Contribution to the nonlinear theory of plasma wave excitation inside the electron foreshock region

Sotnikov, V. I.; Fiala, V.; Décréau, Pierrette; Pivovarov, V. V.; Shapiro, I.

doi:10.1029/94ja01403

Cited by 4 publications

(5 citation statements)

References 15 publications

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“…Figure 2 shows that the first beam plasma instability saturates at W E ≈ 0.05, in agreement with theoretical estimate [ Sotnikov et al , 1994]. The saturation instability is reached together with the plateau formation in the velocity distribution function.…”

Section: Simulation Resultssupporting

confidence: 88%

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One‐dimenssional electromagnetic simulation of multiple electron beams propagating in space plasmas

2010

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[1] It is by now well known that electron beams play an important role in generating radio emissions such as type II and type III radio bursts, commonly observed by spacecraft in the interplanetary medium. Electron beams streaming back from Earth's bow shock into the solar wind have been proposed as a possible source for the electron plasma waves observed by spacecraft in the electron foreshock. Recent observations suggest that during the natural evolution of the foreshock plasma, multiple electron beams could be injected over a period of time, losing their individual identity to coalesce into a single beam. In this work, we use an electromagnetic particle-in-cell (PIC) code "KEMPO 1D, adapted" to simulate two electron beams that are injected into a plasma at different times. The first beam disturbs the background plasma and generates Langmuir waves by electron beam-plasma interaction. Subsequently, another beam is inserted into the system and interacts with the first one and with the driven Langmuir waves to produce electromagnetic radiation. The results of our simulation show that the first beam can produce electrostatic harmonics of the plasma frequency, while the second beam intensifies the emission at the harmonics that is produced by the first one. The behavior of the second beam is strongly determined by the preexisting Langmuir wave electric fields. The simulations also show, as a result of the interaction between both beams, a clear nonlinear frequency shift of the harmonic modes as well as an increase of electromagnetic and kinetic energies of the wave-particle system.

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Section: Simulation Resultssupporting

confidence: 88%

“…The growth of the velocity spread can stabilize the instability. This happens when damping produced by the beam electrons due to the velocity spread exceeds the growth rate connected with the resonant interaction with the background electrons [ Sotnikov et al , 1994].…”

Section: Simulation Resultsmentioning

confidence: 99%

One‐dimenssional electromagnetic simulation of multiple electron beams propagating in space plasmas

2010

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“…The results show that a broadbanded wave spectrum is excited at frequencies below tOpe with wave power highest in the direction along the beam, although a significant fraction of the wave power also occurs at angles oblique to the beam direction. This is in agreement with the calculations done by Sotnikov et al [1994]. The lowest-frequency portion of the excited wave spectrum is primarily at oblique propagation directions, while the higher-frequency end of the spectrum is parallel.…”

Section: Discussionsupporting

confidence: 91%

“…The combination of all of these effects ultimately leads to wave saturation. As pointed out by Sotnikov et al [1994], the waves in the parallel and transverse direction saturate in different ways with saturation in the parallel direction due to beam density depletion and the formation of a plateau in the background distribution, while in the transverse direction saturation is primarily due to the beam depletion.…”

Section: Discussionmentioning

confidence: 97%

“…In this study we consider two-dimensional simulations of slow electron beams compared to the background electrons, whereby the beam speed is less than the background thermal speed. We compare the simulation results with two-dimensional analytical predictions and the wave energy saturation level found by Sotnikov et al [ 1994] for the waves propagating both along the beam and in the oblique direction. In the next section we briefly discuss the linear theory of the electron acoustic instability for electron foreshock conditions, and this is followed by simulations of the instability discussing the nonlinear saturation mechanisms.…”

Section: Previous Particle In Cell Simulations Of Beam-driven Electromentioning

confidence: 95%

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Two‐dimensional saturation of broadband electron acoustic waves in the foreshock region

Schriver¹,

Sotnikov²,

Ashour‐Abdalla³

et al. 1997

J. Geophys. Res.

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Abstract. To analyze the saturation of beam-driven electron acoustic waves that can occur in the electron foreshock region, fully self-consistent two-dimensional electrostatic simulations have been carried out. This has been done for the case of a negative energy beam mode that is excited when the beam velocity is lower than the thermal velocity of the background plasma. This mode can be excited well away from the electron foreshock boundary upstream from the Earth. The nonlinear saturation of the instability in the two-dimensional case is due to spreading of the beam velocity and damping of the initially negative energy mode by the beam particles. Although the saturated wave energy contained in the waves propagating along the beam direction is dominant, a significant amount of wave energy appears in the direction propagating oblique to the beam causing perpendicular heating of beam particles. The electron acoustic wave growth in the simulations is in agreement with linear theory and previous theoretical predictions. An interesting unexpected result was the additional generation of low-frequency part of the electron acoustic wave spectrum propagating in the direction opposite to that of the main spectrum of the electron acoustic waves. These backward propagating waves were found only in the wave spectrum transverse (oblique) to the beam direction.

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Emittance growth mechanisms for laser-accelerated proton beams

et al. 2007

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In recent experiments the transverse normalized rms emittance of laser-accelerated MeV ion beams was found to be < 0.002 mm mrad, which is at least 100 times smaller than the emittance of thermal ion sources used in accelerators [T. E. Cowan, Phys. Rev. Lett. 92, 204801 (2004)]. We investigate the origin for the low emittance of laser-accelerated proton beams by studying several candidates for emittance-growth mechanisms. As our main tools, we use analytical models and one- and two-dimensional particle-in-cell simulations that have been modified to include binary collisions between particles. We find that the dominant source of emittance is filamentation of the laser-generated hot electron jets that drive the ion acceleration. Cold electron-ion collisions that occur before ions are accelerated contribute less than ten percent of the final emittance. Our results are in qualitative agreement with the experiment, for which we present a refined analysis relating emittance to temperature, a better representative of the fundamental beam physics.

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Contribution to the nonlinear theory of plasma wave excitation inside the electron foreshock region

Cited by 4 publications

References 15 publications

One‐dimenssional electromagnetic simulation of multiple electron beams propagating in space plasmas

One‐dimenssional electromagnetic simulation of multiple electron beams propagating in space plasmas

Two‐dimensional saturation of broadband electron acoustic waves in the foreshock region

Emittance growth mechanisms for laser-accelerated proton beams

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