Wall Effects on the Propagation of Compressional Alfv�n Waves in a Cylindrical Plasma with Two-Ion Species

The dispersion relations for the compressional Alfvén waves in a two-ion species plasma of deuterium and hydrogen are calculated for a configuration which includes a vacuum layer between the cylindrical plasma and the conducting wall. The presence of the vacuum layer strongly affects the propagation of the compressional Alfvén wave, permitting some branches to propagate and penetrate the plasmacolumn over most frequencies in the ion-cyclotron range. Basic Alfvén-wave propagation and heating experiments in two-ion species consequently should be possible using tokamak and mirror devces with minor radii smaller than the Alfvén wavelength.