Plasma electron hole oscillatory velocity instability

In this paper, we report a new type of instability of electron holes (EHs) interacting with passing ions. The nonlinear interaction of EHs and ions is investigated using a new theory of hole kinematics. It is shown that the oscillation in the velocity of the EH parallel to the magnetic field direction becomes unstable when the hole velocity in the ion frame is slower than a few times the cold ion sound speed. This instability leads to the emission of ion-acoustic waves from the solitary hole and decay in its magnitude. The instability mechanism can drive significant perturbations in the ion density. The instability threshold, oscillation frequency and instability growth rate derived from the theory yield quantitative agreement with the observations from a novel high-fidelity hole-tracking particle-in-cell code.

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

Nonlinear Processes in Geophysics ◽

10.5194/npg-22-167-2015 ◽

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.

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Particle-In-Cell simulations of resonant interactions between whistler waves and electrons in the near-Sun solar wind: scattering of the strahl into the halo and heat flux regulation.

10.5194/egusphere-egu21-10198 ◽

2021 ◽

Author(s):

Alfredo Micera ◽

Andrei Zhukov ◽

Rodrigo A. López ◽

Maria Elena Innocenti ◽

Marian Lazar ◽

...

Keyword(s):

Magnetic Field ◽

Heat Flux ◽

Solar Wind ◽

Velocity Distribution ◽

Pitch Angle ◽

Electron Velocity ◽

Magnetic Field Direction ◽

Whistler Waves ◽

Electron Velocity Distribution ◽

Particle In Cell

<p>Electron velocity distribution functions, initially composed of core and strahl populations as typically encountered in the near-Sun solar wind and as recently observed by Parker Solar Probe, have been modeled via fully kinetic Particle-In-Cell simulations. It has been demonstrated that, as a consequence of the evolution of the electron velocity distribution function, two branches of the whistler heat flux instability can be excited, which can drive whistler waves propagating in the direction parallel or oblique to the background magnetic field. First, the strahl undergoes pitch-angle scattering with oblique whistler waves, which provokes the reduction of the strahl drift velocity and the simultaneous broadening of its pitch angle distribution. Moreover, the interaction with the oblique whistler waves results in the scattering towards higher perpendicular velocities of resonant strahl electrons and in the appearance of a suprathermal halo population which, at higher energies, deviates from the Maxwellian distribution. Later on, the excited whistler waves shift towards smaller angles of propagation and secondary scattering processes with quasi-parallel whistler waves lead to a redistribution of the scattered particles into a more symmetric halo. All processes are accompanied by a significant decrease of the heat flux carried by the strahl population along the magnetic field direction, although the strongest heat flux rate decrease is simultaneous with the propagation of the oblique whistler waves.</p>

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Electrostatic shock properties inferred from AKR fine structure

Nonlinear Processes in Geophysics ◽

10.5194/npg-10-87-2003 ◽

2003 ◽

Vol 10 (1/2) ◽

pp. 87-92 ◽

Cited By ~ 18

Author(s):

R. Pottelette ◽

R. A. Treumann ◽

M. Berthomier ◽

J. Jasperse

Keyword(s):

Electric Fields ◽

Acoustic Waves ◽

Sagdeev Potential ◽

Plasma Parameters ◽

Fluid Approximation ◽

Auroral Kilometric Radiation ◽

Ion Acoustic ◽

Electron Holes ◽

Spectral Frequency ◽

Electron Acoustic

Abstract. The auroral kilometric radiation (AKR) consists of a large number of fast drifting elementary radiation events that have been interpreted as travelling electron holes resulting from the nonlinear evolution of electron-acoustic waves. The elementary radiation structures sometimes become reflected or trapped in slowly drifting larger structures where the parallel electric fields are located. These latter features have spectral frequency drifts which can be interpreted in terms of the propagation of shock-like disturbances along the auroral field line at velocities near the ion-acoustic speed. The amplitude, speed, and shock width of such localized ion-acoustic shocks are determined here in the fluid approximation from the Sagdeev potential, assuming realistic plasma parameters. It is emphasized that the electrostatic potentials of such nonlinear structures contribute to auroral acceleration.

