  Ideally, binary-collision algorithms conserve kinetic momentum and energy. In
practice, the finite size of collision cells and the finite difference in the
particle locations affect the conservation properties. In the present work, we
investigate numerically how the accuracy of these algorithms is affected when
the size of collision cells is large compared with gradient scale length of the
background plasma, a parameter essential in full-f fusion plasma simulations.
Additionally, we discuss implications for the conserved quantities in
drift-kinetic formulations when fluctuating magnetic and electric fields are
present: we suggest how the accuracy of the algorithms could potentially be
improved with minor modifications.
