Abstract We report on the status of Fast Ion Regulated Enhancement (FIRE) mode experiments in the Korea Superconducting Tokamak Advanced Research. This regime is being developed for high-performance, steady-state operation which features a stationary ion internal transport barrier, enabling a central ion temperature approaching 10 keV to be sustained for up to 50 s, without the need for delicate profile control and with no significant impurity accumulation. As its key novelty lies in the significant contribution of fast ions that stabilize core turbulence, the regime has been named FIRE mode. To achieve this regime, neutral beam injection is applied at moderate power levels near the L–H power threshold, while maintaining low plasma density to avoid the L–H transition. The scenario is typically established in diverted magnetic configurations. The core features of FIRE mode were investigated through power balance analysis and fluctuation measurements, revealing a clear transport bifurcation in the ion channel. At the plasma edge, FIRE mode occasionally exhibits I-mode characteristics, particularly in unfavorable magnetic null configurations with q 95 ∼ 4, including the presence of weakly coherent modes. In terms of MHD activity, sawtooth oscillations are observed but appear to be stabilized during the high-performance phase. Fast ion-driven Alfvénic eigenmodes (AEs), indicated by strong frequency chirping near 200 kHz, are also observed. Additionally, lower-frequency MHD activities, distinct from the fast ion-driven AEs, are present and have some influence on plasma performance. The enhancement of core confinement is primarily attributed to fast ion effects, which were evaluated with respect to dilution, alpha stabilization, and resonant interactions with turbulence using gyrokinetic analyses. Among these, the dilution effect was found to be the most dominant. The characteristics of FIRE mode were compared with those of other hot ion plasma scenarios, such as supershot and hot ion mode. While they share many similarities, FIRE mode is distinguished by the accessibility to conditions with T i ≈ T e , presence of I-mode edge features, and its long-duration sustainment. Predictive simulations of FIRE mode were performed using integrated transport modeling with TRIASSIC, employing the TGLF anomalous transport model. These simulations confirmed the critical role of fast ions in achieving this regime. The future prospect of FIRE mode for application in fusion reactors is discussed, with an emphasis on possibly extending the regime to higher density operation.

Abstract A scenario of ion cyclotron range of frequency (ICRF) wave injection from a top launcher is proposed as an efficient and direct heating method for thermal deuterium ions in deuterium–tritium tokamak plasmas. Positioned between the tritium cyclotron layer and ion–ion hybrid layer, the top launcher allows effective wave penetration to the ion–ion hybrid layer and enables significant power transfer to thermal deuterium. This is achieved through favorable wave polarization for fundamental cyclotron damping. There is a Doppler broadening around the cyclotron resonance and this overlaps with the ion–ion hybrid layer. Low toroidal mode numbers and ion temperature in the range of 5–20 keV are favorable for enhancing the main ion damping relative to electron damping. In contrast to the neutral beam injection, which penetration strongly depends on machine size and plasma density, the proposed ICRF-based direct ion heating scenario is shown to be scalable and applicable to both larger and smaller tokamak devices within practical constraints.

Abstract We report on the status of Fast Ion Regulated Enhancement (FIRE) mode experiments in the Korea Superconducting Tokamak Advanced Research. This regime is being developed for high-performance, steady-state operation which features a stationary ion internal transport barrier, enabling a central ion temperature approaching 10 keV to be sustained for up to 50 s, without the need for delicate profile control and with no significant impurity accumulation. As its key novelty lies in the significant contribution of fast ions that stabilize core turbulence, the regime has been named FIRE mode. To achieve this regime, neutral beam injection is applied at moderate power levels near the L–H power threshold, while maintaining low plasma density to avoid the L–H transition. The scenario is typically established in diverted magnetic configurations. The core features of FIRE mode were investigated through power balance analysis and fluctuation measurements, revealing a clear transport bifurcation in the ion channel. At the plasma edge, FIRE mode occasionally exhibits I-mode characteristics, particularly in unfavorable magnetic null configurations with q 95 ∼ 4, including the presence of weakly coherent modes. In terms of MHD activity, sawtooth oscillations are observed but appear to be stabilized during the high-performance phase. Fast ion-driven Alfvénic eigenmodes (AEs), indicated by strong frequency chirping near 200 kHz, are also observed. Additionally, lower-frequency MHD activities, distinct from the fast ion-driven AEs, are present and have some influence on plasma performance. The enhancement of core confinement is primarily attributed to fast ion effects, which were evaluated with respect to dilution, alpha stabilization, and resonant interactions with turbulence using gyrokinetic analyses. Among these, the dilution effect was found to be the most dominant. The characteristics of FIRE mode were compared with those of other hot ion plasma scenarios, such as supershot and hot ion mode. While they share many similarities, FIRE mode is distinguished by the accessibility to conditions with T i ≈ T e , presence of I-mode edge features, and its long-duration sustainment. Predictive simulations of FIRE mode were performed using integrated transport modeling with TRIASSIC, employing the TGLF anomalous transport model. These simulations confirmed the critical role of fast ions in achieving this regime. The future prospect of FIRE mode for application in fusion reactors is discussed, with an emphasis on possibly extending the regime to higher density operation.

