Sensitivity of Gaussian energy broadening function of MCNP pulse height spectra on CLYC7 scintillation detector

The Cs2LiYCl6:Ce crystal (CLYC) is an inorganic scintillator which has been developed for the γ-ray and neutron measurement with the high detection efficiency, high resolution, and no need unfolding technique. To enhance the measurement of the fast neutron, the CLYC with 7Li-enrichment (CLYC7) scintillator is developed. In this work, the response of the CLYC7 detector to γ-ray is obtained using 137Cs γ-ray calibration source and calculated using Monte Carlo N-Particle transport code (MCNP). A comparison of measured and calculated γ-rays spectra is complicated by the fact that physical radiation detectors have finite energy resolution. In this study, we treated detector energy resolution effect by Gaussian energy broadening (GEB) in MCNP pulse height spectra calculation. We observe the parameters in the GEB function which provides simulation spectrum matches the experiment spectrum, especially on the photopeak region. The detail sensitivity of GEB function on CLYC7 scintillation detector is presented in this work

統計数理核融合学 ～統計数理による核融合研究課題の取り組み～

2022年7 月の第14回核融合エネルギー連合講演会にて特別講演「データ駆動核融合科学」を行った。核融合研究におけるデータ駆動アプローチによる研究遂行の大きな可能性を述べたものであり、その内容を文章としてまとめておくのが本記事の主旨である。特に、リアルタイム制御や、そのための予測や判断が必要とされる課題への挑戦には重要な視点であると考えている。また、核融合の研究課題を、学問分野を超えて共有・協働する上で効果的な視点であり、核融合コミュニティの拡大、学問としての拡がりにも大いに寄与する．特に、統計数理分野との協働を意図して、“統計数理核融合学”（統計数理による核融合研究課題への取り組み）という言葉とともに問いたい

Bonding of Tungsten and Graphite Using Spark Plasma Sintering for Divertor Component in LHD

The manufacturing of tungsten (W) - graphite bonded divertor components for the Large Helical Device (LHD) has been investigated. The spark plasma sintering method was used to bond W and graphite with titanium (Ti) interlayer. Small specimens were fabricated to investigate the bonding strength and to diagnose the bonding interface. The granular structure was formed in the grooved area on the graphite surface. It was suggested that this granular structure had affected the bonding strength

Feasibility study of neutral beam injection in Thailand Tokamak-1

Thailand Institute of Nuclear Technology (TINT) is developing Thailand- 1 (TT-1) from a former device HT-6 M of China. The first hydrogen plasma will be initiated in 2023. To investigate high-β plasma and physics related to fast ions, TT-1 will be equipped with auxiliary heating systems. In this work, a feasibility study for installing a neutral beam injection (NBI) heating system in TT-1 is carried out. This work is motivated to characterize beam ion\u27s orbits in different injection angles and to explore a condition suitable in terms of higher heating efficiency. In this work, we assume that a hydrogen beam will be launched into the TT-1 plasma with an acceleration voltage of 20 kV. The orbit simulations using the gyromotion following code LORBIT are performed in various magnetic field equilibria, i.e., different plasma current (Ip), toroidal magnetic field strength (Bt), and the magnetic axis (Rax). Furthermore, beam ions are injected in different directions, i.e., tangential co-injection and tangential counter-injection. In the case of co-injection, beam ion loss is not significant, by about 6%, whereas beam ion loss fraction is evaluated to be 26–34% in the case of counter-injection. Also, it is found that the number of lost beam ions is significantly affected by changing Ip and Rax. The results obtained in this work will directly support the experiment plan for the high-performance plasmas, design of the fast-ion diagnostic system, and systematic understanding of beam ion\u27s confinement property and beam-ion-driven magnetohydrodynamic (MHD) instabilities in TT-1

Residual magnetic field induced by superconducting magnets of Large Helical Device

