Images of edge turbulence in NSTX

The two-dimensional structure of edge plasma turbulence has been measured in the National Spherical Torus Experiment (NSTX) by viewing the emission of the D/sub a/ spectral line of deuterium. Images have been made at framing rates of up to 250 000 frames/s using an ultra-high speed charged coupled device camera developed by Princeton Scientific Instruments. A sequence of images showing the transition between L-mode and H-mode states is shown.