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Modi K.V.,Indian Institute of Technology Delhi | Modi K.V.,Government Engineering College Valsad | Sharma R.P.,Indian Institute of Technology Delhi
Physics of Plasmas | Year: 2013

In the present paper, authors have investigated nonlinear interaction of kinetic Alfvén wave (KAW) and fast magnetosonic wave for intermediate β-plasma (m e / m i β 1). Authors have developed the set of dimensionless equations in the presence of ponderomotive nonlinearity due to KAW in the dynamics of fast magnetosonic wave. Numerical simulation has been carried out to study the effect of nonlinear coupling and resulting turbulent/power spectrum for the different angles of propagation of fast magnetosonic wave applicable to solar wind at 1 AU. The localization of KAW has been found which becomes more complex as the angle of propagation of fast magnetosonic wave decreases. Results also reveal the steepening of power spectrum as the angle of propagation decreases which can be responsible for heating and acceleration of plasma particles in solar wind. Relevance of the obtained result is pointed out with observation received by Cluster spacecraft for the solar wind 1 AU. © 2013 American Institute of Physics. Source

Rinawa M.L.,Indian Institute of Technology Delhi | Rinawa M.L.,Government of Rajasthan | Sharma R.P.,Indian Institute of Technology Delhi | Modi K.V.,Indian Institute of Technology Delhi | Modi K.V.,Government Engineering College Valsad
Astrophysics and Space Science | Year: 2015

In the present paper, we have investigated nonlinear interaction of inertial Alfvén wave with ion acoustic wave, for low β-plasma (β≪me/mi) where β is the thermal to magnetic pressure ratio. We have developed the dynamical equation of inertial Alfvén wave by considering the finite frequency as well as finite ion temperature correction. The dynamical equation of ion acoustic wave, propagating at an angle with respect to the background magnetic field, in the presence of ponderomotive nonlinearity due to inertial Alfvén wave is also derived. Numerical simulation has been carried out to study the effect of nonlinear coupling between these waves which results in the formation of localized structures and turbulent spectrum, applicable to auroral region. The result reveals that the localized structures become complex and intense in nature (quasi-steady state). Further, we have studied the turbulent spectrum which follows spectral index (∼k−4.46) at smaller scales. Relevance of the obtained results has been shown with the observations reported by various spacecrafts like Hawkeye and HEOS-2 (Highly Eccentric Orbiting Satellite-2). © 2015, Springer Science+Business Media Dordrecht. Source

Modi K.V.,Indian Institute of Technology Delhi | Modi K.V.,Government Engineering College Valsad | Sharma R.P.,Indian Institute of Technology Delhi | Gaur N.,Indian Institute of Technology Delhi
Solar Physics | Year: 2016

The nonlinear interaction between the kinetic Alfvén wave (KAW) and the slow magnetosonic wave is studied. The dynamical equation for the slow magnetosonic wave, in the presence of a ponderomotive force due to finite frequency KAW (ω0<ωci$\omega_{0}<\omega_{\mathrm{ci}}$, where ω0$\omega_{0}$ is the frequency of the KAW and ωci$\omega_{\mathrm{ci}}$ is the ion gyro frequency) is developed and then numerically solved for the solar wind parameters around 1 AU. Three different propagation angles of the slow magnetosonic wave (θ=70∘,75∘$\theta = 70^{\circ},75^{\circ}$, and 85∘$85^{\circ}$) are considered. Our results reveal that due to the nonlinear interplay between the waves, the nature of the formation of localised structures becomes complex and depends on the different propagation angles of the slow magnetosonic wave. The power spectrum of a KAW shows the Kolmogorov scaling in larger scales but exhibits steepening in smaller scales. The scaling index of the power spectrum of the KAW depends on the propagation angles of the slow magnetosonic wave. Therefore, the heating of plasma particles in the solar wind may show such dependence. The present results are consistent with the observation of the Cluster spacecraft for the solar wind around 1 AU. © 2015, Springer Science+Business Media Dordrecht. Source

Sharma R.P.,Indian Institute of Technology Delhi | Tiwary P.P.,Indian Institute of Technology Delhi | Tiwary P.P.,Dayalbagh Educational Institute | Modi K.V.,Indian Institute of Technology Delhi | And 4 more authors.
Physics of Plasmas | Year: 2015

This paper presents a theoretical model for the transient response of nonlinear coupling between magnetosonic wave and ion acoustic wave in the overdense plasma. Filamentation of magnetosonic wave has been considered to be responsible for magnetic turbulence during the laser plasma interaction. The ion acoustic wave gets excited due to the ponderomotive force exerted by magnetosonic wave and this ion acoustic wave in turn generates perturbation in the background density in the form of spatial density harmonics. Numerical simulation has been carried out for dimensionless coupled equations of magnetosonic wave and ion acoustic wave; and the results show quite complex localized structures that grow with time. The power spectrum has also been studied which shows that the spectral index follows an approximate scaling of the order of ∼ k-2.4 at smaller scales. The data obtained from numerical simulation are used in semi analytical model to better understand the mechanism of nonlinear evolution of magnetosonic wave. The results indicate considerable randomness in the spatial structure of the magnetic field profile which gives sufficient indication of turbulence. © 2015 AIP Publishing LLC. Source

Modi K.V.,Indian Institute of Technology Delhi | Modi K.V.,Government Engineering College Valsad | Tiwary P.P.,Indian Institute of Technology Delhi | Tiwary P.P.,Dayal Bagh Educational Institute Deemed University | And 3 more authors.
Physics of Plasmas | Year: 2014

This paper presents a theoretical model for the magnetic turbulence in laser plasma interaction due to the nonlinear coupling of magnetosonic wave with ion acoustic wave in overdense plasma. For this study, dynamical equations of magnetosonic waves and the ion acoustic waves have been developed in the presence of ponderomotive force due to the pump magnetosonic wave. Slowly converging and diverging behavior has been studied semi-analytically, this results in the formation of filaments of the magnetosonic wave. Numerical simulation has also been carried out to study nonlinear stage. From the results, it has been found that the localized structures become quite complex in nature. Further, power spectrum has been studied. Results show that the spectral index follows (∼k-2.0) scaling at smaller scale. Relevance of the present investigation has been shown with the experimental observation. © 2014 AIP Publishing LLC. Source

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