Gas Puff Imaging Diagnostics of Edge Plasma Turbulence in Magnetic Fusion Devices

Gas puff imaging (GPI) is a diagnostic of plasma turbulence which usesa puff of neutral gas at the plasma edge to increase the local visiblelight emission for improved space-time resolution of plasmafluctuations. This paper reviews gas puff imaging diagnostics of edgeplasma turbulence in magnetic fusion research, with a focus on theinstrumentation, diagnostic cross-checks, and interpretationissues. The gas puff imaging hardware, optics, and detectors aredescribed for about 10 GPI systems implemented over the past ~15years. Comparison of GPI results with other edge turbulence diagnosticresults are described and many common features are observed. Severalissues in the interpretation of GPI measurements are discussed, andpotential improvements in hardware and modeling are suggested.