Dependence on plasma shape and plasma fueling for small edge-localized mode regimes in TCV and ASDEX Upgrade

Abstract

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Real-time feedback control of the impurity emission front in tokamak divertor plasmas

“…A significant high frequency disturbance on L pol can result from ELM activity in the H-mode scenario. The ELM size progressively decreases for the scenario used here, ending in the attractive ‘small-ELM’ regime, where the ELM strength is relatively small 41 . During all experiments a core density feedback controller was used together with a programmed density ramp to bring the divertor plasma to a sufficiently cooled state.…”

“…The authors would like to thank the entire TCV team (see author list of 22 ) for making these experiments possible and are especially grateful to Dr. Labit for his expertize on and modifications to the small-ELM plasma scenario. Furthermore, the entire EUROfusion MST1 team (see author list of 41 ) is greatly acknowledged, in particular input from Dr. Bernert. In addition, support from J.T.W.…”

The JOREK non-linear extended MHD code and applications to large-scale instabilities and their control in magnetically confined fusion plasmas

“…The regime of small ELMs is another topic of current research with the JOREK code. Experiments with small ELMs host a quasi-continuous power exhaust and, with appropriate plasma shaping, can avoid type-I ELMs completely [217]. Using the simulation set-up for the type-I ELM cycles described above, but with a lower heating power, an operational regime with small ELM-like behaviour has been also obtained [218], albeit not yet at ITER relevant conditions which remain a topic for future research.…”

Comparing spontaneous and pellet-triggered ELMs via non-linear extended MHD simulations

“…Type-I edge localized modes (ELMs) are expected to induce large losses and consequently excessive transient divertor heat loads in large machines like ITER, which can affect the lifetime of the components [1]. Low-frequency large type-I ELMs must therefore be avoided in ITER either by small-ELM scenarios [2], ELM-free scenarios like QH-mode [3], active control via external resonant magnetic perturbations (RMPs) [4] or pellet ELM triggering [5,6]. Since RMPs may not be applicable in all phases of plasma operation (e.g.…”