Extended Data Fig. 2: Detachment front response in MAST-U.

Observed time and frequency domain D2 Fulcher band front position Ltar (-) response to main chamber D2 gas valve flow request perturbations (–). a-c, Elongated divertor geometry (#47080, #47083, #47086). d-f, Super-X divertor geometry. The exited frequencies and their harmonics are indicated through colour coding. The output response at the excited frequencies is well above the average noise level of the non-exited frequencies (–). Some response can occasionally be observed at the harmonic frequencies which indicates non-linear components are present 49, nevertheless, the response is dominantly linear.