Guiding center orbit following calculation of $\alpha$ particles in tokamaks

Guiding center orbit following code is developed to study $\alpha$ particle transport in tokamak plasmas. The equation of motion is derived from guiding center Lagrangian\footnote{R.G.Littlejohn, J. Plasma Phys. {\bf 29}, 111 (1983).} in a flux coordinate system incorporating electromagnetic perturbations. As an preliminary study, toroidal ripple induced transport\footnote{K. Tani, M.Azumi, H.Kishimoto and S.Tamura, J. Phys. Soc. Japan {\bf 50}, 1726 (1981).} is investigated.