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Axisymmetric waves in compressible Newtonian liquids contained in rigid tubes: steady-periodic mode shapes and dispersion by the method of eigenvalleys

Journal of Fluid Mechanics ◽

10.1017/s0022112073002351 ◽

1973 ◽

Vol 58 (3) ◽

pp. 595-621 ◽

Cited By ~ 20

Author(s):

H. A. Scarton ◽

W. T. Rouleau

Keyword(s):

Boundary Layer ◽

Acoustic Waves ◽

Mode Shapes ◽

Periodic Mode ◽

Rotational Mode ◽

High Frequencies ◽

Wide Range ◽

Propagating Waves ◽

New Type ◽

Newtonian Liquids

In this paper the first thirty-two axisymmetric modes for steady-periodic waves in viscous compressible liquids contained in rigid, impermeable, circular tubes are calculated. These results end long speculation over the effects of viscosity on guided acoustic waves. Sixteen of the modes belong to a family of rotation-dominated modes whose existence was previously unknown. The thirty-two modes were computed for a wide range of frequencies, viscosities and wave-lengths.The modes were found through the use of the method of eigenvalleys, which also led to the discovery of backward-propagating waves, an exact analytical expression for the zeroth rotational mode eigenvalue, definitive boundaries between low and intermediate frequencies and between intermediate and high frequencies, and a new type of boundary layer, called a dilatational boundary layer.

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Boltzmann electron PIC simulation of the E-sail effect

Annales Geophysicae ◽

10.5194/angeo-33-1507-2015 ◽

2015 ◽

Vol 33 (12) ◽

pp. 1507-1512 ◽

Cited By ~ 2

Author(s):

P. Janhunen

Keyword(s):

Solar Wind ◽

Hybrid Simulation ◽

Space Propulsion ◽

Electron Population ◽

Trapped Electrons ◽

Pic Simulation ◽

Particle In Cell ◽

The Poisson Equation ◽

New Type ◽

The One

Abstract. The solar wind electric sail (E-sail) is a planned in-space propulsion device that uses the natural solar wind momentum flux for spacecraft propulsion with the help of long, charged, centrifugally stretched tethers. The problem of accurately predicting the E-sail thrust is still somewhat open, however, due to a possible electron population trapped by the tether. Here we develop a new type of particle-in-cell (PIC) simulation for predicting E-sail thrust. In the new simulation, electrons are modelled as a fluid, hence resembling hybrid simulation, but in contrast to normal hybrid simulation, the Poisson equation is used as in normal PIC to calculate the self-consistent electrostatic field. For electron-repulsive parts of the potential, the Boltzmann relation is used. For electron-attractive parts of the potential we employ a power law which contains a parameter that can be used to control the number of trapped electrons. We perform a set of runs varying the parameter and select the one with the smallest number of trapped electrons which still behaves in a physically meaningful way in the sense of producing not more than one solar wind ion deflection shock upstream of the tether. By this prescription we obtain thrust per tether length values that are in line with earlier estimates, although somewhat smaller. We conclude that the Boltzmann PIC simulation is a new tool for simulating the E-sail thrust. This tool enables us to calculate solutions rapidly and allows to easily study different scenarios for trapped electrons.

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The research of LWD acoustic isolator based on SAW spatial separation

MATEC Web of Conferences ◽

10.1051/matecconf/201928302004 ◽

2019 ◽

Vol 283 ◽

pp. 02004

Author(s):

Peinian Yang ◽

Dehua Chen ◽

Wang Xiuming

Keyword(s):

