Ion Tail Plasma Density and Magnetic Pile-Up Pressure at One Astronomical Unit

This paper examines the plasma density inside a comet ion tail and the magnetic field piled up against the coma. Using only published input values and transparent formulae, the calculation obtains the following headline results: tail_ion_density_per_m3 = 6.366e+04; tail_ion_density_per_cm3 = 0.0637; solar_wind_ram_pressure_Pa = 1.338e-09. The mean tail density is about sixty-four thousand ions per cubic metre, or about six hundredths of an ion per cubic centimetre, roughly eighty times more tenuous than the undisturbed solar wind. The method, inputs and limitations behind the study of the plasma density inside a comet ion tail and the magnetic field piled up against the coma are stated in full so that any reader can reproduce or rescale every number from the deposited calculation script. Agreement and disagreement with independent published estimates are reported at their actual size, and the conclusions are limited to what the budget arithmetic for the plasma tail channel downstream of an active comet at 1 AU supports.