Göttingen 2025 – wissenschaftliches Programm

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P: Fachverband Plasmaphysik

P 1: Magnetic Confinment Fusion/HEPP I

P 1.2: Vortrag

Montag, 31. März 2025, 14:15–14:40, ZHG102

Avenues to steady-state turbulence suppression at Wendelstein 7-X — •Markus Wappl, Sergey Bozhenkov, Jürgen Baldzuhn, Sebastian Bannmann, Håkan Smith, Edgardo Villalobos, and Pavlos Xanthopoulos — Max Planck Institute for Plasma Physics, Greifswald, Germany

Plasma scenarios of transient turbulence suppression, featuring improved energy confinement and high ion temperature, are well known at W7-X. By means of injecting neutral beams or frozen hydrogen pellets, the electron density gradient can be momentarily increased which suppresses ITG-driven turbulent heat transport in the ion channel to nearly zero. However, collapse of the density gradient and return to conventional turbulent heat transport usually occurs after only a few confinement times.

Recent plasma scenario development suggests paths to steady-state turbulence suppression. A newly commissioned steady-state pellet injector along with careful adjustment of microwave heating power allows to maintain the increased density gradient. In addition, a self-ordering process leading to a similar density gradient and turbulence suppresion is observed in microwave heated plasmas at low power, following boronization of the first wall.

This talk provides an overview of a large turbulent transport database obtained by power balance analysis. Several transient and steady-state turbulence-suppressed plasma scenarios are discussed in detail and compared to gyrokinetic transport simulations. An outlook to future steady-state turbulence-suppressed scenarios is given.

Keywords: Stellarator; Wendelstein 7-X; Turbulence; ITG; Power Balance