Experimental turbulence spectra in neutral and ion components of a weakly ionized gas

A weakly ionized argon gas flows in a 2 cm diam tube at 60‐100 m/sec velocities and at mean pressures of 20‐50 Torr, producing turbulence in the channel with Reynolds numbers ranging from 2000 to 6000. One‐dimensional turbulence spectra are detected by laser interferometry and Langmuir probes. The experimental results obtained by these two methods show a new region between the Kolmogoroff and the dissipation region where the spectrum of both the neutrals and the ions vary as ${\mathrm{k\hspace{0.17em}}}^{\text{−13/3}}$ (where $k$ is the wave number). It is concluded that this intermediary region is associated with fluid effects rather than being a consequence of ambipolar diffusion of particles in the plasma as has been suggested. Furthermore, it is suggested that compressibility may be responsible for the intermediary region of turbulence spectra.