Study of Low-Frequency Microturbulence in the Microtor Tokamak by Far-Infrared Laser Scattering

The first far-infrared laser scattering measurements from a tokamak plasma are reported. Spatially and temporally resolved power spectra of density fluctuations in the Microtor plasma have been studied with an absolutely calibrated far-infrared scattering system which allowed measurement of the wide range of wave numbers from $k=3\mathrm{} \mathrm{to} 50$ ${\mathrm{cm}}^{-1\mathrm{}}$. The wave-number dependence of the scattered power of $0.6\lesssim k_{\perp }{\rho }_i\lesssim 2$ was found to satisfy a $k^{-3.5\mathrm{}}$ form.