The response of a heavy ion seed component to the passage of a plane shock in the neutral background gas has been analyzed. The translational equilibrium of the ion trace occurs in a region of effectively frozen ionization level and electron temperature where the ion behavior is controlled by a momentum balance of electrical, inertial, and collisional forces. Three distinct types of solutions are found to occur: quasi‐ neutral downstream relaxation at low electron temperatures; quasi‐neutral upstream accommodation at high electron temperatures; and non‐quasi‐ neutral damped electrostatic oscillations at intermediate electron temperatures.