Optimizing particle transport for enhanced confinement in quasi-isodynamic stellarators

Area of Science:

• Plasma Physics
• Fusion Energy
• Stellarator Design

Background:

• Turbulent heat losses in stellarators are being mitigated, but particle confinement remains a key challenge.
• Previous optimization efforts have not fully addressed particle transport limitations in quasi-isodynamic stellarators.

Purpose of the Study:

• Identify the primary cause of poor particle confinement in quasi-isodynamic stellarators.
• Design a new stellarator configuration to overcome particle transport limitations and improve confinement.

Main Methods:

• Utilized gyrokinetic simulations within the gene-Tango framework.
• Identified suppressed inward thermodiffusion due to unfavorable magnetic geometry as the main issue.
• Designed a new configuration with a reduced mirror ratio to enhance inward particle flux.

Main Results:

• The new configuration enhances the contribution of passing electrons to the inward particle flux.
• Achieved strongly peaked density profiles and suppressed turbulence.
• Demonstrated a nearly twofold increase in energy confinement compared to the Stellaris configuration.

Conclusions:

• Optimizing particle transport is critical for next-generation stellarator designs.
• Reducing the mirror ratio is an effective strategy for improving particle confinement in quasi-isodynamic stellarators.
• The designed configuration shows significant potential for advancing fusion energy research.