Near-axis quasi-isodynamic database

Abstract

In this work, we investigate the landscape of quasi-isodynamic stellarators using the near-axis expansion of the magnetic field. Building on recent theoretical developments, we construct a database of more than 800,000 stable, approximately quasi-isodynamic vacuum magnetic configurations. These configurations span a range of field period numbers and other geometric control parameters, including the magnetic axis shape and plasma elongation. To evaluate each configuration, we use a broad set of measures, including effective ripple, sensitivity of the Shafranov shift to changes in plasma beta, the prevalence of maximum-J trapped particles, and the Rosenbluth-Hinton residual, among others. This enables an exhaustive, thorough and quantitative characterization of the database. Statistical analysis and modern machine learning techniques are then employed to find correlations, and identify key descriptors and heuristics to help understand tendencies that govern the behaviour of numerical optimization. The database provides baseline configurations for further studies, and to serve as tailored initial conditions for optimization. With this work we initiate a long term program to complete a systematic exploration of quasi-isodynamic stellarator design space.

References in corpus (26)

• Predictive learning via rule ensembles
• Accelerated Hierarchical Density Clustering
• Resilience of quasi-isodynamic stellarators against trapped-particle instabilities
• Constructing stellarators with quasisymmetry to high order
• Collisionless microinstabilities in stellarators I - analytical theory of trapped-particle modes
• Necessary and Sufficient Conditions for Quasisymmetry
• Constructing precisely quasi-isodynamic magnetic fields
• Mapping the space of quasisymmetric stellarators using optimized near-axis expansion
• Direct construction of optimized stellarator shapes. III. Omnigenity near the magnetic axis
• A quasi-isodynamic configuration with good confinement of fast ions at low plasma $\beta$
• A Guide to Feature Importance Methods for Scientific Inference
• Magnetic well and Mercier stability of stellarators near the magnetic axis
• Less constrained omnigeneous stellarators
• Residual zonal flows in tokamaks and stellarators at arbitrary wavelengths
• A single-field-period quasi-isodynamic stellarator
• Direct stellarator coil design using global optimization: application to a comprehensive exploration of quasi-axisymmetric devices
• Phases and phase-transitions in quasisymmetric configuration space
• Constructing the space of quasisymmetric stellarators
• MHD stability and the effects of shaping: a near-axis view for tokamaks and quasisymmetric stellarators
• The Use of Near-Axis Magnetic Fields for Stellarator Turbulence Simulations
• Magnetic Fields with General Omnigenity
• Figures of merit for stellarators near the magnetic axis
• Higher order theory of quasi-isodynamicity near the magnetic axis of stellarators
• Non-planar elasticae as optimal curves for the magnetic axis of stellarators
• Collisionless zonal-flow dynamics in quasisymmetric stellarators
• The zonal-flow residual does not tend to zero in the limit of small mirror ratio