G. C. Das

Ion-acoustic solitons in an inhomogeneous multicomponent plasma with negative ions

Ion-acoustic solitary waves are studied in an inhomogeneous multicomponent plasma by the augmentation of a K-dV equation wherein a simple form of ionization has been taken to show its interaction in changing the salient features of the soliton, as compared to those observed in a homogeneous plasma. As expected, the negative ions in the plasma bring a drastic alteration on the ion-acoustic solitons, thereby establishing a new era by showing the solitary waves to be studied by a modified K-dV equation. The emphasis has been on determining how the ionization and density gradient in the inhomogeneous plasma affect the solitons. >

Propagation of various K-dV solitary waves in an inhomogeneous two temperature electron plasma

Abstract Despite several observations on soliton propagation in plasmas a satisfactory account in actual situations is still needed. As a sequel to the observations in laboratory plasmas, we consider a generalized multi-component inhomogeneous plasma embedded by a simple effect of ionization with a view to bringing out the salient features of soliton structures most expeditiously in relation to the interest there could be in laboratory plasmas. Based on the occurrence of various plasma situations in nature, the Boltzmann relation is modified to take account of the non-isothermality of the plasma and later the results have been used to provide an adequate theoretical basis for observing an enhancement in the soliton propagation for providing a theoretical basis for future experiments.

Solitons in a relativistic plasma with negative ions

The interaction of the nonlinearity and the dispersiveness causing the solitary waves is studied in a relativistic plasma with negative ions through the derivation of a nonlinear partial-differential equation known as the Korteweg-de Vries equation. The negative ions play a salient part in the existence and behavior of the solitons and could be of interest in laboratory plasmas. First, the observations are made in a nonisothermal plasma, and later the reduction to the nonisothermality of the plasma shows entirely different characteristics as compared to the solitons in the isothermal plasmas. Comparison with the various solitons is emphasized. >

Ion-acoustic solitary waves in ion-beam plasma with multiple-electron-temperatures

The solitary wave solution has been studied in an ion-beam plasma with multiple-electron-temperatures stemmed through the derivation of a modified Korteweg-deVries (KdV) equation. The evolution of solitons shows that the existence and the behaviour depend effectively on the ion-beam as well as on the multiple-electron-temperatures. It has been shown that the solitons might be large amplitude waves with the addition of a small percentage of ion-beam concentration or by the increase of electron-temperatures. The present investigators believe and conclude that the solitons should also show experimentally these fascinating properties, but one has to be careful about the range of the physical parameters in ion-beam plasma.

Cylindrical and spherical solitons at the critical density of negative ions in a generalised multicomponent plasma

Propagation of nonlinear ion-acoustic waves in generalised multicomponent plasmas bounded by cylindrical and spherical geometries is investigated. At the critical density of negative ions where the nonlinearity of the Korteweg-deVries (K-dV) equation vanishes, the ion-acoustic solitary wave is described by a modified K-dV (mK-dV) equation. It is also emphasised that near the critical density neither the K-dV nor mK-dV equation is sufficient to describe fully the ion-acoustic waves and thus there is a need to derive a further mK-dV (fmK-dV) equation in the vicinity of this critical density. Furthermore, the amplitude variations of the K-dV and mK-dV solitons depending on the limitations of geometrical effects are also discussed, emphasising that the results could be of interest for diagnosing the soliton properties of laboratory plasmas.

KdV-type solitons in multicomponent relativistic plasmas

A reductive perturbation technique is used to derive modified Korteweg-deVries (KdV) equations with different degrees of isothermality in a plasma, in order to study the existence and behavior of ion-acoustic solitary wave propagation ingoing in a multicomponent relativistic plasma. The solutions of the KdV equations are obtained. It is found that the presence of multiple ions and electrons in the relativistic plasma causes a different behavior regarding the formation of solitons in plasmas.

Nonlinear ion-acoustic solitary waves in ion-beam plasma

Investigates the dynamics of solitary waves in an ion-beam plasma having multiple electron temperatures. The investigation is based on the derivation of the Korteweg-de Vries (Kd V) equation by applying the reductive perturbation technique to the basic equations governing the plasma dynamics. Fascinating results are derived first for a plasma with a small percentage of non-isothermality, then the solitons behaviour is obtained for an isothermal as well as for a non-isothermal plasma, and finally a general comparison is made and conclusions given.

Whistlers and negative ions

Using an appropriate model of the ionosphere, we find the travel time for proton whistlers to go from their source to an observer at a satellite. The results differ from earlier ones. The physical parameters obtained through whistler observations agree with these results. Damping and attenuation of whistlers are related to the ionospheric parameters.

Recent progress in biotechnological interventions in Piper species: A review

Medicinal plants have tremendous potential for the development of new drugs molecule effective against various diseases. Genus Piper is the largest genus in family Piperaceae and indigenous to India with one of the most widely used spice in the world. Biotechnological innovations in Piper species have lead to the development of plant-derived molecules which exhibit a promising effect in therapeutics. The present paper reviews the genetic diversity analysis of major Piper species through DNA markers, to establish in vitro protocol for mass multiplication of elite clone of different species, phytochemical compounds extracted in various solvent systems in Piper species and comparative analysis of active compounds associated with Piper species through HPTLC analysis as well as testing their antimicrobial activities. The activity has been tested against bacteria like E. coli, Micrococcus luteus, Streptomyces epidermidis, etc. and fungi like Aspergillus niger, A. flavus and Rhizoctonia solani using agar well diffusion method. The review also highlights the use of in vitro strategy in genetic manipulation of transgenic traits using specific promoters to accomplish high tissue specific protein production and overcome biotic stresses.