Sketch of the assumed magnetic field geometry. The different parameters change the shape and curvature of the field lines where the thread is allocated (based on Dahlburg et al. 1998). The configurations are labelled A, B, and C. The three configurations are represented with different total lengths for visualisation purposes only. The parameters of each curve following the definition in Dahlburg et al. (1998) are A (bottom curve): s₁ = 0.05L, s₂ = 0.5L, d = 0.1L; B (middle curve): s₁ = 0.1L, s₂ = 0.5L, d = 0.05L; and C (top curve): s₁ = 0.2L, s₂ = 0.5L, d = 0.01L. L is half the length of the magnetic field line.