Kinetic Analysis of the Energy Transport of Two-Flow Components in the Plasma Sheet

Satellite observations indicate that multiple components often exist in the plasma sheet, particularly during impulsive fast flow events. In this paper, we perform a kinetic analysis of the energy transport of plasma sheet ion flow using a model of two-component plasma sheet ion flows (Background convection flow represented by subscript "b" and Fast flow represented by subscript "f") and compare the energy transport calculated by kinetic approach Q(k) with those obtained from magnetohydrodynamic (MHD) approach Q(MHD). The ratio of Q(k)/Q(MHD) is always larger than unity and is positively proportional to the ratios of V-f/V-b and T-f/T-b. The maximum values of Q(k)/Q(MHD) occur in the low-speed ranges (i.e., small density ratio N-f/N). When N-f/N exceeds 0.4, the ratio of Q(k)/Q(MHD) is almost the same for a wide parameter ranges of V-f, T-f, and V-b. Heat flux is important in low-speed range and is neglectable in the high-speed range. The adiabatic polytropic index 5/3 cannot correctly describe energy transport rate. A density ratio N-f/N of 0.3% of high-speed ion flow can make the effective polytropic index obviously deviate from adiabatic polytropic index (5/3). The above theoretic results can well explain previously reported satellite in situ observations.