This is a set of waveforms recorded during the first pulsed RF operation (5Hz, 18MV/m) of a TESLA-like 9-cell cavity in a horizontal cryostat at KEK's Superconducting rf Test Facility. The graph shows a successful compensation of Lorentz detuning using a fast Piezo tuner.

Horizontal scale: 200 micro.sec / division
Blue: L-band input RF power. 124kW during fill and 87kW during flattop.
Green: Drive signal for the fast Piezo tuner (max 500V, 300Hz).
Purple: Accelerating gradient (18 MV/m in a 1ms-long flattop).
Light-blue: Phase difference between the input and output RF from the cavity.