Papers by PRASHANT KUMAR CHAUHAN
Laser and Particle Beams, 2021
In the present paper, filamentous structure formation, associated turbulent spectrum, and density... more In the present paper, filamentous structure formation, associated turbulent spectrum, and density cavity formation phenomena have been investigated for low- β plasma β ≪ m e / m i applicable to the auroral region. A set of dimensionless equations governing the dynamics of three dimensionally propagating inertial Alfvén wave (3D-IAW) and perpendicularly propagating magnetosonic wave (PMSW) has been developed. Ponderomotive force due to 3D-IAW has been included in the dynamics of the PMSW. Numerical simulation has been performed to study the nonlinear coupling of these two waves. From the obtained results, we found that the field intensity localization takes place which may further lead to the additional dissipation/turbulence process for particle heating and acceleration in space plasma. The associated turbulent spectrum is obtained with scaling nearly k − 4.28 at smaller scales (in the dissipation range). Relevance of the obtained results with the observations reported by various sp...
Indian Journal of Physics
The transmission and reflection properties of one-dimensional magnetized plasma photonic crystal ... more The transmission and reflection properties of one-dimensional magnetized plasma photonic crystal heterostructures have been theoretically investigated. The proposed structure is composed of two sub-PCs containing magnetized cold plasma and lossless dielectric materials. The optical properties of the structure are suitable for multichannel tunable transmission filter and omnidirectional band-stop filters applications. The investigations have been carried out by applying transfer matrix method and employing electrostatic boundary conditions for TE and TM wave, respectively, in microwave region. The transmission spectra of the proposed structure possess external magnetic field-dependent 3 N − 3 comb-like resonant peaks called as transmission channels for period number ( N ) > 1. Due to multiple interactions between forward and backward decaying evanescent waves in plasma and dielectric layers, respectively, 3 N − 3 transmission channels are found in defect-free magnetized plasma photonic crystal heterostructure, enabling the structure to work as a multichannel filter. Next, the filter properties have been made tunable, i.e., channel frequency of each channel can either be red or blue shifted, depending upon the RHP and LHP configurations of external magnetic field under magneto-optical Faraday effect, respectively. The number of channels and their positions can also be modulated by changing the number of periods ( N ) and the incident angle ( θ 0 ) for TE and TM waves both besides other plasma parameters. Apart from the transmission properties of the proposed structure, we have also studied the reflection properties to obtain multichannel tunable omnidirectional photonic band gaps under the influence of external magnetic field. These results may be utilized to develop new kind of externally tunable single to multichannel omnidirectional band-stop filters.
Laser and Particle Beams
Effects of external static magnetic field (applied in$\hat y$-direction) on resonant excitation o... more Effects of external static magnetic field (applied in$\hat y$-direction) on resonant excitation of surface plasma waves (SPW) have been investigated over the metal free space interface. The high power laser$({\rm \omega} _0,\;\vec k_{0z})$is incident over the metal surface and exerts a ponderomotive force on the metal electrons in the skin layer. The ponderomotive force disturbs the quasi-neutrality of plasma which results into the excitation of space charge field at the frequency 2ω0. The electron density perturbation at frequency 2ω0driven by self-consistent space charge potential couples with the oscillatory velocity due to the seed SPW$({\rm \omega}, \;\vec k_z)$and produces nonlinear current to drive another counter propagating SPW$({\rm \omega} _1,\;\vec k_{1z})$at the phase matching conditions of frequency ω = ω1− 2ω0and wavenumber$\vec k_z = \vec k_{1z} - 2\vec k{}_{0z}$(by feedback mechanism). The parametric process becomes resonant at 2ω0≈ ωpand the maximum growth rate is ...
