Ion beam driven resonant ion-cyclotron instability in a magnetized dusty plasma

Abstract

Electrostatic ion cyclotron waves are excited by axial ion beam in a dusty plasma via Cerenkov and slow cyclotron interaction. The dispersion relation of the instability is derived in the presence of positively/negatively charged dust grains. The minimum beam velocity needed for the excitation is estimated for different values of relative density of negatively charged dust grains. It is shown that the minimum beam velocity needed for excitation increases as the charge density carried by dust increases. Temperature of electrons and ions, charge and mass of dust grains, external static magnetic field and finite boundary of dusty plasma significantly modify the dispersion properties of these waves and play a crucial role in the growth of resonant ion cyclotron instability. The ion cyclotron modes with phase velocity comparable to the beam velocity possess a large growth rate. The maximum value of growth rate increases with the beam density and scales as the one-third power of the beam density in Cerenkov interaction and is proportional to the square root of beam density in slow cyclotron interaction.

Theoretical Modelling of Kelvin Helmholtz Instability Driven by an Ion Beam in a Negative Ion Plasma

“…For finite boundaries of plasma waveguide, the frequencies of KHI modes are lesser than for infinite boundary effects. These results are in line with the results for finite geometry effects obtained by Prakash et al [27].…”

“…45). A comparison of finite and infinite geometry effects describe that the frequency and growth rate of KHI is reduced for cylindrical plasma waveguide, it may be due to reduction in beam plasma interaction region [27]. The results showing increase in frequency and growth rate of Low frequency KHI modes are in line with the experimental observations of electrostatic ion Cyclotron waves [29] and Ion Acoustic waves [21] in negative ion plasma.…”

“…In this paper, we develop a theoretical model on KHI driven by an ion beam in a negative ion plasma as no work on the effect of ion beam on KHI in a magnetized plasma having negative ions has been reported so far. We also study the effects of finite boundaries on the growth of KHI modes as it is observed that finite geometry effects tend to reduce the growth of waves and instabilities [27]. We choose SF − 6 negative ions as SF 6 has a large electron capture cross section for low-energy electrons in Q-machine plasmas [21].…”