Korea Institute of Fusion Energy

Quench detection is critical to protect superconducting coils, especially in fusion superconducting magnets, due to enormous energy. A quench event can result in significant damage to fusion superconducting magnets. A High Voltage Signal Conditioner (HVSC) designed for quench voltage detection in the ITER superconducting magnet system has been developed collaboratively by the Korea Institute of Fusion Energy (KFE) and JH Engineering. Various types of HVSCs for ITER magnets and feeder systems were successfully designed, fabricated, and tested under high-voltage conditions and external magnetic fields simulating the fusion tokamak operational environment. However, long-term tests under actual tokamak plasma operation are essential to validate their reliability prior to deployment in ITER. Four types of HVSCs were installed and integrated with quench detection voltage taps of the Korea Superconducting Tokamak Advanced Research (KSTAR) superconducting magnets and bus lines. The long-term reliability tests of HVSCs were conducted during the 2024-2025 KSTAR campaign. The performance and reliability of the HVSCs were evaluated by comparing the recorded data with that of the KSTAR quench detection system.

Protein-Inspired Reconfigurable Nanovector-Based Coacervates Intrinsically disordered protein–inspired nanovectors undergo reversible conformational transitions that enable coacervate formation with diverse biomacromolecules. The resulting nanocoacervates remain stable under physiological conditions and can directly penetrate cellular membranes through the dynamic motion of the nanovectors. This platform supports efficient cytosolic delivery of a wide range of cargos, providing a versatile approach for intracellular transport technologies. More details can be found in the Research Article by Kwan Hyi Lee, Ja-Hyoung Ryu, Youngdo Jeong, and co-workers (DOI: 10.1002/adma.202507877).

Abstract This paper reports on the generic prediction capability of full electromagnetic plasma initiation modelling with DYON, which was carried out for the first time in fusion research by the joint modelling of the International Tokamak Physics Activity—Integrating Operation Scenario group. The following devices were included in the experiment database: VEST (spherical torus, copper coils, Stainless steel wall, R / a = 0.3 m/0.2 m, V v = 3.7 m 3 ), MAST-U (spherical torus, copper coils, C wall, R / a = 0.7 m/0.5 m, V v = 55 m 3 ), EAST (conventional tokamak, superconducting coils, metallic wall, R / a = 1.85 m/0.5 m, V v = 38 m 3 ), DIII-D (conventional tokamak, copper coils, C wall, R / a = 1.67 m/0.65 m, V v = 35 m 3 ), and KSTAR (conventional tokamak, superconducting coils, C wall, R / a = 1.8 m/0.5 m, V v = 55 m 3 ). Despite the different hardware features of the devices, the required operating spaces of the loop voltage induction and prefill gas pressure for inductive plasma initiation in each device were successfully reproduced by the predictive simulations with DYON using only the individual hardware design and the control room input data for each discharge. This successful validation across multiple machines demonstrates that the full electromagnetic DYON modelling can capture the essential physics of inductive plasma initiation. The simulation settings commonly employed for all modelling and the modifications necessary to account for the discrepancies between individual devices are reported. Predictions for ITER based on the multi-machine validation indicate that a wide range of prefill gas pressures exists for the Townsend breakdown and the plasma burn-through (0.01–1.5 mPa).

• Core-shell droplet fabrication system was developed to form a protective coating layer for breeder materials with high lithium density and low strength, such as Li 4 SiO 4 . • Core-shell droplet fabrication system was developed from the T–shape based fluidic system used in many previous studies. • Li 4 SiO 4 –Li 2 TiO 3 pebbles manufactured using the core–shell droplet fabrication system were found to have a diameter of approximately 2.3 mm and a Li 2 TiO 3 coating layer of 200–300 μm. • Li 4 SiO 4 –Li 2 TiO 3 pebble had a crush load that is 2.03 times higher than of a single Li 4 SiO 4 pebbles. Li 4 SiO 4 , used as a tritium breeder material in fusion reactors, has high lithium density but suffers from lower mechanical strength compared to another promising material, Li 2 TiO 3 . In this study, a fluidic system was designed to fabricate core-shell structured pebbles (Li 4 SiO 4 –Li 2 TiO 3 ) consisting of a Li 4 SiO 4 core and a Li 2 TiO 3 shell. The system was constructed using a T–shaped fluid flow channel with a double–tube design, enabling the controlled formation of core-shell droplets by adjusting the flow rates of the continuous and dispersed phases. The resulting Li 4 SiO 4 –Li 2 TiO 3 pebbles exhibited a crush load approximately 2.03 times higher than that of single-phase Li 4 SiO 4 pebbles, and the stable formation of the core–shell structure was confirmed. This study presents a novel fabrication process with the potential to enhance the mechanical performance of Li 4 SiO 4 as a tritium breeder material.

Recent evidence indicates that elimination of senescent cells from tissue can be a therapeutic approach to treat age-related disease, but selective targeting of senescent cells remains a challenge. Here, we report a dual-responsive self-assembly system selectively targeting senescent cells by responding to two hallmark features: elevated reactive oxygen species levels and increased alkaline phosphatase (ALP) activity. The engineered monomer (p-Mito-1), bearing phosphate-protected thiol groups and mitochondrial-targeting moieties, assembles into zwitterionic bioinactive spherical nanostructures with low membrane affinity. In senescent cells, ALP-mediated dephosphorylation of p-Mito-1 triggers disassembly and mitochondrial accumulation of the deprotected monomer (Mito-1), followed by ROS-induced transformation into bioactive fiber structures via disulfide bond formation. This morphological transition exposes surface positive charges, facilitating mitochondrial membrane disruption and the selective activation of apoptosis in senescent cells. In vitro, p-Mito-1 showed selective cytotoxicity toward senescent RPE (SnC_RPE; IC50 ≈ 80 μM) with negligible effects on normal RPE even at 200 μM. We further validated efficacy in an AMD-relevant model, where localized administration selectively depleted senescent RPE cells without overt local toxicity. Our findings demonstrate the potential of dual-responsive supramolecular systems for precise targeting of senescent cells and highlight a modular design strategy for aging-related disease intervention.

Zonal flows and turbulence spreading play important roles in magnetic fusion plasma confinement, yet their coupling mechanisms remain elusive. Using global nonlinear gyrokinetic simulations, we show that turbulence spreading transports zonal flow radially, extending into the linearly stable regions after local nonlinear saturation of turbulence. Theoretical understanding has been gained by analyzing the simulation results in the context of a momentum theorem in toroidal plasmas [Hahm et al., Phys. Plasmas 31, 032310 (2024)] which is an extension of the Charney–Drazin non-acceleration theorem [Charney and Drazin, J. Geophys. Res. 66, 83 (1961)]. It indicates a direct relation between turbulence-driven enstrophy transport and perpendicular momentum generation.