Pseudomoment fluid modeling: Electron Landau damping of ion-acoustic waves

This Brief Communication introduces a hierarchy of electron pseudomoment fl uid equations to derive electron Landau damping of ion-acoustic waves. Exac t agreement with kinetic predictions is obtained. The pseudomoment fluid fo rmulation allows simple, analytic estimates of Landau damping for general, nonthermal electron distribution functions in Vlasov plasmas. Successful tr uncation of the pseudomoment hierarchy suggests a novel definition of elect ron temperature away from thermal equilibrium in the low-frequency regime. (C) 2001 American Institute of Physics.