Investigation into effect of pitch angle and initial energy. a) Variation of the particle trajectories at position A (specifically their final positions) with initial pitch angle at an energy of 2 eV. b) The same result for initial energies of 200 eV. c) and d) Trajectories and end-point locations for particles beginning at position C (see Table 1). In all cases the final positions are colour-coded, depending on initial pitch angle (for key, see colour bar).