Dissipative Ion-Acoustic Solitary Waves in Magnetized κ-Distributed Non-Maxwellian Plasmas

The propagation of dissipative electrostatic (ion-acoustic) solitary waves in a magnetized plasma with trapped electrons is considered via the Schamel formalism. The direction of propagation is assumed to be arbitrary, i.e., oblique with respect to the magnetic field, for generality. A non-Maxwellian (nonthermal) two-component plasma is considered, consisting of an inertial ion fluid, assumed to be cold for simplicity, and electrons. A (kappa) κ-type distribution is adopted for the electron population, in addition to particle trapping taken into account in phase space. A damped version of the Schamel-type equation is derived for the electrostatic potential, and its analytical solution, representing a damped solitary wave, is used to examine the nonlinear features of dissipative ion-acoustic solitary waves in the presence of trapped electrons. The influence of relevant plasma configuration parameters, namely the percentage of trapped electrons, the electron superthermality (spectral) index, and the direction of propagation on the solitary wave characteristics is investigated.

Nonextensive Statistical Mechanics: Equivalence Between Dual Entropy and Dual Probabilities

The concept of duality of probability distributions constitutes a fundamental “brick” in the solid framework of nonextensive statistical mechanics—the generalization of Boltzmann–Gibbs statistical mechanics under the consideration of the q-entropy. The probability duality is solving old-standing issues of the theory, e.g., it ascertains the additivity for the internal energy given the additivity in the energy of microstates. However, it is a rather complex part of the theory, and certainly, it cannot be trivially explained along the Gibb’s path of entropy maximization. Recently, it was shown that an alternative picture exists, considering a dual entropy, instead of a dual probability. In particular, the framework of nonextensive statistical mechanics can be equivalently developed using q- and 1/q- entropies. The canonical probability distribution coincides again with the known q-exponential distribution, but without the necessity of the duality of ordinary-escort probabilities. Furthermore, it is shown that the dual entropies, q-entropy and 1/q-entropy, as well as, the 1-entropy, are involved in an identity, useful in theoretical development and applications.

Multispecies plasma expansion into vacuum: The role of secondary ions and suprathermal electrons

The self-similar expansion of multispecies ion plasma is investigated by a two-ion fluid model with adiabatic equation of state for each ionic species. Our aim is to elucidate the effect of secondary ions on a plasma expansion front, in combination with energetic (suprathermal) electrons in the background, modeled by a kappa-type distribution function. The plasma density, velocity, and electric-field profile is investigated. It is shown that energetic electrons have a significant effect on the expansion front dynamics, essentially energizing the front, thus enhancing the ion acceleration mechanism. Different special cases are considered as regards the relative magnitude of the ion mass and/or charge state.