Excitation Of Collective Oscillations Research Articles

Energy loss of a fast-electron beam due to the excitation of collective oscillation in hot plasma

Energy loss due to a fast-electron beam interacting with the hot plasma at a high density is analysed theoretically. By splitting the particle density fluctuations into the individual part due to the random thermal motion of the individual electrons and the collective part due to plasma–wave excitation, we are concerned with the collective interaction of the relativistic plasma electrons resulting from the Coulomb interactions. Consequently, we derive the frequency of the hot plasma and the ``Debye length'' with the modification of the relativistic effect. And finally we calculate the energy loss of a fast-electron beam due to the excitation of collective oscillation in the hot plasma.

Les Pertes d'Energie Caractèristiques des Electrons dans les Solides

B. Gauthe Paris: Gauthier–Villars. 1968 Pp. viii + 72. Price £2 2s. The main progress in the field of electron energy losses in solids in the last 10 years or so has been the discovery of the excitation of collective oscillations, both in the bulk and on the surface. This book reviews the interpretations that have been given of the electronic spectra of some metals, in terms of these two kinds of excitation, and their relation to the optical properties.

Collective Excitations of a Granular Superconductor in the Presence of a Steady Uniform Current Flow

By a suitable linearization of the isospin equations of motion, a calculation is made of the collective excitations of a granular superconductor in the presence of a steady, uniform current flow. Aside from the case of vanishing frequency or wave vector, only collective excitations with wave vectors perpendicular to the direction of current flow can occur physically (all others violating the condition of electric charge neutrality in the superconductor). This insures that the uniform supercurrent is stable against decay by excitation of collective oscillations (excitations bounded in space and time). Those excitations which can occur in the presence of the steady, uniform current are appreciably modified by the latter.