FP3D: A code for calculating 3D magnetic field and particle motion

Abstract: An efficient numerical code FP3D has been developed to calculate particle orbits and evaluate particle confinement in 3D magnetic fields including stellarators and tokamaks with 3D fields. The magnetic field is either calculated from coils directly or obtained from equilibrium codes. FP3D has been verified with the 3D equilibrium code VMEC (S. P. Hirshman, Phys. Fluids 26, 3553 (1983)) for magnetic field calculation and with the drift-kinetic code SFINCS (M. Landreman, Physics of Plasmas 21 (4) (2014)) for neoclassical transport. The code has been applied successfully to the NCSX stellarator (B. Nelson, Fusion Engineering and design 66 (2003)) for the calculation of neoclassical transport coefficient with the 3D magnetic field obtained directly from coils. FP3D is also used to calculate ripple losses in the tokamak EAST (W. Yuanxi, Plasma Science Technology 8 (3) (2006)).