Results from the simplified coma model for a water-dominated coma and low outgassing rate. All ion number densities decrease with increasing distance from the comet because of competing factors of the 1/r² density decrease and the increases and decreases due to ionization and ion-neutral chemistry. Whereas the chemical equations that govern the H₃O⁺ and HCO⁺ number densities have no loss terms in this simple model, the equations that govern the H₂O⁺ and CO⁺ number densities do have loss terms. Therefore, the H₃O⁺ and HCO⁺ number densities decrease more slowly than those for H₂O⁺ and CO⁺. At 30 km from the comet, the H₃O⁺/H₂O⁺ and HCO⁺/CO⁺ ratios are both lower than 1, indicating weak ion-neutral chemistry for this low outgassing case.