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Research Achievements Electromagnetic analyses of the K-DEMO divertor during the abnormal behavior of plasma Main Contributor Sungjin Kwon, Kihak Im, Suk-Ho Hong Related Research Project Study of Demonstration Plant Design Concept and Base Technology Main Contributor Qualitative Achievements - Establishment of a basis for the electromagnetic analyses of tokamak structures for abnormal behavior of K-DEMO plasma. - Plasma current profile evolution and calculation of electromagnetic force applied on divertor in MD Quantitative Achievements - 1 International Conference Presentation (30th Symposium on Fusion Technology, September 2018, Sicily, Italy) - 1 International Journal Paper (Fusion Engineering and Design, 2019, in press) Superiorities & differences Superiorities - Establishment of the quantitative evaluation of the electromagnetic force applied to the major components of the K-DEMO tokamak in the event of abnormal behavior of plasma such as MD or VDE (Vertical Displacement Event) and acquisition of the scalability for various scenarios. Differences - In other DEMO devices, the electromagnetic force was not evaluated since the plasma scenarios were not established. However, electromagnetic analyses were carried out for the K-DEMO with the aid of the in-house program converting plasma data. Expected Effect & Ripple Effect Technical Perspectives - Providing a basis for evaluating the electromagnetic force applied to the K-DEMO tokamak, and essential design parameters in evaluating the structural integrity of major in-vessel components such as divertor and blanket. Economical & Social Perspectives - Establishment of the research foundation and the development of the fundamental technology for the Korean demonstration fusion reactor. - Providing the technological feasibility towards the K-DEMO detailed engineering design phase. Evidence K-DEMO modelfor electromagnetic analysis. Plasma current evolution in MD. Magnetic flux density(left) & Eddy current(right) distribution on the K-DEMO divertor in MD. EM force (top) and EM moment (bottom) on the K-DEMO divertor in MD.
Research Achievements Analysis of fast ion loss due to RMP in KSTAR Main Contributor Kimin Kim Related Research Project Integrated Modelling of Turbulence and Transport in Tokamak Fusion Plasmas Major Research Achievements Qualitative Achievements - While resonant magnetic perturbation(RMP) is beneficial in enhancing H-mode performance by controlling ELM, it can be detrimental in confining fast ions, which can result in the degradation of NBI and RF heating efficiency. So it is important to understand the physical mechanisms of fast ion loss by RMP. - In this work, a new test particle code was developed to calculate fast ion orbit under perturbed equilibrium magnetic fields in tokamak. Then, the code was employed to simulate NBI ion losses by RMP in KSTAR plasmas. - The simulations successfully reproduced the experimentally measured loss patterns of NBI fast ions for varying RMP strengths in the KSTAR plasmas. Quantitative Achievements - Published in Physics of Plasmas 25, 122511 - Presented in 2018 ITPA-EP workshop and APTWG conference Superiorities & differences Superiorities - The new code incorporated accurate magnetic field perturbations by RMP including realistic plasma response model. - The new code could quantitatively reproduce the KSTAR experimental results. Differences - The new code employs more accurate RMP models including plasma responses and also realistic PFC geometry, while many existing test particle codes employ simplified models. This unique feature enables the new code to reproduce experimental results quantitatively. Expected Effect & Ripple Effect Technical Perspectives - The new code can be utilized to simulate and optimize alpha particle confinement in future tokamaks such as ITER. Evidence Simulation of the changes of fast ion losses according to varying particle pitches
Research Achievements Spontaneous plasma flow generation by symmetry breaking of global electromagnetic ion temperature gradient modes Main Contributor Helen Kaang Related Research Project Integrated Modelling of Turbulence and Transport in Tokamak Fusion Plasmas Major Research Achievements Qualitative Achievements - Plasma flow (or rotation) has been reported to play an important role in reducing turbulent transport and stabilizing magnetohydrodynamic instabilities. The spontaneous generation of plasma flow is necessary for ITER to achieve a desirable plasma performance. We developed a quasilinear theory based code for the estimation of spontaneous plasma flow generation which is induced by ITG modes. - We showed that the plasma flow can be enhanced spontaneously with increasing plasma beta(=plasma thermal energy/magnetic energy). This means that enhanced confinement mode aimed by ITER can generate a large plasma flow. - We suggested a new mechanism for the spontaneous plasma flow generation: the global electromagnetic effects by the increase of plasma beta induce the parity mixing of ITG mode, by which symmetry breaking in ITG mode occurs resulting in the spontaneous flow generation. Quantitative Achievements - Published in Physics of Plasmas 25, 012505- Presented as invited talk at 8th Asia Pacific Transport Working Group conference Superiorities & differences Superiorities - We presented a theoretical basis on the strong generation of plasma flow experimently observed in enhanced confinement mode and the change of plasma flow distribution observed when an additional heating source is applied to the plasma. Differences - Up until now, most of the studies on the spontaneous flow generation have been performed by considering electrostatic ITG turbulence. In this work, we studied global electromagnetic ITG mode, through which we presented parity mixing in ITG mode by the global electromagnetic effect as a new symmetry breaking mechanism for the spontaneous flow generation. Expected Effect & Ripple Effect Technical Perspectives - The developed code and newly suggested concept on the spontaneous flow generation is expected to be usefully applicable to the analysis of plasma flow observed in experiments. Evidence Change of Reynolds stress (source of plasma flow generation) with increasing plasma beta

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