Surface-Wave Propagation in Inhomogeneous Plasmas

Abstract

Compared with the numerous studies in the literature of the 1960s and 1970s on SWs in homogeneous plasmas, the number of publications during the same period on properties of waves in inhomogeneous plasmas was quite smaIler [4.1–13]. This can be blamed on the complexity of the analytical treatment of the problem and on the lack of good computing capabilities at that time. Since the research on SWs in this period was concerned with DC discharge plasmas, the plasma-density inhomogeneity involved was in the transverse direction. In spite of not too much extended research, the main effects related to the plasma inhomogeneity were weIl understood. Weak inhomogeneity leads to changes in the wave dispersion which are quite pronounced in the range towards the SW resonance (3.1) in cold collisionless plasmas (Fig. 3.3). Like the effects of collisions (Fig. 3.2) and thermal motion, the inhomogeneity also removes the resonance. However, whereas the influence of collisons and thermal motion is in the direction of extending the range of the waves ahove the resonance, the inhomogeneity, forming a maximum of W / wp in the phase curves moves the w/wp range down.