Beam emission imaging system for 2D plasma turbulence measurements

A two‐dimensional analog to the beam emission spectroscopy (BES) diagnostic has been designed to acquire vorticity and plasma flow‐field information by resolving the spatial and temporal intermittency of plasma turbulent structures. The beam emission imaging diagnostic measures collisionally induced neutral beam fluorescence to infer local plasma density variations. It consists of a high‐throughput, interline‐transfer CCD camera viewing, with narrow spectral bandwidth, a 10 cm high diagnostic neutral beam as it traverses the plasma. The camera is coupled to a gated image intensifier that provides for two images with exposure times up to a few ms to be separated by as little as 10 μs. Sensitivity to density fluctuations of n/n≳1.0% is expected using the Phaedrus‐T beam operating at 20–25 keV in He0 or D0.