DIAGNOSTIC OF DUSTY PLASMA CONDITIONS BY THE OBSERVATION OF MACH CONES CAUSED BY DUST ACOUSTIC-WAVES

The theory of dust acoustic waves in dusty plasmas is well developed f or conditions with monosized dust particles. It was proposed [O. Havne s et al., J. Geophys. Res. 100, 1731 (1995)] that such waves may be ge nerated in planetary dust rings by boulders moving through the dust at a velocity that is somewhat higher than the dust acoustic velocity. I n this manner Mach cones can form with an opening angle that is depend ent on the boulder velocity and the local dust acoustic velocity. Meas urements of this opening angle will therefore provide additional infor mation on dusty plasma conditions since the dust acoustic velocity can be determined when the boulder velocity is known. We suggest that thi s method may also be applied under laboratory conditions if a suitable controlled disturbance can be made and we discuss how the dust acoust ic velocity and resulting Mach cones are affected if the dusty plasma have a distribution of dust sizes. (C) 1996 American Vacuum Society.