Ion Acoustic Waves in an Electron Cyclotron Resonance Plasma

Ion acoustic waves have been generated in an electron cyclotron resonance plasma. The plasma was produced in a long microwave cavity at the heating frequency of 3.025 Gc/sec. When the resonance condition ωₚ²=2ω(ω-ωb) is approached, the plasma constricts, corresponding to present theory. The waves appeared when the magnetic field was increased slightly above the value necessary to achieve the resonance condition. The waves were observed by means of a photomultiplier, a Langmuir probe, and a shift in frequency of a higher order cavity mode. Harmonics of the waves up to and including the 4th have been seen.