Solitary Dust--Acoustic Waves in a Plasma with Two-Temperature Ions and Distributed Grain Size

The propagation of weakly nonlinear dust--acoustic waves in a dusty plasma containing two ion species with different temperatures is explored. The nonlinear equations describing both the quadratic and cubic plasma nonlinearities are derived. It is shown that the properties of dust--acoustic waves depend substantially on the grain size distribution. In particular, for solitary dust--acoustic waves with a positive potential to exist in a plasma with distributed grain size, it is necessary that the difference between the temperatures of two ion species be large that that in the case of unusized grains.Comment: 16 pages, 6 figure

PVDF copolymer transducers used to evaluate microparticle suspensions

The ability of using high frequency ultrasonic transducers made from piezoelectric polymers, to characterize microparticle suspensions, has been investigated both in an experimental setup and in a numerical model. Both investigations, which consider microparticles settled on a glass substrate, show that the backscattered frequency spectra contain a number of minima values arising from wave resonances in the microparticles. The locations of these resonances are in the experiments, found to be independent of the particle concentration, but strongly dependent on the particle size. A comparison to previous results for floating microspheres, show that the material properties of the glass substrate, also has to be included for obtaining the correct resonance frequencies for settled particles