scholarly journals Space-time evolution of electron-beam driven electron holes and their effects on the plasma

2003 ◽  
Vol 10 (1/2) ◽  
pp. 53-63 ◽  
Author(s):  
N. Singh
Keyword(s):  
Electron Beam ◽  
Plasma Density ◽  
Three Dimensional ◽  
Low Frequency ◽  
Velocity Distribution Function ◽  
Lower Hybrid ◽  
Particle In Cell ◽  
Short Transverse ◽  
Electron Holes ◽  
Number Of Electron Holes

Abstract. We report here further results from the three-dimensional particle-in-cell simulations of the electron-beam driven electron holes. We focus here on (i) the transformation of oscillatory waves driven by the electron-beam instability into electron holes, (ii) the continued evolution and propagation of electron holes after their formation, including merging of electron holes, and (iii) the effects of the evolution on the plasma density and ion velocity distribution function. We find that initially electron-beam modes with perpendicular wave numbers k^ = 0 and as well as k^ ≠ 0 are driven resonantly below the electron plasma frequency of the target plasma. The modes interact nonlinearly and modulate each other both in space and time, producing wave structures with finite perpendicular scale lengths. Nonlinear evolution of such wave structures generates the electron holes in the simulations. Initially, a large number of electron holes form in the plasma. Their merging yields continuously a decreasing number of electron holes. The propagation velocity of the electron holes evolves dynamically and is affected by their merging. At late times only a few electron holes are left in the simulation and they decay by emitting low-frequency electrostatic whistler waves just above the lower hybrid (LH) frequency vlh . These waves, which are long structures parallel to the ambient magnetic field B0 and quite short transverse to B0, are associated with similar structures in the plasma density, producing density filaments. It turns out that electron-beam driven plasmas, in general, develop such filaments at some stage of the evolution of the beam-driven waves. In view of the excitation of the LH waves near vlh, which could resonate with the ions, an analysis shows that it is possible to heat transversely the ions in a time scale of a few seconds in the auroral return current plasma, in which electron holes and transversely heated ions have been simultaneously observed.

scholarly journals Brief Communication: The double layer in the separatrix region during magnetic reconnection

2015 ◽  
Vol 22 (2) ◽  
pp. 167-171
Author(s):  
J. Guo ◽  
B. Yu
Keyword(s):  
Electron Beam ◽  
Magnetic Reconnection ◽  
Double Layer ◽  
Particle In Cell ◽  
Acoustic Instability ◽  
Ion Acoustic ◽  
Evolution Stage ◽  
Spatial Size ◽  
Electron Holes ◽  
Observation Results

Abstract. With two-dimensional (2-D) particle-in-cell (PIC) simulations we investigate the evolution of the double layer (DL) driven by magnetic reconnection. Our results show that an electron beam can be generated in the separatrix region as magnetic reconnection proceeds. This electron beam could trigger the ion-acoustic instability; as a result, a DL accompanied with electron holes (EHs) can be found during the nonlinear evolution stage of this instability. The spatial size of the DL is about 10 Debye lengths. This DL propagates along the magnetic field at a velocity of about the ion-acoustic speed, which is consistent with the observation results.

Excitation of lower hybrid waves by electron beams in finite geometry plasmas. Part 2. Surface waves

1978 ◽  
Vol 19 (2) ◽  
pp. 295-299
Author(s):  
Réal R. J. Gagné ◽  
Magdi M. Shoucri
Keyword(s):  
Electron Beam ◽  
Surface Waves ◽  
Electron Beams ◽  
Low Frequency ◽  
Finite Geometry ◽  
Dispersion Relations ◽  
Lower Hybrid ◽  
Small Density ◽  
Hybrid Waves ◽  
Lower Hybrid Waves

The dispersion relations for the quasi-static lower hybrid surface waves are derived. Conditions for their existence and their linear excitation by a small density electron beam are discussed. Instabilities appearing in low-frequency surface waves are also discussed.

scholarly journals Nondrifting relativistic electromagnetic solitons in plasmas

2003 ◽  
Vol 21 (4) ◽  
pp. 541-544 ◽  
Author(s):  
M. LONTANO ◽  
M. BORGHESI ◽  
S.V. BULANOV ◽  
T.Z. ESIRKEPOV ◽  
D. FARINA ◽  
...  
Keyword(s):  
Three Dimensional ◽  
Low Frequency ◽  
Laser Pulses ◽  
Particle In Cell ◽  
High Intensity Laser ◽  
Theoretical Investigations ◽  
Plasma Response ◽  
Warm Plasma ◽  
Electromagnetic Solitons

