Time evolution of helicity (﹩\mathstrut{\cal H} ﹩), magnetic energy (M), kinetic energy (K), and time derivative of helicity (﹩d\mathstrut{\cal H} / dt^{*}﹩) for the RR6 ﹩\mathstrut{\cal T} =5.5﹩ tunnel simulation (solid lines) and for the RR6 ﹩\mathstrut{\cal T} =5﹩ slingshot simulation (dashed lines). The energy curves are normalized by the initial magnetic energy (﹩M_{0}﹩) for the respective simulation, while the helicity curves are normalized by the initial helicity (﹩\mathstrut{\cal H} _{0}﹩) for the respective simulation.