Toroidal Flux and Separatrix Effects in Tokamak Plasma Physics
A physics paper proposes using toroidal magnetic flux rather than poloidal flux as the primary radial coordinate in tokamak plasma analysis. The toroidal flux approach simplifies equilibrium conditions at the separatrix boundary and provides clearer interpretation of Faraday's Law in tokamak systems. This refinement could improve the identification and control of measurable parameters critical for preventing disruptions in future tokamak power plants.
Researchers present an analytical framework demonstrating how toroidal magnetic flux can be more effectively applied to tokamak equilibrium analysis, particularly near the separatrix—the boundary between confined and unconfined plasma regions. The paper argues that toroidal flux has been underutilized in tokamak literature despite its importance for correctly interpreting Faraday's Law and the slippage between poloidal and toroidal magnetic flux through loop voltage. The authors show that using the conventional metric of q₉₅ (edge rotational transform based on 95% of poloidal flux) introduces unnecessary sensitivity to the current profile in the plasma core. By shifting to toroidal flux as the radial coordinate, the analysis becomes more precise and less dependent on central plasma properties. The authors emphasize that this approach would clarify which parameters can be both measured and controlled in tokamak power plants, with direct implications for disruption avoidance—a critical challenge for fusion energy development.
What different sources said
- arXiv physicsCenter
The toroidal flux and separatrix effects in tokamaks
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