Energy transfer, pressure tensor, and heating of kinetic plasma

Abstract

Kinetic plasma turbulence cascade spans multiple scales ranging from macroscopic fluid flow to sub-electron scales. Mechanisms that dissipate large scale energy, terminate the inertial range cascade and convert kinetic energy into heat are hotly debated. Here we revisit these puzzles using fully kinetic simulation. By performing scale-dependent spatial filtering on the Vlasov equation, we extract information at prescribed scales and introduce several energy transfer functions. This approach allows highly inhomogeneous energy cascade to be quantified as it proceeds down to kinetic scales. The pressure work, − (P · ∇) · u, can trigger a channel of the energy conversion between fluid flow and random motions, which is a collision-free generalization of the viscous dissipation in collisional fluid. Both the energy transfer and the pressure work are strongly correlated with velocity gradients.

Kinetic Dissipation Around a Dipolarization Front

“…In this paper new measures of kinetic dissipation, the pressure dilatation, and the Pi-D (i,e) parameters, recently proposed by Yang, Matthaeus, Parashar, Wu, et al (2017) and Yang, Matthaeus, Parashar, Haggerty, et al (2017) for studies of collisionless plasma turbulence, have been applied for the analysis of spontaneous dipolarizations reproduced in 3-D PIC simulations of the magnetotail CS (Sitnov et al, 2017). The analysis shows that in contrast to the fluid dissipation measure, the Joule heating rate j ⋅ E ′ , which cannot distinguish between ion and electron dissipation and reveals deep negative spikes at the DF, the Pi-D (i,e) parameters are largely positive and drastically different for ions and electrons.…”

“…Since the parameter log [p ( ) ( ( ) ) −5∕3 ] resembles the entropy of the species , it is reasonable to suppose that the difference between the parameters p ( ) ( ) and p ( ) (3) is usually termed in the turbulence theory as the pressure dilatation (Yang, Matthaeus, Parashar, Haggerty, et al, 2017;Yang, Matthaeus, Parashar, Wu, et al, 2017, and references therein). Since the parameter log [p ( ) ( ( ) ) −5∕3 ] resembles the entropy of the species , it is reasonable to suppose that the difference between the parameters p ( ) ( ) and p ( ) (3) is usually termed in the turbulence theory as the pressure dilatation (Yang, Matthaeus, Parashar, Haggerty, et al, 2017;Yang, Matthaeus, Parashar, Wu, et al, 2017, and references therein).…”

“…In their recent works Yang, Matthaeus, Parashar, Wu, et al (2017) and Yang, Matthaeus, Parashar, Haggerty, et al (2017) applied the pressure dilatation and Pi-D ( ) parameters to the analysis of collisionless plasma turbulence in 2-D PIC simulations. They have found that these parameters correlate with velocity gradients and are highly localized in similar spatial regions, with their quantities integrated over the simulation box being persistently positive.…”

“…In this paper we consider new kinetic measures of dissipation, which have recently been proposed in studies of collisionless plasma turbulence (Yang, Matthaeus, Parashar, Haggerty, et al, 2017;Yang, Matthaeus, Parashar, Wu, et al, 2017). The new measures are applied for the analysis of magnetotail dipolarization regimes associated with the IDMR, which have recently been reproduced in 3-D particle-in-cell (PIC) simulations (Sitnov et al, 2017).…”

Magnetic Reconnection, Turbulence, and Particle Acceleration: Observations in the Earth's Magnetotail

“…One of the most important yet least understood processes of turbulence in collisionless plasmas is kinetic-scale dissipation (e.g. Karimabadi et al, 2013;TenBarge & Howes, 2013;Wan et al, 2012Wan et al, , 2016Yang et al, 2017).…”