Abstract A scenario of ion cyclotron range of frequency (ICRF) wave injection from a top launcher is proposed as an efficient and direct heating method for thermal deuterium ions in deuterium–tritium tokamak plasmas. Positioned between the tritium cyclotron layer and ion–ion hybrid layer, the top launcher allows effective wave penetration to the ion–ion hybrid layer and enables significant power transfer to thermal deuterium. This is achieved through favorable wave polarization for fundamental cyclotron damping. There is a Doppler broadening around the cyclotron resonance and this overlaps with the ion–ion hybrid layer. Low toroidal mode numbers and ion temperature in the range of 5–20 keV are favorable for enhancing the main ion damping relative to electron damping. In contrast to the neutral beam injection, which penetration strongly depends on machine size and plasma density, the proposed ICRF-based direct ion heating scenario is shown to be scalable and applicable to both larger and smaller tokamak devices within practical constraints.

To understand the role of ion cyclotron resonance heating (ICRH) in mitigating tungsten accumulation, we evaluate the impact of ICRH-induced poloidal asymmetries on neoclassical impurity transport using a newly developed 4-D Fokker–Planck code (FP4D). Unlike conventional approaches that separate RF heating and transport modelling, FP4D solves both fast-ion distribution formation and impurity transport self-consistently without bounce-averaging. Benchmarking against the NEO code confirms the accuracy of the neoclassical physics in FP4D. Using FP4D, we analyze anisotropic and non-Maxwellian minority distributions under ICRH and their effects on the equilibrium potential and tungsten transport. Results show that anisotropy induced poloidal potential variations can reduce inward tungsten flux, depending on the modelling approach. Our findings highlight the importance of resolving the full velocity and poloidal structure of minority species in predicting impurity transport under strong RF heating conditions.

Abstract Finite orbit width (FOW) effects on energetic particle induced geodesic acoustic modes (EGAMs) are investigated using gyrokinetic theory. A dispersion relation is derived, accounting for the FOW effects and assuming a double-shifted Maxwellian distribution in parallel velocity for energetic particles. Numerical solutions of the dispersion relation show good agreement with gyrokinetic simulations. The FOW effects are shown to enhance EGAM damping, consistent with their conventional role in GAM dynamics. Interestingly, when the FOW becomes large enough, a new unstable EGAM branch, referred to as δ EGAM, emerges at a higher frequency than the GAM. This phenomenon is consistent with recent analytic EGAM results obtained using a slowing-down distribution for energetic particles. Depending on the safety factor and the parallel velocity shift of energetic particles, the δ EGAM shows two distinct destabilization patterns and its relationship with the GAM. Based on these characteristics, the δ EGAM is classified into two types, each showing a distinct energetic particle density threshold and frequency range. If energetic particles exhibit a positive slope at the FOW-induced transit resonance, their kinetic energy is transferred to the δ EGAM via inverse Landau damping.

Abstract The fast ion relevant mode shown in a previous study (Kim et al 2024 Nucl. Fusion 64 066013) is further investigated via gyrokinetic simulations in the present work. This mode is identified as a kinetic ballooning mode (KBM) based on its mode structure, polarization, parametric dependence, dominant energy flux component, and mode frequency. In addition, we find that the presence of fast ions is essential for the destabilization of this KBM. The mode is destabilized by fast ion pressure and its gradient, with a threshold present, indicating that the fast ion relevant mode is a fast ion driven KBM. Energy transfer analysis shows that the fast ion driven KBM transfers energy directly to the zonal potential energy, increasing the zonal flow and zonal field. However, this mode can also increase both fast ion and electron transport by increasing the fluctuation quantities, such as energy fluctuation and fluctuating E × B flow velocity, rather than the changes in the phase angle between them. These findings enhance the comprehensive understanding of the physics of the fast ion driven KBM, which can be destabilized in future burning plasma due to high-temperature fast ions.

