ヘリオトロンJにおける高エネルギー粒子駆動不安定性の運動論的磁気流体力学ハイブリッドシミュレーション研究

京都大学新制・課程博士博士(エネルギー科学)甲第23538号エネ博第429号新制||エネ||81(附属図書館)京都大学大学院エネルギー科学研究科エネルギー基礎科学専攻(主査)准教授 門 信一郎, 教授 中村 祐司, 教授 長﨑 百伸学位規則第4条第1項該当Doctor of Energy ScienceKyoto UniversityDFA

Simulations of energetic particle driven instabilities in CFQS

A nonlinear simulation of the energetic particle driven instabilities in the Chinese First Quasi-axisymmetric Stellarator (CFQS) has been conducted for the first time. MEGA, a hybrid simulation code for energetic particles interacting with a magneto-hydrodynamic fluid, was used in the present work. Both the m/n = 3/1 energetic-particle-mode (EPM) like mode and the m/n = 5/2 toroidal Alfvén eigenmode (TAE) were found, where m is the poloidal mode number and n is the toroidal mode number. Four important results were obtained as follows. First, the instability in the CFQS in three-dimensional form was shown for the first time. Second, strong toroidal mode coupling was found for the spatial profiles, and it is consistent with the theoretical prediction. Third, the resonant condition caused by the absence of axial symmetry in CFQS was demonstrated for the first time. The general resonant condition is fmode = Nfϕ − Lfθ, where fmode, fϕ, and fθ are mode frequency, particle toroidal transit frequency, and particle poloidal transit frequency, respectively; N and L are arbitrary integers, represent toroidal and poloidal resonance numbers. For EPM-like mode, the dominant and subdominant resonant conditions are fmode = 3fϕ − 7fθ and fmode = fϕ − fθ, respectively. For TAE, the dominant and subdominant resonant conditions are fmode = 4fϕ − 9fθ and fmode = 2fϕ − 3fθ, respectively. On the one hand, the toroidal resonance numbers are different from the toroidal mode numbers by 2. This indicates that the two-fold rotational symmetry affects the resonance condition. On the other hand, the subdominant resonances satisfy N = n, which is expected for the axisymmetric plasmas and most of the toroidal plasmas including stellarators. Fourth, the nonlinear frequency chirpings in CFQS were demonstrated for the first time. Hole and clump structures were formed in the pitch angle and energy phase space, and the particles comprising the hole and clump were kept resonant with the modes during the mode frequencies chirping

Evaluation of Sida’s Model for Bilateral Research Cooperation

The purpose of the evaluation is to provide an overall assessment of the extent to which Sida’s model for bilateral research cooperation builds research capacity in low-income countries. The assessment will serve as input to the in-depth review for the strategy for research cooperation and research in development cooperation

Simulation study of interaction between energetic particles and magnetohydrodynamic modes in the JT-60SA inductive scenario with a flat q≈1 profile

ORCID　0000-0001-7332-037XInteractions between energetic particles (EPs), an internal kink mode, and other magnetohydrodynamic (MHD) instabilities in the inductive scenario of JT-60SA (scenario #2) are simulated with MEGA, a global EP–MHD hybrid code. For this scenario, it was predicted by TOPICS, an integrated transport code that the internal kink mode can be unstable and the sawtooth relaxation results in a flat safety factor (q) profile with q ≈ 1 for r/a ⩽ 0.6. In this equilibrium, it is found in the simulation results that the stability of the internal kink mode depends strongly on the bulk plasma pressure gradient (∇Pb). In the n = 1 simulations where the toroidal mode number is restricted to n = 0 and 1, the pressure-driven internal kink mode is dominant. In the presence of co-passing EPs generated by the negative-ion-based neutral beam (NB), these EPs transfer energy to the internal kink mode; however, the EP driving rate (γh) is much lower than the driving rate from the bulk plasma pressure gradient (γP). The mode’s frequency is less than 1 kHz because the toroidal orbit frequency (ωϕ) and poloidal orbit frequency (ωθ) of the co-passing EPs are approximately equal within the q = 1 surfaces. This mode affects the EP and bulk plasma pressure redistributions. The feasibility of stabilizing the internal kink mode using trapped EPs is also investigated. It is found that the trapped EPs with energy 85 keV generated by the positive-ion-based NBs cannot stabilize the internal kink mode. Stabilization is observed when the injection energy is greater than 500 keV. In the multi-n simulations, where n ⩽ 8 modes are retained, the most unstable modes are high n interchange loidal number m = n whose linear growth rates exceed that of the pressure-drive

