Electrostatic ion-cyclotron waves in a plasma with heavy negative ions

Results of a laboratory study of electrostatic ion-cyclotron (EIC) waves in a plasma containing K+ (39 amu) positive ions, electrons and C7F14− (350 amu) negative ions are presented. Excitation of the fundamental and higher harmonic light and heavy ion EIC modes was observed. The presence of heavy negative ions in the plasma has a significant effect on the excitation of the light ion EIC modes. The results may be relevant to the understanding of plasma wave properties in plasmas containing negative ions, such as those found in the Earthʹs ionosphere, the solar system, and, in particular, near Saturnʹs moon Titan, where an abundance of heavy negative ion species has recently been discovered [Coates, et al., 2007. Discovery of heavy negative ions in Titanʹs ionosphere. Geophys. Res. Lett. 34, L22103].