Date: July 24, 2014 (Physics Meeting)
Eric Edlund: A proposed phase contrast imaging for density fluctuation measurements in Wendelstein 7-X (revised 8/1/2014)
Upcoming experiments in Wendelstein 7-X are expected to exhibit a wide range of instabilties and waves, and despite being optimized with regard to neoclassical transport, will likely exhibit significant fluctuations from ITG turbulence. Connections between the global confinement properties and the turbulence-induced transport will require a host of fluctuation diagnostics. In this talk we will examine a new proposal for construction of a phase contrast imaging (PCI) diagnostic in support of turbulence measurements in Wendelstein 7-X. The phase contrast technique will be presented, followed by a discussion of recent measurements from the PCI systems on the Alcator C-Mod and DIII-D tokamaks, including drift wave turbulence, edge-localized modes, Alfven waves and ICRF mode-converted waves. Implementation of a PCI system on the LHD stellarator will be examined as a relevant comparison for Wendelstein 7-X.