Compatibility of pellet fuelling with ELM suppression by RMPs in the ASDEX Upgrade tokamak

Abstract

It is demonstrated that tokamak plasma can be fuelled by pellets while simultaneously maintaining ELM suppression by external resonant magnetic perturbations (RMPs). Pellets are injected verically from high field site and deposited at outer part of plasma cross section. Each pellet triggers a benign MHD event followed by a short lived ELM-free phase. The ELM suppression phase with pellet fuelling lasts 11 pellet cycles and is terminated by intentionally increasing the pellet rate to cause a transition to the ELMy phase.

Multiple-isotope pellet cycles captured by turbulent transport modelling in the JET tokamak

“…Pellet fuelling and simultaneous ELMs mitigation have been demonstrated experimentally [9][10][11], ensuring the viability of this fuelling method. Regarding turbulent transport, the pellets have a significant impact.…”

Integrated ELM and divertor power flux control using RMPs with low input torque in EAST in support of the ITER research plan

“…Since pellet injection is predicted to be necessary to fuel ITER high Q DT plasmas [12,13], it is of particular importance for ITER to determine if pellet fuelling in ELM-suppressed Hmodes leads to the triggering of ELMs due to the injection of the pellets themselves, rather than because of the associated density increase by a continuous train of injected pellets, which could lead to the re-appearance of ELMs due to changing pedestal plasma conditions. To study this, a few isolated pellets have been injected in EAST ELM-suppressed H-mode plasmas with n = 4 RMPs.…”

“…Secondly, since fuelling of the plasma by gas fuelling is very ineffective in high Q DT ITER scenarios, the core plasma density will be controlled by pellet fuelling in ITER [12,13]. Therefore, the demonstration that an ELMsuppressed H-mode can be sustained together with pellet fuelling, while avoiding ELMs, is also required, particular for pellets with peripheral pellet deposition as in ITER.…”

“…Therefore, the demonstration that an ELMsuppressed H-mode can be sustained together with pellet fuelling, while avoiding ELMs, is also required, particular for pellets with peripheral pellet deposition as in ITER. Although pellet fuelling during RMP ELM-suppression has been attempted in several tokamaks, only in ASDEX-Upgrade pellet fuelling with ITER-like particle deposition profiles was shown to preserve ELM suppression with n = 2 RMP [12]. Experiments in DIII-D showed that injecting pellets trigger frequent ELMs for full ELM suppressed H-modes while reduce the number of ELM events for partially ELM suppressed H-modes [14].…”

Pellet Core Fueling in Tokamaks, Stellarators and Reversed Field Pinches

“…to H-mode ( [2], see [36] for recent results), allowing to operate at a density larger than the Greenwald limit and to simultaneously control the ELMs by RMP ( [2] and references therein [37][38][39][40], see an example of one of the most spectacular results in this field in Fig. 10) or by shallow pellet injection [41].…”