‘Fit for school’ – a school-based water, sanitation and hygiene programme to improve child health: Results from a longitudinal study in Cambodia, Indonesia and Lao PDR

Abstract Background The Fit for School (FIT) programme integrates school health and Water, Sanitation and Hygiene interventions, which are implemented by the Ministries of Education in four Southeast Asian countries. This paper describes the findings of a Health Outcome Study, which aimed to assess the two-year effect of the FIT programme on the parasitological, weight, and oral health status of children attending schools implementing the programme in Cambodia, Indonesia and Lao PDR. Methods The study was a non-randomized clustered controlled trial with a follow-up period of two years. The intervention group consisted of children attending public elementary schools implementing the FIT programme, including daily group handwashing with soap and toothbrushing with fluoride toothpaste, biannual school-based deworming; as well as construction of group handwashing facilities. Control schools implemented the regular government health education curriculum and biannual deworming. Per school, a random selection of six to seven-year-old grade-one students was drawn. Data on parasitological infections, anthropometric measurements, dental caries, odontogenic infections and sociodemographic characteristics were collected at baseline and at follow-up (24 months later). Data were analysed using the χ2-test, Mann Whitney U-test and multilevel logistic and linear regression. Results A total of 1847 children (mean age = 6.7 years, range 6.0–8.0 years) participated in the baseline survey. Of these, 1499 children were available for follow-up examination – 478, 486 and 535 children in Cambodia, Indonesia and Lao PDR, respectively. In all three countries, children in intervention schools had a lower increment in the number of decayed, missing and filled permanent teeth between baseline and follow-up, in comparison to children in controls schools. The preventive fraction was 24% at average. The prevalence of soil-transmitted helminth infection (which was unexpectedly low at baseline), the prevalence of thinness and the prevalence of odontogenic infections did not significantly differ between baseline and follow-up, nor between intervention and control schools. Conclusions The study found that the FIT programme significantly contributed to the prevention of dental caries in children. This study describes the challenges, learnings and, moreover, the importance of conducting real-life implementation research to evaluate health programmes to transform school settings into healthy learning environments for children. The study is retrospectively registered with the German Clinical Trials Register, University of Freiburg (Trial registration number: DRKS00004485, date of registration: 26th of February, 2013)

Research Plan of Complex Global Simulation Unit

ORCID　0000-0001-9323-8285Global simulation, which takes into account the interactions between multiple hierarchies, is expected to be realized not only in the field of nuclear fusion research but also in other academic fields. However, such a complex global simulation is difficult to realize because the temporal and spatial scales of the microscopic hierarchy and those of the entire system are generally extremely different. The aim of the Complex Global Simulation Unit at the National Institute for Fusion Science is to develop simulation methods to address the abovementioned issue and to promote simulation research. This unit aims to develop 1) a global simulation of the whole magnetically-confined fusion plasma, including the core and peripheral plasma, based on the kinetic-magnetohydrodynamic hybrid simulation coupled with the gyrokinetic Poisson equation, and 2) a methodology with broad applicability for enabling simulations that closely reproduce real-world phenomena, transcending the strong limitations imposed by the capacity and capability of supercomputers. In addition, the unit aims to develop a method for coupling a particle-in-cell simulation and a global analysis of plasma waves. Furthermore, it aims to develop a multiphase (solid, liquid, gas, and plasma) simulation method for pellet injection into fusion plasmas