Diagnosis of the surface morphology of laser-ablated materials using the weighted-DCT approach in laser speckle interferometry for application to plasma facing materials

摘要

To implement on-line,real-time monitoring for the surface morphology of Plasma-Facing Materials (PFMs) in tokamak,we developed a Laser Speckle Interferometry measurement approach.A laser ablation method was used to simulate the erosion process during Plasma-Wall Interactions in a tokamak.In the present investigation,we evaluated the results of laser ablation morphology changes on the surface of Mo material reconstructed by four different approaches (Flood-fill,Quality-guided,Discrete Cosine Transform (DCT) and Weighted-DCT).The morphology results measured by the weighted-DCT approach are very close to the measurement results from confocal microscopy with an average error rate within 7％.It is verified that the weighted-DCT algorithm has high accuracy and can efficiently reduce the influence of noise pollution coming from laser ablation,which is used as a proxy for erosion from plasma wall interaction.Additionally,the CPU computer time has been shortened.This is of great significance for the real-time monitoring of PFMs' morphology in the Experimental Advanced Superconducting Tokamak (EAST) in the future.