arXiv subjects

H. Hakimi Pajouh

Publications and source records attributed to H. Hakimi Pajouh.

3 recordsLinked to original sources

arXiv2010

Vlasov model using kinetic phase point trajectories

A method of solution of the collisionless Vlasov equation, by following collisionless phase point trajectories in phase space, is presented. It is shown that by increasing the number of phase points, without enhancing the resolution of phase space grid, the accuracy of simulation will be improved. Besides, the phase points spacing introduces a smaller scale than grid spacing on which fine structures might be more conveniently handled. In order to perform simulation with a large population of phase points, an effective interpolation scheme is introduced that reduces the number of operations. It is shown that by randomizing initial position of the phase points along velocity axis, the recurrence effect does not happen. Finally, the standard problem of linear Landau damping will be examined.

physics.plasm-ph↗

arXiv2005

Subsonic ion-acoustic solitons

In this paper, the nonlinear theory of plasma waves is extended to the plasmas that their equilibrium state are specified by the non-Maxwellian (here kappa) distribution. We believe that the extension is very important since most of the space and some of laboratory plasmas are not in the Maxwellian equilibrium. Although the linear theory of this issue has been known for the decades but, to our knowledge, this is the first attempt in opening the gate to the nonlinear world of plasma waves with the non-Maxwellian equilibrium. As an example the ion-acoustic solitons are studied in this framework taking into account the electron trapping in the trough of longitudinal field. It is shown, as the most important result regarding to the non-Maxwillian equilibrium, that there is the possibility for the ion-acoustic solitons to move subsonically. The solitons velocity and their width are monotonically increasing functions of spectral index ($κ$) and approach to the their Maxwellian values as $κ\to \infty$.

physics.plasm-ph↗

arXiv2005

A Computational Fluid Model for Investigation of Plasma Waves and Instabilities

A computational fluid model is developed to study waves and instabilities. A new technique involving initial perturbations in configuration space have been implemented to excite the plasma waves; i.e. the perturbations acting similar to a random velocity distribution in particle in cell (PIC) codes. This forms a new powerful tool for investigation of many waves arising in both thermal and cold plasmas and as such will allow investigation of problems demanding scales and resolution not yet possible by PIC codes. The model predicts Langmuir waves, two stream instabilities, nonlinear wave-wave interaction, and the Debye screening effects. The agreement between theory and simulation where analytic results are available are excellent.

physics.plasm-ph↗