The I-phase is an H-mode confinement regime of tokamaks characterized by limit cycle oscillations, the so-called LCOs or bursts. These bursts are the manifestation of a periodic flattening of the plasma edge pressure profile. The profile flattening is caused by increased radial transport, driven by a high-frequency plasma edge mode that periodically appears. This short-living mode is intrinsically connected to each burst. It vanishes once the profiles are fully flattened, and it reestablishes during profile recovery once critical gradients are reached and a new cycle begins. In this paper, we describe for the first time the unambiguous presence of the I-phase at the tokamak `a configuration variable (TCV). As the I-phase confinement regime is found in the parameter regime between the L-mode and the fully developed H-mode, it is often confused with dithers between H-mode and L-mode. Therefore, we are highlighting the differences between these two phenomena. Furthermore, we show the two-dimensional dynamics of the I-phase mode and bursts and the associated filamentary transport, enabled by the outstanding capabilities of the 2D TCV Gas Puff Imaging diagnostics.

Griener, M., Wuthrich, C., Wang, Y., Brida, D., Faitsch, M., Offeddu, N., et al. (2025). Characterization of the I-phase regime at TCV. NUCLEAR FUSION, 65(1) [10.1088/1741-4326/ad96cb].

Characterization of the I-phase regime at TCV

Cavedon M.;Nocente M.;Cancelli S.;Caruggi F.;Celora A.;Croci G.;Gorini G.;Kushoro M. H.;Marcer G.;
2025

Abstract

The I-phase is an H-mode confinement regime of tokamaks characterized by limit cycle oscillations, the so-called LCOs or bursts. These bursts are the manifestation of a periodic flattening of the plasma edge pressure profile. The profile flattening is caused by increased radial transport, driven by a high-frequency plasma edge mode that periodically appears. This short-living mode is intrinsically connected to each burst. It vanishes once the profiles are fully flattened, and it reestablishes during profile recovery once critical gradients are reached and a new cycle begins. In this paper, we describe for the first time the unambiguous presence of the I-phase at the tokamak `a configuration variable (TCV). As the I-phase confinement regime is found in the parameter regime between the L-mode and the fully developed H-mode, it is often confused with dithers between H-mode and L-mode. Therefore, we are highlighting the differences between these two phenomena. Furthermore, we show the two-dimensional dynamics of the I-phase mode and bursts and the associated filamentary transport, enabled by the outstanding capabilities of the 2D TCV Gas Puff Imaging diagnostics.
Articolo in rivista - Articolo scientifico
fusion; gas puff imaging; I-phase; LCO; limit cycle oscillations; plasma modes; TCV;
English
6-dic-2024
2025
65
1
016041
none
Griener, M., Wuthrich, C., Wang, Y., Brida, D., Faitsch, M., Offeddu, N., et al. (2025). Characterization of the I-phase regime at TCV. NUCLEAR FUSION, 65(1) [10.1088/1741-4326/ad96cb].
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/10281/548160
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