Ion motion control by the field of ion-acoustic wave

Ion motion in the field of an ion-acoustic wave (IAW) is studied. Low-frequency waves are considered. The ions are effectively accelerated by the field of the IAW during a half a period of IAW. When the length of the oscillation is of order of the distance between the initial position of the ions and the surface being processed the interaction of the ions with the surface is possible. The propagation of the IAW is considered in the plasma layer bounded by metal planes. The metal planes are the surfaces being processed. The consideration is carried out for wave which is travelling in a direction parallel to the metal planes and standing in perpendicular direction. The expressions for the electric field of the wave are obtained analytically from Maxwell and quasi-hydrodynamical equations. Using these expressions the ion motion in the structure studied is investigated numerically. The investigation is carried out by using the Runge-Kutta method. It was assumed that initially ions are distributed in the regular intervals in the plasma volume and the initial velocity of ions is zero. The energy and angle distribution of the particle flux on the metal surfaces are obtained for different plasma parameters. The angle and energy distribution of the incident particles can be changed by controlling ion density, wave frequency, wave length and amplitude of the wave. The conditions when the number of particles with large incidence angles and large energy is great enough are determined. Such ion flows can be used for surface processing such as polishing and film deposition.