Images of turbulence in a tokamak plasma

Two-dimensional measurements of density fluctuations in the DIII-D tokamak, obtained with the Beam Emission Spectroscopy diagnostic, have allowed for construction of images and movies of plasma turbulence which are greatly aiding an understanding of tokamak turbulence phenomena. The measurements are obtained in the radial and poloidal plane at a spatial resolution of near 1 cm (about five ion gyroradii). Assembly of synchronized discrete measurements provides a low spatial resolution, high sensitivity, high throughput, high time resolution (Deltat = 1 mus) imaging system. These measurements have shed light on such processes as flow shear, turbulent eddy interaction and shearing, and provide direct visualization of long wavelength turbulence in a hot plasma.