Limit cycle oscillations measurements with Langmuir and ball-pen probes on COMPASS. (3rd October 2018)

• Record Type: Journal Article
• Authors: Grover, O.; Seidl, J.; Refy, D.; Adamek, J.; Vondracek, P.; Tomes, M.; Junek, P.; Hacek, P.; Krbec, J.; Weinzettl, V.; Hron, M.; Zoletnik, S.
• Other Names: collab.
• Is Part Of: Nuclear fusion. Volume 58:Number 11(2018:Nov.)
• Publication Date: 2018-10-03
• Subjects: magnetic confinement -- tokamak -- L-H transition -- limit-cycle oscillations -- edge-localized modes; Nuclear fusion -- Periodicals; 621.48405
• DOI: 10.1088/1741-4326/aabb19
• Languages: English
• ISSNs: 0029-5515

Abstract

Abstract: This contribution presents the experimentally observed edge plasma evolution during limit cycle oscillations (LCO) measured with a new Langmuir and ball-pen multi-pin probe head at the COMPASS tokamak. The observed LCO regime modulates the intensity of density fluctuations, radial electric field E r and intensity of emission with a frequency 3–5 kHz. The density fluctuations grow after E r decreases in strength which appears to be strongly correlated with the evolution of the pressure gradient . The magnetic signature of the LCO shows a left–right asymmetry with propagation from the low to high field side. High-frequency (above 100 kHz) precursor-like oscillations are observed as well.