2-D phase contrast imaging of turbulence structure on LHD

CO/sub 2/ laser-based phase contrast imaging (PCI) equipped with a 6 by 8 element two-dimensional (2-D) array of photoconductors is used on the large helical device (LHD) for studying plasma density microfluctuations. Observing 2-D structures of turbulence and strong magnetic shear along the viewing line on LHD permit conversion of a 2-D-PCI image to a 2-D picture of the radial distribution of the turbulence k-spectrum. The PCI images are sampled at 1 MHz so the images or associated spectral distributions, when assembled in a movie, present the dynamic radial structure of turbulence.