Observation of the Effects of Dust Particles on Plasma Fluctuation Spectra

Charged dust particles are theoretically expected to modify the amplitude and spectrum of plasma fluctuations, and this can eventually provide novel diagnostic tools. Direct experimental evidence of the effects of dust particles on the fluctuations of a low collisionality plasma is reported, in agreement with the expectations of kinetic theory.

Figure 1

Power spectra of ion density fluctuations in different gas mixtures for two different runs, (a) and (b).

Figure 2

Spectral density of ion density fluctuations versus wave number $k$ normalized to the ion Debye length for two values of the frequency and density parameter $P$. The grain radius is $a=8\mathrm{nm}$.

Figure 3

The integrated spectral density of ion density fluctuations for four values of the density parameter $P$. For the smallest value the curve coincides with the case of no dust present. The grain radius is $a=8\mathrm{nm}$.