Drift waves in the corona: heating and acceleration of ions at frequencies far below the gyro frequency

In the solar corona, several mechanisms of the drift wave instability can make the mode growing up to amplitudes at which particle acceleration and stochastic heating by the drift wave take place. The stochastic heating, well known from laboratory plasma physics where it has been confirmed in numerous experiments, has been completely ignored in past studies of coronal heating. However, in the present study and in our very recent works it has been shown that the inhomogeneous coronal plasma is, in fact, a perfect environment for fast growing drift waves. As a matter of fact, the large growth rates are typically of the same order as the plasma frequency. The consequent heating rates may exceed the required values for a sustained coronal heating by several orders of magnitude. Some aspects of these phenomena are investigated here. In particular the analysis of the particle dynamics within the growing wave is compared with the corresponding fluid analysis. While both of them predict the stochastic heating, the threshold for the heating obtained from the single particle analysis is higher. The explanation for this effect is given.Comment: To appear in MNRAS (2010

New features of ion acoustic waves in inhomogeneous and permeating plasmas

It is generally accepted that the ion acoustic (IA) wave in plasmas containing ions and electrons with the same temperature is of minor importance due to strong damping of the wave by hot resonant ions. In this work it will be shown that the IA wave is susceptible to excitation even in plasmas with hot ions when both an electromagnetic transverse wave and a background density gradient are present in the plasma, and in addition the wave is in fact unstable (i.e., growing) in the case of permeating homogeneous plasmas. The multi-component fluid theory is used to describe the IA wave susceptibility for excitation in inhomogeneous plasmas and its coupling with electromagnetic waves. The growing IA wave in permeating homogeneous plasmas is described by the kinetic theory. In plasmas with density and temperature gradients the IA wave is effectively coupled with the electromagnetic waves. In comparison to ordinary IA wave in homogeneous plasma, the Landau damping of the present wave is much smaller, and to demonstrate this effect a simple but accurate fluid model is presented for the Landau damping. In the case of permeating plasmas, a kinetic mechanism for the current-less IA wave instability is presented, with a very low threshold for excitation as compared with ordinary electron-current-driven kinetic instability. Such growing IA waves can effectively heat plasma in the upper solar atmosphere by a stochastic heating mechanism presented in the work. The results of this work suggest that the IA wave role in the heating of the solar atmosphere (chromosphere and corona) should be reexamined

Response to Comment of Shukla and Akbari-Moghanjoughi

Shukla and Akbari-Moghanjoughi have {\it corrected} their Comment (see their version 1 on `arXiv:1207.7029v1) to EPL on our work [1] after receiving our Response from the Editors of EPL. We have a pleasant duty at hand to present our second Response to their second version of the Comment. It is hoped that this response adds strength to our plea {\it for a common sense} [1] on quantum description of plasmas.Comment: Submitted to EP

The universally growing mode in the solar atmosphere: coronal heating by drift waves

The heating of the plasma in the solar atmosphere is discussed within both frameworks of fluid and kinetic drift wave theory. We show that the basic ingredient necessary for the heating is the presence of density gradients in the direction perpendicular to the magnetic field vector. Such density gradients are a source of free energy for the excitation of drift waves. We use only well established basic theory, verified experimentally in laboratory plasmas. Two mechanisms of the energy exchange and heating are shown to take place simultaneously: one due to the Landau effect in the direction parallel to the magnetic field, and another one, stochastic heating, in the perpendicular direction. The stochastic heating i) is due to the electrostatic nature of the waves, ii) is more effective on ions than on electrons, iii) acts predominantly in the perpendicular direction, iv) heats heavy ions more efficiently than lighter ions, and v) may easily provide a drift wave heating rate that is orders of magnitude above the value that is presently believed to be sufficient for the coronal heating, i.e., $\simeq 6 \cdot 10^{-5}$J/(m$^3$s) for active regions and $\simeq 8 \cdot 10^{-6}$J/(m$^3$s) for coronal holes. This heating acts naturally through well known effects that are, however, beyond the current standard models and theories.Comment: To appear in MNRA

Current-less solar wind driven dust acoustic instability in cometary plasma

A quantitative analysis is presented of the dust acoustic wave instability driven by the solar and stellar winds. This is a current-less kinetic instability which develops in permeating plasmas, i.e.., when one quasi-neutral electron-ion wind plasma in its propagation penetrates through another quasi-neutral plasma which contains dust, electrons and ions

Inclusive searches for squarks and gluinos with the ATLAS detector

Despite the absence of experimental evidence, weak scale supersymmetry remains one of the best motivated and studied Standard Model extensions. This report summarises recent ATLAS results on inclusive searches for supersymmetric squarks and gluinos, including third generation squarks produced in the decay of gluinos. Results are presented for both R-parity conserving and R-parity violating scenarios, with final states containing jets with and without missing transverse momentum, light leptons, taus or photons.Comment: Proceedings for the LHCP 2014 conferenc

Features of ion acoustic waves in collisional plasmas

The effects of friction on the ion acoustic (IA) wave in fully and partially ionized plasmas are studied. In a quasi-neutral electron-ion plasma the friction between the two species cancels out exactly and the wave propagates without any damping. If the Poisson equation is used instead of the quasi-neutrality, however, the IA wave is damped and the damping is dispersive. In a partially ionized plasma, the collisions with the neutrals modify the IA wave beyond recognition. For a low density of neutrals the mode is damped. Upon increasing the neutral density, the mode becomes first evanescent and then reappears for a still larger number of neutrals. A similar behavior is obtained by varying the mode wave-length. The explanation for this behavior is given. In an inhomogeneous plasma placed in an external magnetic field, and for magnetized electrons and un-magnetized ions, the IA mode propagates in any direction and in this case the collisions make it growing on the account of the energy stored in the density gradient. The growth rate is angle dependent. A comparison with the collision-less kinetic density gradient driven IA instability is also given.Comment: The following article has been accepted by Physics of Plasmas. After it is published, it will be found at http://pop.aip.org