“…The resulting model, which can be cast in the framework of extended thermodynamics [16,17] or equivalently of Levermore's moment theory [18], comprises balance equations of electron density, energy density, velocity, and energy flux, coupled to the Poisson equation for the electric potential. The presence of a balance equation for energy flux is at variance with the standard hydrodynamical models usually employed, which are based on Navier-Stokes-Fourier like equations [20,21]. Moreover, apart from the Poisson equation, the system is hyperbolic in the physically relevant region of the field variables.…”