One of the most promising proposals for achieving a nuclear fusion reactor is the stellarator. These toroidal devices take advantage of the fact that the fusion fuel, the plasma, consists of charged particles to achieve confinement through the application of external magnetic fields. Over the years, extensive research has focused on reducing confinement losses in these plasmas within the neoclassical regime (losses due to drifts and particle collisions). Once this objective was achieved through the optimization of the magnetic configuration, losses due to fluctuations in electromagnetic fields, the turbulent losses, have become dominant.
The study of turbulent transport is, thereby, of critical importance in order to physically understand the plasma behavior and to ensure its proper confinement, marking the next major step toward the future nuclear fusion reactor.
Gyrokinetic theory provides a highly suitable framework for this objective. In this research, two magnetic configurations were analyzed: the high mirror (KJM) configuration of the W7-X stellarator, currently in operation at the Max Planck Institute for Plasma Physics (Germany), and CIEMAT-QI, a configuration designed at the Laboratorio Nacional de Fusión (CIEMAT, Spain). These analyses were conducted using the Stella code in both linear and nonlinear regimes. By studying the impact on the plasma stability of the normalized plasma pressure, , and the density gradient, , seemingly contradictory conclusions were drawn, depending on the regime considered, regarding which configuration is more stable and how stability depends on .
Such results underscore the necessity and utmost importance of further advancing in the understanding of plasma behavior and turbulent transport, topics of critical relevance in nuclear fusion research nowadays.
