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Recent theoretical and numerical studies on laser-driven ion acceleration shows sub- relativistic ion acceleration with multistep acceleration schemes. The multistep acceleration with multiple laser pulses and multiple targets allow us to access the relativistic ion regime with the current and the future laser facilities. However, there is no relativistic ion detectors available in the field of laser ion acceleration. We have been developing energetic ion diagnostics using a combination of solid state nuclear path tracker and Thomson parabola, and scintillator base relativistic ion detectors commonly used in nuclear physics. We introduce our recent progress on the laser driven ion acceleration and the novel diagnostics., 日本物理学会2021年秋季大会

JT-60SAは、トカマク本体に加え、真空排気設備、極低温設備、電源設備、加熱設備など大規模な設備が複合した装置である。各設備が完成した後に統合コミッショニングを開始した。統合コミッショニングの項目としては主に、(1)真空容器及びクライオスタットの真空排気、(2)超伝導コイル冷却、(3)真空容器壁ベーキング、(4)超伝導コイル通電試験、(5)プラズマ試験、(6)超伝導コイル昇温、(7)真空容器及びクライオスタットの大気開放から構成される。統合コミッショニングにおいては、各設備との連携を確保しながら進めた。本講演では、統合コミッショニングの進捗、及び統合コミッショニングの後に予定されている装置増強に関して説明する。, 日本原子力学会 2021年秋の大会

国際トカマク物理活動（ITPA）の「輸送と閉じ込め物理」、「MHD安定性」、「計測」、高エネルギー粒子物理」，「周辺ペデスタル物理」及び「統合運転シナリオ」の各トピカルグループの会合が、平成31年3月から4月にかけてそれぞれオースチン（米国），デジョン（韓国），キャンベラ（オーストラリア），ロヴァニエミ（フィンランド） ，デジョン（韓国），那珂（日本）にて開催された。本稿では、各会合において議論した重要課題への取り組み状況やマルチマシン国際共同実験、ITERへの適用に向けた研究の進捗とともに、日本国内の開発の進展を中心に報告する。

プラズマ核融合学会にて、JT-60Uにおける内部輸送障壁に関する実験解析結果を報告した。, プラズマ核融合学会年会

We discuss the relativistic ion acceleration by irradiating a nanostructure target with ultra- intense laser. The nanostructure target is mounted on a large-area suspended graphene (LSG), which is a novel solid target with remarkable features such as the thinnest, lightest, strongest, transparent, and reasonable, for laser ion acceleration. We have developed various types of targets such as nanometer thin gold, and other materials on LSG, and now carbon nanotube on LSG. This will enable us to access the unexplored regime, relativistic ions., 日本物理学会 2020年秋季大会

国際トカマク物理活動（ITPA）の「高エネルギー粒子物理」、「計測」、「周辺ペデスタル物理」、「輸送と閉じ込め」、「統合運転シナリオ」、「MHD安定性」の各トピカルグループの会合が、2019年9月から10月にかけて開催された。各会合において議論した重要課題への取り組みや国際共同実験/解析の状況について、プラズマ・核融合学会誌を通して国内の研究者に報告する。

内部輸送障壁形成時のプラズマの過渡応答を観測し、プラズマの大域的応答の性質を見出し、プラズマ核融合学会にてポスター発表を行った。, 第36回プラズマ・核融合学会年会

2018年の秋季に国際トカマク物理活動（ITPA）に関する４つの会合（「MHD安定性」、「周辺ペデスタル物理」、「計測」、「統合運転シナリオ」）が開催された。各会合の概要をまとめて報告する。なお、次回会合は、2019年4月中に各々開催する予定である。

