Dynamics of Electron Holes in an Electron–Oxygen-Ion Plasma

Eliasson, Bengt; Shukła, P. K.

doi:10.1103/physrevlett.93.045001

Cited by 47 publications

(39 citation statements)

References 30 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This should enable the ESWs to remain stable. In contrast, low-speed ESWs with very large potentials would tend to reflect ions, making the ESWs unstable Drake et al, 2003] or accelerating them out of the ion frame [Eliasson and Shukla, 2004]. We conclude that these ESWs are stable because the potentials are too small to significantly scatter or reflections.…”

Section: Warm Bistream Instabilitymentioning

confidence: 82%

“…ESWs are observed with ± polarity and have similar pp . In contrast, low-speed ESWs with very large potentials would tend to reflect ions, making the ESWs unstable Drake et al, 2003] or accelerating them out of the ion frame [Eliasson and Shukla, 2004]. The maximum potential is ≈ 0.14 V, so individual ESWs do not strongly interact with electrons or ions.…”

Section: Warm Bistream Instabilitymentioning

confidence: 99%

See 1 more Smart Citation

Electrostatic solitary waves and electrostatic waves at the magnetopause

et al. 2016

View full text Add to dashboard Cite

Electrostatic solitary waves (ESWs) are characterized by localized bipolar electric fields parallel to the magnetic field and are frequently observed in space plasmas. In this paper a study of ESWs and field‐aligned electrostatic waves, which do not exhibit localized bipolar fields, near the magnetopause is presented using the Cluster spacecraft. The speeds, length scales, field strengths, and potentials are calculated and compared with the local plasma conditions. A large range of speeds is observed, suggesting different generation mechanisms. In contrast, a smaller range of length scales normalized to the Debye length λD is found. For ESWs the average length between the positive and negative peak fields is 9 λD, comparable to the average half wavelength of electrostatic waves. Statistically, the lengths and speeds of ESWs and electrostatic waves are shown to be similar. The length scales and potentials of the ESWs are consistent with predictions for stable electron holes. The maximum ESW potentials are shown to be constrained by the length scale and the magnetic field strength at the magnetopause and in the magnetosheath. The observed waves are consistent with those generated by the warm bistreaming instability, beam‐plasma instability, and electron‐ion instabilities, which account for the observed speeds and length scales. The large range of wave speeds suggests that the waves can couple different electron populations and electrons with ions, heating the plasma and contributing to anomalous resistivity.

show abstract

Section: Warm Bistream Instabilitymentioning

confidence: 82%

Section: Warm Bistream Instabilitymentioning

confidence: 99%

Electrostatic solitary waves and electrostatic waves at the magnetopause

et al. 2016

View full text Add to dashboard Cite

show abstract

“…The total potential energy W pot = (1/2) E 2 dx as a function of time (upper panels) and the minimum of the electrostatic potential (lower panels) for e = −0.7 (left panels) and e = −0.5 (right panels), obtained from the model for a stationary electron hole in the presence of a varying ion density, where the ion density is obtained from the Vlasov simulations (after Ref. [108]). …”

Section: Self-acceleration Of Electron Holesmentioning

confidence: 99%

“…Let us discuss the numerical results for the dynamics of non-relativistic electron holes in an electron-ion plasma [108]. In order to investigate the dynamics of electron holes numerically in a controlled manner, we use Schamel's solution of the stationary Vlasov-Poisson system with immobile ions to construct initial conditions for our simulations.…”

Section: Self-acceleration Of Electron Holesmentioning

confidence: 99%

Formation and dynamics of coherent structures involving phase-space vortices in plasmas

2006

Self Cite

View full text Add to dashboard Cite

We present a comprehensive review of recent theoretical and numerical studies of the formation and dynamics of electron and ion holes in a collisionless plasma. The electron hole is characterized by a localized positive potential in which a population of electrons is trapped, and a depletion of the electron number density, while the ion hole is associated with localized negative potential in which a population of ions is trapped and a depletion of both the ion and electron densities occur. We present conditions for the existence of quasi-stationary electron and ion holes in unmagnetized and magnetized electron-ion plasmas, as well as in an unmagnetized pair-ion plasma. An interesting aspect is the dynamic interactions between ion and electron holes and the surrounding plasma. The dynamics is investigated by means of numerical simulations in which analytical solutions of quasistationary electron and ion holes are used as initial conditions. Our Vlasov simulations of two colliding ion holes reveal the acceleration of electrons and a modification of the initially Maxwellian electron distribution function by the ion hole potentials, which work as barriers for the electrons. A secondary effect is the excitation of high-frequency plasma waves by the streams of electrons. On the other hand, we find that electron holes show an interesting dynamics in the presence of mobile ions. Since electron holes are associated with a positive electrostatic potential, they repel positively charged ions. Numerical simulations of electron holes in a plasma with mobile ions exhibit that the electron holes are, in general, attracted by ion density maxima and repelled by ion density minima. Therefore, standing electron holes can be accelerated by the self-created ion cavities. In a pair plasma, both the temperatures and masses of the positively and negatively charged particles are assumed equal, and therefore one must treat both species with a kinetic theory on an equal footing. Accordingly, a phase-space hole in one of the species is associated with reflected particles in the opposite species. Here standing solitary large-amplitude holes are not allowed, but they must have a propagation speed close to the thermal speed of the particles. We discuss extensions of the existing non-relativistic theories for the electron and ion holes in two directions. First, we describe a fully nonlinear kinetic theory for relativistic electron holes (REHs) in an unmagnetized plasma, and show that the REHs have amplitudes and widths much larger than their non-relativistic counterparts. Second, we extend the weakly nonlinear theories for the electron and ion holes to include the effects of the external magnetic field and the plasma inhomogeneity. The presence of the external magnetic field gives rise to the electron and ion hole structures which have differential scale sizes along and across the magnetic field direction. Consideration of the density inhomogeneity in a magnetized plasma with non-isothermal electron distribution function provides the p...

show abstract

“…Numerical studies show that the trapped Langmuir waves are Landau damped due to the relatively small Debye-scale of the ion holes (Eliasson and Shukla, 2004a). We have also studied the fully nonlinear interaction between electron holes and oxygen ions by means of a Vlasov simulations (Eliasson and Shukla, 2004b), where it is found that the large-amplitude electron hole potential accelerates the ions locally and that the self-created ion density cavity accelerates the electron hole, which propagates away from the ion cavity with a constant speed close to half the electron thermal speed. Finally, we have extended the idea of Schamel to relativistic plasma, where the trapped and free particles are given by solutions of the relativistic Vlasov equation.…”

Section: Introductionmentioning

confidence: 99%

The dynamics of electron and ion holes in a collisionless plasma

Eliasson

Shukła

2005

Nonlin. Processes Geophys.

Self Cite

View full text Add to dashboard Cite

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 scalelength 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 selfcreated 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 Correspondence to: B. Eliasson (bengt@tp4.rub.de) our simulations could be helpful to understand the nonlinear dynamics of electron and ion holes in space and laboratory plasmas.

show abstract

Dynamics of Electron Holes in an Electron–Oxygen-Ion Plasma

Cited by 47 publications

References 30 publications

Electrostatic solitary waves and electrostatic waves at the magnetopause

Electrostatic solitary waves and electrostatic waves at the magnetopause

Formation and dynamics of coherent structures involving phase-space vortices in plasmas

The dynamics of electron and ion holes in a collisionless plasma

Contact Info

Product

Resources

About