This is a genuine 2D reconnection model, not a flattened 3D scene: an antiparallel Harris current sheet is described by a stream function whose contours are the magnetic field lines you see, traced by numerically integrating along the local field direction:
ψ(x,y) = δ·ln(cosh(y/δ)) + A(t)·cos(kx)·sech(y/δ)
Bx = ∂ψ/∂y , By = −∂ψ/∂x
With no perturbation this is the textbook reversing field Bx = tanh(y/δ) — anti-parallel above and below the sheet. Continued shear thins the sheet, δ(t), which by Ohm's law (E = ηJ, with sheet current density J ≈ B₀/δ) drives up the reconnection electric field:
dδ/dt = −(thinning rate)·δ (driven compression)
E_rec = η·B₀/δ (Ohm's-law reconnecting field)
Once δ hits its resistive floor, reconnection releases: δ relaxes back exponentially with your chosen time constant τ, E_rec falls as 1/δ rises, and a fast-rise/slow-decay outflow ramp (the finite Alfvén-transit time for the exhaust jet to reach the loop footpoints) turns that into the light curve — every point on the curve is E_rec(δ(t)) computed from the live current-sheet state, not a fitted formula. The result is classified live on the same real GOES 1–8 Å A-B-C-M-X scale NOAA uses:
A 10⁻⁸–10⁻⁷ W/m² B 10⁻⁷–10⁻⁶ C 10⁻⁶–10⁻⁵
M 10⁻⁵–10⁻⁴ X 10⁻⁴ and above (record ≈X28, 2003)
- Shear-driven thinning rate — how fast continued driving compresses the sheet toward its resistive threshold.
- Outflow relaxation time τ — how long the sheet takes to reform and drain after release, stretching or compressing the decay tail.
- Force reconnection now — releases whatever compression is currently stored, so a partially-thinned sheet gives a visibly weaker flare than a fully-thinned one.
- Eject plasmoids — when the perturbation amplitude A(t) grows, the field lines pinch into magnetic islands (O-points either side of the X-point) that are advected out along the sheet — the 2D analogue of blob/plasmoid ejections that seed a coronal mass ejection.
Real-world relevance: current-sheet thinning followed by fast, plasmoid-mediated reconnection is the mechanism space-weather researchers now believe underlies most observed solar flares, and the same Harris-sheet/X-point picture describes reconnection in Earth's magnetotail during substorms.