Improved Open Boundary Model for Plasma Particle Simulations

Abstract

An open system one-dimensional electrostatic particle code that adopts the new constant current generator model has been developed. Using this new model, we have been able to study various phenomena at large electron drift velocities, where the original model is not applicable. In this new model, the contribution of the ion flux, which is not considered in the original model, is added into the electric current. By examining the code, we find that the result in a case where the electron drift velocity is smaller than the electron thermal velocity is similar to that of a previous study, which showed double layer creation as a result of ion-acoustic instability. We also present the results of simulations of an electron drift velocity comparable to or larger than the electron thermal velocity.

Response of the Magnetosphere to Microscopic Effects in Auroral Arc Formation

“…7 in Ref. [7]). Furthermore, the ionospheric plasma density increases at around t = 3,850 s after the pulse of the upward current.…”

“…The threshold of the field-aligned current is j c = 1.0 × 10 −6 Am −2 . If j peak = j c , the electron drift velocity is v d /v Te = 0.4, which is close to the lower threshold of the ion-acoustic double layer creation [3,7]. Here, v Te is the electron thermal velocity.…”

“…Furthermore, the particle code adopts an open boundary system with the constant current model, in which injected particles at boundaries of a simulation box are determined by constant current condition throughout the system [6] (A more detailed description of the particle code is presented in Ref. [7]. ).…”

“…There are 10,240 electrons and an equal number of ions per grid. The total number of time steps for one run is N [7]). Here, ω pe is the plasma frequency.…”

“…[2,7]. and downward (blue line) field-aligned current densities at the ionosphere height and the ionospheric plasma density (black line).…”