Ion Acoustic Shock Waves in a Magnetized, Cometary Plasma Containing Warm Ions

The formation of ion acoustic shock waves in a magnetized, anisotropic plasma has been studied in a five-component, magnetized cometary plasma consisting of two components of electrons (of solar and cometary origin) described by kappa distribution functions with different temperatures and spectral indices, a drifting, ion component ( {\text {H}}_{{3}}\text {O}^{+} ions) and a pair of oppositely charged oxygen ion components. The Korteweg-deVries-Burger's (KdVB) equation, which describes weakly nonlinear waves in a dissipative medium, has been derived for this system using the momentum, continuity, and Poisson's equations and studied for parameters at the inner shock region of comet Halley. When the plasma gets magnetized, the dispersion coefficient is found to be larger than for the unmagnetized case. Obviously, the magnetic field has contributed to the parallel and perpendicular anisotropic ion pressures of the {\text {H}}_{{3}}\text {O}^{+} and the positively and negatively charged oxygen ions. We find that the magnetic field profoundly influences both the propagation and width of the shock waves, which have been interpreted as "shocklets." The width of these shocklets decreases as the magnetic field increases. As regards various stages of magnetization, the greater amplitude is for the case in which both positively and negatively charged oxygen ions are magnetized than for the case in which all the three ions are magnetized. Also, as the gyrofrequencies of all the three ions increase, the shock amplitude is found to increase. In addition, the parallel anisotropic ion pressures of all the three ion components decrease the amplitude of the shocklets. This study would be useful in understanding the in situ measurements of shock waves in cometary plasmas.