Ion acoustic shock waves with drifting ions in a five component cometary plasma

A shock wave can be formed by continuous mass loading of the solar wind by the newly formed cometary ions. The formation of ion acoustic shocklets has thus been studied in a plasma of solar and cometary electrons, described by kappa distribution functions with different temperatures and spectral indices, a drifting H3O+ ion component and a pair of oppositely charged oxygen ion components. The Korteweg-deVries-Burger's equation which describes weakly nonlinear waves in a dissipative medium has been derived for the above plasma composition using the momentum, continuity and Poisson's equations and studied for parameters observed at the inner shock region of comet Halley. We find that the spectral index of the cometary electrons plays a key role in the formation, speed of propagation and width of the shock wave, which has been interpreted as a shocklet, whose strength decreases as the spectral indices increase or as the suprathermal distribution relaxes to a Maxwellian distribution, with a buildup of colder electrons. Also, all three components of ions contribute to the formation of shocklets; thus bringing out the additive nature of the contributions of various types of ions to their formation. This study could aid the understanding of in-situ measurements of shock waves in cometary plasmas. (C 2021 COSPAR. Published by Elsevier B.V. All rights reserved.

Automated summary

The study investigates the formation of ion acoustic shocklets in a plasma of solar and cometary electrons, highlighting the key role played by the spectral index of cometary electrons. The findings help in understanding the in-situ measurements of shock waves in cometary plasmas.