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Researchers from the MIT Plasma Science and Fusion Center, PSFC, and the University of Texas at Austin have had promising results in terms of plasma stability in experiments with "negative triangularity" on the DIII-D tokamak; that is, with reversing the conventional shape of the plasma in the tokamak chamber.

In results published recently in Physical Review Letters and Physics of Plasmas, researchers Alessandro Marinoni (MIT) and Max Austin (UT Austin) discovered evidence that reversing the conventional shape of the plasma in the tokamak chamber can create a more stable environment for fusion to occur, even under high pressure.

Marinoni and colleagues are planning future experiments to further demonstrate the potential of this approach in an even more fusion-power relevant magnetic topology, based on a "diverted" tokamak concept.

Read more on the subject on the PFSC website.

At ITER's Neutral Beam Test Facility, one testbed has been launched and another is in the procurement/assembly phase.

SPIDER—the ITER-scale negative ion source—turned on last year. Experiments on MITICA—a full-size prototype of ITER's 1 MV heating neutral beam injectors—are scheduled beginning 2022. Procurement is underway in Europe on the beam source and at Consorzio RFX in Padua, Italy, work is underway to install auxiliary components and systems.

In May, the first part of the MITICA beam source vacuum vessel was installed (photo). This stainless steel component was procured by the European Domestic Agency, Fusion for Energy, as a voluntary contribution to the ITER neutral beam development program.

See more about the manufacturing of the vessel here.

See more about the Neutral Beam Test Facility at Consorzio RFX here.

Physics of Plasmas (American Institute of Physics) has published a paper on research carried out under a collaboration between the Eindhoven Technical University (TU/e, Netherlands) and the ITER Organization.

"Kinetic modeling of ELM-induced tungsten transport in a tokamak plasma" (D. C. van Vugt, G. T. A. Huijsmans, M. Hoelzl, A. Loarte, et al) describes the role of edge-localized modes (ELMs) in exhausting tungsten impurities from the core plasma of tokamaks to ensure that their concentration remains low.

The collaboration modelled tungsten impurity behaviour and power fluxes to plasma-facing components during controlled ELMs in ITER with advanced modelling by the JOREK code, which required specific upgrades to the code to include the necessary plasma-wall interaction and impurity transport processes.

The authors write: "This publication shows that the role of ELMs in cleaning up the plasma from tungsten eroded at the divertor in ITER can be opposite to that in present experiments, particularly when we approach the conditions required for high fusion energy production gain. This implies that the use of the ELM control coils, included in the ITER baseline design to modify ELM behaviour and eventually suppress ELMs, will be required not only for the control of power fluxes to the divertor but also to exhaust the eroded tungsten from the confined plasma to keep it clean."

Read the complete article on the TU/e website here.