Spatial and temporal structure of edge-localized modes

The periodic eruptions in magnetically confined edge-localized modes (ELM) were investigated to study the spatial and temporal structures. The cool deuterium atoms at the plasma periphery and those released from the target by recycling were excited through collisions with the expelled plasma. The consequent burst of Balmer α-series light together with the detection of heat and particles arriving at the divertor target plates, are characteristic signatures of the ELM events. The results show that the ELM process is not only up-down symmetric but also that it is extended in the poloidal direction.