Current Collection in a Magnetic Field

In accordance with the contract, two problem were studied: the upper-bound limit of current collection taking into account the current's magnetic field and preparation toward numerical computation of current collection. Also investigated was a proposed scheme of measuring the location of the end body

Parametric excitation of high‐frequency electromagnetic waves by the lower‐frequency dipole pumping

The possibility of parametric excitation of high‐frequency electromagnetic waves by lower‐frequency dipole pumping is studied. It is shown that the obtained general dispersive equation may be reduced to the Mathieu equation, provided the case of the flux instability is neglected. In the framework of the developed approach, the excitation of magnetohydrodynamic waves and whistler oscillations is examined.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/70436/2/PFBPEI-5-1-92-1.pd

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

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/95445/1/grl9158.pd

Lower Hybrid Oscillations in Multicomponent Space Plasmas Subjected to Ion Cyclotron Waves

It is found that in multicomponent plasmas subjected to Alfven or fast magnetosonic waves, such as are observed in regions of the outer plasmasphere and ring current-plasmapause overlap, lower hybrid oscillations are generated. The addition of a minor heavy ion component to a proton-electron plasma significantly lowers the low-frequency 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 light 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

The nonlinear coupling of electromagnetic ion cyclotron and lower hybrid waves in the ring current region: the magnetic storm 1-7May 1998

International audienceThe excitation of lower hybrid waves (LHWs) is a widely discussed mechanism of interaction between plasma species in space, and is one of the unresolved questions of magnetospheric multi-ion plasmas. In this paper we present the morphology, dynamics, and level of LHW activity generated by electromagnetic ion cyclotron (EMIC) waves during the 2-7 May 1998 storm period on the global scale. The LHWs were calculated based on a newly developed self-consistent model (Khazanov et. al., 2002) that couples the system of two kinetic equations: one equation describes the ring current (RC) ion dynamic, and another equation describes the evolution of EMIC waves. It is found that the LHWs are excited by helium ions due to their mass dependent drift in the electric field of EMIC waves. The level of LHW activity is calculated assuming that the induced scattering process is the main saturation mechanism for these waves. The calculated LHWs electric fields are consistent with the observational data

Saturation of Alfven oscillations in the ring current region due to generation of lower hybrid waves

The possibility of flux generation of lower hybrid oscillations in the ring current region of the Earth's magnetosphere is suggested in this paper. The energy level of lower hybrid oscillations can exceed the modulational instability threshold, which leads to the formation of caverns. The consequences of this are qualitatively analysed. Also, an assumption is made that the flux instability of lower hybrid oscillations may limit the level of Alfven oscillations in the ring current region.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/30137/1/0000514.pd

A theoretical model for the ring current interaction with the earth's plasmasphere

This paper reports on a theoretical study of the magnetospheric ring current effect on the topside plasmasphere and ionosphere. MHD waves generated by energetic anisotropic protons of the ring current are used as the mechanism for energy transfer to plasmaspheric electrons and ions. Plasmaspheric parameters are calculated in a numerical model for ionospherelasmasphere coupling using a complete system of modelling equations in the 13-moment approximation of the Grad method. The calculations made have shown that the wave mechanism for energy transfer to the thermal plasma ensures its heating in the equatorial plasmasphere to experimentally observed temperatures. The resulting heat flux is able to considerably heat the plasma in the region of the topside ionosphere. It is also shown that the MHD waves present in the plasmasphere substantially influence the height profile of the electron density. The results obtained in this paper lend support to the existence of the experimentally discovered "hot" (or "warm") zone and to its influence on the underlying ionosphere.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/30027/1/0000395.pd

Plasma hydrodynamics in view of quasilinear effects

In this paper we have obtained expressions for the moments of the quasilinear integral of anisotropic plasma collisions. Resonant and adiabatic interactions of particles with an arbitrary wave mode are considered. Expressions for the moments describing the interactions of ion-cyclotron waves with ring current and magnetospheric helium ions have been derived as an example using obtained results.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/31020/1/0000696.pd

Ponderomotive Force in the Presence of Electric Fields

This paper presents averaged equations of particle motion in an electromagnetic wave of arbitrary frequency with its wave vector directed along the ambient magnetic field. The particle is also subjected to an E cross B drift and a background electric field slowly changing in space and acting along the magnetic field line. The fields, wave amplitude, and the wave vector depend on the coordinate along the magnetic field line. The derivations of the ponderomotive forces are done by assuming that the drift velocity in the ambient magnetic field is comparable to the particle velocity. Such a scenario leads to new ponderomotive forces, dependent on the wave magnetic field intensity, and, as a result, to the additional energy exchange between the wave and the plasma particles. It is found that the parallel electric field can lead to the change of the particle-wave energy exchange rate comparable to that produced by the previously discussed ponderomotive forces