Scaling of incremental energy confinement time in the JFT-2M tokamak

Decay time of stored energy was measured when additional heating power decreased abruptly. The energy decay time is almost constant at 15 ms, irrespective of the gross energy confinement time tau/sub E//sup G/, which is changed by ion cyclotron radio frequency heating up to 1.5 MW. The decay time coincides with a confinement time of the additionally heated power defined by tau/sub ad/ = ΔW/sub T//ΔP/sub Tot/, which indicates that the incremental energy from the additional heating behaves independently of the gross plasma energy. It is also shown that tau/sub ad/ is almost independent of density and plasma current as well as heating power