Oblique electron fire hose instability: Particle‐in‐cell simulations

Abstract

Nonlinear properties of the oblique resonant electron fire hose instability are investigated using two‐dimensional particle‐in‐cell simulations in the Darwin approximation for weak initial growth rates. The weak electron fire hose instability has a self‐destructive nonlinear behavior; it destabilizes a nonpropagating branch which only exists for a sufficiently strong temperature anisotropy. The nonlinear evolution leads to generation of nonpropagating waves which in turn scatter electrons and reduce their temperature anisotropy. As the temperature anisotropy is being reduced, the nonpropagating branch disappears and the generated standing waves are transformed to propagating whistler waves which are rapidly damped. Consequently, the oblique electron fire hose efficiently reduces the electron temperature anisotropy.

Properties of current sheet thinning at x ∼− 10 to −12 RE

“…A possible explanation for this evolution is that Λ e ∼1 is maintained by waves near the marginal firehose instability. Any increase in A e that moves Λ e beyond the instability threshold might trigger the electron oblique firehose instability and scatter electrons back to Λ e ∼1 in a very short time [ Hellinger et al , ]. Although this scenario describes the Λ e ∼1 observations, it cannot explain why after 06:35 we observe Λ e >1.…”

Near‐Earth Solar Wind: Plasma Characteristics From ARTEMIS Measurements

“…Note that the data shown in Figure are averaged over 3 min, and this averaging can mitigate peak values of the electron anisotropy. The electron anisotropy approaches the electron firehose instability threshold (Gary & Nishimura, ; Hellinger et al, ) but seems to be far from the whistler instability threshold (Gary & Wang, ).…”

Wave-particle interactions with parallel whistler waves: Nonlinear and time-dependent effects revealed by particle-in-cell simulations

“…Temperature anisotropy instabilities have a "selfdestructing" character, in the sense that the generated electromagnetic fluctuations reduce the anisotropy that drives the instability, and therefore, a marginal stability condition is usually rapidly reached. [35][36][37][38][39] Figure 1 shows the reduction of temperature anisotropy (red line, right axes) and the increasing magnetic field amplitude (black line, left axes). The linear instability saturates around the time TX e ¼ 900, and although the anisotropy response to the magnetic field fluctuations is somewhat delayed, the correlation is clear.…”