The residual magnetic field was measured to investigate its source for the Large Helical Device, the superconducting magnet system of which consists of two Helical Coils (HCs), two Inner Vertical (IV) coils, two Inner Shaping (IS) coils, and two Outer Vertical (OV) coils. NbTi cable-in-conduit conductors were adopted for the IV, IS, and OV coils. Firstly, Hall probes were installed at five periodic positions on the mid-plane of the inner cylinder of the cryostat. Since the residual field was changed by around 0.1 mT at all the positions during the warm-up of the superconducting coils, a major part of the residual field had to be induced by magnetization of the coils. In the next campaign (cool-down, plasma experiment, and warm-up), the Hall probes were moved to the five different vertical positions in order to measure the distribution of the residual field. Calculation of the residual field has been carried out under the assumption that NbTi filaments in each conductor are magnetized in the same direction as the field at the center of the conductor during excitation. From comparison between the measured and calculated values, we conclude that the residual field from the coils that had been excited to high currents should be reduced by around 35%, due to the self-field in strands in the conductor. The best fitted critical current densities of the IV and IS coils are 1.31 and 2.81 × 1010 A/m2, respectively, which are consistent with the field dependence obtained from the magnetization curve of each strand

First measurements of p11B fusion in a magnetically confined plasma

Proton-boron (p11B) fusion is an attractive potential energy source but technically challenging to implement. Developing techniques to realize its potential requires first developing the experimental capability to produce p11B fusion in the magnetically-confined, thermonuclear plasma environment. Here we report clear experimental measurements supported by simulation of p11B fusion with high-energy neutral beams and boron powder injection in a high-temperature fusion plasma (the Large Helical Device) that have resulted in diagnostically significant levels of alpha particle emission. The injection of boron powder into the plasma edge results in boron accumulation in the core. Three 2 MW, 160 kV hydrogen neutral beam injectors create a large population of well-confined, high -energy protons to react with the boron plasma. The fusion products, MeV alpha particles, are measured with a custom designed particle detector which gives a fusion rate in very good relative agreement with calculations of the global rate. This is the first such realization of p11B fusion in a magnetically confined plasma

The design of a slit ICRF antenna in EU-DEMO

Although ICRF heating has achieved the high heating efficiency necessary to achieve high-performance plasmas, it has not overcome the reliability and economic problems associated with the antenna structure inside the vacuum vessel in fusion reactors. We suggested a slit ICRF antenna that uses the blanket surface as a transmission line to solve these problems. With a single slit ICRF antenna with a width of 3 m and a height of 15 cm, the electric field strength to the magnetic field direction was successfully suppressed to 5 kV/cm when 20 MW of power radiation was achieved from the single slit. The slit ICRF antenna had a bending angle in the electromagnetic wave transmission path to prevent direct neutron impact on the first wall and a vacuum gate from rapidly preventing water or air leakage accidents. The slit ICRF antenna has a simple structure that allows heating at high power density while minimizing blanket volume reduction

Numerical Analysis of Hysteresis Loss in Stacked REBCO Tapes for Large Current-Carrying Conductors

To evaluate the hysteresis loss in stacked HTS tapes for large current-carrying conductors, a single REBCO tape and 50 stacked REBCO tapes were modeled with the finite element method, including T-A formulation. Using the model, hysteresis losses in the single and stacked tapes were calculated under a condition that the direction of an external varying magnetic field was perpendicular to the tape plane. The calculation results were in good agreement with the measurement results. Consequently, the developed models are valid for a hysteresis loss calculation. In addition, we investigated magnetic field penetration into the stacked tapes using the model. The investigation shows that the external varying magnetic field used in the measurements cannot penetrate the center of the stacked tapes

Conceptual Design of Fusion Power Complex with Hydrogen Storage Function in Superconducting Magnet System

This paper is the first to define a conceptual design of a fusion power complex with hydrogen storage capability in a superconducting magnet system using cryogenic hydrogen. The fusion power complex realizes a carbon-neutral society by combining a large-capacity power source of renewable energy with the flexibility of energy output. Therefore, the proposed design is positioned as one of the most important next-generation power sources