Understanding of energetic particle (EP) confinement is one of the critical issues in realizing fusion reactor. In stellarator/helical devices, the research on EP confinement is one of the key topics to obtain better confinement by utilizing the flexibility of three-dimensional magnetic field. Study of EP transport in the Large Helical Device (LHD) has been performed by means of escaping EP diagnostics in hydrogen plasma operation. By starting deuterium operation of the LHD, confinement study of EPs has progressed remarkably by using newly developed comprehensive neutron diagnostics providing the information of EPs confined in the core region. The total neutron emission rate (Sn) increases due to the relatively low deviation of beam ion orbit from the flux surface with the inward shift of the magnetic axis. Sn has the peak around the electron density of 2×10 19 m -3 to 3×10 19 m -3 , as predicted. It is found that the fraction of beam-beam components in Sn is evaluated to be approximately 20% by the Fokker-Planck models TASK/FP in the plasma with both co-and counter-neutral beam injections. The equivalent fusion gain in DT plasma achieved 0.11 in a negative-ion-based neutral beam heated 2 plasma. Time evolution of Sn following the short pulse neutral beam injection into the electroncyclotron-heated low-beta plasma is reproduced by drift kinetic simulation, indicating that transport of beam ion injected by short pulse neutral beam can be described with neoclassical models in magnetohydrodynamic quiescent low-beta plasmas. The vertical neutron camera works successfully, demonstrating that in the co-neutral beam injected plasma, neutron emission profile shifts according to magnetic axis position. The shift of the neutron emission profile is reproduced by orbit-following models. The triton burnup study is performed for the first time in stellarator/heliotron so as to understand the alpha particle confinement. It is found that the triton burnup ratio, which largely increases at inward shifted configurations due to the better triton orbit and better plasma performance in inward shifted configuration is similar to that measured in tokamak having a similar minor radius with the LHD. We study the confinement capability of EPs toward a helical reactor in magnetohydrodynamic -quiescent region and expansion of the energetic-ion physics study in toroidal fusion plasmas.

The deuterium operation was initiated in the LHD in 2017. In the first campaign of the deuterium experiments, we successfully extended the high temperature regime in the LHD. The new record of the ion temperature of 10 keV associated with the ion internal transport barrier (ITB) was achieved due to several operational optimization. The confinement characteristics of ITB plasmas were compared between hydrogen and deuterium discharges. The ion thermal diffusivity was reduced in the ion-ITB plasmas with deuterium compared with the plasmas without deuterium. It was also found that the electron thermal confinement of the electron-ITB plasmas was clearly improved in the deuterium case.

Our findings indicate that the preoperative serum HA level is a good predictor of postoperative complications in patients who undergo hepatectomy for injured liver disease.

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The surveys of the ion and electron heat transports of Neutral Beam (NB) heating plasma were carried out by power balance analysis in He and H rich plasma of LHD. Collisionality was scanned by changing density and heating power. The characteristics of the transport vary depending on collisionality.In low collisionality with low density and high heating power, ion internal transport barrier (ITB) was formed. The ion heat conductivities (ci) is lower than electron heat conductivities (ce) in the core region at r < 0.7. On the other hand, in high collisionality with high density and low heating power, ci is higher than ce in the entire region of the plasma. These different confinement regimes are associated with different fluctuation characteristics. In ion ITB, fluctuation has a peak at r =0.7, and in normal confinement, fluctuation has a peak at r = 1.0. The two confinement mode changes gradually depending on the collisionality. The scan of concentration ratio between He and H were also performed. The ion confinement improvements were investigated by gyro-Bohm normalization taking account of the effective mass and charge. The concentration ratio affected the normalized ci only in the edge region ( r ~ 1.0 ). This indicates ion species effects vary depending on collisionality. Turbulence was modulated by the fast ion loss instability. The modulation of turbulence is higher in H rich than in He rich plasma.

A pulse detonation engine (PDE) can be operated even if there are no compression mechanisms such as compressors or pistons, and a rocket engine with an extremely low combustor fill pressure (pulse detonation rocket, PDR) thus becomes possible. In this research, we made a model PDR system with increased specific impulse by partial fill. The performance predicted by this model was then confirmed experimentally. The thrust can be calculated by using the simplified PDE model of Endo et al. and the partial filling effect models of Sato et al. The mass flow rate of the propellant supplied from the pressurized cylinders is considered in this calculation. As a result, the thrust performance can be determined by the kind of propellant, the initial conditions of the gas in the cylinders, the supply-valve orifice and PDE-tube volume, and the operation frequencies. We fabricated a pulse detonation rocket (PDR) named "TODOROKI" and verified the thrust calculation model via a horizontal sliding test. We confirmed that the stability of the PDE operation depends on the ratio between the purge-gas thickness and the tube diameter. The thrust predicted by the model was identical to experimental results within 4%.

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In this work, energetic-ion confinement and loss due to energetic-ion driven magnetohydrodynamic modes are studied using comprehensive neutron diagnostics and orbit-following numerical simulations for the Large Helical Device (LHD). The neutron flux monitor is employed in order to obtain global confinement of energetic ions and two installed vertical neutron cameras (VNCs) viewing different poloidal cross-sections are utilized in order to measure the radial profile of energetic ions. A strong helically-trapped energetic-ion-driven resistive interchange mode (EIC) excited in relatively low-density plasma terminated high-temperature state in LHD. Changes in the 2 neutron emission profile due to the EIC excitation are clearly visualized by the VNCs. The reduction in the neutron signal for the helical ripple valley increases with EIC amplitude, which reaches approximately 50%. In addition to the EIC experiment, orbit-following simulations using the DELTA5D code with EIC fluctuations were performed to assess the energetic-ion transport and loss. Two-dimensional temporal evolution results show that the neutron emissivity at the helical ripple decreases significantly due to the EIC. The rapid reduction in neutron emissivity shows that the helically-trapped beam ions immediately escape from the plasma. The reduction in the VNC signals for the helical ripple valley and the total neutron emission rate increase with increasing EIC amplitude, as observed in the experiment. Calculated line-integrated neutron emission results show that the profile measured by VNC1 has one peak, whereas the profile measured by VNC2 has two peaks, as observed in the experiment. Although the neutron emission profile for VNC2 has a relatively wide peak compared with the experimental results, the significant decrease in neutron signal corresponding to the helical ripple valley was successfully reproduced.