Relativistic guiding-center equations including slow equilibrium changes in magnetic coordinates

Matsuyama, Akinobu; Yagi, Masatoshi

Guiding-center equations for relativistic particles are presented in axisymmetric toroidal geometry using Boozer coordinates. Effects of slow equilibrium change are included for describing the electron acceleration due to the induction field, which is a fundamental process of the runaway electron generation during disruptions. For a consistent treatment of the runaway orbit in finite pressure plasma, the equations are given in both canonical and noncanonical forms with retaining the radial covariant component of the equilibrium magnetic field. For this, the Lagrangian formulation by White and Zakharov is applied to axisymmetric equilibria with slowly-varying magnetic flux functions.