Temporal Evolution of lmpurity Profile Measured by a Soft X-ray Detector Array on LHD

A stable method to reconstruct the soft X-ray (SX) emissivity profile is described in detail from the measurements of the SX detector array system on the Large Helical System (LHD). Sudden peaking of the SX emissivity profile after hydrogen ice-pellet injection is discussed, as an interesting application of this reconstruction method.