We extract the KW cascade extent (filled symbols and open diamond) in the k space as discussed in the main text. The dot-dashed line corresponds to the single-scale scenario with k_end = k_start (same as solid line in b). The cascade extends further in the k space with decreasing α, in line with numerical simulations from ref. 43 (open squares). At the lowest temperatures (α ≲ 3 × 10^{-5}), the KW cascade extends to the length scales smaller than the inter-vortex distance (short dashed line). The largest statistical error from b is shown for the corresponding point (29.1 bar). For other points, the statistical errors are smaller than the symbol size. The highest temperature (26.4 bar) and lowest temperature (9.6 bar) points display the estimated systematic errors (Methods) in α, drawn as capless error bars. Symbol colours in b and c mark different pressures shown in the key in c.
