Overview of the KSTAR Research Progress and Future Plan Toward ITER and K-DEMO

Full text: The KSTAR research efforts have been focussed on expansion of the KSTAR operating space for ITER and K-DEMO, validation of critical physics and search of new physics. The operating regimes are high-β_p (up to ∼ 2.8) noninductive long pulse up to ∼ 8 s, high-β_N up to ∼ 4.3, and elongation K ∼ 2.16 and a long H-mode discharge over a minute. An improved underlying physics of resonant and nonresonant magnetic perturbation (RMP and NRMP) with the IVCC coils resulted in a long pulse edge localized mode (ELM)-crash suppressed H-mode discharge (∼ 34 s). The ELM-crash suppression dependence on critical physical parameters, such as q₉₅, δ, and v* was extensively investigated. Identification of the role of turbulence induced by RMPs in suppression of the ELMs identified the turbulence flow (!pKeq) physics during the RMP ramp up and down periods. The study of L-H transition threshold power (P_th) dependence on the nonaxisymmetric field found that the P_th is significantly affected by RMPs while NRMP components had no influence on P_th. New physics of interaction between the macroscopic fluctuation (m/n = 2/1 island) and microturbulences and validation of q₀ issue in sawtooth instability has been explored. Also the misaligned RMP configurations are used to test the divertor heat flux dispersal. A major upgrade plan in KSTAR will be initiated near 2021 for stable higher long β pulse operation. Emphasis will be placed on a new actively cooled tungsten divertor possibly with new first wall materials and current drive (LHCD/Helicon). For the search of metal wall materials in the KSTAR upgrade plan, test of specially designed castellated tungsten block tiles of various shapes, impurity transport physics experiments via injection of trace Ar and Kr gases and tungsten dust were performed. This work is supported by the KSTAR research project funded by Korea Ministry of Science, ICT and Future Planning. (author)