Nonlinear quantum hydrodynamical model of the electron gas

It is well known that the hydrodynamical model of the electron gas is suitable when the electron density can be considered as the fundamental quantity, small wavelength effects being less important. This is the case when the electron gas is excited by the passage of swift charged particles. In this paper we make use of the quantum hydrodynamical model of the electron gas to derive, within this model, the nonlinear wake potential of fast charged particles passing through matter, the Barkas effect, and double-plasmon excitation probabilities. This is compared with results obtained by following many-body schemes within the random-phase-approximation.