Acoustic Waves ◽

Acoustic Analysis ◽

Surface Acoustic Waves ◽

Spatial Separation ◽

P Wave ◽

S Wave ◽

Finite Element Software ◽

Acoustic Insulation ◽

New Type ◽

Sufficient Strength

Acoustic logging while drilling (LWD) can extract P-wave and S-wave information from the formation. However, the transmission of the collar wave propagated directly from the emitter to the receiver may interfere with the P-wave and S-wave and affect the extraction of formation information. Therefore, it is necessary to design a suitable acoustic isolator between the transmitter and the receiver to attenuate the drill waves. The commonly used acoustic LWD isolator is that the outer surface of the drill collar is evenly grooved to attenuate the collar wave. However, there are still disadvantages such as the lack of mechanical strength of the evenly grooved acoustic insulators and the ability to extract clean longitudinal wave under certain circumstances. Therefore, there is an urgent requirement to design a new type of acoustic LWD isolator with sufficient strength and acoustic insulation requirements. In recent years, spoof surface acoustic waves (SSAWs) generated by periodic corrugated surface rigid plates have attracted the attention of many researchers, who can spatially separate the surface waves to attenuate acoustic waves. In this paper, a new type of acoustic LWD insulator based on SAW space separation structure is proposed. The finite element software ANSYS is used for acoustic analysis.

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Boundary layer leading-edge receptivity to sound at incidence angles

Journal of Fluid Mechanics ◽

10.1017/s0022112001005456 ◽

2001 ◽

Vol 444 ◽

pp. 383-407 ◽

Cited By ~ 20

Author(s):

ERCAN ERTURK ◽

THOMAS C. CORKE

Keyword(s):

Acoustic Waves ◽

Stokes Equations ◽

Incidence Angle ◽

Leading Edge ◽

Quantitative Agreement ◽

Navier Stokes ◽

Angle Of Incidence ◽

Sound Waves ◽

Nose Radius ◽

Navier Stokes Equations

The leading-edge receptivity to acoustic waves of two-dimensional parabolic bodies was investigated using a spatial solution of the Navier–Stokes equations in vorticity/streamfunction form in parabolic coordinates. The free stream is composed of a uniform flow with a superposed periodic velocity fluctuation of small amplitude. The method follows that of Haddad & Corke (1998) in which the solution for the basic flow and linearized perturbation flow are solved separately. We primarily investigated the effect of frequency and angle of incidence (−180° [les ] α2 [les ] 180°) of the acoustic waves on the leading-edge receptivity. The results at α2 = 0° were found to be in quantitative agreement with those of Haddad & Corke (1998), and substantiated the Strouhal number scaling based on the nose radius. The results with sound waves at angles of incidence agreed qualitatively with the analysis of Hammerton & Kerschen (1996). These included a maximum receptivity at α2 = 90°, and an asymmetric variation in the receptivity with sound incidence angle, with minima at angles which were slightly less than α2 = 0° and α2 = 180°.

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Energy dissipation of ion beam in two-component plasma in the presence of laser irradiation

Laser and Particle Beams ◽

10.1017/s0263034611000334 ◽

2011 ◽

Vol 29 (3) ◽

pp. 299-304 ◽

Cited By ~ 8

Author(s):

Zhang-Hu Hu ◽

Yuan-Hong Song ◽

Z.L. Mišković ◽

You-Nian Wang

Keyword(s):

Laser Pulse ◽

Ion Beam ◽

Plasma Temperature ◽

Laser Frequency ◽

Plasma Electron ◽

Stopping Power ◽

Dynamic Polarization ◽

Particle In Cell ◽

Two Component ◽

Component Plasma

AbstractWe use a two-dimensional particle-in-cell simulation to investigate the dynamic polarization and stopping power for an ion beam propagating through a two-component plasma, which is simultaneously irradiated by a strong laser pulse. Compared to the laser-free case, we observe a reduction in the instantaneous stopping power that initially follows the shape of the laser pulse and becomes particularly large as the laser frequency approaches the plasma electron frequency. We attribute this large reduction in the ion stopping power to an increase in plasma temperature due to the energy absorbed in the plasma from the laser pulse through the process of wave heating. In addition, dynamic polarization of the plasma by the ion is found to be strongly modulated by the laser field.

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