arXiv subjects

M. K. Islam

Publications and source records attributed to M. K. Islam.

6 recordsLinked to original sources

arXiv2021

Obliquely propagating ion-acoustic shock waves in degenerate quantum plasma

A theoretical investigation has been carried out on the propagation of nonlinear ion-acoustic shock waves (IASHWs) in a collsionless magnetized degenerate quantum plasma system composed of inertial non-relativistic positively charged light and heavy ions, inertialess ultra-relativistically degenerate electrons and positrons. The reductive perturbation method has been employed to drive the Burgers' equation. It has been observed that under consideration, our plasma model supports only positive potential shock structure. It is also found that the amplitude and steepness of the IASHWs have been significantly modified by the variation of ion kinematic viscosity, oblique angle, number density, and charge state of the plasma species. The results of our present investigation will be helpful for understanding the propagation of IASHWs in white dwarfs and neutron stars.

physics.plasm-ph↗

arXiv2021

Modulational instability of dust-ion-acoustic waves in pair-ion plasma having non-thermal non-extensive electrons

The modulational instability (MI) criteria of dust-ion-acoustic (DIA) waves (DIAWs) have been investigated in a four-component pair-ion plasma having inertial pair-ions, inertialess non-thermal non-extensive electrons, and immobile negatively charged massive dust grains. A nonlinear Schrödinger equation (NLSE) is derived by using reductive perturbation method. The nonlinear and dispersive coefficients of the NLSE can predict the modulationally stable and unstable parametric regimes of DIAWs and associated first and second order DIA rogue waves (DIARWs). The MI growth rate and the configuration of the DIARWs are examined, and it is found that the MI growth rate increases (decreases) with increasing the number density of the negatively charged dust grains in the presence (absence) of the negative ions. It is also observed that the amplitude and width of the DIARWs increase (decrease) with the negative (positive) ion mass. The implications of the results to laboratory and space plasmas are briefly discussed.

physics.plasm-ph↗

arXiv2021

Dust-ion-acoustic rogue waves in dusty plasma having super-thermal electrons

The standard nonlinear Schrödinger equation (NLSE) is one of the elegant equations to find the information about the modulational instability criteria of dust-ion-acoustic (DIA) waves (DIAWs) and associated DIA rogue waves (DIARWs) in a three-component dusty plasma medium having inertialess super-thermal kappa distributed electrons, and inertial warm positive ions and negative dust grains. It can be seen that under the consideration of inertial warm ions along with inertial negatively charged dust grains, the plasma system supports both fast and slow DIA modes. The charge state and number density of the ion and dust grain are responsible to change the instability conditions of the DIAWs and the configuration of DIARWs. These results are to be considered the cornerstone for explaining the real puzzles in space and laboratory dusty plasmas.

physics.plasm-ph↗

arXiv2020

Modulational instability of dust-ion-acoustic waves and associated envelope solitons in a non-thermal plasma

A theoretical investigation has been made to understand the mechanism of the formation of both bright and dark envelope soltions associated with dust-ion-acoustic waves (DIAWs) propagating in an unmagnetized three component dusty plasma medium having inertial warm positive ions and negative dust grains, and inertialess non-thermal Cairns' distributed electrons. A nonlinear Schrödinger equation (NLSE) is derived by employing reductive perturbation method. The effects of plasma parameters, viz., $γ_2$ (the ratio of the positive ion temperature to electron temperature times the charge state of ion) and $ν$ (the ratio of the charge state of negative dust grain to positive ion) on the modulational instability of DIAW which is governed by NLSE, are extensively studied. It is found that increasing the value of the ion (electron) temperature reduces (enhances) the critical wave number ($k_c$). The results of our present theoretical work may be used to interpret the nonlinear electrostatic structures which can exist in many astrophysical environments and laboratory plasmas.

physics.plasm-ph↗

arXiv2019

Effect of copper content on thermal and mechanical properties of eutectoid zn-al alloy

Zn-Al alloys have become one of the major engineering alloys among commercially available alloys. This study was conducted on eutectoid composition of Zn-Al alloy with an observation of the effect of copper addition. For this purpose, one eutectoid (Zn-22wt%Al) and three other alloys, adding 1wt%, 3wt% and 5wt% copper with this eutectoid composition, were molded in permanent metal mould. Microscopic studies exhibited varied grains which confirmed the formation of different phases. Moreover, the formation of different phases in micro study was supported by XRD analysis. Hardness of the samples were tested on Rockwell B scale and it was observed that the hardness of these alloys was substantially increased with the addition of copper. With increasing amount of copper, phase changing temperature of the alloys reveals a growing trend, which was observed by DTA analysis. From this study it was concluded that addition of copper can significantly add to the mechanical properties of Zn-Al alloys.

cond-mat.mtrl-sci↗

arXiv2018

Optimization of Neon Soft X-ray Emission in Low Energy Dense Plasma Focus Device

The Lee model code is used in numerical experiments for characterizing and optimizing neon soft X-ray (Ysxr) yield of UNU/ICTP PFF machine operated at 14 kV and 30 micro F. The neon Ysxr yield of the dense plasma focus device is enhanced by reducing static inductance (L0) and anode length (z0) along with increasing anode radius (a) and cathode radius (b), keeping their ratio (c = b/a) constant at 3.368. At the optimum combination of the electrodes geometry and static inductance, the maximum computed value of neon Ysxr yield is 63.61 J at operating pressure 3.3 Torr with corresponding X-ray yield efficiency 2.16%, while the end axial speed becomes 6.42 cm/s. This value of neon Ysxr yield is twelve to thirteen times higher than the measured value (5.4 J) at 3.0 Torr. It is also found that this neon Ysxr yield is improved around seven times from previously computed value (9.5 J) at 3.5 Torr for optimum anode configuration of this machine. Our obtained results of neon Ysxr yield are also compared with the computed results of AECS-PF2 machine operated at 15 kV and 25 micro F and is found that our results are about three times better than that from the optimized AECS-PF2 at L0 = 15 nH.

physics.plasm-ph↗