Simulations of the ion–dust streaming instability with non-Maxwellian ions

The dust acoustic, or dust density, wave is a very low frequency collective mode in a dusty plasma that is associated with the motion of the charged and massive dust grains. An ion flow due to an electric field can excite these waves via an ion–dust streaming instability. Theories of this instability have often assumed a shifted-Maxwellian ion velocity distribution. Recently, the linear kinetic theory of this instability was considered using a non-Maxwellian ion velocity distribution (Kählert, Phys. Plasmas, vol. 22, 2015, 073703). In this paper, we present one-dimensional PIC simulations of the nonlinear development of the ion–dust streaming instability, comparing the results for these two types of ion velocity distributions, for several values of the ion drift speed and collision rate. Parameters are considered that reflect the ordering of plasma and dust quantities in laboratory dusty plasma experiments. It is found that, in general, the wave energy density is smaller in the simulations with a non-Maxwellian ion distribution.

Landau fluid closures with nonlinear large-scale finite Larmor radius corrections for collisionless plasmas

With the aim to develop a tool for simulating turbulence in collisionless magnetized plasmas, fluid models retaining low-frequency kinetic effects such as Landau damping and finite Larmor radius (FLR) corrections are discussed. It turns out that, in the absence of ion-cyclotron resonance, the dispersion and damping of kinetic Alfvén waves at scales as small as a fraction of the ion Larmor radius are accurately reproduced when using fluid estimates of the non-gyrotropic moments, at leading-order within a large-scale asymptotics. Differently, evaluations based on the low-frequency linear kinetic theory are necessary in regimes of large temperature anisotropies, and in particular in the presence of the mirror instability. Combining both descriptions leads to a new Landau fluid model retaining large-scale FLR nonlinearities, while reproducing the linear dynamics of low-frequency modes at the sub-ionic scales.

Current-driven drift wave instability in a collisional dusty negative ion plasma

The excitation of drift waves by an electron current parallel to the magnetic field is investigated in a nonuniform plasma composed of electrons, positive ions, negative ions, and massive, negatively charged dust. Electrostatic drift waves with frequencies smaller than the ion gyrofrequencies and wavelengths larger than the ion gyroradii are considered. Linear kinetic theory is used, and collisions of charged particles with neutrals are taken into account. The present results may be relevant to laboratory collisional magnetoplasmas containing negative ions and dust.

Drift instability in a positive ion–negative ion plasma

Drift wave instability in a magnetized plasma composed of positive ions and negative ions is considered using linear kinetic theory in the local approximation. We consider the case where the mass (temperature) of the negative ions is much larger (smaller) than that of the positive ions, and where the gyroradii of the two ion species are comparable. Weak collisional effects are taken into account. Application to possible laboratory parameters is discussed.