Side view · trajectories vs z
End view · (x,y) at current z (and trail)
Advanced · lens parameters

Ideal linear lenses: \(x''+Kx=0\). Quad: \(K=B_{\mathrm{edge}}/(a\,B\rho)\) in F, \(-K\) in D. Solenoid: hard-edge Larmor model \(K_s=(B_s/2B\rho)^2\) (focus in the Larmor frame; lab image rotates). Same numerical \(B\) as a quad/APL is much weaker — solenoid mode starts at \(B_s=8\,\mathrm{T}\). Plasma lens: same \(K\) as quad F, but in all radial directions.