Inter-ELM pedestal localized fluctuations in tokamaks: Summary of multi-machine observations. (May 2019) - Laggner, F.M.
Highlights: Experimental studies on pedestal localized fluctuations across several tokamaks are summarized. Three profile recovery phases are interlinked with different kinds of pedestal fluctuations. At least three categories of inter-ELM pedestal fluctuations are identified across machines. Abstract: A variety of experimental studies on pedestal localized fluctuations appearing in between crashes of edge localized modes (ELMs) across several tokamaks have been reviewed and summarized. The onset of the inter-ELM fluctuations is correlated with the evolution of the pedestal gradients. Three profile recovery phases are extracted, which are interlinked with the onsets of different kinds of pedestal fluctuations. Across machines it is found that the pedestal fluctuations can be assorted into at least three categories. These are determined by the fluctuation onset in the ELM cycle, observed frequency range and radial location in the pedestal. Further, the categories might be also related to different instabilities. Similar observations at various machines may point to a underlying generation mechanism that acts similarly for presently accessible pedestal parameter ranges.