Visualization of characteristic plasma radiation structure in radiative collapse on Large Helical Device

Abstract

Characteristics of plasma radiation structure in radiative collapse were visualized using a two-dimensional radiation measurement and AutoEncoder (AE) on the Large Helical Device of the National Institute for Fusion Science, Japan. The state without collapse was treated as normal, and the state in which collapse is evolving was treated as abnormal. Using the anomaly detection by the AE, the collapse could be detected ~ 0.36 s before the collapse as increase in abnormality. Moreover, the abnormal radiation structure could be visualized as the profile of the reconstruction error which appeared ~ 0.46 s before the collapse from inboard side of the torus plasma.