First divertor cassette covering a 10° sector in the toroidal direction has been manufactured for JT-60SA. Modularized plasma facing components such as inner and outer targets, baffles, and domes are assembled into the divertor cassette. All plasma facing components are actively cooled. Carbon armor tiles bolted to water-cooled copper alloy heat sinks are used to remove heat loads of 0.3–1MW/m2 for 100 s and 10 MW/m2 for less than 5 s. The divertor cassette has two pipe joints between it and the inlet and outlet pipes on the vacuum vessel side. After removing the divertor cassette, the inner target can be replaced by cutting and welding the other two pipe joints with the divertor cassette. A remote pipe welding tool has been developed both to install the divertor cassette into the vacuum vessel and to connect the inner target with the divertor cassette. The space around the cooling pipes is so limited that they are cut and welded remotely from the inside for replacement. The laser welding method was used, and the focusing mirror inside the pipe was rotated to perform circumferential welding. As a countermeasure for welding groove misalignment, the aiming accuracy of the laser was improved by simultaneously controlling the rotation and lifting of the tool. Thereby, reliable welding is achieved even with large gaps of up to 0.5 mm and grooves with a maximum angular deviation of 0.5 ° between connecting pipes. The outer diameter of the cooling pipe is 59.8 mm, the wall thickness is 2.8 mm, and the material is SUS316L. After connecting the inner target, the other plasma facing components have been assembled into the first lower divertor cassette. When installing the divertor cassette towards the vacuum vessel, the laser welding tool described above is used to connect the cooling pipes between divertor cassette and vacuum vessel in JT-60SA, because the outer diameter and wall thickness of the cooling pipe are the same as the inner target.

For local governments, it is indispensable to keep up emergency medical systems. But, young staff are not willing to work in local regions. I feel not a few patients are transported into hospitals in other medical care zones. I think we should know what kinds of characteristics of emergency medical systems are hidden in a local municipality such as Bibai City. I try to make them clear, analyzing indices of ambulance transports of Bibai and its neighborhood municipalities in Sorachi Subprefecture by comparison. Furthermore, the circumstances of nationwide emergency medical systems are made into consideration.

量研が開発する抵抗性MHDシミュレーションコードAEOLUS-ITにより、誤差磁場に捕捉された磁気島の三次元回転磁場による安定化の物理過程について議論する。特に、本発表では誤差磁場・磁気島と異なるヘリシティの回転磁場の磁気島成長に対する安定化効果について議論する。, 日本物理学会 第74回年次大会

量研が開発する抵抗性MHDシミュレーションコードAEOLUS-ITにより三次元回転磁場によるロックトモード制御の為の研究が進展している。本発表では、テアリング安定・不安定なプラズマにおける回転磁場のロックトモード解放/安定化の効果について、AEOLUS-ITによる非線形シミュレーション結果について発表する。, IFERC-CSC研究会

In JT-60U, simultaneous excitation of n = 1 helical cores (HCs) and m/n = 2/1 Tearing Modes (TMs) was observed [T. Bando et al., Plasma Phys. Control. Fusion 61 115014 (2019)]. In this paper, we have investigated the excitation mechanism of n = 1 HCs with m/n = 2/1 TMs based on the experimental observations and a simple quasi-linear MHD model. In the previous study, it was reported that a "coupling" on the phase of the MHD mode is observed between n = 1 HCs and m/n = 2/1 TMs. In this study, it is found that the coupling is observed with the mode frequency from several Hz to 6 kHz. This indicates that the resistive wall and the plasma control system do not induce the coupling because the both time scales are different from the mode frequency. In addition, n = 1 HCs appear to be the non-resonant mode from the two observations: n = 1 HCs do not rotate with the plasma around the q = 1 surface in the core and the coupling is also observed even when qmin > 1. It is also observed that the electron fluctuation due to an n = 1 HC in the core region disappears with the stabilization of an m/n = 2/1 neoclassical tearing mode by electron cyclotron current drive, implying that n = 1 HCs are driven by m/n = 2/1 TMs. This perspective, n = 1 HCs are driven by m/n = 2/1 TMs, is supported by the observation that the saturated amplitude of the m/n = 1/1 component of the radial displacement in the core is smaller than that of the m/n = 2/1 component. Finally, we revisit a quasi-linear MHD model where the m/n = 1/1 HC is induced directly by the sideband of the current for the m/n = 2/1 TM, which allows to excite the non-resonant m/n = 1/1 mode. The model also describes the characteristic of the coupling, fm/n=1/1(HC) = 2fm/n=2/1(TM).

