THAO03
Amity University, Amity School of Applied Sciences, Gurugram, India
IIT Delhi, New Delhi, India
In the present paper, the effect of dust grains on the parametric coupling of neutral beam driven ion-cyclotron wave instability with the lower hybrid pump wave is explored. A high amplitude lower hybrid pump, which is launched into a tokamak for heating purposes in the existence of neutral beam driven ion-cyclotron wave, can excite the parametric coupling involving two lower hybrid side bands. In a tokamak, the lower hybrid waves results into parametric excitation of ion-cyclotron mode and quasi- modes near the edge, when electron oscillatory velocity is greater than the sound velocity. This parametric coupling increases the growth rate of instability, when the lower sideband wave is resonant. Moreover, the presence of dust grains in tokamak plasma, their size and number density significantly affect the growth rate of the instability which in turn can affect the advanced stage operations of a tokamak. The growth rate of parametric instability scales with the amplitude of the pump wave. The growth rate is found to be linearly increased with the dust grain density but it decreased with increasing the size of dust grains. That means, large sized dust grain stabilizes the instability. The theoretical results explained in the present paper are very helpful in explaining the complexity produced in plasma properties in a tokamak due to the dust-plasma interactions which can diminish the performance of ITER due to potential safety.
