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Experimental Study of Parameters of a Plasma Antenna

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Plasma Science and Technology 2010年第5期12卷 592-600页

作者： rajneesh kumar Dhiraj BORA Institute for Plasma Research ITER Organisation

A plasma column excited by a surface wave can act as a plasma antenna. Experiments are carried out to study the current and conductivity distributions, field, power patterns, directivity and efficiency of such a plasma antenna. In addition, an equivalent metallic copper antenna is built up and its antenna parameters are compared with that of the plasma antenna. Our findings indicate that the power content in the harmonics of the plasma antenna is more prominent as compared to the copper antenna （which only generates a fundamental frequency）. However, the power patterns for both antennae are quite similar. To provide a more qualitative understanding regarding the generation of harmonics in the field of the plasma antenna, a bi-spectral analysis is performed to study the nonlinear interactions in the current fluctuations. Some specific features of the plasma antenna are investigated in our study, which may enhance the application prospect of the plasma antenna with respect to the conventional metallic antenna.

关键词： plasma column antenna parameters plasma antenna metallic copper antenna non-linear interactions

Propagation of waves in an electro-microstretch generalized thermoelastic semi-space

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Acta Mechanica Sinica 2009年第5期25卷 619-628页

作者： rajneesh kumar.Rupender Department of Mathematics Kurukshetra University

The present investigation is concerned with wave propagation in an electro-microstretch generalized thermoelastic solid half space. Two different cases have been discussed：（i） reflection of plane wave at the free surface of an electro-microstretch generalized thermoelastic solid; and （ii） propagation of Rayleigh waves in an electro-microstretch generalized thermoelastic solid half space. In case （i）, the amplitude ratios of the various reflected waves have been computed numerically and depicted graphically against angle of incidence. In case （ii）, the frequency equation is derived and dispersion curves giving phase velocity and attenuation coefficient as a function of wave number, have been plot- ted graphically for a specific model. Some special cases of interest are also deduced, for both the cases.

关键词： Amplitude ratios Electro-microstretch thermoelastic solid Frequency equation Rayleigh waves

Elastodynamics of axi-symmetric deformation in magneto-micropolar generalized thermoelastic medium

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Applied Mathematics and Mechanics(English Edition) 2009年第1期30卷 39-48页

作者： rajneesh kumar Rupender Department of Mathematics Kurukshetra University Kurukshetra-136 119 India

The present investigation is concerned with an axi-symmetric problem in the electromagnetic micropolar thermoelastic half-space whose surface is subjected to the mechanical or thermal source. Laplace and Hankel transform techniques are used to solve the problem. Various types of sources are taken to illustrate the utility of the approach. Integral transforms are inverted by using a numerical technique to obtain the components of stresses, temperature distribution, and induced electric and magnetic fields. The expressions of these quantities are illustrated graphically to depict the magnetic effect for two different generalized thermoelasticity theories, i.e., Lord and Shulman （L-S theory） and Green and Lindsay （G-L theory）. Some particular interesting cases are also deduced from the present investigation.

关键词： generalized magneto-micropolar thermoelasticity axi-symmetric problem mechanical and thermal sources Laplace and Hankel transforms

Uniqueness,reciprocity theorem,and plane waves in thermoelastic diffusion with a fractional order derivative

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Chinese Physics B 2013年第7期22卷 286-297页

作者： rajneesh kumar Vandana Gupta Department of Mathematics Kurukshetra University

In this work, a theory of thermoelasticity with diffusion is taken into consideration by using the methodology of fractional calculus. The governing equations for particle motion in a homogeneous anisotropic fractional order generalized thermoelastic diffusive medium are presented. Uniqueness and reciprocity theorems are proved. The plane wave propagation in the homogeneous transversely isotropic thermoelastic diffusive medium with fractional order derivative is studied. For the two-dimensional problem, there exist a quasi-longitudinal wave, a quasi-transverse wave, a quasi-mass diffusion wave, and a quasi-thermal wave. From the obtained results, the different characteristics of waves, like phase velocity, attenuation coefficient, specific loss, and penetration depth, are computed numerically and presented graphically. Some special cases are also discussed.

关键词： thermoelastic diffusion fractional calculus uniqueness theorem reciprocity theorem

Propagation of wave at the boundary surface of transversely isotropic thermoelastic material with voids and isotropic elastic half-space

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Applied Mathematics and Mechanics(English Edition) 2010年第9期31卷 1153-1172页

作者： rajneesh kumar Rajeev kumar Department of Mathematics Kurukshetra UniversityKurukshetra 136119India

The purpose of this research is to study the effect of voids on the surface wave propagation in a layer of a transversely isotropic thermoelastic material with voids lying over an isotropic elastic half-space. The frequency equation is derived after developing a mathematical model for welded and smooth contact boundary conditions. The dispersion curves giving the phase velocity and attenuation coefficient via wave number are plotted graphically to depict the effects of voids and anisotropy for welded contact boundary conditions. The specific loss and amplitudes of the volume fraction field, the normal stress, and the temperature change for welded contact are obtained and shown graphically for a particular model to depict the voids and anisotropy effects. Some special cases are also deduced from the present investigation.

