brake as they propagate toward the boundaries of the current sheets. This effect is stronger for higher magnetic field gradient and larger electron field-aligned anisotropy. These simulations demonstrate that slow electron holes observed in the plasma sheet boundary layer may appear due to that effect of electron hole braking.</p>

scholarly journals Plasma formation through field ionization in intense laser–matter interaction

2003 ◽  
Vol 21 (4) ◽  
pp. 489-495 ◽  
Author(s):  
D. BAUER
Keyword(s):  
Laser Light ◽  
Laser Pulses ◽  
Optical Field ◽  
Intense Laser ◽  
Field Ionization ◽  
Free Electron Density ◽  
Numerical Studies ◽  
Intense Laser Pulses ◽  
Optical Effects ◽  
Nonlinear Optical Effects

Optical field ionization is the earliest and fastest plasma-generating process during the interaction of intense laser light with matter. By using short and rapidly rising laser pulses, the free electron density may turn from being transparent for an incoming laser pulse to reflective in less than half a laser cycle, that is, on a subfemtosecond timescale. Extremely nonlinear optical effects arise as a consequence of this. In this article, the basics of optical field ionization that are relevant in analytical or numerical studies of intense laser–matter interactions are reviewed. Several macroscopic effects of field ionization in the interaction of intense laser pulses with solid targets are briefly surveyed.

Scattering of electromagnetic waves by hybrid waves in a two-electron-temperature plasma

1991 ◽  
Vol 46 (1) ◽  
pp. 99-106 ◽  
Author(s):  
S. K. Sharma ◽  
A. Sudarshan
Keyword(s):  
Growth Rate ◽  
Electron Temperature ◽  
High Frequency ◽  
Electromagnetic Waves ◽  
Low Frequency ◽  
Lower Hybrid ◽  
Stimulated Scattering ◽  
Coupled Modes ◽  
Temperature Plasma ◽  
Electrostatic Perturbation

In this paper, we use the hydrodynamic approach to study the stimulated scattering of high-frequency electromagnetic waves by a low-frequency electrostatic perturbation that is either an upper- or lower-hybrid wave in a two-electron-temperature plasma. Considering the four-wave interaction between a strong high-frequency pump and the low-frequency electrostatic perturbation (LHW or UHW), we obtain the dispersion relation for the scattered wave, which is then solved to obtain an explicit expression for the growth rate of the coupled modes. For a typical Q-machine plasma, results show that in both cases the growth rate increases with noh/noc. This is in contrast with the results of Guha & Asthana (1989), who predicted that, for scattering by a UHW perturbation, the growth rate should decrease with increasing noh/noc.

scholarly journals Radiation in the neighbourhood of a double layer

2014 ◽  
Vol 32 (6) ◽  
pp. 677-687 ◽  
Author(s):  
R. Pottelette ◽  
M. Berthomier ◽  
J. Pickett
Keyword(s):  
Phase Space ◽  
Electron Distribution ◽  
Electron Distribution Function ◽  
Source Region ◽  
Double Layers ◽  
Small Scale ◽  
High Time Resolution ◽  
Local Electron ◽  
Nonlinear Phase ◽  
Electron Holes

Abstract. In the auroral kilometric radiation (AKR) source region, acceleration layers narrow in altitude and associated with parallel field-aligned potential drops of several kV can be identified by using both particles and wave-field high time-resolution measurements from the Fast Auroral SnapshoT explorer spacecraft (FAST). These so-called double layers (DLs) are recorded around density enhancements in the auroral cavity, where the enhancement can be at the edge of the cavity or even within the cavity at a small scale. Once immersed in the plasma, DLs necessarily accelerate particles along the magnetic field lines, thereby generating locally strong turbulent processes leading to the formation of nonlinear phase space holes. The FAST data reveal the asymmetric character of the turbulence: the regions located on the high-potential side of the DLs are characterized by the presence of electron holes, while on the low-potential side, ion holes are recorded. The existence of these nonlinear phase space holes may affect the AKR radiation pattern in the neighbourhood of a DL where the electron distribution function is drastically different from a horseshoe shape. We present some observations which illustrate the systematic generation of elementary radiation events occurring significantly above the local electron gyrofrequency in the presence of electron holes. These fine-scale AKR radiators are associated with a local electron distribution which presents a pronounced beam-like shape.

Effects of Non-Maxwellian Electron Distribution Function to the Propagation Coefficients of Electromagnetic Waves in Plasma

2019 ◽  
Vol 47 (1) ◽  
pp. 100-103 ◽  
Author(s):  
Jinming Li ◽  
Ying Wang ◽  
Junjie Wei ◽  
Chengxun Yuan ◽  
Zhongxiang Zhou ◽  
...  
Keyword(s):  
Distribution Function ◽  
Electromagnetic Waves ◽  
Electron Distribution ◽  
Electron Distribution Function

A new three-phase heterocrystal catalysts and their superior treatment efficiency for tetracycline

2016 ◽  
Vol 10 (03) ◽  
pp. 1750015
Author(s):  
Feng-Rui Wang ◽  
Hui-Ping Sun ◽  
Yan Wang ◽  
Jin-Ku Liu ◽  
Yi Fang ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Band Structure ◽  
Antibiotic Residues ◽  
Treatment Efficiency ◽  
Electron Hole ◽  
Three Phase ◽  
Catalytic Material ◽  
Water Based ◽  
The Stability ◽  
Functional Components

An easy recyclable and interesting Ag3PO4@Pt@TiO2 (APTP) three-phase heterocrystal chains were self-assembled by the cohesive action and chemical construction of polyvinylpyrrolidone (PVP). We found that a new electron–hole transmission path has been built via the rematch of the band structure of Ag3PO4, Pt and TiO2 which extends the light absorption and promoted the electron–hole separation to treat the antibiotic residues in the water. Based on the thorough investigations, a new catalytic material was provided for antibiotics degradation. The catalytic activity of APTP toward the degradation of tetracycline solution was enhanced by 166.67% and the stability increased remarkably compared with pure Ag3PO4 through the integration of different functional components.

scholarly journals Further Investigations on the Dynamics and Multistability Coexisted in a Memory-Based Cobweb Model

Complexity ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
S. S. Askar
Keyword(s):  
Fixed Point ◽  
Equilibrium Point ◽  
Profit Maximization ◽  
Period Doubling ◽  
Speed Of Adjustment ◽  
Discrete Dynamic ◽  
Cobweb Model ◽  
Numerical Studies ◽  
Market Clearing Price ◽  
The Stability

Based on a nonlinear demand function and a market-clearing price, a cobweb model is introduced in this paper. A gradient mechanism that depends on the marginal profit is adopted to form the 1D discrete dynamic cobweb map. Analytical studies show that the map possesses four fixed points and only one attains the profit maximization. The stability/instability conditions for this fixed point are calculated and numerically studied. The numerical studies provide some insights about the cobweb map and confirm that this fixed point can be destabilized due to period-doubling bifurcation. The second part of the paper discusses the memory factor on the stabilization of the map’s equilibrium point. A gradient mechanism that depends on the marginal profit in the past two time steps is adopted to incorporate memory in the model. Hence, a 2D discrete dynamic map is constructed. Through theoretical and numerical investigations, we show that the equilibrium point of the 2D map becomes unstable due to two types of bifurcations that are Neimark–Sacker and flip bifurcations. Furthermore, the influence of the speed of adjustment parameter on the map’s equilibrium is analyzed via numerical experiments.

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