Spatio-temporal evolution of Buneman instability has been followed numerically till its quasilinear quenching and beyond, using an in-house developed electrostatic 1Dand for a wide range of electron to ion mass ratios (m/M), growth rate obtained from simulation agrees well with the numerical solution of the fourth order dispersion relation. Quasi-linear saturation of Buneman instability occurs when ratio of electrostatic field energy density () reaches up to a constant value, which as predicted by Hirose [Plasma Physics 20, 481(1978)], is independent of initial electron drift velocity but depends on electron to ion mass ratio m/M as. This result stands verified in our simulations. Growth of the instability beyond the first saturation (quasilinear saturation ) till its final saturation [Ishihara et. al., PRL 44, 1404(1980] follows an algebraic scaling with time. In contrast to the quasilinear saturation, the ratio of final saturated electrostatic field energy density to initial kinetic energy density, is relatively independent of electron to ion mass ratio and is found to depend only on the initial drift velocity. Beyond the final saturation, electron phase space holes coupled to large amplitude ion solitary waves, a state known as coupled hole-soliton , are seen in our simulations. The propagation characteristics ( amplitude -speed relation ) of these coherent modes is found to be consistent with

Spatio-temporal evolution of the relativistic Buneman instability has been investigated in one dimension using an in-house developed particle-in-cell simulation code. Starting from the excitation of the instability, its evolution has been followed numerically till its quenching and beyond. As compared to the well understood non-relativistic case, it is found that the maximum growth rate (γ max ) reduces due to relativistic effects and varies with γ e0 and m/M as γ max ∼where γ e0 is Lorentz factor associated with the initial electron drift velocity (v 0 ) and (m/M) is the electron to ion mass ratio. Further it is observed that in contrast to the non-relativistic results [Hirose,Plasma Phys. 20, 481(1978)] at the saturation point, ratio of electrostatic field energy density ( k |E k | 2 /8π) to initial drift kinetic energy density (W 0 ) scales with γ e0 as ∼ 1/γ 2 e0 .These simulation results are found to be in good agreement with that derived using fluid theory. * rupendra@ipr.res.in 1 arXiv:1606.03178v1 [physics.plasm-ph]

The topological properties of the magnetized plasma have recently been studied for Hermitian (undamped) edge states. Taking a step further, we present non-Hermitian effects (collisionless damping) of topological edge states in an inhomogeneous magnetized plasma. We show that at an inhomogeneous plasma-vacuum interface, a resonant coupling between an edge state and a local plasma bulk mode (upper-hybrid) leads to collisionless damping of former. By analysis of theoretical model and ab-initio particle-in-cell simulation, we found that the damping rate increases with the increasing scale length of density inhomogeneity. We also present that coupling with bulk modes does not break topological protection of damped edge states.

Nonlinear stationary structures formed in a cold plasma with immobile ions in the presence of a relativistic electron current beam have been investigated analytically in the collisionless limit. The structure profile is governed by the ratio of maximum electrostatic field energy density to the kinetic energy density of the electron beam,, where E m is the maximum electric field associated with the nonlinear structure and v 0 is the electron beam velocity. It is found that, in the linear limit, i.e., κ 2γ 0 /(1 + γ 0 ), the fluid variables, viz, density, electric field, and velocity vary harmonically in space, where γ 0 is the Lorentz factor associated with beam velocity (v 0 ). In the range 0 < κ ≤ κ c (= 2γ 0 /(1 + γ 0 )), the fluid variables exhibit an-harmonic behavior. For values of κ c < κ < +∞, the electric field shows finite discontinuities at specific spatial locations indicating the formation of negatively charged planes at these locations.