Blob properties in L- And H-mode from gas-puff imaging in ASDEX upgrade

ASDEX Upgrade Team

Research output: Contribution to journalArticlepeer-review

60 Scopus citations

Abstract

Blob properties are studied in the scrape-off layer of the tokamak ASDEX Upgrade with a fast camera. The gas-puff imaging technique is used to investigate the detection rate as well as the blob size and velocity scaling. The experiments were performed in L- and H-mode phases of the same discharges to study the change in blob properties after the L-H transition. In both regimes the detection rate is of the order of a few thousand blobs per second, which is compatible with the picture of blob generation by edge micro instabilities. The blob size increases in H-mode, while the radial velocity decreases slightly. The changes are, however, not indicating a drastic change in the blob dynamics in both phases. The experimentally found blob properties were compared to predictions from a novel blob model including effects due to a finite ion temperature, which should be more appropriate for the conditions in the SOL of fusion plasmas.

Original languageEnglish
Article number125001
JournalPlasma Physics and Controlled Fusion
Volume56
Issue number12
DOIs
StatePublished - 1 Dec 2014

Keywords

  • Blobs
  • Gas-puff imaging
  • Plasma turbulence
  • Tokamak

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