Different kinds of waves and instabilities in the F-region of the ionosphere excited by the relative streaming of the dust beam to the background plasma are studied in the present paper. The dispersion relations of different waves are obtained on different time scales. It is found from our numerical results that there are both a stable upper hybrid wave on the electron vibration time scale and a stable dust ion cyclotron wave on the ion vibration time scale. However, the chaotic behaviour appears on the dust particles vibration time scale due to the relative streaming of the dust particles to the background plasma. Such instabilities may drive plasma irregularities that could affect radar backscatter from the clouds.

We present the effective optical potential of the interaction of an electron with an atom in dense semiclassical plasma of noble gases. This potential takes into account the collective screening effect and the quantum mechanical effect of diffraction. The influence of diffraction and screening effects on the characteristics of electron–atom collisions was investigated. Scattering phase shifts decrease with increase of the de Broglie wave. The electron–atom momentum-transfer cross-section at $\lambda _{B}\to 0$ tends to the data obtained earlier with a neglecting of the diffraction effect.

We study the nonlinear interaction of three parallel Alfvén wave packets (AWPs) in an initially uniform plasma using 2.5-dimensional particle-in-cell (PIC) numerical simulations. We aim to help to explain the observation of suprathermal electrons by the collision of multiple Alfvén waves in regions where these waves are trapped like the IAR (Ionospheric Alfvén Resonator), Earth radiation belts or coronal magnetic loops. In the context of the acceleration by the parallel Alfvén waves interactions (APAWI) process that has been described by Mottez (Ann. Geophys., vol. 30, issue 1, 2012, pp. 81–95; J. Plasma Phys., vol. 81, issue 1, 2015, p. 325810104), the interaction of two parallel Alfvén waves (AWs) generates longitudinal density modulations and parallel electric fields at the APAWI crossing region that can accelerate particles effectively in the direction of the background magnetic field. Our simulations show that when a third parallel AWP of different initial position arrives at the APAWI crossing region, it gives rise to a strong parallel electron beam ($V \sim 5\text {--}7 V_{Te}$) at longitudinal cavity density gradients. We suggest that velocity drift from an outgoing AW generates interface waves in the transverse direction, which allows propagating waves to develop parallel electric fields by the phase mixing process when $k_{\perp }^{-1}$ of the wavy density gradient (oblique gradient) is in the range of the electron inertial length $c/\omega _{p0}$.

The magnetosphere–ionosphere dynamics comprises processes both directly related to solar wind variability and of purely internal origin. The latter represent a huge drawback for correctly forecasting the magnetosphere–ionosphere dynamics during geomagnetic storms and substorms. Here, we use wavelet analysis to further characterize the storm–substorm relationship through the use of the AL and SYM-H geomagnetic indices. We focus our analysis on one of the strongest geomagnetic storms of solar cycle 23 that occurred on 20 November 2003. Our findings suggest that, during disturbed periods, a significant amount of information comes from the interactions between geomagnetic storms and magnetospheric substorms. Thus, predicting the intensity and the duration of a geomagnetic storm requires information coming not only from the solar wind variability but also from the nonlinear variability of the magnetosphere–ionosphere system occurring on short time scales. Our results are also discussed in the framework of Space Weather, suggesting an extended use of non-traditional dynamical systems approaches (such as those based on extreme value statistics and tipping point analysis) to deal with emergent behaviours coming from different sources during geomagnetic storms and magnetospheric substorms.

Anisotropic heat conduction in a plasma embedded in a magnetic field with irregular, possibly chaotic, field lines is discussed. If the collisional mean free path exceeds the electron gyroradius, the heat conductivity is much larger along the field lines than across them, and this enhances the transport across a domain where good flux surfaces do not exist. Recognising that anisotropic heat conduction may be cast in a variational form, and by constructing increasingly sophisticated trial functions that are based on invariant and almost-invariant structures under the magnetic field-line flow, bounds are derived on this enhancement and on the temperature variation along the magnetic field. In this way, remarkably accurate approximations for the temperature can be rapidly constructed without solving the diffusion equation, even in the small perpendicular-diffusion limit when the solution for the temperature is dominated by the fractal structure the magnetic field lines.