Ion phase space vortices in 3 spatial dimensions

Daldorff, L. K. S.; Guio, P.; Børve, S.; Pécseli, H. L.; Trulsen, J.

doi:10.1209/epl/i2001-00290-6

Cited by 22 publications

(23 citation statements)

References 22 publications

(32 reference statements)

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“…The conspicuous features of the potential structures seem to be associated with phase space vortices, where all the relevant dynamics seem to take place in {x, v x }-plane, as expected for potential structures elongated in the y-direction, as here. Such ion phase space vortices are well-known, and have been observed experimentally by Pécseli et al (1981Pécseli et al ( , 1984, as well as in a number of numerical simulations (Sakanaka, 1972;Børve et al, 2001;Daldorff et al, 2001;. In particular, the coalescence seen in Fig.…”

Section: Numerical Resultssupporting

confidence: 61%

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Phase space structures generated by absorbing obstacles in streaming plasmas

Guio

Pécseli

2005

Ann. Geophys.

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Abstract. The dynamic behavior of a collisionless plasma flowing around an obstacle is investigated by numerical methods. In the present studies, the obstacle is formed by an absorbing cylinder, and a 2-D electrostatic particle-in-cell simulation is used to study the flow characteristics, with extensions to a fully 3-D generalization of the problem demonstrated as well. The formation of irregular filamented density depletions, oblique to the flow, is observed. The structures form behind the obstacle, in a region with a strong velocity shear, but also other instability mechanisms can be identified. The dynamics of these structures is highly dependent on the physical parameters of the plasma, and they can either be quasi-stationary or undergo a dynamic evolution. The structures are found to be associated with phase-space vortices, observed especially in the phase space spanned by the velocity direction perpendicular to the flow and the spatial coordinate in the same direction. The bias of the obstacle with respect to the plasma potential is found to be an important parameter for the dynamics of the structures, but seemingly not for their formation as such. The results can be of interest in the interpretation of structures in space plasmas as observed by instrumented spacecrafts.

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Section: Numerical Resultssupporting

confidence: 61%

“…The present code allows for an externally applied magnetic field , but for the present results we consider an unmagnetized plasma. Phase space structures can be formed in magnetized plasma as well Daldorff et al, 2001;Jovanović and Shukla, 2003).…”

Section: Numerical Simulationsmentioning

confidence: 99%

Phase space structures generated by absorbing obstacles in streaming plasmas

Guio

Pécseli

2005

Ann. Geophys.

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“…Numerical and theoretical studies of the interaction between the electron and ion holes have since then been performed by several authors. Newman et al [8] studied numerically the dynamics and instability of 2D phase-space tubes, whereas Daldorff et al [9] investigated the formation and dynamics of ion holes in three dimensions. Krasovsky et al [10] showed theoretically and by computer simulations that the electron holes perform inelastic collisions.…”

Section: Introductionmentioning

confidence: 99%

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

2006

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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...

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“…Newman et al (2001) in their numerical experiments studied the dynamics and instability of twodimensional phase-space tubes, and Daldorff et al (2001) investigated the formation and dynamics of ion holes in thee dimensions. Krasovsky et al (1999) showed theoretically and by computer simulations that that electron holes perform inelastic collisions, and Vetoulis (2001) studied the radiation generation due to bounce resonances in electron holes.…”

Section: Introductionmentioning

confidence: 99%

The dynamics of electron and ion holes in a collisionless plasma

Eliasson

Shukła

2005

Nonlin. Processes Geophys.

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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.

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Ion phase space vortices in 3 spatial dimensions

Cited by 22 publications

References 22 publications

Phase space structures generated by absorbing obstacles in streaming plasmas

Phase space structures generated by absorbing obstacles in streaming plasmas

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

The dynamics of electron and ion holes in a collisionless plasma

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