Simulations of electron/electron instabilities: Electromagnetic fluctuations

Gary, S. Peter; Kazimura, Yoshihiro; Li, Hui; Sakai, Jun–ichi

doi:10.1063/1.873829

Cited by 15 publications

(13 citation statements)

References 24 publications

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“…On the other hand, Dum and Nishikawa [1994] did two‐dimensional PIC simulations of the instability in a strongly magnetized plasma, and showed weak perpendicular scattering of the beam component. Later simulations [ Yin et al , 1998; Gary et al , 2000] suggested that pitch angle widths of the beam component tend to be broader with larger frequency ratio ω e /∣Ω e ∣, where ω e and Ω e are the electron plasma and cyclotron frequencies. Lately, Gary and Saito [2007] demonstrated electron beam broadening by the e/e instability in a weakly magnetized plasma similar to that of the solar wind using a two‐dimensional PIC simulation.…”

Section: Introductionmentioning

confidence: 99%

“…On the other hand, Dum and Nishikawa [1994] did two-dimensional PIC simulations of the instability in a strongly magnetized plasma, and showed weak perpendicular scattering of the beam component. Later simulations [Yin et al, 1998;Gary et al, 2000] suggested that pitch angle widths of the beam component tend to be broader with larger frequency ratio w e /jW e j, where w e and W e are the electron plasma and cyclotron frequencies.…”

Section: Introductionmentioning

confidence: 99%

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Perpendicular scattering for electron beams by the electron/electron instability in solar electron bursts

Saito

Gary

2008

J. Geophys. Res.

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[1] Energy dependence of electron pitch angle distributions in solar electron bursts is studied using both particle-in-cell simulations of the electron/electron instability and a time-of-flight model for streaming electrons. The simulations show that the electron/ electron instability leads to a maximum of electron pitch angle width in electron kinetic energy. The energy where the maximum appears varies with electron beam parameters. The simulations further show that the maximum electron pitch angle width increases with increasing electron beam density. The time-of-flight effect which leads to positive slopes in electron velocity distributions implies that the probability of electron/electron instability growth in the solar wind depends on electron kinetic energy because of the presence of an electron halo distribution. It is concluded that the electron/electron instability induced by the time-of-flight effect is likely to yield a maximum electron pitch angle width near 1 keV.Citation: Saito, S., and S. P. Gary (2008), Perpendicular scattering for electron beams by the electron/electron instability in solar electron bursts,

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Perpendicular scattering for electron beams by the electron/electron instability in solar electron bursts

Saito

Gary

2008

J. Geophys. Res.

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“…Kazimura et al [24] reported that electron/electron instabilities are generated in the auroral region at ω e /Ω e < 1 by tenuous electron beam propagating in the dense plasma with a sufficiently large beam relative drift velocity. Gary et al [25] using electromagnetic linear theory and particle-in cell simulations have studied the electron/electron beam instability driven by relatively dense and fast electron beams in the plasma with ω e /Ω e = 1 (polar and auroral regimes of the terrestrial magnetosphere). They found that electron/electron beam instability can account for several properties of plasma waves observed in the auroral plasmas.…”

Section: Resultsmentioning

confidence: 99%

Effect of upflowing field-aligned electron beams on the electron cyclotron waves in the auroral magnetosphere

2007

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The role of low density upflowing field-aligned electron beams (FEBs) on the growth rate of the electron cyclotron waves at the frequencies ωr < Ωe, propagating downward in the direction of the Earth's magnetic field, has been analysed in the auroral region at ωe/Ωe < 1 where ωe is the plasma frequency and Ωe is the gyrofrequency. The FEBs with low to high energy (E b ) but with low temperature (T b ) have no effect on these waves. The FEBs with E b < 1 keV and T b (>1.5 keV) have been found to have significant effect on the growth rate. Analysis has revealed that it is mainly the T b which inhibits the growth rate (magnitude) and the range of frequency (bandwidth) of the instability mainly in the higher frequency spectrum. The inhibition in the growth rate and bandwidth increases with increase in T b . The FEBs with less E b (giving drift velocity) reduce growth rate more than the beams with larger E b . The inhibition of growth rate increases with the increase in the ratio ωe/Ωe indicating that the beams are more effective at higher altitudes.

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“…Nevertheless, the consequences of the instability are similar: the enhanced electric field fluctuations are primarily in the beam direction and scatter the beam electrons to reduce the beam velocity and increase the parallel temperature and sometimes also the perpendicular temperature. [17][18][19] In addition, oblique whistler waves can be excited by the beam in a finite beta plasma via the Landau resonance, even when the beam is isotropic. 16,20,21 These waves occur below the electron cyclotron frequency and have both electrostatic and electromagnetic components.…”

Section: Introductionmentioning

confidence: 99%

Particle-in-cell simulations of velocity scattering of an anisotropic electron beam by electrostatic and electromagnetic instabilities

Cowee

Liu

et al. 2014

Physics of Plasmas

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The velocity space scattering of an anisotropic electron beam (T⊥b/T∥b>1) flowing along a background magnetic field B0 through a cold plasma is investigated using both linear theory and 2D particle-in-cell simulations. Here, ⊥ and ∥ represent the directions perpendicular and parallel to B0, respectively. In this scenario, we find that two primary instabilities contribute to the scattering in electron pitch angle: an electrostatic electron beam instability and a predominantly parallel-propagating electromagnetic whistler anisotropy instability. Our results show that at relative beam densities nb/ne≤0.05 and beam temperature anisotropies Tb⊥/Tb∥≤25, the electrostatic beam instability grows much faster than the whistler instabilities for a reasonably fast hot beam. The enhanced fluctuating fields from the beam instability scatter the beam electrons, slowing their average speed and increasing their parallel temperature, thereby increasing their pitch angles. In an inhomogeneous magnetic field, such as the geomagnetic field, this could result in beam electrons scattered out of the loss cone. After saturation of the electrostatic instability, the parallel-propagating whistler anisotropy instability shows appreciable growth, provided that the beam density and late-time anisotropy are sufficiently large. Although the whistler anisotropy instability acts to pitch-angle scatter the electrons, reducing perpendicular energy in favor of parallel energy, these changes are weak compared to the pitch-angle increases resulting from the deceleration of the beam due to the electrostatic instability.

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Simulations of electron/electron instabilities: Electromagnetic fluctuations

Cited by 15 publications

References 24 publications

Perpendicular scattering for electron beams by the electron/electron instability in solar electron bursts

Perpendicular scattering for electron beams by the electron/electron instability in solar electron bursts

Effect of upflowing field-aligned electron beams on the electron cyclotron waves in the auroral magnetosphere

Particle-in-cell simulations of velocity scattering of an anisotropic electron beam by electrostatic and electromagnetic instabilities

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