Unveiling dust-acoustic wave dynamics in cometary plasmas: Insights from Doppler-shifted growth rates at Comet Halley

Dusty plasmas, composed of charged dust grains, ions, and electrons, exhibit complex dynamical behavior in cometary environments. This study investigates the Doppler-shifted linear growth of dust-acoustic modes in the vicinity of Comet Halley under magnetized conditions. The model considers warm dust-fluid inertia, inertialess Boltzmann responses of electrons and negative ions, and nonthermal positive ions described by the Cairns distribution. The influence of dust cyclotron frequency, nonthermal ion effects, wave number, plasma response, and magnetic field obliqueness on the instability characteristics is examined. The results show that higher dust cyclotron frequency and stronger nonthermal ion contribution enhance the linear growth rate, while low propagation angles produce larger growth rates than high propagation angles in the present parameter regime. The wide-range analysis gives a maximum growth rate of γ max ≈ 0.028571 at k max = 0.1 m − 1 within the investigated wave-number range, corresponding to a dominant wavelength of λ max = 62.83 m . Using an electric-field estimate of E = 1 × 1 0 − 3 V m − 1 , the wave energy density is estimated as E w = 4.43 × 1 0 − 18 J m − 3 , and the corresponding linear energy-transfer rate is P d ≈ 2.53 × 1 0 − 19 W m − 3 . The turbulence-transfer estimate, treated as an order-of-magnitude implication of the dominant linear scale, is approximately ϵ t = 6.33 × 1 0 − 27 W m − 3 . These findings suggest that Doppler-shifted dust-acoustic instabilities may provide initial perturbations for energy transfer in Halley-like cometary dusty plasma environments.