  For magnetic confinement fusion in tokamak plasmas, some of the limitations
to the particle and energy confinement times are caused by turbulence and
collisions between particles in toroidal geometry, which determine the
"anomalous" and the neoclassical transport, respectively. In this work, we
focus on the implementation of neoclassical physics in the gyrokinetic code
TRIMEG, which is a TRIangular MEsh-based Gyrokinetic code that can handle both
the closed and open field line geometries of a divertor tokamak. We report on
the implementation of a simplified Lorentz collision operator in TRIMEG. Since
the code uses an unstructured mesh, a procedure for calculating the flux
surface averages of particle and energy fluxes and the bootstrap current is
derived without relying on the poloidal coordinate, which is useful also for
other simulations in unstructured meshes. With the newly implemented collision
operator, we study electron transport and bootstrap current generation for
various simplified and realistic geometries. In comparison to neoclassical
theory, good agreement is obtained for the large aspect ratio case regarding
the particle and energy fluxes as well as the bootstrap current. However, some
discrepancies are observed at moderate aspect ratio and for a case with the
realistic geometry of the ASDEX Upgrade tokamak. These deviations can be
explained by different treatments and approximations in theory and simulation.
In this paper, we demonstrate the capability to calculate the electron
transport and bootstrap current generation in TRIMEG, which will allow for the
self-consistent inclusion of neoclassical effects in gyrokinetic simulations in
the future.
