The equations for electronegative plasmas are not singular at the plasma centre at low pressures

Franklin, R. N. (2005). The equations for electronegative plasmas are not singular at the plasma centre at low pressures. Journal of Physics D: Applied Physics, 38(16) pp. 2790–2792.

DOI: https://doi.org/10.1088/0022-3727/38/16/007

Abstract

When one considers electronegative plasmas at low pressures the attachment rate is small compared with the ionization rate and in some formulations of the problem the equations apparently become singular. This is a consequence of assuming mobility-controlled motion for the ions, whereas at low pressure, the ion motion is inertia-controlled (though this not true for the electrons), and the charged particle distributions are regular as a result. Since at low pressures the negative ions closely obey a Boltzmann relation governed by their temperature, no singularity can exist.