Paraboloidal model for formation of plasma envelopes and ray structures in the cometary ionosphere

A three-dimensional model of the large-scale stratification of the cometary ionosphere is studied. A physical mechanism for the development of filamentation instability is proposed. The study is carried out in terms of linear magnetohydrodynamics in the paraboloidal geometry of the cometary ionosphere. This model enables the formation of both paraboloidal envelopes covering the cometary head and ray system in the tail to be studied. A numerical simulation of the nonlinear processes by the CIC method is made. Shape, thickness and formation time of these plasma structures are discussed. Formation processes are simulated for different physical parameters.