Lower hybrid turbulence and ponderomotive force effects in space plasmas subjected to large‐amplitude low‐frequency waves

Khazanov, G. V.; Moore, T. E.; Krivorutsky, E. N.; Horwitz, J. L.; Liemohn, Michael W.

doi:10.1029/96gl00844

Cited by 27 publications

(29 citation statements)

References 24 publications

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“…The level of energy density of LFWs which leads to excitation of LHWs in a hydrogen plasma, was discussed by Khazanov et al [1996]. It can be estimated by taking into account that the ion-electron relative velocity needed for LHW excitation is of the same order of magnitude as the thermal ion velocity.…”

Section: Description Of the Problemmentioning

confidence: 99%

“…Depending on the frequency of the LFW, the magnitude of the electric field, plasma composition, temperatures of different plasma species, and the external magnetic field, strong or weak LHW turbulence may develop. In the case of large-amplitude LFWs, strong lower hybrid (LH) turbulence could be produced Khazanov et al, 1996]. Strong LH turbulence results in plasma heating and acceleration [Shapiro et al, 1993], the formation of ion conics [Chang and Coppi, 1981;Retterer et al, 1986], and possibly the saturation of Alfv6n oscillations in the ring current region .…”

Section: Description Of the Problemmentioning

confidence: 99%

“…This leads to a requirement for the LFW energy density I01 E02 > toni (1) 8nrnT 2 2 too to pi where toBi and topi are the cyclotron and plasma frequencies for ions, respectively; n T is the thermal plasma energy density; and too is the LFW frequency. Khazanov et al [1996] assumed that the plasma consists of only electrons and protons and that the LFW electric field is strong enough not only to make the relative proton velocity greater than its thermal velocity, but also to create strong LHW turbulence. From (1), however, it can be seen that the LFW energy density needed for LHW excitation may be lower in the presence of a heavy ion component.…”

Section: Description Of the Problemmentioning

confidence: 99%

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Lower hybrid oscillations in multicomponent space plasmas subjected to ion cyclotron waves

Khazanov¹,

Krivorutsky²,

Moore³

et al. 1997

J. Geophys. Res.

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Abstract. It is found that in multicomponent plasmas subjected to Alfv6n or fast magnetosonic waves, such as are observed in regions of the outer plasmasphere and ring currentplasmapause overlap, lower hybrid oscillations are generated. The addition of a minor heavy ion component to a proton-electron plasma significantly lowers the low-frequen9y electric wave amplitude needed for lower hybrid wave excitation. It is found that the lower hybrid wave energy density level is determined by the nonlinear process of induced scattering by ions and electrons; hydrogen ions in the region of resonant velocities are accelerated; and nonresonant particles are weakly heated due to the induced scattering. For a given example, the ligh.t resonant ions have an energy gain factor of 20, leading to the development of a high-energy tail in the H + distribution function due to low-frequency waves. By interacting with charged particles, the waves influence the behavior of the plasma as a whole, and therefore wave effects must be included in corresponding models. Ganguli and Palmadesso [1987, 1988], Singh [1988], Singh and Torr [1990], Brown et al. [1991, 1995], and Lin et al. [1992, 1994] took into account effects from the low-frequency (LF) electrostatic turbulence, and they demonstrated that wave-particle interactions lead to significant effects on the evolution of the core plasma distribution functions.In developing a mathematical model to describe plasma transport in the magnetosphere-ionosphere system that accounts for the active wave processes which occur there, we must develop a general scheme to include an analysis of the dispersion characteristics of the medium in order to choose suitable wave modes, a wave-particle interaction mechanism, and a system of hydrodynamical equations governing ma6ro-scopic plasma parameters which properly accounts for the presence of wave-particle interactions. One basis for this scheme's development has been described elsewhere Khazanov et al. [1996] assumed that the plasma consists of only electrons and protons and that the LFW electric field is strong enough not only to make the relative proton velocity greater than its thermal velocity, but also to create strong LHW turbulence. From (1), however, it can be seen that the LFW energy density needed for LHW excitation may be lower in the presence of a heavy ion component. Since the magnetosphere and ionosphere have multicomponent plasmas, it can be supposed that LHWs can be excited in such plasmas by LFWs with amplitudes less than that needed for a proton-electron plasma.This leads us to the problem of LFW interaction with a multicomponent plasma due to LHW excitation. In accordance with this problem, we will study the following questions:1 LHW excitation are analyzed, and an estimation of particle

