It is the time to ramp the energy of the machine. For FCC-ee it is not relevant since FCC-ee operates at constant energy and the beam are topped-up continously from a booster ring. The booster ring has to deliver on average around 10¹² e⁺ and e^- per second. The booster is cycling its energy between its injection energy (12-40 GeV - to be defined) and the operating energy of FCC-ee. The cycle time is roughly 5 seconds - details to be worked out.