Excitation of magnetosonic waves with discrete spectrum in the equatorial vicinity of the plasmapause

Gulelmi, A. V.; Klaine, B.I.; Potapov, A. S.

doi:10.1016/0032-0633(75)90133-6

Cited by 59 publications

(59 citation statements)

References 2 publications

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“…However, the reduced parameters lower the lower hybrid frequency to about 8Ω p . This limits the excited waves to the first few proton cyclotron harmonics, while some observations [ Boardsen et al , 1992] and linear theories [ Gul ' elmi et al , 1975; Horne et al , 2000] show spectra which peak at higher harmonics of the proton cyclotron frequency. Our current linear kinetic dispersion code is based on bi‐Maxwellian velocity distributions and only applies to the subtracted Maxwellian distribution case.…”

Section: Summary and Discussionmentioning

confidence: 99%

“…The waves propagate nearly perpendicular to B 0 , are primarily confined within 2 ∼ 3° of the geomagnetic equator, and are mainly observed in the afternoon and premidnight sectors. Observations [ Perraut et al , 1982; Boardsen et al , 1992; Meredith et al , 2008] and theoretical studies [ Gul'elmi et al , 1975; McClements et al , 1994; Chen et al , 2010] suggest that the waves are driven by energetic protons at energies of tens keV which have ring‐like distributions with ∂ f p ( v )/∂ v > 0 ( f p ( v ) is the perpendicular velocity distribution function).…”

Section: Introductionmentioning

confidence: 99%

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Excitation of magnetosonic waves in the terrestrial magnetosphere: Particle-in-cell simulations

2011

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[1] Two-dimensional electromagnetic particle-in-cell simulations are performed to study the temporal development of an ion Bernstein instability driven by a proton velocity distribution with positive slope in the perpendicular velocity distribution f p (v ? ), where ? denotes directions perpendicular to the background magnetic field B 0 . A subtracted Maxwellian distribution is first used to construct the positive slope in f p (v ? ), and linear kinetic dispersion analysis is performed. The results of a simulation using such an initial proton distribution agree well with the linear kinetic analysis. The simulation results demonstrate that the ion Bernstein instability grows at propagation angles nearly perpendicular to B 0 and at frequencies close to the harmonics of the proton cyclotron frequency. The distribution in the simulation is further generalized to contain a proton shell with a finite thermal spread and a relatively cold ion background. The simulation results show that the presence of the cold background protons and the increase of the shell velocity shift the excited waves close to the cold plasma dispersion relation for magnetosonic waves, i.e., w r = kv A , where w r is the wave frequency, k is the wave number, and v A is the Alfvén velocity. The general features of the simulated field fluctuations resemble observations of fast magnetosonic waves near the geomagnetic equator in the terrestrial magnetosphere. A test particle computation of energetic electrons interacting with the simulated electromagnetic fluctuations suggests that this growing mode may play an important role in the acceleration of radiation belt relativistic electrons.

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Section: Summary and Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Excitation of magnetosonic waves in the terrestrial magnetosphere: Particle-in-cell simulations

2011

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“…Generally, the noise at the lowest frequencies is predominantly electromagnetic in nature, whereas the fluctuations at the higher frequencies are mostly electrostatic in nature (Russell et al, 1970;Anderson and Gumett, 1973;Gumett, 1976;Gumett andFrank, 1977, 1978;Perraut et al, 1982;Laakso et al, 1990). It has been shown that various types of energetic proton distribution in the ring current region can excite ULF waves over a broad range of frequencies spanning from much below the proton cyclotron frequency to several of its harmonics (Cornwall et al, 1971;Gul'elmi et al, 1975;Curtis and Wu, 1979;Bhatia and Lakhina, 1980a,b;McClements and Dendy, 1993;McClements et al, 1994). Energetic ion distributions can also excite electrostatic waves in various regions of the magnetosphere.…”

Section: Introductionmentioning

confidence: 99%

Low-frequency electric field fluctuations excited by ring current protons

1996

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Energetic protons having ring type distributions are shown to generate low-frequency electrostatic waves, propagating nearly transverse to the geomagnetic field lines, in the ring current region by exciting Mode 1 and Mode 2 nonresonant instabilities and a resonant instability. Mode 1 nonresonant instability has frequencies around -4 Hz with transverse wavelengths of +%SO) km, and it is likely to occur in the region L = (7-8). Mode 2 nonresonant instability can generate frequencies +85&1450)Hz with transverse wavelengths ~(2-20) km. The typical frequencies and transverse wavelengths associated with the resonant instability are (950-1250) Hz and (3@65) km. Both the Mode 2 nonresonant instability and the resonant instability can occur in the ring current region with L = (46). The low-frequency modes driven by energetic protons could attain maximum saturation electric field amplitude varying from 0.8 mV/m to 70 mV/m. It is suggested that the turbulence produced by the low-frequency modes may cause pitch angle scattering of ring current protons in the region outside the plasmapause resulting in the ring current decay.

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“…The Bernstein mode instability of hot protons with a velocity ring distribution can destabilize the magnetosonic waves at the quasi-perpendicular normal angles (Boardsen et al, 1992;Curtis & Wu, 1979;Gary et al, 2010;Gulelmi et al, 1975;Horne et al, 2000;Liu et al, 2011;Min et al, 2018;Perraut et al, 1982). Near the source region, the magnetosonic waves are characterized as the emission lines along the proton gyrofrequency harmonics in the high-resolution frequency-time spectrograms (e.g., Balikhin et al, 2015;Perraut et al, 1982).…”

Section: Introductionmentioning

confidence: 99%

Quenching of Equatorial Magnetosonic Waves by Substorm Proton Injections

Dai

Liu

et al. 2019

Geophysical Research Letters

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Near equatorial (fast) magnetosonic waves, characterized by high magnetic compressibility, are whistler‐mode emissions destabilized by proton shell/ring distributions. In the past, substorm proton injections are widely known to intensify magnetosonic waves in the inner magnetosphere. Here we report the unexpected observations by the Van Allen Probes of the magnetosonic wave quenching associated with the substorm proton injections under both high‐ and low‐density conditions. The enhanced proton thermal pressure distorted the background magnetic field configuration and the cold plasma density distribution. The reduced phase velocities locally allowed the weak growth or even damping of magnetosonic waves. Meanwhile, the spatially irregularly varying refractive indices might suppress the cumulative growth of magnetosonic waves. For intense injections, this wave quenching region could extend over 2 hr in magnetic local time and 0.5 Earth radii in radial distance. These results provide a new understanding of the generation and distribution of magnetosonic waves.

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Excitation of magnetosonic waves with discrete spectrum in the equatorial vicinity of the plasmapause

Cited by 59 publications

References 2 publications

Excitation of magnetosonic waves in the terrestrial magnetosphere: Particle-in-cell simulations

Excitation of magnetosonic waves in the terrestrial magnetosphere: Particle-in-cell simulations

Low-frequency electric field fluctuations excited by ring current protons

Quenching of Equatorial Magnetosonic Waves by Substorm Proton Injections

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