Measurement of the deposition morphology using temporal phase-shifting laser speckle interferometry

Abstract

Monitoring the deformation caused by wall erosion and deposition on the Plasma-Facing Components (PFCs) in tokamak has been essential issues for the maintenance of a long duration plasma discharge and safety. As an in situ, real-time and non-destructive optical diagnostic technique, Laser Speckle Interferometry (LSI) based on temporal phase-shifting approach has been considered as the most potential approach for the measurement of erosion and deposition on PFCs. This paper focuses on the measurement of the deposition morphology and thickness based on the temporal phase-shifting laser speckle interferometry. Here the deposition was conducted by Pulse Laser Deposition (PLD) in a vacuum chamber, which is simulated to the deposition process on PFCs. The LSI measurements are compared with those of profilometry and the results show that the temporal phase-shifting laser speckle interferometry is capable of online measuring deposition morphology as well as thickness. The LSI approach has great possibility for the further application on the real-time monitoring impurity and fuel deposition on PFCs in fusion devices.