Unconventional Ballooning Structures for Toroidal Drift Waves

Abstract

With strong gradients in the pedestal of high confinement mode (H-mode) fusion plasmas, gyrokinetic simulations are carried out for the trapped electron and ion temperature gradient modes. A broad class of unconventional mode structures is found to localize at arbitrary poloidal positions or with multiple peaks. It is found that these unconventional ballooning structures are associated with different eigen states for the most unstable mode. At weak gradient (low confinement mode or L-mode), the most unstable mode is usually in the ground eigen state, which corresponds to a conventional ballooning mode structure peaking in the outboard mid-plane of tokamaks. However, at strong gradient (H-mode), the most unstable mode is usually not the ground eigen state and the ballooning mode structure becomes unconventional. This result implies that the pedestal of H-mode could have better confinement than L-mode.

5 pages, 6 figures

References in corpus (1)

• Structure of Micro-instabilities in Tokamak Plasmas: Stiff Transport or Plasma Eruptions?

Cited by in corpus (8)

• A New Paradigm for Turbulent Transport Across a Steep Gradient in Toroidal Plasmas
• Comparisons and Applications of Four Independent Numerical Approaches for Linear Gyrokinetic Drift Modes
• Global Theory to Understand Toroidal Drift Waves in Steep Gradient
• Kinetic Ballooning Mode Under Steep Gradient: High Order Eigenstates and Mode Structure Parity Transition
• The unified ballooning theory with weak up-down asymmetric mode structure and the numerical studies
• The collisional drift wave instability in steep density gradient regimes
• Local Gyrokinetic Study of Electrostatic Microinstabilities in Dipole Plasmas
• The physics of a small-scale tearing mode in collisionless slab plasmas