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- Divin, A., et al.
(författare)
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Inner and outer electron diffusion region of antiparallel collisionless reconnection : Density dependence
- 2019
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Ingår i: Physics of Plasmas. - : AMER INST PHYSICS. - 1070-664X .- 1089-7674. ; 26:10
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Tidskriftsartikel (refereegranskat)abstract
- We study inflow density dependence of substructures within electron diffusion region (EDR) of collisionless symmetric magnetic reconnection. We perform a set of 2.5D particle-in-cell simulations which start from a Harris current layer with a uniform background density n(b). A scan of n(b) ranging from 0:02 n(0) to 2 n(0) of the peak current layer density (n(0)) is studied keeping other plasma parameters the same. Various quantities measuring reconnection rate, EDR spatial scales, and characteristic velocities are introduced. We analyze EDR properties during quasisteady stage when the EDR length measures saturate. Consistent with past kinetic simulations, electrons are heated parallel to the B field in the inflow region. The presence of the strong parallel anisotropy acts twofold: (1) electron pressure anisotropy drift gets important at the EDR upstream edge in addition to the E x B drift speed and (2) the pressure anisotropy term -del.P-(e)/(ne) modifies the force balance there. We find that the width of the EDR demagnetization region and EDR current are proportional to the electron inertial length similar to d(e) and similar to d(e)n(b)(0.22), respectively. Magnetic reconnection is fast with a rate of similar to 0.1 but depends weakly on density as similar to n(b)(-1/8). Such reconnection rate proxies as EDR geometrical aspect or the inflow-to-outflow electron velocity ratio are shown to have different density trends, making electric field the only reliable measure of the reconnection rate. Published under license by AIP Publishing.
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