Low-frequency, relativistic, subcycle solitary waves are found in two-dimensional and three-dimensional particle-in-cell (PIC) numerical simulations, as a result of the interaction of ultrashort, high-intensity laser pulses with plasmas. Moreover, nondrifting, subcycle relativistic electromagnetic solitons have been obtained as solutions of the hydrodynamic equations for an electron–ion warm plasma, by assuming the quasi-neutrality character of the plasma response. In addition, the formation of long-living macroscopic soliton-like structures has been experimentally observed by means of the proton imaging diagnostics. Several common features result from these investigations, as, for example, the quasi-neutral plasma response to the soliton radiation, in the long-term evolution of the system, which leads to the almost complete expulsion of the plasma from the region where the electromagnetic radiation is concentrated, even at subrelativistic field intensity. The results of the theoretical investigations are reviewed with special attention to these similarities.

scholarly journals Particle acceleration in a reconnecting current sheet: PIC simulation

2009 ◽  
Vol 75 (5) ◽  
pp. 619-636 ◽  
Author(s):  
TARAS V. SIVERSKY ◽  
VALENTINA V. ZHARKOVA
Keyword(s):  
Electric Field ◽  
Energy Distribution ◽  
Current Sheet ◽  
Plasma Density ◽  
Three Dimensional ◽  
Polarization Field ◽  
Electron Mass ◽  
Langmuir Waves ◽  
Particle In Cell ◽  
Reconnecting Current Sheet

AbstractThe acceleration of protons and electrons in a reconnecting current sheet (RCS) is simulated with a particle-in-cell (PIC) 2D3V (two-dimensional in space and three-dimensional in velocity space) code for the proton-to-electron mass ratio of 100. The electromagnetic configuration forming the RCS incorporates all three components of the magnetic field (including the guiding field) and a drifted electric field. PIC simulations reveal that there is a polarization electric field that appears during acceleration owing to a separation of electrons from protons towards the midplane of the RCS. If the plasma density is low, the polarization field is weak and the particle trajectories in the PIC simulations are similar to those in the test particle (TP) approach. For the higher plasma density the polarization field is stronger and it affects the trajectories of protons by increasing their orbits during acceleration. This field also leads to a less asymmetrical abundance of ejected protons towards the midplane in comparison with the TP approach. For a given magnetic topology electrons in PIC simulations are ejected to the same semispace as protons, in contrast to the TP results. This happens because the polarization field extends far beyond the thickness of a current sheet. This field decelerates the electrons, which are initially ejected into the semispace opposite to the protons, returns them back to the RCS, and, eventually, leads to the electron ejection into the same semispace as protons. The energy distribution of the ejected electrons is rather wide and single-peaked, in contrast to the two-peak narrow-energy distribution obtained in the TP approach. In the case of a strong guiding field, the mean energy of the ejected electrons is found to be smaller than it is predicted analytically and by the TP simulations. The beam of accelerated electrons is also found to generate turbulent electric field in the form of Langmuir waves.

scholarly journals Ion-channel laser growth rate and beam quality requirements

2018 ◽  
Vol 84 (3) ◽  
Author(s):  
X. Davoine ◽  
F. Fiúza ◽  
R. A. Fonseca ◽  
W. B. Mori ◽  
L. O. Silva
Keyword(s):  
Growth Rate ◽  
Electron Beam ◽  
Ion Channel ◽  
Beam Quality ◽  
Three Dimensional ◽  
Quality Requirements ◽  
Particle In Cell ◽  
Theoretical Predictions ◽  
First Time ◽  
Wakefield Accelerator

In this paper, we determine the growth rate of the exponential radiation amplification in the ion-channel laser, where a relativistic electron beam wiggles in a focusing ion channel that can be created in a wakefield accelerator. For the first time the radiation diffraction, which can limit the amplification, is taken into account. The electron beam quality requirements to obtain this amplification are also presented. It is shown that both the beam energy and wiggler parameter spreads should be limited. Two-dimensional and three-dimensional particle-in-cell simulations of the self-consistent ion-channel laser confirm our theoretical predictions.

