Neoclassical quasilinear theory and universal collision frequency landscape in wave-particle interaction in tokamaks

Abstract

The neoclassical quasilinear theory is extended to the collisional boundary layer and 1/ν regimes. The theory is for electromagnetic waves with frequencies lower than the bounce frequency of the trapped particles and wavelengths either comparable to or shorter than the width of bananas, but much longer than the gyro-radius. Here, ν is the collision frequency. This is accomplished by solving the banana kinetic equation. The results can be used to model energetic alpha particle and thermal particle losses in the presence of the electromagnetic waves in fusion relevant tokamak plasmas. They can also be employed to quantify transport losses in chaotic magnetic fields; these regimes are not known to exist in the theory of the chaotic magnetic field induced transport. The results of the theory together with those of the theory for neoclassical toroidal plasma viscosity reveal the existence of a universal collision frequency scaling law that governs the physics of the wave-particle interaction. The detailed collision frequency landscape in the theory for neoclassical toroidal viscosity is the universal feature of the wave-particle interaction in non-axisymmetric tori.