Nonlinear second order electromagnetic gyrokinetic theory for a tokamak plasma

The steep plasma pressure gradient that forms at the edge of the high confinement, H-mode regime of tokamak operation provides free energy to drive electromagnetic micro-instabilities that are widely believed to influence the transport processes in this so-called pedestal region. This high pressure gradient also provides a high current density (bootstrap current), known to influence ballooning mode stability and to be important for driving kink modes in the ideal magneto-hydrodynamic plasma model (so-called peeling-ballooning modes). Furthermore, efficient, steady state future tokamak power plants must operate with a large bootstrap current in the core and especially concerning spherical tokamaks, confinement will be influenced by electromagnetic turbulence. To accommodate these important situations, conventional electromagnetic gyrokinetic theory is extended to incorporate neoclassical effects in the equilibrium drives, allowing B-& thetasym; similar to B-0 (B-0 is the confining magnetic field, and B-& thetasym; is its poloidal component). This provides a global gyrokinetic model that self-consistently captures the consequences of large bootstrap current fractions on the equilibrium distribution functions.

Automated summary

The steep plasma pressure gradient at the edge of the high confinement H-mode regime of tokamak operation drives electromagnetic micro-instabilities in the pedestal region. This pressure gradient also influences the stability of ballooning and kink modes and affects confinement in future tokamak power plants. Conventional gyrokinetic theory is extended to incorporate neoclassical effects and provide a model that captures the consequences of large bootstrap current fractions.