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We report the neoclassical tearing mode (NTM) stabilization experimental results by injection of the electron cyclotron (EC) beam in KSTAR, and its analysis with integrated modelling. In the KSTAR experiment, NTM was intentionally induced and the EC beam was injected by the plasma control system (PCS) to stabilize it. Here, the EC angle was controlled based on the minimum seeking algorithm for the island growth rate. Although the EC angle was not changed significantly, the island width significantly decreased towards the end of the experiment followed by the recovery of plasma performance. To assess the NTM stabilization experiment from a stability perspective, we performed integrated modelling with TRIASSIC utilizing the reconstructed equilibrium with magnetic diagnostics and motional stark effect diagnostics. As a result, we observed that the NTM is stabilized by EC.

A 3D analysis of plasma wall interactions and global impurity transport for the edge localized mode suppression window in KSTAR during H-Mode discharges has shown that carbon erosion at the divertor plates is a strong function of the resonant magnetic perturbation (n = 1) coil current and relative phasing. The Generalized Perturbation Equilibrium Code was used to determine a realistic initial perturbed plasma equilibrium, and EMC3-EIRENE was used to calculate the resulting scrape-off layer plasma used in this study as a fixed background for the ERO2.0 plasma–material interaction model. The resulting transport leads to deposition of impurities along the targets positioned at the high-field side of the device. An attempt at calculating the resulting effective charge state has demonstrated a similar dependence on the perturbation coil current and has been able to determine a window for the experimentally observed values of Z eff by including contributions of all ionized carbon charge states and deuterium. [ABSTRACT FROM AUTHOR]

In gas–metal arc welding (GMAW), the welding quality is influenced by various factors, including the welding conditions and external environment. Achieving a high welding quality requires careful observation and control. Welding monitoring is crucial for validating a planned welding process and assessing its quality. This study introduces a vision system for the online acquisition of clear molten pool images. It uses a small camera equipped with a complementary metal-oxide-semiconductor sensor during GMAW, as well as a method for constructing this system. The proposed vision system does not require triggering using devices such as field-programmable gate arrays, facilitating lower costs and online quality monitoring under various welding conditions during mild-steel GMAW. Accurate measurement of radiation from the weld is essential for clear observation of the molten pool during welding, emphasizing the importance of selecting an optical system with appropriate lenses and filters. In addition, appropriate digital camera parameters must be set for monitoring. High-quality images were successfully captured using the proposed method, and the image quality was evaluated using the blind/referenceless image spatial quality evaluator algorithm. [ABSTRACT FROM AUTHOR]

Research focuses on developing a novel flame-retardant filament utilizing acrylonitrile–butadiene–styrene (ABS) and ammonium polyphosphate (APP) by the numerical approach using finite element analysis (FEM)-based software, COMSOL Multiphysics to overcome nozzle clogging and establish optimal three-dimensional (3D)-printing parameters. The developed FEM model enabled the numerical testing of differently shaped nozzles and proven the benefit of using a low-convergence angle (60°) nozzle because of the greater magnitude of pressure drop at nozzle tip compared with that of a high-convergence angle (120°) nozzle, a slightly better temperature distribution at the nozzle region, and smoother flow of the melted filament. Experimental tests results demonstrated the feasibility of using fused filament fabrication 3D printing to apply on ABS composite directly, and the printed samples retain their properties. An improvement in the burning test showed a V0 rating, thermal stability 13% at 800 °C, and the heat release rate of ∼390 W/g compared with neat ABS (∼501 W/g). [ABSTRACT FROM AUTHOR]