We report the experimental finding of n = 1 helical cores (HCs) accompanied by saturated m/n = 2/1 tearing modes (TMs) with low mode frequencies in JT-60U. The HCs accompanied by TMs were observed after an increase in the mode amplitude and a decrease in the mode frequency of m/n = 2/1 precursors with tearing parity. The decreased mode frequency is typically lower than 20 Hz. With various diagnostics, the coupling of n = 1 HCs and m/n = 2/1 TMs has been clearly observed. Because the coherent oscillations in the ion temperature are observed in both the core region and the edge region, the flux surfaces including the m/n = 2/1 magnetic island appear to have m = 1 helical deformation. It has also been suggested that the m/n = 2/1 TM and the HC rotate in the electron diamagnetic direction keeping fm/n=1/1(HC) = 2fm/n=2/1(TM) in several plasmas. Here, fm/n=1/1(HC) is the mode frequency of HCs and fm/n=2/1(TM) is the mode frequency of TMs. In addition, the core seems to be shifted to the high-field side when the O-points of the m/n = 2/1 magnetic island line up in the midplane, which is confirmed by reconstructions of magnetohydrodynamic equilibria with motional Stark effect measurement and the MEUDAS code. Our observation of m/n = 2/1 TMs having HCs contributes to the understanding of the excitation mechanism of HCs in tokamak plasmas.

2015年の春季に国際トカマク物理活動(ITPA)に関する全4グループの会合が各グループ独立に開催された。「高エネルギー粒子物理」はフランスのITER機構で開催し日本からは2名の参加があった。「MHD安定性」はフランスのITER機構で開催し日本からは1名の参加があった。「統合運転シナリオ」はスペインのFusion for Energyで開催し日本からは3名の参加があった。「輸送と閉じ込め物理」はフランスのITER機構で開催し日本からは2名(TV会議参加)の参加があった。それぞれ、各極の関係者と国際装置間比較実験、ITERの物理に関する今後の課題、及び、各グループの活動計画の議論が行われた。これらの会合の概要をまとめて報告する。なお、次回会合は2015年の秋季に各グループ独立に開催する予定である。

In this study, we have simulated counterflow premixed flames to discuss burning velocity and OH concentration. Two-types of flow configuration are considered. One is twin premixed flames in symmetric counterflow premixed mixtures. The other is a single-flame in counterflows consisted of premixed mixture and air. The fuel is propane, and the equivalence ratio is 0.7 to 1.0. The detailed chemical kinetics model of GRI-Mech 3.0 using 53 species and 325 reactions is adopted. To change the stretch rate, the inflow velocity is varied from 0.5 to 3.5 m/s. The distance between two inflow boundaries is 15 mm. Based on the reaction rate, we have estimated the burning velocity at different stretch rates. Results show that the burning velocity is decreased with an increase of stretch rate. The burning velocity of the single-flame is smaller than that of twin flames at the same equivalence ratio and stretch rate. The clear relationship between maximum OH concentration in the flame zone and burning velocity is observed especially in the case of single-flame.

平成25年度宇宙輸送シンポジウム（2014年1月16日-17日. 宇宙航空研究開発機構宇宙科学研究所（JAXA)(ISAS)）, 相模原市, 神奈川県, Space Transportation Symposium FY2013 (January 16-17, 2014. Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency (JAXA)(ISAS)), Sagamihara, Kanagawa Japan, 資料番号: SA6000016093, レポート番号: STEP-2013-020