Ajay Gahlot

Excitation of upper-hybrid waves by a gyrating relativistic electron beam in a magnetized dusty plasma cylinder

A gyrating relativistic electron beam propagating through a magnetized dusty plasma cylinder drives an upper-hybrid wave to instability via cyclotron interaction. Numerical calculations of the growth rate and unstable mode frequencies have been carried out for the typical parameters of dusty plasma experiments. It is found that as the density ratio of negatively charged dust grains to electrons increases, the unstable mode frequency of the upper-hybrid waves increases. Moreover, the growth rate of the instability also increases with the density ratio. The growth rate of the unstable mode has the largest value for the modes whose eigenfunctions peak at the location of the beam. The growth rate of the unstable mode scales as the one-third power of the beam density.

Effect of dust on an amplitude modulated electromagnetic beam in a plasma

A large amplitude modulated Gaussian electromagnetic beam propagating in a dusty plasma has been studied. The electrons are heated nonuniformly by the beam. For the nonsteady state, we obtain nonlinear current density in the presence of dust grains. This expression has been used to study the nonstationary self-focusing and resulting self-distortion of the amplitude modulated electromagnetic beam. It has been observed that the effect of dust is drastic on the modulation index in comparison to dust free plasma. A simple scaling showing the dependence of modulation index on dust grain size and charge has been presented.

The effect of dust charge fluctuations on lower-hybrid suppression of drift waves in a magnetized plasma cylinder

The nonlinear coupling between drift waves and a lower-hybrid pump wave is studied in a magnetized dusty plasma cylinder. The growth rate and mode frequencies were evaluated based on typical dusty plasma parameters. It is found that the unstable drift mode frequency increases and the growth rate decreases sharply with the relative density of negatively charged dust grains. In addition, the growth rate and unstable mode frequency depend on pump wave amplitudes.

Effect of dust charge fluctuations on current-driven electrostatic ion-cyclotron instability in a collisional magnetized plasma

Current-driven electrostatic ion-cyclotron (EIC) instability is studied in a collisional magnetized dusty plasma. The growth rate and unstable mode frequencies were evaluated based on existing physical parameters relevant to ion cyclotron waves in dusty plasmas. It is found that the unstable mode frequency and growth rate of current-driven EIC instability increase with δ (ion-to-electron density ratio). Moreover, the increase in electron neutral collisional frequency (νe) has no effect on the unstable mode frequency while the normalized growth rate has linear dependence on νe.

Excitation of lower hybrid waves by a gyrating ion beam in a negative ion plasma

A gyrating ion beam propagating through a magnetized plasma cylinder containing K+ positive ions, electrons, and SF6− negative ions drives electrostatic lower hybrid waves to instability via Cyclotron interaction. Numerical calculations of the unstable mode frequencies and growth rates of both the unstable positive ion and negative ion modes have been carried out for the existing negative ion plasma parameters. It is found that the unstable mode frequencies of both the modes increase, with the relative density of negative ions. In addition, the growth rates of both the unstable modes also increases with relative density of negative ions. Moreover, the growth rates of both the unstable modes scale as the one-third power of the beam density. The frequencies of both the unstable modes also increase with the magnetic fields. The real part of the unstable wave frequency increases as almost the square root of the beam energy.

Higher harmonics generation by a spiraling ion beam in collisionless magnetized plasma

A spiraling ion beam propagating through a magnetized plasma cylinder containing K + light positive ions, electrons, and C 7 F 14 − heavy negative ions drives electrostatic ion–cyclotron waves to instability via cyclotron interaction. Higher harmonics of the beam cyclotron frequency can be generated in this way. The unstable mode frequencies and growth rates of both unstable light positive ions and heavy negative ions increase with the relative density of heavy negative ions. Moreover, the growth rate of unstable modes scales as the one-third power of the beam density. The growth rate of unstable modes increases with harmonic number. The frequencies of both unstable modes also increase with magnetic fields. In addition, the real part of both unstable modes (K + and C 7 F 14 − ) increases with the beam energy and scales as almost one-half power of the beam energy.

Effect of dust charge fluctuations on upper hybrid wave instabilities in magnetized dusty plasma

The decay instability of an upper hybrid electrostatic wave into an upper hybrid sideband wave and lower hybrid wave is studied in magnetized dusty plasma. A local theory of this process has been developed. The growth rate and mode frequencies of the unstable wave were evaluated based on existing dusty plasma parameters and it is found that the unstable mode frequency and growth rate increases with δ (ion-to-electron density ratio) in the presence and absence of dust charge fluctuations in addition to dust dynamics.

The effect of dust charge fluctuations on collisional drift waves in a magnetized plasma cylinder

The nonlinear coupling between collisional drift waves and a lower-hybrid pump wave is studied in a magnetized dusty plasma cylinder. A dispersion relation for the collisional drift wave and growth rate is derived incorporating both pondermotive and Ohmic heating effects. The growth rate and mode frequencies were evaluated based on existing dusty plasma parameters. It is found that the unstable collisional drift mode frequency increases and the growth rate decreases sharply with the relative density of negatively charged dust grains. Moreover, the collisional frequency has no effect on the unstable drift mode frequency. However, the increases in collisional frequency and electron temperature are playing an important role in the damping effect.

Excitation of dust acoustic waves by an ion beam in a plasma cylinder with negatively charged dust grains

An ion beam propagating through a plasma cylinder having negatively charged dust grains drives a low frequency electrostatic dust acoustic wave (DAW) to instability via Cerenkov interaction. The unstable wave frequencies and the growth rate increase with the relative density of negatively charged dust grains. The growth rate of the unstable mode scales to the one-third power of the beam density. The real part of the frequency of the unstable mode increases with the beam energy and scales to almost one-half power of the beam energy. The phase velocity, frequency, and wavelength results of the unstable mode are in compliance with the experimental observations.

Decay instability of an upper hybrid wave in a magnetized dusty plasmas

The decay instability of an upper hybrid wave into an upper hybrid sideband wave and low frequency ion-cyclotron wave are studied in a magnetized dusty plasma cylinder. The growth rate and ion-cyclotron mode frequencies were evaluated based on existing dusty plasma parameters. It is found that the unstable mode frequency increases linearly with δ (ion-to-electron density ratio). In addition, the growth rate of the unstable ion-cyclotron mode decreases sharply for lower values of δ in the presence of dust charge fluctuations, i.e., the dust grains increases the damping effect in three wave interaction process.