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Recent control advances at KSTAR enabled us not only to establish but also to sustain the ITER-similar shape (ISS) in a stationary manner, matching the ITER-like dimensionless shape parameters in lower single null (LSN) configuration with vastly contrasting upper/lower triangularities. The kinetic parameters of the ISS are different from the typical KSTAR configurations seen in ELM-RMP suppression experiments. It is experimentally demonstrated the ISS-compatible RMP control in KSTAR for the first time, using the n=2, +90 degrees phasing RMP.

Excellent reproducibility of KSTAR resonant magnetic perturbation (RMP)-driven, edge-localized mode (ELM)-crash suppression enables us to construct a database reliably for the study of ELM-crash suppression conditions. To establish a high-fidelity database, we have selected one of the frequently used RMP configurations in KSTAR, n = 1, + 90 ° phasing RMP-coil configuration. A series of fitting curves based on edge profile diagnostics data is used for normalized electron collisionality ( ν e *) and plasma toroidal rotation ( V tor) at pedestal top. Since ITER is expected to employ slowly rotating, low-collisionality, high-density plasmas whose conditions are not readily accessible in the existing devices, the exploration and understanding of these two parameters would be important not only for RMP-driven, ELM-crash-suppression physics but also for the success of ITER. The data points for the ELM-crash suppression phase are in the range of 0.2 40 km/s. Suppression thresholds or boundaries in ν e , ped * or V tor , ped are not confirmed in the investigated parameter ranges so far. The KSTAR database still needs additional experimental datasets in ITER-relevant conditions ( ν e , ped * ∼ 0.1 and low-torque low-rotation) to confirm the boundary of the ELM-crash suppression window in KSTAR and reduce the uncertainties of the RMP ELM-crash control technique in ITER. In both ν e , ped * and V tor , ped parameters, the phase-space distribution of the ELM-crash suppression has no clear distinction from that of the ELM-crash mitigation. Linear discriminant analysis provides a linear combination of parameters relevant to ELM-crash suppression, best separating two data categories. Recursive feature elimination indicates that n e , ped and I RMP, as well as ν e , ped * and V tor , ped, are critical variables in the separation of the data groups.

A decade long operation of KSTAR has contributed significantly to operation of superconducting tokamak device and advancement of tokamak physics which will be beneficial for the ITER and K-DEMO programs. Even with limited heating capability, various conventional as well as new operating regimes have been explored and achieved great performance. As examples, a long pulse H-mode operation with and without the ELM-crash was well over 60 seconds and over 30 seconds, respectively. Unique capabilities of KSTAR allowed to improve control capability of harmful instabilities and have been instrumental for many exciting new physics. The intricate IVCC system has been a great perturbation tool in studying of threshold power of the L/H transition in the presence of non-axisymmetric fields, rotation physics due to NTV effects, heat dispersal in divertor system and predictive control of the ELM-crash with a priori modeling. The state-of-the-art 2D/3D microwave imaging systems uncovered many new exciting new physics in the MHD and turbulence transport physics. They are validation of q0agt;1 right after the sawtooth crash, self-consistent asymmetric distribution of plasma turbulence amplitude and flow in the presence of 2/1 island, and underlying physics of low frequency turbulence induced by 3D resonant fields in suppression of the ELM-crash through non-linear interaction with the ELMs. In the turbulence area, non-diffusive "avalanche" transport event and role of quiescent coherent mode in confinement are studied. To accommodate anticipating higher performance of the KSTAR plasmas with the increased heating powers (NBI and ECH), new divertor/internal interface with full active cooling system will be implemented after the increased heating power systems and new current drive systems are fully tested. Upgrade plan for the internal hardware and efficient current drive system may allow a long pulse operation of higher performance plasmas at βNagt;3.0 with fbs~0.5 and Tiagt;10keV. a#13; a#13