Nondegenerate electron plasma in a layer in an external electric field with a mirror boundary condition

An analytical solution is obtained for the linearized problem on the behavior of collisionless nondegenerate electron plasma in a layer located in an external alternating electric field. It is assumed that the electrons are mirror-reflected from the plasma boundary. The expansion of the solution in eigenfunctions of the corresponding characteristic system is established. The value of the absorption of the electric field energy in the layer is calculated. A case in which the frequency of the external field is close to the plasma frequency is investigated. It is shown that oscillations are observed in the dependence of the absorption on the frequency at frequencies above that of the plasma. These oscillations are associated with the excitation of plasma oscillations in the layer.