Influence of the ion/neutral atom mass ratio on the damping of electrostatic ion-cyclotron waves

The damping of electrostatic ion--cyclotron waves by ion--neutral collisions was studied in a single-ended Q machine. The amplitudes of K+ and Cs+ electrostatic ion-cyclotron waves were measured as a function of neutral pressure in helium, neon, argon, krypton, and xenon. For each ion/neutral atom combination, the electrostatic ion-cyclotron wave amplitude maximizes at a neutral pressure that scales monotonically with the m/sub +//m/sub n/ mass ratio. This result is interpreted by considering the dynamics of elastic collisions between the ions and the neutral atoms