## A billion trillion “clashes” make a plasma

A systematic treatment of microscopic collisions to extend fluid models of plasmas At the microscopic level, binary collisions between charged particles conserve two fundamental quantities, namely momentum and energy. This conservation must be present in fluid models in order to describe the macroscopic evolution of plasmas correctly. A systematic treatment of collisional effects is presented to derive fluid models beyond the usual assumption of “thermal equilibrium”. Such extended models will