Dartmouth Events

Abstract: Space plasmas are intrinsically collisionless and may exhibit various nonthermal characteristics. In particular, in magnetized plasmas the temperature tends to exhibit the gyrotropic forms with distinct parallel and perpendicular components. The issue of energy closures to the plasma fluid models with temperature anisotropy has existed for more than half a century. The well-known double-adiabatic or CGL laws proposed by Chew et al. (1956) have been tested in the space plasma environment and shown not to be suitable as the energy closures due to the imbedded physical assumptions. This defect is further confirmed by the recent spacecraft observations of the mirror waves occurring in the planetary magnetosheath. In this seminar we will present the recent progress and discoveries in the search of suitable energy closures to the plasma fluid models. It is shown based on the kinetic theory of mirror instability that there exist analytical energy equations in the form of double-polytropic laws first proposed by Hau and Sonnerup (1993). However, the two polytropic exponents are functions of plasma betas which implies that the energy laws are unique to different plasma beta regimes. The theoretical predictions are shown to provide excellent framework to the observed mirror waves events in terms of the phase relations and thermodynamics. 

Hosted by Professor Yi-Hsin Liu

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https://dartmouth.zoom.us/j/92751420885?pwd=QnIwN0RiSGkzMUtjQVZxRlZLMkcwQT09

Meeting ID: 927 5142 0885
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