Phenomenological approach to the two-stream instability in two parallel two-dimensional metals

Phenomenologic description of the two-stream instability in two parallel tw o-dimensional (2D) metals is derived. The frequency and rate of growth of a n instable mode is expressed in terms of frequencies and damping of plasma waves in isolated 2D metals. These input parameters are experimentally acce ssible, e.g., by the far-infrared spectroscopy or by the Raman scattering. The presented theory indicates that a system with one metal driven and the second one kept under the zero current condition is more promising for the instability than two metals driven in the opposite directions.