关键词： propagation of wave transverse isotropy thermoelastic with voids isotropic elastic half-spaze phase velocity attenuation coefficient

Propagation of plane waves at the imperfect boundary of elastic and electro-microstretch generalized thermoelastic solids

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Applied Mathematics and Mechanics(English Edition) 2009年第11期30卷 1445-1454页

作者： rajneesh kumar Rupender Department of Mathematics Kurukshetra University

The problem of reflection and transmission of plane waves incident on the contact surface of an elastic solid and an electro-microstretch generalized thermoelastic solid is discussed. It is found that there exist five reflected waves, i.e., longitudinal displacement （LD） wave, thermal （T） wave, longitudinal microstretch （LM） wave and two coupled transverse displacement and microrotational （CD（I） and CD（II）） waves in the electro-microstretch generalized thermoelastic solid, and two transmitted waves, i.e., longitudinal （P） and transverse （SV） waves in the elastic solid. The amplitude ratios of different reflected and transmitted waves are obtained for an imperfect boundary and deduced for normal force stiffness, transverse force stiffness, and perfect bonding. The variations of amplitude ratios with incidence angles have been depicted graphically for the LD wave and the CD（I） wave. It is noticed that the amplitude ratios of reflected and transmitted waves are affected by the stiffness, electric field, stretch, and thermal properties of the media. Some particular interest cases have been deduced from the present investigations.

关键词： amplitude ratios electro-microstretch thermoelastic solid normal forcestiffness transverse force stiffness welded contact

Response of loose bonding on reflection and transmission of elastic waves at interface between elastic solid and micropolar porous cubic crystal

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Applied Mathematics and Mechanics(English Edition) 2010年第5期31卷 605-616页

作者： rajneesh kumar Meenakshi PANCHAL Department of Mathematics Kurukshetra University

The problem of reflection and transmission of plane periodic waves incident on the interface between the loosely bonded elastic solid and micropolar porous cubic crystal half spaces is investigated. This is done by assuming that the interface behaves like a dislocation, which preserves the continuity of traction while allowing a finite amount of slip. Amplitude ratios of various reflected and transmitted waves have been depicted graphically. Some special cases of interest have been deduced from the present investigation.

关键词： micropolar porous cubic crystal reflection coefficients transmission coefficients bonding parameter

Propagation of Rayleigh waves on free surface of transversely isotropic generalized thermoelastic diffusion

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Applied Mathematics and Mechanics(English Edition) 2008年第11期29卷 1451-1462页

作者： rajneesh kumar Tarun Kansal Department of Mathematics Kurukshetra UniversityKurukshetra-136 119India

The present paper is devoted to the study of Rayleigh wave propagation in a homogeneous, transversely isotropic, thermoelastic diffusive half-space, subject to stress free, thermally insulated/isothermal, and chemical potential boundary conditions in the context of the generalized thermoelastic diffusion theory. The Green-Lindsay（GL） theory is used in the study. In this theory, thermodiffusion and thermodiffusion mechanical relaxations are governed by four different time constants. Secular equations for surface wave propagation in the considered media are derived. Anisotropy and diffusion effects on the phase velocity, attenuation coefficient are graphically presented in order to present the analytical results and make comparison. Some special cases of frequency equations are derived from the present investigation.

关键词： wave propagation transversely isotropic generalized thermoelastic diffusion phase velocity attenuation coefficient

Propagation of plane waves in thermoelastic cubic crystal material with two relaxation times

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Applied Mathematics and Mechanics(English Edition) 2007年第5期28卷 627-641页

作者： rajneesh kumar Manjeet Singh Department of Mathematics Kurukshetra University Department of Mathematics S.U.S. Govt. College

A problem concerned with the reflection and refraction of thermoelastic plane waves at an imperfect interface between two generalized thermally conducting cubic crystal solid half-spaces of different elastic and thermal properties with two relaxation times has been investigated. The generalized thermoelastic theory with two relaxation times developed by Green and Lindsay has been used to study the problem. The expressions for the reflection and refraction coefficients which are the ratios of the amplitudes of reflected and refracted waves to the amplitude of incident waves are obtained for an imperfect boundary and deduced for normal stiffness, transverse stiffness, thermal contact conductance, slip and welded boundaries. Amplitude ratios of different reflected and refracted waves for different boundaries with angle of emergence have been compared graphically for different incident waves. It is observed that the amplitude ratios of reflected and refracted waves are affected by the stiffness and thermal properties of the media.

关键词： generalized thermoelasticity normal stiffness transverse stiffness thermal contact conductance cubic crystal amplitude ratios