Youichi Ogata

Demonstrated fossil-fuel-free energy cycle using magnesium and laser

The authors propose an energy cycle based on a renewable fuel. Magnesium is chosen as an energy carrier and is combusted with water to retrieve energy using many power devices. MgO, the combustion residue, is reduced back to Mg by laser radiation generated from solar and other renewable energy sources. They have achieved an energy recovery efficiency of 42.5% for converting MgO to magnesium, using a laser. Combined with a demonstrated 38% efficiency for converting an artificial sunlight source (metal halide lamp) into laser output energy indicates that the proposed energy cycle is already in a feasible range for practical use.

Microairplane propelled by laser driven exotic target

We propose a propulsion concept to drive a microairplane by laser that can be used for observation of climate and volcanic eruption. Since it does not have to develop thrust for vertical takeoff, and it has no engine in the normal sense, the microairplane can be very light, with its payload consisting only of observation and communication equipment. In order to demonstrate the concept, we succeeded in flying a paper microairplane driven by a 590 mJ, 5 ns pulse yttrium–aluminum–garnet laser that impinges on a double-layer “exotic target.” The coupling efficiency agrees well with simulations and with experiments.

The next generation CIP as a conservative semi-Lagrangian solver for solid, liquid and gas

We present a review of the CIP method, which is a kind of semi-Lagrangian scheme and has been extended to treat incompressible flow in the framework of compressible fluid. Since it uses primitive Euler representation, it is suitable for multi-phase analysis. The recent version of this method guarantees the exact mass conservation even in the framework of semi-Lagrangian scheme. Comprehensive review is given for the strategy of the CIP method that has a compact support and subcell resolution including front capturing algorithm with functional transformation.

Three-dimensional simulations of molecular cloud fragmentation regulated by magnetic fields and ambipolar diffusion

We employ the first fully three-dimensional simulation to study the role of magnetic fields and ion-neutral friction in regulating gravitationally-driven fragmentation of molecular clouds. The cores in an initially subcritical cloud develop gradually over an ambipolar diffusion time while the cores in an initially supercritical cloud develop in a dynamical time. The infall speeds on to cores are subsonic in the case of an initially subcritical cloud, while an extended (& 0.1 pc) region of supersonic infall exists in the case of an initially supercritical cloud. These results are consistent with previous two-dimensional simulations. We also found that a snapshot of the relation between density (ρ) and the strength of the magnetic field (B) at different spatial points of the cloud coincides with the evolutionary track of an individual core. When the density becomes large, both relations tend to B / ρ 0.5 .

Simulation and Experiments on Laser Propulsion by Water Cannon Target

In previous papers, we reported the successful flight of paper‐airplane about 5 cm. Application of such micro‐airplane to CO2 measurement and tornado observation is proposed. For practical application, repetitive water supply system and levitation system are proposed and examined by experiments. The latter can also be used for launching waste of nuclear reactor and structural materials for space station. Some future applications like stratospheric airplane and microship in human blood vessel are discussed.

EFFICIENT COMPUTATION OF MAGNETO-HYDRODYNAMIC PHENOMENA IN ASTROPHYSICS BY CCUP-MOCCT METHOD

We proved that the CIP (Constrained Interpolation Profile/Cubic Interpolated Pseudoparticle)-MOCCT (Method of Characteristics/Constrained Transport) is capable of treating MHD phenomena using a mesh several times coarser than the conventional schemes. Comparing the present method with the modified Lax-Wendroff methods in the Parker instability in two and three dimensions, the superiority of the CIP scheme has been demonstrated from its low numerical phase error and damping rate. In addition, we employ the CIP-CUP (CIP-combined unified procedure/CCUP) method that solves the Poisson equation for pressure in order to make the present scheme more stable. This method is able to treat the pressure scale height having just one grid, which is five times coarser than the conventional scheme, as well as the magnetic reconnection, which has been described with a coarse grid.

Laser‐Driven Water‐Powered Propulsion and Air Curtain for Vacuum Insulation

In previous papers, we reported the successful flight of paper‐airplane‐about 5 cm‐size [1]. Since then, we try to find out a new possibility of the laser propulsion that uses overlay structure especially using water leading to high efficiency [2]. In order to this concept in high altitude, we need to insulate the water layer from vacuum, otherwise water will be evaporated or freeze in vacuum condition. For this purpose, we here propose an “air curtain”. We have done simulation and experiments on this concept. Furthermore, we examined in detail the various features of water exotic target by pendulum and semi‐conductor load cell. The coupling coefficient and specific impulse are discussed both by simulation and experiments.

Experimental Study of Solar Pumped Laser for Magnesium‐Hydrogen Energy Cycle

This paper describes the initial experiments on solar pumped laser which is intended to be used as an energy converter for a new reusable energy cycle. Research has been conducted with the use of devices and elements which are compatible with industrial production. Frasnel lens and Chromium ion co‐doped Nd:YAG ceramic laser media have been employed for the lasing demonstration of a solar pumped laser system for the first time. Basic properties of the system such as solar power concentration for lasing threshold and enhancements of pumping efficiency have been experimentally measured.

A Dream to Solve All Phases of Matter, Solid, Liquid, and Gas, Simultaneously

Various innovations in basic technology have made the developing speed of computer hardware faster than that of software technology. Similar innovations are required in order to accelerate the developing speed of software. A universal solver for computational engineering problems would be such an innovation. Recently developed high technology requires new tools for the combined analysis of materials in the different phase states, i.e., solid, liquid, and gas. A universal treatment of all phases by one simple algorithm is essential, and we are at a turning point to achieve this goal. We need to treat the topology and phase changes of the structure in processes like welding and cutting. In processes such as freezing, condensation, melting, and evaporation, the grid system initially aligned to the solid or liquid surface does not provide correct information of the surface at later time, and the mesh is sometimes distorted or even broken up.

Recent Advances of Multi-phase Flow Computation with the Adaptive Soroban-grid Cubic Interpolated Propagation (CIP) Method

Recent developments of simulation technology have enabled the combined analysis of solid, liquid and gas. However, it is still challenging to establish simultaneous treatment of materials undergoing phase state transition. This is because the conventional combined analysis relies on the separate treatment of each phase.