Ultra-High Speed Imaging of Plasma Edge Turbulence

60292 Edge density turbulence in magnetic fusion plasmas is important for determining the edge plasma temperature and radial width of the plasma ¿ scrape-off layer¿. Edge parameters also strongly influence the global plasma confinement and the pattern of power and particle flux to the chamber wall. Although edge plasma turbulence has been studied for many years, the high speed dynamics of its two-dimensional structure is still highly uncertain due to a lack of appropriate diagnostics. This project will develop new ultra-high frame imaging to make two-dimensional images of edge turbulence with a high enough framing rate to resolve the time evolution of the turbulence within one autocorrelation time (i.e. one ¿eddy turnover¿ time, on the order of microseconds). In Phase I, a prototype camera with 64 x 64 pixels, operating at 100,000 frames/sec, was optically interfaced to NSTX to capture images of plasma edge turbulence. Initial measurements indicated a need for improved shuttering and increased sensitivity, such as could be obtained using an image intensifier preceding ultra-high speed imager. Phase II will develop an intensified camera with a 128 x 128 pixel format and 300 frame capacity and evaluate/demonstrate plasma diagnostic capabilities on NSTX and Alcator C-Mod. Commercial Applications and Other Benefits as described by the awardee: In addition to magnetic fusion research, a considerable industrial and scientific market should exist for instrumentation capable of imaging at such ultra-high frame rates.