Physics of Plasmas
By using the transfer matrix method, theoretical investigations have been carried out in the micr... more By using the transfer matrix method, theoretical investigations have been carried out in the microwave region to study the reflection properties of multichannel tunable omnidirectional photonic bandgaps (OPBGs) based on the magneto-optic Faraday effect. The proposed one dimensional ternary plasma photonic crystal consists of alternate layers of quartz, magnetized cold plasma (MCP), and air. In the absence of an external magnetic field, the proposed structure possesses two OPBGs induced by Bragg scattering and is strongly dependent on the incident angle, the polarization of the incident light, and the lattice constant unlike to the single-negative gap and zero- n¯ gap. Next, the reflection properties of OPBGs have been made tunable by the application of external magnetic field under right hand and left hand polarization configurations. The results of this manuscript may be utilized for the development of a new kind of tunable omnidirectional band stop filter with ability to completely stop single to multiple bands (called channels) of microwave frequencies in the presence of external static magnetic field under left-hand polarization and right-hand polarization configurations, respectively. Moreover, outcomes of this study open a promising way to design tunable magneto-optical devices, omnidirectional total reflectors, and planar waveguides of high Q microcavities as a result of evanescent fields in the MCP layer to allow propagation of light.By using the transfer matrix method, theoretical investigations have been carried out in the microwave region to study the reflection properties of multichannel tunable omnidirectional photonic bandgaps (OPBGs) based on the magneto-optic Faraday effect. The proposed one dimensional ternary plasma photonic crystal consists of alternate layers of quartz, magnetized cold plasma (MCP), and air. In the absence of an external magnetic field, the proposed structure possesses two OPBGs induced by Bragg scattering and is strongly dependent on the incident angle, the polarization of the incident light, and the lattice constant unlike to the single-negative gap and zero- n¯ gap. Next, the reflection properties of OPBGs have been made tunable by the application of external magnetic field under right hand and left hand polarization configurations. The results of this manuscript may be utilized for the development of a new kind of tunable omnidirectional band stop filter with ability to completely stop single to multip...
Laser and Particle Beams, 2015
Electron acceleration is studied during the resonant interaction of launched electron beam with t... more Electron acceleration is studied during the resonant interaction of launched electron beam with the surface plasma wave (SPW) in the presence of static magnetic field. A configuration of two parallel metal sheets separated by a vacuum region supports the SPW of amplitude maximum on the two parallel interfaces and minimum in the middle. Kretschmann geometry is used to excite surface plasma mode by shinning laser on a glass prism. Dispersion relation of SPW is established in the presence of magnetic field and smaller cut-off frequencies are observed as compared with that of without magnetic field. An electron beam launched in the middle region, experiences a longitudinal ponderomotive force due to SPWs and gets accelerated to the velocity of the order of phase velocity of the surface wave. The energy gained by electron is higher in the presence of magnetic field as compared with zero magnetic field. The electron energy and trajectory are also presented for varying parameters such as a...
Laser and Particle Beams, 2014
Resonant excitation of terahertz (THz) radiation by nonlinear coupling of two filamented spatial-... more Resonant excitation of terahertz (THz) radiation by nonlinear coupling of two filamented spatial-Gaussian laser beams of different frequencies and wave numbers is studied in plasma having transverse static electric field. The static ponderomotive force due to filamented lasers is balanced by the pressure gradient force which gives rise to transverse density ripple, while, the nonlinear ponderomotive force at frequency difference of beating lasers couples with density ripple giving rise to stronger transverse nonlinear current which results into the excitation of THz radiation at resonance. The coupling is further enhanced by the presence of static electric field and spatial-Gaussian nature of laser beams. An increase of six-fold in the normalized amplitude of THz is observed by applying a direct current field of about 50 KV. Effects of frequency, laser beam width, and periodicity factor of modulated laser amplitude are studied for the efficient THz radiation generation. These result...
Physics of Plasmas, 2008
ABSTRACT
Physics of Plasmas, 2007
This paper presents the ponderomotive filamentation (single hot spot) of a laser beam, propagatin... more This paper presents the ponderomotive filamentation (single hot spot) of a laser beam, propagating in homogeneous plasma in a nonparaxial region. Electron plasma wave coupling in these filaments has been studied. It is found that initially launched weak plasma wave (small amplitude) gets excited and becomes highly localized (wave packet) with a broad spectrum. By expanding the eikonal and other
Physics of Plasmas, 2009
This paper investigates the generation of plasma wave and third harmonic generation in a hot coll... more This paper investigates the generation of plasma wave and third harmonic generation in a hot collision less plasma by an intense laser beam. On the account of the force, a plasma wave at (here is the pump laser frequency) is generated. The solution of the pump laser beam has ...
