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P: Plasmaphysik

P 4: Poster I

P 4.5: Poster

Monday, March 17, 2003, 17:45–19:15, Foyer

Experimental study on ion-acoustic wave propagation in multi-component plasmas — •Albrecht Stark, Olaf Grulke, and Thomas Klinger — Max-Planck-Institute for Plasma Physics, Greifswald Branch, EURATOM Association

Ion-acoustic waves are electrostatic compressional waves with frequencies below the ion plasma frequency. In the low-frequency limit their phase velocity is given by the ion sound speed. In multi-component plasmas, i.e. plasmas consisting of different ion species, the ion sound speed is mainly determined by the respective ion masses weighted by their relative concentrations. Thus, ion-acoustic waves provide a diagnostic tool for ion concentration measurements.

In the linear plasma device VINETA ion-acoustic waves are launched by a grid and the plasma density compressions are detected spatially and temporally resolved by electrostatic probes. In a single-component plasma the waves are identified by full dispersion measurements. Using the same excitation and detection setup the relative ion concentrations in two-component noble gas plasmas are obtained by measurements of the ion-acoustic phase velocity. The results are compared with the respective neutral gas concentrations.