Effects of Vibration on Dual-Laser Digital Holography for In-Situ PFC Surface Characterization*

The ability to make real-time in-situ measurements of surface changes of Plasma Facing Components (PFCs) in magnetic fusion devices would be a considerable advantage to fusion researchers. A digital holography device is under development at Oak Ridge National Laboratory for in-situ surface characterization of PFCs. A brief review of single laser and dual laser techniques, along with measurements of targets with known surface variations, will be presented. Additionally, ex situ measurements of targets exposed in the Proto-MPEX linear plasma device, and also an initial target exposed to a high power Electro-Thermal arc plasma device, will be shown. The relative vibration of the diagnostic table and the plasma target plays a large role in determining the measurement resolution of the technique, as the diagnostic system transitions from ex situ to in situ characterization of PFCs during plasma exposure.