MHD Parameters
Sweet-Parker Predictions
Layer width δ: —
Rec. rate v_in: —
Outflow v_out: —
Rate / v_A: —
Resistive MHD current sheet, X-point topology, reconnection rate S⁻¹/²
When opposing magnetic field lines are brought together in a resistive plasma, they break and reconnect — converting magnetic energy to kinetic and thermal energy. The Sweet-Parker model predicts a current sheet of length L and width δ = L·S⁻¹/² where S = v_A·L/η is the Lundquist number.
The reconnection rate (inflow velocity): v_in = v_A·S⁻¹/². In solar flares where S ~ 10⁸–10¹², this gives timescales far too slow — real flares reconnect ~10⁴× faster, motivating Petschek's model (localised diffusion region, slow shocks) and later plasmoid instability.
The X-point separatrix topology is shown with field lines coloured by their reconnection status. Newly reconnected field lines form characteristic "hyperbolic" outflow jets.