| AVS 57th International Symposium & Exhibition | |
| Plasma Science and Technology | Tuesday Sessions |
| Session PS2-TuM |
| Session: | Plasma Diagnostics, Sensors and Control |
| Presenter: | N. Hershkowitz, University of Wisconsin-Madison |
| Authors: | N. Hershkowitz, University of Wisconsin-Madison C.-S. Yip, University of Wisconsin-Madison G. Severn, University of San Diego |
| Correspondent: | Click to Email |
Recent experiments have shown that ions in weakly collisional plasmas containing two ion species of comparable densities nearly reach a common velocity at the sheath edge. A new theory suggests that collisional friction between the two ion species enhanced by two stream instability reduces the drift velocity of each ion species relative to each other near the sheath edge and finds that the difference in velocities at the sheath edge depends on the relative concentrations of the species. It is small when the concentrations are comparable and is large, with each species reaching its own Bohm velocity, when the relative concentration differences are large. To test these findings, ion drift velocities were measured near the near sheath edge in Argon-Xenon plasmas as a function of the concentration ratio using the laser-induced fluorescence technique. We show that the predictions are in good agreement with a revised version of the model. This is the first experimental test of the collisional friction model.