The effects of low frequency waves on ion trajectories in the Earth's magnetotail

Abstract

The trajectories of ions in the Tsyganenko magnetic field model with a convection electric field have been compared to the trajectories when a perturbation electric field based on ISEE‐1 and Geotail observations of lower hybrid frequency waves is included. The inclusion of waves dramatically modifies the characteristics of the ion trajectories. For example, initial conditions which result in adiabatic orbits in the absence of waves are often non‐adiabatic when waves are included. In addition, both the regions of space accessible to the particles and the energization are changed. Although only individual trajectories were examined in this study, it is argued that the effect of the waves is to mix previously distinct regions of phase space.

Spiky electric fields in the magnetotail

“…Preliminary results indicate that these fields dramatically modify individual particle trajectories, result in particle energization, and modify particle distributions, in both configuration and velocity space. Previous studies have also shown that the presence of lower hybrid waves, which the spikes seen in this study are always embedded upon, result in greater energization of ions [Cattell et al, 1995a[Cattell et al, , 1996 and are important in magnetotail dynamics [Cattell andMozer, 1986, 1987…”

“…Preliminary results indicate that these fields dramatically modify individual particle trajectories, result in particle energization, and modify particle distributions, in both configuration and velocity space. Previous studies have also shown that the presence of lower hybrid waves, which the spikes seen in this study are always embedded upon, result in greater energization of ions [Cattell et al, 1995a[Cattell et al, , 1996 and are important in magnetotail dynamics [Cattell andMozer, 1986, 1987 The outline of this paper is as follows: in section 2, the three possible theoretical mechanisms for these spikes will be discussed, emphasizing empirical tests which separate these alternatives. This discussion will be followed by a brief introduction to the Geotail spacecraft orbit and instrumentation in section 3, the event selection process for the statistical database in section 4, and the methodology behind the statistical study in section 5.…”

“…This suggests that normalization testing is not an effective method for differentiating between generation mechanisms over this altitude range. The facts that the spikes are found in regions with lower hybrid waves, that wave amplitudes are large enough for collapse to occur, and that the predominance of oblique angles does not match the mapping of electrostatic shocks, which are mostly perpendicular, strongly suggest that these spikes are related to lower hybrid drift wave collapse [ Simulation work using a particle tracing code has shown the inclusion of lower hybrid waves in the magnetotail has a large effect on particle trajectories and energization [Cattell et al, 1995a [Borovsky• 1984] in the auroral zone. Work will continue in this area.…”

Resonances and Particle Stochastization in Nonhomogeneous Electromagnetic Fields

“…Natural source of perturbations in the magnetotail are the electromagnetic waves (Cattell et al, 1995;Ma and Summers, 1998). The problem of particle's motion in the field of electromagnetic or electrostatic waves is one of the classical problems of plasma physics (Sagdeev, 1983) and was well explored in the case of homogeneous external magnetic field (Karney, et al, 1989;Zaslavskii et al, 1989;Neishtadt et al, 1989;Chernikov et al, 1992;Itin et al, 2000).…”

Quasiadiabatic description of nonlinear particle dynamics in typical magnetotail configurations

“…The impact of the electromagnetic waves on the dynamics of particles in the magnetotail was studied started in Cattell et al (1995); Ma and Summers (1998). A range of parameters for which the structure obtained for stationary field configurations survive in the presence of the electromagnetic waves was obtained analytically in Vainchtein et al (2004).…”