Classical and quantum plasmas

Abstract

A brief survey is given of the different theoretical approaches to the study of the low-density, high-temperature `classical' plasma and of the high-density, low-temperature `quantum' plasma. The random phase approximation, collective-variables method is shown to yield the same result as the collisionless Boltzmann equation combined with the self-consistent field method. Dynamic behaviour is studied in the classical plasma, with particular attention to the relationship between individual particle and collective behaviour. The frequency and wave number dependent longitudinal dielectric constant of the plasma is used to establish the many similarities in behaviour of quantum and classical plasmas in the random phase approximation; the validity of the random phase approximation is discussed. Applications of the theory are made to the ground state energy of the quantum plasma and to the explanation of the characteristic energy losses in solids. The generalizations required to take into account the ionic motion are indicated and the results are described.