The properties of charged‐particle motion in Hamiltonian dynamics are studied in a magnetotaillike magnetic field configuration. It is shown by numerical integration of the equation of motion that the system is generally nonintegrable and that the particle motion can be classified into three distinct types of orbits: bounded integrable orbits, unbounded stochastic orbits, and unbounded transient orbits. It is also shown that different regions of the phase space exhibit qualitatively different responses to external influences. The concept of “differential memory” in single‐particle distributions is proposed. Physical implications for the dynamical properties of the magnetotail plasmas and the possible generation of non‐Maxwellian features in the distribution function are discussed.

A kinetic theory in the form of an integral equation is provided to study the electrostatic oscillations in a collisionless plasma immersed in a uniform magnetic field and a nonuniform transverse electric field. In the low temperature limit (kyρi ≪1, where ky is the wave vector in the y direction and ρi is the ion gyroradius) the dispersion differential equation is recovered for the transverse Kelvin–Helmholtz modes for arbitrary values of k∥, where k∥ is the component of the wave vector in the direction of the external magnetic field assumed in the z direction. For higher temperatures (kyρi>1) the ion-cyclotron-like modes described earlier in the literature by Ganguli, Lee, and Palmadesso [Phys. Fluids 28, 761 (1985)] are recovered. In this article the integral equation is reduced to a second-order differential equation and a study is made of the kinetic Kelvin–Helmholtz and the ion-cyclotron-like modes that constitute the two branches of oscillation in a magnetized plasma including a transverse inhomogeneous dc electric field.

A new mechanism that can destabilize kinetic ion-cyclotron waves in the presence of a nonuniform electric field perpendicular to the uniform ambient magnetic field is given. In the absence of the electric field, the mode energy is positive, while in the presence of a uniform electric field the mode energy could be negative. However, when the electric field is nonuniform, it is possible for a finite region to be a negative wave energy surrounded by regions of positive wave energy. A nonlocal wave packet couples the two regions so that a flow of energy from the region of negative wave energy to the region of positive wave energy will cause the mode to brow. This gives rise to the instability.

A study is made of the collisionless tearing-mode stability properties of a neutral sheet whose temperature distribution is anisotropic. A kinetic description is used for both ions and electrons. The wave vector k of the perturbation is taken to be parallel to the equilibrium magnetic field B0 and perpendicular to the equilibrium current J0. The analysis is carried out for the low-frequency perturbation (‖ω‖≪ωci). It is found that the conventional technique of matching the inner and outer asymptotic solutions at the electron inner region (two-region approximation), thus neglecting the axis-crossing ion orbits outside the electron inner region, is inadequate for the anisotropic case. An intermediate region in which the axis-crossing ion orbits make the dominant contribution is identified. The eigenvalue equation is solved using both analytic approximations and numerical methods to obtain the eigenmode structure and the linear dispersion relation. Specializing primarily to anisotropic ions with isotropic or weakly anisotropic electrons, it is shown that inclusion of the ion intermediate region can enhance the growth rate by one order of magnitude over the conventional isotropic and anisotropic results based on the neglect of the ion intermediate region.

Abstract. This paper describes a feature-based pattern-recognition technique that utilizes real-time solar wind measurements to identify and predict the occurrence of solar wind structures that can cause geomagnetic storms. The technique is based on the knowledge that storms are caused by solar wind events with certain identifiable features, the two most important ones being (1) extended periods and (2) Because of the cosily damage to technological systems that can result from severe geomagnetic disturbances, much attention has been paid to the prediction of storms and substorms [Joselyn, 1995]. Although observation of solar eruptions can provide a key predictor, the precise propagation of geoeffective solar ejecta to 1 AU, and therefore the occurrence, the time of onset, the duration, and the severity of the resulting Now at The Blackett Laboratory, Imperial College, London.