Energy conversion by electron beam-driven waves in a compressed reconnection separatrix

2020 ◽  
Author(s):  
Justin Holmes ◽  
Rumi Nakamura ◽  
Owen Roberts ◽  
Daniel Schmid ◽  
Takuma Nakamura ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Electron Beam ◽  
Energy Conversion ◽  
Electric Fields ◽  
Spatial Configuration ◽  
Three Dimensional ◽  
Lower Hybrid ◽  
Magnetic Compression ◽  
Rotational Discontinuity ◽  
Highly Correlated

<p>We investigate magnetic compression near the reconnection separatrix observed by Magnetospheric MultiScale (MMS) on July 11<sup>th</sup> 2017. A clear transition between inflow and outflow in both ions and electrons is observed across an ion gyro-scale region of enhanced magnetic field. Multispacecraft techniques for magnetic curvature and local gradients along with timing of highly-correlated wave packets are used to determine the spatial configuration of the compressed region. Structure of the system is found to be inherently three dimensional; electron beam-driven modes propagating parallel to the magnetic field are observed concurrent with perpendicular-propagating lower hybrid waves. Larger scale surface waves are also present behind the compression front. Transforming to a deHoffmann-Teller frame across the boundary results in a distinctly non-rotational discontinuity with structure similar to a quasi-2D, Petschek-like slow shock. However, MHD jump conditions are not satisfied, indicating kinetic dissipation may occur within the thin layer. The largest amplitude measurements of $\mathbf{J}\cdot\mathbf{E}$ energy conversion are associated with an inflowing electron beam and parallel electric fields near the magnetic peak. Spikes in $\mathbf{J}\cdot\mathbf{E}$ are predominantly negative, suggesting electron-scale mixing between the reconnection inflow and outflow is partially responsible for the observed magnetic compression.</p>

scholarly journals Optical control of transverse motion of ionization injected electrons in a laser plasma accelerator

2021 ◽  
Vol 9 ◽  
Author(s):  
Jie Feng ◽  
Yifei Li ◽  
Jinguang Wang ◽  
Dazhang Li ◽  
Changqing Zhu ◽  
...  
Keyword(s):  
Electron Beam ◽  
Laser Plasma ◽  
Optical Method ◽  
Three Dimensional ◽  
Plasma Accelerator ◽  
Transverse Motion ◽  
Particle In Cell ◽  
Laser Focus ◽  
All Optical ◽  
Laser Plasma Accelerator

Abstract We demonstrate an all-optical method for controlling the transverse motion of an ionization injected electron beam in a laser plasma accelerator by using the transversely asymmetrical plasma wakefield. The laser focus shape can control the distribution of a transversal wakefield. When the laser focus shape is changed from circular to slanted elliptical in the experiment, the electron beam profiles change from an ellipse to three typical shapes. The three-dimensional particle-in-cell simulation result agrees well with the experiment, and it shows that the trajectories of these accelerated electrons change from undulating to helical. Such an all-optical method could be useful for convenient control of the transverse motion of an electron beam, which results in synchrotron radiation from orbit angular momentum.

scholarly journals Three-dimensional structure of electron holes driven by an electron beam

2000 ◽  
Vol 27 (16) ◽  
pp. 2469-2472 ◽  
Author(s):  
Nagendra Singh ◽  
S. M. Loo ◽  
B. Earl Wells ◽  
C. Deverapalli
Keyword(s):  
Electron Beam ◽  
Three Dimensional ◽  
Dimensional Structure ◽  
Three Dimensional Structure ◽  
Electron Holes

Nonlinear propagation of lower-hybrid waves in an inhomogeneous plasma

1978 ◽  
Vol 20 (2) ◽  
pp. 189-203 ◽  
Author(s):  
M. Y. Yu ◽  
P. K. Shukla ◽  
K. H. Spatschek
Keyword(s):  
Nonlinear Evolution ◽  
Inhomogeneous Plasma ◽  
Three Dimensional ◽  
Low Frequency ◽  
Nonlinear Propagation ◽  
Lower Hybrid ◽  
Density Perturbations ◽  
Hybrid Waves ◽  
Lower Hybrid Waves ◽  
Pump Depletion

We investigate the problem of spatial depletion of propagating lower-hybrid waves in an inhomogeneous plasma. In particular, we consider the nonlinear evolution of a lower-hybrid pump which is coupled to a daughter lower-hybrid decay wave excited by low-frequency density perturbations. Our results show that pump depletion occurs when three-dimensional effects are included. This phenomenon competes with the filamentation of the pump caused by self- interaction. Implications to lower-hybrid heating experiments are discussed.

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