Confinement characteristics of the extended operation regime of KSTAR toward advanced scenarios

Na, Y. S.*; Suzuki, Takahiro; Ide, Shunsuke; Mueller, D.*; Kim, J. H.*; Miyata, Yoshiaki; Kim, S. H.*; Kim, H. S.*; Jeon, Y. M.*; Bae, Y. S.*; Jeong, J. H.*; Joung, M.*; Lee, S. G.*; Park, S. I.*; Kim, W. C.*; Oh, Y. K.*; Kwak, J. G.*; KSTAR Team*

Development of advanced scenarios, an important experimental goal for the KSTAR project, has just begun. Target plasmas were successfully produced using large bore plasma and early divertor formation which exhibit low internal inductance with low magnetic shear at the centre and no sawtooth instability. Auxilliary heating during the current rampup phase was employed to slow the inductive current diffusion to the centre of the plasma. With respect to hybrid scenario development, so-called "Ip-overshoot" method being used in JET is applied for tailoring magnetic shear at reduced plasma current for higher poloidal beta and bootstrap current fraction. The confinement characteristics of these scenarios are investigated. Transport modeling is performed self-consistently with an integrated simulation package incorporating plasma equilibrium, transport, heating and current drive. Firstly, the current rampup phase is simulated and its impact on the target q-profile is addressed. Secondly, energy confinement of flattop phases is discussed. In addition, the non-inductive current drive fraction including the bootstrap current fraction is calculated. Lastly, these scenarios are compared with advanced scenarios developed in other tokamak devices and future directions in achieving advanced regimes are discussed.