PROBLEMS OF GEOCOSMOS

Proceedings of the 7th International Conference "Problems of Geocosmos" (St. Petersburg, Russia, 26-30 May 2008)
Ψ(x, y) = Ψ0cos 2πx
cos
Lx
πy
, (1)
Ly
where Lx and Ly are the size of computational box in ion inertial lengths di. In this work we report on the
results of two runs: one with Lx = Ly = 19.2di (Run 1) and second with the size of computational box doubled
Lx = Ly = 38.4di (Run 2). For the smaller run (Run 1) we extracted particle data (positions, velocities) to
investigate particle motion in detail. Intensity of perturbation is Ψ0 = 0.3. We explore the EDR current layer
in the phase when reconnection rate and main plasma parameters throughout the computational box enter the
quasistationary state (t = 15Ω −1
i for Run 1 and t = 20Ω −1
i for Run 2). Here Ωi = eB0
mic is ion gyrofrequency.
The mass ratio is mi/me = 64, the temperature ratio Ti/Te = 3/2 for both runs.
Open boundary conditions for fields
and particles
∂Bx,y
∂x
∂ne,i
= 0, ∂Ey
∂x = 0, Ex,z = 0, δBz = 0. (2)
∂Ve,i
= 0,
∂x
= 0,
∂x
T = T(t = 0), (3)
are implemented at the exhaust boundaries to allow free outflow of plasma [11], [12]
3 Results
Figure 1: Current density jz in Run 1 (top), out-of-plane magnetic field Bz in Run 1 (bottom)
Here we briefly present general results on the kinetic simulation of reconnection.
Reconnection starts as initially imposed X-line perturbation drives system out of equilibrium. Details of
non-stationary phase could be found in e.g. [12],[13]. As Me reaches the value of 0.1 ÷ 0.2, process turns to
quasistationary phase ([8] and references herein). In the simulations by [6] slow decay of Me was claimed, but
this result was considered to be controversial in recent works and attributed to the particular set of boundary
conditions.
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