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Section: Description Of the Problemmentioning

confidence: 99%

Section: Description Of the Problemmentioning

confidence: 99%

Section: Description Of the Problemmentioning

confidence: 99%

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Lower hybrid oscillations in multicomponent space plasmas subjected to ion cyclotron waves

Khazanov¹,

Krivorutsky²,

Moore³

et al. 1997

J. Geophys. Res.

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“…Such simultaneous wave activities were also observed during active ionospheric sounding rocket experiments [Arnoldy, 1993;Bale et al, 1998]. In these situations, LHWs can be generated because of low-frequency wave (LFW) activity [Khazanov et al, 1996[Khazanov et al, , 1997a. It is well known from the plasma physics literature that LFWs with frequencies o: < o:Bi, where o:Bi is the ion cyclotron frequency, could drive a host of high-frequency waves through drifts of plasma particles produced by the former waves [see, e.g., Akhiezer et al, 1975].…”

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confidence: 92%

“…If the drift velocity exceeds the ion thermal velocity, LHW generation is possible because of the flux instability. Only recently has this idea been adopted to explain some observations in space plasmas [Khazanov et al, 1996[Khazanov et al, , 1997aBale et al, 1998]. As far as we know, these studies were the first time attention has been paid to the special role of heavy plasma ions in this well-known mechanism.…”

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confidence: 99%

Alfvén waves as a source of lower‐hybrid activity in the ring current region

Khazanov¹,

Gamayunov²,

Liemohn³

2000

J. Geophys. Res.

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Abstract. A coupling mechanism between lower-hybrid waves and low-frequency electromagnetic activity in the Earth's ring current region is analyzed. In the ring current region the observed amplitudes of AlfvSn and/or fast magnetosonic waves, as a rule, do not exceed the threshold of flux instability of lower-hybrid waves in an electromagnetic field of a low-frequency wave. Even for these conditions, however, a mechanism of parametric generation of lower-hybrid waves from low-frequency AlfvSn or fast magnetosonic waves is possible, and this theory is presented. In the studied case, lower-hybrid waves are saturated because of induced scattering with plasma electrons. For typical plasma and low-frequency wave parameters in the Earth's ring current region the saturation level of lower-hybrid waves, excited by the proposed mechanism, is in good agreement with experimental data.

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Magnetospheric boundary perturbations on MHD and kinetic scales

Chen

Fok

2015

JGR Space Physics

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To study the magnetopause on both MHD and kinetic scales, we have analyzed two Time History of Events and Macroscale Interactions during Substorms/Acceleration, Reconnection, Turbulence, and Electrodynamics of the Moon' s Interaction with the Sun magnetopause crossings under steady slow-solar wind and minimum magnetic shear conditions. These events approximate a ground state of the magnetospheric boundary with minimum influences from large-solar wind disturbances and magnetic reconnection. Our observations reveal evidence for the Kelvin-Helmholtz instability, the quasi-periodicity of magnetopause surface waves accompanied by highly asymmetrical plasma signatures between the inbound (from magnetosheath to low-latitude boundary layer (LLBL)) and the outbound (from LLBL to magnetosheath) magnetopause crossings. Stronger plasma and magnetic gradients were observed during the outbound crossings but more gradual and volatile variations at higher frequencies during the inbounds. The scale lengths of the magnetic and plasma gradients were comparable or less than the proton gyroradius. Enhancements of lower hybrid waves occurred at the locations of strong gradients or variations. We interpreted the collocations of the lower hybrid waves and plasma gradients and their variations in terms of (1) lower hybrid instabilities that directly convert solar wind flow energy into lower hybrid waves and other wave modes in the LLBL, or (2) Kelvin-Helmholtz instability and magnetic reconnection which produce the conditions for the lower hybrid instabilities to grow. The rate of ion diffusion across the magnetopause caused by the lower hybrid instability is marginally sufficient to populate the LLBL. The diffusion coefficient of O + is~30 times larger than that of H + . The lower hybrid waves could contribute to the energy dissipation at plasma gradients in magnetopause surface wave structures and limit Kelvin-Helmholtz instability growth further downstream.

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Lower hybrid turbulence and ponderomotive force effects in space plasmas subjected to large‐amplitude low‐frequency waves

Cited by 27 publications

References 24 publications

Lower hybrid oscillations in multicomponent space plasmas subjected to ion cyclotron waves

Lower hybrid oscillations in multicomponent space plasmas subjected to ion cyclotron waves

Alfvén waves as a source of lower‐hybrid activity in the ring current region

Magnetospheric boundary perturbations on MHD and kinetic scales

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