Optics Communications, 2013
ABSTRACT This paperpresentsaninvestigationofthepropagationofrippledlaserbeaminacollisionlessplasm... more ABSTRACT This paperpresentsaninvestigationofthepropagationofrippledlaserbeaminacollisionlessplasma and itseffectonandtheexcitationofelectronplasmawaveandparticleacceleration,whenrelativistic and ponderomotivenonlinearitiesaresimultaneouslyoperative.Electronplasmawave(EPW)coupling with rippledlaserbeamarisesonaccountoftherelativisticchangeintheelectronmassandthe modification ofthebackgroundelectrondensityduetoponderomotivenonlinearity.Whentheelectron plasma wavegetscoupledtotherippledlaserbeam,alargefractionofthepumpenergygetstransferred to EPWandthisexcitedEPWcanacceleratetheelectrons.Analyticalexpressionsforthegrowthrateof the laserspikeinplasma,beamwidthoftherippledlaserbeamandexcitedelectronplasmawavehave been obtainedusingparaxialrayapproximation.Thesecoupledequationsaresolvedanalyticallyand numerically tostudythegrowthoflaserspikeinplasmaanditseffectontheselffocusingofrippledlaser beam inplasma,amplitudeoftheexcitedelectronplasmawaveandparticleacceleration.Theresult showsthattheeffectofincludingponderomotivenonlinearitysignificantly affectsthegrowthoflaser spike inplasma,excitationofelectronplasmawaveaswellasthenumberofenergeticelectronsin particle accelerationprocess.Theresultsarepresentedfortypicallaserplasmaparameters.
Laser and Particle Beams, 2008
In the present investigation, the excitation of an upper hybrid wave (UHW) in a hot collisionless... more In the present investigation, the excitation of an upper hybrid wave (UHW) in a hot collisionless magneto-plasma by a relativistic laser beam propagating perpendicular to the static magnetic field and having its electric vector polarized along the direction of the static magnetic field (ordinary mode) is presented. Due to nonuniform intensity distribution of pump laser, the background electron concentration is modified. The amplitude of the UHW, which depends on the background electron concentration, is thus nonlinearly coupled with the laser beam. The effect of nonlinear coupling between the pump laser and UHW is studied. The effect of the relativistic electron mass nonlinearity and the relativistic self-focusing of the pump laser on the excitation of the UHW have been incorporated. The dynamics of the excitation of the UHW in different power domains of the laser beam is accordingly modified. It has been seen that the effect of changing the strength of the static magnetic field on ...
Laser and Particle Beams, 2013
A scheme of terahertz radiation generation is proposed by beating of two extra-ordinary lasers ha... more A scheme of terahertz radiation generation is proposed by beating of two extra-ordinary lasers having frequencies and wave numbers $\lpar {\rm \omega}_1\comma \; \vec k_1 \rpar $ and $\lpar {\rm \omega}_2\comma \; \vec k_2 \rpar $, respectively in a magnetized plasma. Terahertz wave is resonantly excited at frequency $\lpar {\rm \omega}_1 - {\rm \omega}_2 \rpar $ and wave number (k1 − k2 + q) with a wave number mismatch factor q which is introduced by the periodicity of plasma density ripples. In this process, the lasers exert a beat ponderomotive force on plasma electrons and impart them an oscillatory velocity with both transverse and longitudinal components in the presence of transverse static magnetic field. The oscillatory velocity couples with density ripples and produces a nonlinear current that resonantly excites the terahertz radiation. Effects of periodicity of density ripples and applied magnetic field are analyzed for strong THz radiation generation. The terahertz radiat...
