Current sheets and pressure anisotropy in the reconnection exhaust

Abstract

A particle-in-cell simulation shows that the exhaust during anti-parallel reconnection in the collisionless regime contains a current sheet extending 100 inertial lengths from the X line. The current sheet is supported by electron pressure anisotropy near the X line and ion anisotropy farther downstream. Field-aligned electron currents flowing outside the magnetic separatrices feed the exhaust current sheet and generate the out-of-plane, or Hall, magnetic field. Existing models based on different mechanisms for each particle species provide good estimates for the levels of pressure anisotropy. The ion anisotropy, which is strong enough to reach the firehose instability threshold, is also important for overall force balance. It reduces the outflow speed of the plasma. V C 2014 AIP Publishing LLC. [http://dx.

Two-stage bulk electron heating in the diffusion region of anti-parallel symmetric reconnection

“…Additional evidence comes from the electron temperature illustrated in Figs 1(a-d) at late times from a particle-in-cell (PIC) simulation of anti-parallel reconnection (similar to Ref. [16], but with an ion-to-electron temperature ratio of 5 and background density of 0.25 the peak Harris density). Figure 1(e) shows the time evolution of the electron temperature along the mid-plane (z = 0).…”

Pseudo-3D PIC modeling of drift-induced spatial inhomogeneities in planar magnetron plasmas

“…In the downstream of the remagnetization front, the unmagnetized ions form a broad current layer. 34,66 Properties of this ion current layer was studied in our previous work. 66 In Figure 2(b), it is interesting to see the electron divergent flows in the vertical (6z) directions near the remagnetization front.…”

Role of Ion Kinetic Physics in the Interaction of Magnetic Flux Ropes

“…The importance of kinetic ions has been argued previously [26], but for an isolated current sheet the peak rate was similar to that in Hall-MHD. We also note that although electron kinetics were not crucial for this problem, studies in Harris geometry have found them important to set the length of electron layers [36,39], and can affect global behaviour through formation of secondary magnetic islands. The most important consequence of the present study is the different global evolution of the system between the Hall-MHD and kinetic ion codes.…”

“…Second, along y = 0 the exhaust approaches the firehose instability threshold, 1 + (p i⊥ − p i )/(B 2 /µ 0 ) ≈ 0, reducing tension in the reconnected field and thus may reduce the outflows with respect to the inflow Alfvén speed (see below and Ref. [36]). The AØ i and firehose parameter in PIC runs (not shown) agree well with hybrid.…”