New dispersion relation and threshold expression for parametric decay instability
Xiang Wang
Lancaster University
Farideh Honary, Chen Zhou, Xudong Gu, Binbin Ni, Yuannong Zhang, Zhengyu Zhao
Many phenomena observed in the ionospheric heating experiments, such as field-aligned irregularities, high frequency-enhanced plasma line (HFPLs), stimulated electromagnetic emissions (SEE) can be explained by Parametric Decay Instability (PDI). In this paper, a new dispersion relation of PDI and the threshold expression employing the magneto-hydrodynamics equations, Poisson equation and Landau damping is presented. The threshold of the PDI is proportion to the plasma number density and the product of the collision frequencies and agrees well with the previous experimental observations at Arecibo and Tromso. Inclusion of the collision frequencies has resulted in higher threshold for the excitation of the upper hybrid wave by PDI compared to the Langmuir wave at Tromso, but this scenario is different for conditions at Arecibo.