This study explored the substantive meaning of elementary school teachers’ multicultural awareness and acceptance attitudes. To this end, this study began two researchers’ self-report statements. Then, research questions were formulated and multicultural awareness was divided into uncanny, prejudice, discrimination, and hatred. In addition, the researcher conducted in-depth interviews with eight elementary school teachers to collect and analyze relevant data. As a result of the study, it was found that elementary school teachers teach multicultural students and that their self-perception changes as teachers. In this process, elementary school teachers build relationships with multicultural students by going through the pre-meeting stage, the meeting stage, and the post-meeting stage. From this, the elementary teachers reflected on their existing selves. They understand that their self changed from an initial integrated perception to a separate perception, and they experienced the strengthening of their Persona as a teacher. The findings of the study reveal the empirical implications of what elementary teachers experience in multicultural awareness and acceptance and how they are guided in this process. Based on the results of the study, the researcher discussed the need for educational practice and training for pre-service teachers and teachers who have entered the teaching profession to experience multicultural awareness and separation of self, and discussed the direction of teacher education to separate the personal and professional self for the professionalism of the teaching profession and the need to solidify the area of teacher-centered pedagogy.

This study analyzes trends in Korean applied music research using content analysis and topic modeling.The research examined 186 papers published in KCI-listed journals from 2002 to 2024.The methodology employed a combination of quantitative techniques, including content analysis, TF-IDF analysis, and LDA topic modeling.Content analysis was used to examine publication patterns over time and across disciplines.TF-IDF analysis was applied to identify key terms and concepts prevalent in the research corpus.LDA topic modeling, a probabilistic method for discovering latent topics in large text collections, was utilized to uncover the main research themes.The optimal number of topics was determined using coherence and perplexity scores.Content analysis revealed an increasing number of publications over time, with a peak in 2020-2021.The research spans various disciplines, with interdisciplinary studies being the most prevalent.TF-IDF analysis identified key terms such as "art," "vocal," "class," and "major," reflecting the field's focus on education and practical skills.Topic modeling uncovered six main research themes: applied music education structure, vocal education specialization, artistic expertise development, practice-oriented learning, university curriculum design, and music industry-linked education.These findings indicate that applied music research in Korea balances theoretical and practical aspects, emphasizing both artistic value and industry relevance.This research contributes to understanding the current state of applied music studies in Korea.

Objectives The purpose of this study is to apply PBL(Problem-Based Learning) to the teaching subject class of preservice early childhood teachers and to analyze how PBL affects the improvement of the key competencies. Methods PBL was conducted for 15 weeks, focusing on making and solving problems that beginner early child-hood teachers may face in the educational field and to preparing a PBL class plan for infants. Participants in the study were 44 second-year early childhood education students who took education methods and educational technology class for the second semester of 2022 at H vocational college in Seoul. In order to analyze whether the PBL class of pre-service early childhood teachers is effective in key competencies, a pre-post survey was con-ducted to diagnose key competencies, and reflection journals and PBL results were collected and analyzed. Results As a result of the pre-post examination, the performance of improving key competencies (creativity, con-vergence, challenge, and growth) through PBL classes showed a significant difference at the statistical .001 level. In particular, the degree of improvement was high in terms of openness to change, comprehensive thinking, goal orientation, and self-efficacy, which are sub-detailed competencies. As a result of analyzing the reflection journal, it was found that students improved throughout key competencies such as creative competency, convergence competency, challenge competency, and growth competency through PBL classes. In particular, as an early child-hood teacher in the future, they showed confidence in the application of PBL classes for infants, and they have expectations that infants, like themselves, will be able to grow through PBL. It also showed a sense of efficacy that various and complex problems that may be raised in the field of early childhood education can be solved coop-eratively through PBL. Conclusions To improve the effectiveness of PBL classes, it is necessary to develop instructors' PBL teaching ca-pabilities, to understand the theoretical and practical instruction design and education methods, make efforts to enhance mutual learning and key competencies through PBL activities, and utilize various teaching methods and multimedia technologies.