Instability near the lower-hybrid frequency in an ion beam--plasma system

An ion beam is generated by extracting ions from a dc discharge plasma and injecting them into a plasma produced independently of the beam source. Thus, an ion beam--plasma system is produced in which the beam parameters vary independently from those of the plasma. It is confirmed by using this system that a test wave becomes unstable near the lower-hybrid frequency f/sub lh/, and the unstable wave is observed only in the region where the beam is present