Markus Wappl

Significance of Microtearing Turbulence in Turbulence-Reduced High-Density-Gradient Plasmas in Wendelstein 7-X

H. Cu-Castillo, Alejandro Bañón Navarro, G. Merlo, F. Reimold et autres

Gyrokinetic simulations of a turbulence-reduced Wendelstein 7-X discharge-characterized by a steep density gradient, moderate temperature gradients, and low plasma beta-show that microtearing mode (MTM) turbulence dominates transport. The simulated heat and particle fluxes agree with experimental measurements, leaving MTMs as the only …

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Routes to high-performance operation in Wendelstein 7-X: turbulence suppression with shaping of the density profile

S. Bozhenkov, Oliver P. Ford, Markus Wappl, S. Bannmann et autres

Abstract Steep density gradients generally lead to improved plasma performance in the neoclassically optimized stellarator W7-X. This is evident in the global energy confinement time as well as in the ion temperature and can be explained by a strong reduction of the …

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Tokamak level performance in the optimized stellarator Wendelstein 7-X with stable peaked density profiles

S. Bannmann, Oliver P. Ford, S. Bozhenkov, T. Stange et autres

Progress towards achieving net gain from nuclear fusion is typically characterized by the triple product nTτ. Although stellarators have several benefits for a reactor, such as the inherent steady-state capability and the lack of disruptions, the maximum achieved triple product has historically …

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Stellarator-reactor confinement studies based on results from Wendelstein 7-X

Markus Wappl

Magnetic confinement devices like stellarators and tokamaks can confine a hot fusion plasma and could serve as nuclear fusion reactors. Prerequisites for a surplus energy production are sufficient plasma density, temperature and energy confinement time. Wendelstein 7-X is an optimized stellarator located …

Experimental power balance study on turbulent heat transport at Wendelstein 7-X

Markus Wappl, S. Bozhenkov, Tamara L Andreeva, S. Bannmann et autres

Abstract Power balance analysis is used to compile an experimental database of turbulent heat transport in various plasma scenarios at the stellarator Wendelstein 7-X. As figures of merit for turbulence suppression, turbulent transport coefficients χ e , χ i and χ eff …

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The suppression of anomalous impurity transport above a critical normalized density gradient scale length in Wendelstein 7-X

Thilo Romba, F. Reimold, S. Bannmann, Tom Bleher et autres

Abstract In purely neutral-beam-heated scenarios in Wendelstein 7-X (W7-X), central peaking of impurity density profiles is observed. These are discharges typically considered as the main path towards high energy confinement in W7-X. Understanding the undesirable impurity peaking in this kind of discharge …

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Assessment of validity of local neoclassical transport theory for studies of electric-field root-transitions in the W7-X stellarator

M.D. Kuczyński, Ralf Kleiber, Håkan M. Smith, P. Helander et autres

Abstract The neoclassical ambipolarity condition governing the radial electric field in stellarators can have several solutions, and sudden transitions (in radius) between these can then take place. The radial position and structure of such a transition cannot be determined from local transport …

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Web apps for profile fitting and power balance analysis at Wendelstein 7-X

Markus Wappl, S. Bozhenkov, M. Beurskens, S. Bannmann et autres

Two novel web apps for W7-X are introduced: Profile Cooker and Power House. They are designed to streamline the workflow of profile fitting and power balance analysis while offering a graphical user interface that works in any common browser. This allows us …

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Quantifying Space Weathering of Phobos by Martian Planetary Oxygen Ions

Paul Stefan Szabo, Herbert Biber, Noah Jäggi, Markus Wappl et autres

Recent modelling efforts based on MAVEN measurements suggest that the Martian Moon Phobos is affected by a unique space weathering scenario [1]. On rocky bodies in the solar system, mostly solar wind ions cause ion-induced space weathering of their surfaces. Space weathering …

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Experimental Investigation of the Space Weathering of Phobos by Planetary Oxygen Ions

Paul Stefan Szabo, Herbert Biber, Noah Jäggi, Markus Wappl et autres

Laboratory experiments on the space weathering of Phobos by planetary oxygen ions

Paul Stefan Szabo, André Galli, Peter Wurz, Helmut Lammer et autres

Experimental Insights Into Space Weathering of Phobos: Laboratory Investigation of Sputtering by Atomic and Molecular Planetary Ions

Paul Stefan Szabo, Herbert Biber, Noah Jäggi, Markus Wappl et autres

Abstract Investigating the space weathering of the Martian moon Phobos represents an important step toward understanding the development from its origin to its present‐day appearance. Depending on Phobos’ orbital position, its surface is continuously sputtered by the solar wind and planetary ions …

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