We evaluate the characteristics of global energy confinement in KSTAR (τE,KSTAR) quantitatively in three ways; firstly by comparing it with multi-machine scalings, secondly by deriving multiple regression equations for the L- and the H-mode plasmas, respectively, and lastly by comparing confinement enhancement of the H-mode phase with respect to the L-mode phase in each discharge defined as Hexp. The KSTAR database exhibits τE,KSTAR of ∼0.04 to ∼0.16 s and of ∼0.06 to ∼0.19 s in L-mode and in H-mode plasmas, respectively. The multiple regression equations derived by statistical analysis present the similar dependency on PL and higher dependency on Ip compared with the multi-machine scalings, however the dependency on κ in both L- and H-mode plasmas draw the negative power dependency of κ−0.68 and κ−0.76 for H-mode and for L-mode database, respectively on the contrary to the positive dependency in all multi-machine empirical scalings. It is found that the energy confinement of both L-mode and H-mode of the discharges with Hexp > 1.5 can be well-predicted by multi-machine scalings, τE,89L and τE,92H. Apart from this, the H-mode confinement with 1.5 < Hexp < 2.0 is well-predicted by using the multi-machine empirical L-mode scaling τE,89L.
Power threshold and confinement of the I-mode in the EAST tokamak