Laser and Particle Beams, 2009
This article presents the resonant excitation of the upper hybrid wave (UHW) by cross focusing of... more This article presents the resonant excitation of the upper hybrid wave (UHW) by cross focusing of two high power laser beams in a collisionless hot magnetoplasma; taking into account the relativistic nonlinearity. The electric vectors of the two beams are polarized along uniform static magnetic field and the beams propagate perpendicular to the static magnetic field. The resonant excitation of the UHW occurs when the frequency difference (FD) of the two laser beams and difference of their propagation vector satisfy the dispersion relation corresponding to the UHW. It has been observed that the power associated with the excited UHW, which depends on the background electron concentration, magnetic field and the intensity of the two laser beams, becomes drastically modified with the distance of propagation. The effect of the excited UHW at the FD on the acceleration of electrons has also been discussed. The amplitude of the UHW, excited by two high power laser beams and the electron en...
Laser and Particle Beams, 2005
ABSTRACT
Laser and Particle Beams, 2010
This paper presents an investigation of the excitation of a Tera hertz (THz) radiation by nonline... more This paper presents an investigation of the excitation of a Tera hertz (THz) radiation by nonlinear interaction of a circularly polarized high power laser beam and density ripple in collisionless magneto plasma. The ponderomotive force due to the nonlinear interaction between the laser and density ripple generates a nonlinear current at a difference frequency. If the appropriate phase matching conditions are satisfied and the frequency of the ripple is appropriate, then this difference frequency can be brought in the THz range. Filamentation (self focusing) of a circularly polarized beam propagating along the direction of ambient magnetic field in plasma is first investigated within paraxial ray approximation. The beam gets focused when the initial power of the laser beam is greater than its critical power. Resulting localized beam couples with the pre-existing density ripple to produce a nonlinear current driving the THz radiation. Analytical expressions for the beam width of the l...
Laser and Particle Beams, 2005
ABSTRACT
IEEE Transactions on Plasma Science, 2009
In this paper, the influence of ponderomotive and relativistic nonlinearities on the filamentatio... more In this paper, the influence of ponderomotive and relativistic nonlinearities on the filamentation of an ultraintense laser pulse is investigated in three dimensions within the paraxial ray approximations. Generation of electron plasma wave (EPW) structure at pump ...
Laser and Particle Beams, 2008
In the present investigation, the excitation of an upper hybrid wave (UHW) in a hot collisionless... more In the present investigation, the excitation of an upper hybrid wave (UHW) in a hot collisionless magneto-plasma by a relativistic laser beam propagating perpendicular to the static magnetic field and having its electric vector polarized along the direction of the static magnetic field (ordinary mode) is presented. Due to nonuniform intensity distribution of pump laser, the background electron concentration is modified. The amplitude of the UHW, which depends on the background electron concentration, is thus nonlinearly coupled with the laser beam. The effect of nonlinear coupling between the pump laser and UHW is studied. The effect of the relativistic electron mass nonlinearity and the relativistic self-focusing of the pump laser on the excitation of the UHW have been incorporated. The dynamics of the excitation of the UHW in different power domains of the laser beam is accordingly modified. It has been seen that the effect of changing the strength of the static magnetic field on ...
Laser and Particle Beams, 2009
This article presents the resonant excitation of the upper hybrid wave (UHW) by cross focusing of... more This article presents the resonant excitation of the upper hybrid wave (UHW) by cross focusing of two high power laser beams in a collisionless hot magnetoplasma; taking into account the relativistic nonlinearity. The electric vectors of the two beams are polarized along uniform static magnetic field and the beams propagate perpendicular to the static magnetic field. The resonant excitation of the UHW occurs when the frequency difference (FD) of the two laser beams and difference of their propagation vector satisfy the dispersion relation corresponding to the UHW. It has been observed that the power associated with the excited UHW, which depends on the background electron concentration, magnetic field and the intensity of the two laser beams, becomes drastically modified with the distance of propagation. The effect of the excited UHW at the FD on the acceleration of electrons has also been discussed. The amplitude of the UHW, excited by two high power laser beams and the electron en...
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Papers by PRASHANT KUMAR CHAUHAN