Contours of current,  | J | , illustrating snapshots of the λ_i = 0.072 simulations, focusing closely on behaviour near the null, highlighting the presence and locations of multiple nulls, overlaid with selected contours of A_z (in black). Each null is assigned a symbol and a colour based on the null position relative to the central null, which is indicated by a black star. Nulls above this along the contour of B_y = 0 would be seen in green and those below are shown in light blue. The distance along the B_y = 0 line is indicated by the symbol – a snapshot containing 7 nulls would thus display, from left to right,  ×  +  △    (in   blue)    ∗    (in   black)   □ +  ×    (in   green).