Effect of charged dust grains on the electrical conductivity of hypervelocity impact plasmas

Hypervelocity impacts generate plasma plumes containing significant quantities of micrometer/sub-micrometer dust grains. The charging dynamics of these grains significantly modulate the kinetic evolution and electromagnetic response characteristics of the plasma. To elucidate the control mechanisms of charged dust on the electromagnetic properties of impact-generated plasma, this study establishes a theoretical model for the complex electrical conductivity of dusty plasma in hypervelocity impact environment. Rooted in electron transport kinetic theory and the linearized Boltzmann equation, the model rigorously incorporates both inelastic electron–dust charging collisions and elastic Coulomb scattering mechanisms to derive an analytical expression for macroscopic conductivity. Numerical analyses reveal that the presence of dust induces a distinct frequency dependence in plasma conductivity: in the low-frequency regime, dust grains suppress conductivity by enhancing electron momentum dissipation; conversely, in the high-frequency regime, dust effects lead to a slight enhancement in conductivity. Furthermore, the study identifies that thermionic emission, while reducing the net negative charge on dust, significantly increases the electron–dust Coulomb collision frequency, thereby further attenuating low-frequency conductivity. Parametric studies demonstrate that plasma temperature, dust number density, and particle radius exert nonlinear modulation effects on conductivity. Finally, a power-law particle size distribution is introduced to correct the mono-disperse assumption. The results confirm that non-uniform size distributions yield a higher effective collision frequency compared to average-size models. This work not only refines the electromagnetic transport theory for Hypervelocity impact plasmas but also provides a critical theoretical basis for assessing electromagnetic damage and designing protection systems for spacecraft.