Stellarators Resist Turbulent Transport on the Electron Larmor Scale

Area of Science:

• Plasma physics
• Fusion energy research
• Computational astrophysics

Background:

• Electron temperature gradient (ETG) driven turbulence is a key mechanism for thermal energy transport in magnetic fusion devices.
• Understanding ETG turbulence in stellarators is crucial for advancing fusion energy.
• Previous studies have primarily focused on tokamaks, leaving stellarator behavior less explored.

Purpose of the Study:

• To investigate the role and impact of ETG-driven turbulence in the Wendelstein 7-X stellarator.
• To compare the significance of ETG turbulence transport with other transport mechanisms in stellarators.
• To determine the influence of stellarator-specific geometry on ETG turbulence.

Main Methods:

• Performing the first numerical simulations of ETG turbulence specifically for the Wendelstein 7-X stellarator.
• Utilizing power balance analysis from the initial experimental operation phase of Wendelstein 7-X.
• Analyzing the impact of geometric constraints, such as multiple field periods, on turbulence.

Main Results:

• Simulations indicate that ETG turbulence in Wendelstein 7-X results in negligible thermal transport.
• The calculated ETG-driven transport is significantly smaller than other known transport channels in the device.
• The unique geometric configuration of stellarators, specifically the multiple field periods, is identified as the primary reason for this suppression.

Conclusions:

• ETG-driven turbulence plays a minor role in thermal energy transport in the Wendelstein 7-X stellarator.
• The inherent geometry of stellarators effectively suppresses ETG turbulence, unlike in other magnetic confinement devices.
• This finding has important implications for stellarator design and performance optimization in fusion energy research.