Existence of Two Types of Electron‐Plasma‐Oscillation Resonant Modes as a Function of Changes in Initial Electron Distributions and Temperature

摘要

Starting with the hydrodynamic equations for the motion of electrons in a plasma, the electron‐plasma‐oscillation resonances in a slab geometry have been calculated for various spatial distributions of the initial electron densities and for different electron temperatures. The eigenstates for the perturbed electric field and the electron fluctuation density as well as the resonance frequencies have been computed for the lowest frequency mode and the next‐higher frequency mode. Two kinds of mode exist, one having the resonance frequency higher than the maximum local plasma frequency, so that the wave can propagate throughout the entire body of the plasma, and the other having resonance frequencies lower than the maximum local plasma frequency, so that the wave propagation is limited to part of the plasma, and is excluded from a cutoff region. The relationship between the two types of mode is demonstrated.