See a complete list of our publications here.


Small resonant magnetic perturbations result in three-dimensional material transport in the fusion plasma edge

Marcos Navarro,1 Juri Romazanov, Andreas Kirschner, Jonathan Van Blarcum, Edward Hinson, Tyler Abrams and Oliver Schmitz

DOI 10.1088/1741-4326/ad2b2d Published February 27 2024

This publication focuses on the study of erosion in a 3D magnetic configuration as in the case of resonant magnetic perturbations (RMP’s) for low confinement discharges (L-Mode) in DIII-D. When these RMPs are applied, many eroded impurities can buildup in regions where an axisymmetric plasma would otherwise lead to zones of net erosion across the full toroidal length of the divertor. The reduction on the local and integrated erosion observed across a parametric study of the anomalous diffusion and impurity content in a plasma, can lead to the extension of divertor lifetimes in low power scenarios when 3D fields are applied. This is only a step towards modeling H-Mode erosion and transport in tokamaks and is an active field of study within our group for DIII-D, KSTAR, and ITER.


Numerical implications of including drifts in SOLPS-ITER simulations of EAST

D. Boeyaert, S. Carli, W. Dekeyser, S. Wiesen, M. Baelmans

DOI 10.1063/5.0175163  Published February 12 2024

Numerical parameters influence the inclusion from drifts in SOLPS-ITER. This paper analysis the effect on the plasma quantities of the artificial anomalous conductivity, the artificial anomalous thermo-electric coefficient, the effect of the employed grid, and the effect of the used time step and the influence of the available numerical switches in SOLPS-ITER for three different EAST simulations. The paper demonstrates that the influence of these parameters is depending on the particular case which is simulated and that a careful consideration of the numerical parameters is needed to run successfully a simulation.


Preference of right-handed whistler modes and helicon discharge directionality due to plasma density gradients

M. Granetzny, O. Schmitz, M. Zepp

DOI/10.1063/5.017391 Published December 08 2023
Abstract: “Whistlers are magnetized plasma waves in planetary magnetospheres. Bounded whistlers, known as helicons, can create high-density laboratory plasmas. We demonstrate reversal of the plasma discharge direction by changing either antenna helicity or magnetic field direction. Simulations reproduce these findings only in the presence of a radial density gradient. Inclusion of such a gradient in the wave equation gives rise to azimuthal shear currents, which for the first time consistently explains the preference of right- over left-handed whistlers and the discharge directionality in helicon plasmas.”


Analysis of the neutral fluxes in the divertor region of Wendelstein 7-X under attached and detached conditions using EMC3-EIRENE

Dieter Boeyaert4,1, Yuhe Feng2, Heinke Frerichs1, Thierry Kremeyer2, Dirk Naujoks2, Felix Reimold2, Oliver Schmitz1, Victoria Winters2, Sergey Bozhenkov2, Joris Fellinger2, Marcin Jakubowski2, Ralf König2, Maciej Krychowiak2, Valeria Perseo2, Georg Schlisio2, Uwe Wenzel2 and the W7-X Team3

DOI 10.1088/1361-6587/ad0e22 Published November 27th 2023

This paper analyzes the neutral fluxes in the divertor region of W7-X for the standard configuration with EMC3-EIRENE. The simulations show the importance of the horizontal divertor to generate neutrals, and to resolve the neutral plugging in the divertor region. Simulations of detached cases show a decrease in the number of generated neutrals and a higher fraction of the ion flux arriving on the baffles instead of on the divertor targets. In detachement, the fraction of pumped particles increases with a factor two, but stays below one percent. This demonstrates that detachment with the current target geometry, althoug it improves power exhaust, is not leading to an increased particle exhaust.


Exploration of Non-Resonant Divertor Features on the Compact Toroidal Hybrid

K. A. Garcia (1), A. Bader (1 and 3), H. Frerichs (1), G. J. Hartwell (2), J. C. Schmitt (2 and 3), N. Allen (2), O. Schmitz (1) ((1) University of Wisconsin – Madison, (2) Auburn University, (3) Type One Energy)

DOI 10.1088/1741-4326/ad0160 Published October 25th 2023

Abstract: “Non-resonant divertors (NRDs) separate the confined plasma from the surrounding plasma facing components (PFCs). The resulting striking field line intersection pattern on these PFCs is insensitive to plasma equilibrium effects. However, a complex scrape-off layer (SOL), created by chaotic magnetic topology in the plasma edge, connects the core plasma to the PFCs through varying magnetic flux tubes. The Compact Toroidal Hybrid (CTH) serves as a test-bed to study this by scanning across its inductive current. Simulations observe a significant change of the chaotic edge structure and an effective distance between the confined plasma and the instrumented wall targets. The intersection pattern is observed to be a narrow helical band, which we claim is a resilient strike line pattern. However, signatures of finger-like structures, defined as heteroclinic tangles in chaotic domains, within the plasma edge connect the island chains to this resilient pattern. The dominant connection length field lines intersecting the targets are observed via heat flux modeling with EMC3-EIRENE. At low inductive current levels, the excursion of the field lines resembles a limited plasma wall scenario. At high currents, a private flux region is created in the area where the helical strike line pattern splits into two bands. These bands are divertor legs with distinct SOL parallel particle flow channels. The results demonstrate the NRD strike line pattern resiliency within CTH, but also show the underlying chaotic edge structure determining if the configuration is diverted or limited. This work supports future design efforts for a mechanical structure for the NRD.”