A plasma mirror for electronic microwave beam steering

Summary form only given. A planar plasma may be used as a reflector for microwaves if the plasma frequency (at the angle of incidence) is greater than the microwave frequency. If this plasma mirror can be repositioned electronically, it could have the capability of redirecting microwave beams on a very fast time scale, and as such it could have important applications to radar and communication systems. The goal is the generation of planar plasmas which have the potential of reflecting microwave beams. The plasma is formed with a unique hollow cathode glow discharge. It produces a sheet plasma, square and about 60 cm on a side. This plasma has been studied mostly in air, although other gases have been used also with similar results. The background pressure is about 100 mtorr, and a uniform magnetic field of about 100 g is in the plane of the plasma. Microwave experiments show that as far as flatness and noise temperature are concerned, the plasma acts like a metal plate. Furthermore, the velocity of the reflecting surface can be as low as a few centimeters per second.