The penetration of water during water flooding has been observed over many years using several methods. A microfocused X-ray computed tomography scanner can be used to directly observe 3D water flooding in a nondestru...The penetration of water during water flooding has been observed over many years using several methods. A microfocused X-ray computed tomography scanner can be used to directly observe 3D water flooding in a nondestructive manner. To eliminate the possibility of false images being produced because of X-ray broadening effects, we developed a visualization method by arranging the brightness distribution of all phases involved. Water flooding experiments were conducted using oil-wet and water-wet porous media. The water phase was injected upward into packed glass beads containing an oil phase, and the process was scanned every minute until steady state was reached. Using this scheme, real-time, the water invasion pattern and oil trapping process in clusters of pores and individual pores can be observed clearly. By eliminating false images, the boundary of each phase could be identified with high precision, even in a single pore. Porelevel phenomena, including snap off (which has never before been captured in a real 3D porous medium), piston-like displacement, and the curvature of the interface, were also observed. Direct measurement of the pore throat radius and the contact angle between the wetting and nonwetting phases gave an approximation of the capillary pressure during the piston-like displacement and snap-off processes.展开更多
Research activities in Japan relevant to particle beam inertial fusion are briefly reviewed.These activities can be ascended to the 1980s.During the past three decades,significant progress in particle beam fusion,puls...Research activities in Japan relevant to particle beam inertial fusion are briefly reviewed.These activities can be ascended to the 1980s.During the past three decades,significant progress in particle beam fusion,pulsed power systems,accelerator schemes for intense beams,target physics,and high-energy-density physics research has been made by a number of research groups at universities and accelerator facilities in Japan.High-flux ions have been extracted from laser ablation plasmas.Controllability of the ion velocity distribution in the plasma by an axial magnetic and/or electric field has realized a stable high-flux low-emittance beam injector.Beam dynamics have been studied both theoretically and experimentally.The efforts have been concentrated on the beam behavior during the final compression stage of intense beam accelerators.A novel accelerator scheme based on a repetitive induction modulator has been proposed as a cost-effective particle-beam driver scheme.Beam-plasma interaction and pulse-powered plasma experiments have been investigated as relevant studies of particle beam inertial fusion.An irradiation method to mitigate the instability in imploding target has been proposed using oscillating heavy-ion beams.The new irradiation method has reopened the exploration of direct drive scheme of particle beam fusion.展开更多
A global transport model is proposed in which a multimoment constrained finite volume （MCV） scheme is applied to a Yin-Yang overset grid. The MCV scheme defines 16 degrees of freedom （DOFs） within each element to ...A global transport model is proposed in which a multimoment constrained finite volume （MCV） scheme is applied to a Yin-Yang overset grid. The MCV scheme defines 16 degrees of freedom （DOFs） within each element to build a 2D cubic reconstruction polynomial. The time evolution equations for DOFs are derived from constraint conditions on moments of line-integrated averages （LIA）, point values （PV）, and values of first-order derivatives （DV）. The Yin-Yang grid eliminates polar singularities and results in a quasi-uniform mesh. A limiting projection is designed to remove nonphysical oscillations around discontinuities. Our model was tested against widely used benchmarks; the competitive results reveal that the model is accurate and promising for developing general circulation models.展开更多
A new cavitating model by using bubble size distribution based on mass of bubbles is proposed. Liquid phase is treated with Eulerian framework as a mixture containing minute cavitating bubbles. Vapor phase consists of...A new cavitating model by using bubble size distribution based on mass of bubbles is proposed. Liquid phase is treated with Eulerian framework as a mixture containing minute cavitating bubbles. Vapor phase consists of various sizes of minute vapor bubbles, which is distributed to classes based on their mass. The change of bubble number density for each class was solved by considering the change of bubble mass due to phase change as well as generation of new bubbles due to heterogeneous nucleation. In this method the mass of bubbles is treated as an independent variable, in other word, a new coordinate, and dependant variables are solved in Eulerian framework for spatial coordinates and bubble-mass coordinate. The present method is applied to a cavitating flow in a convergent-divergent nozzle, and the two-phase flow with bubble size distribution and phase change was successfully predicted.展开更多
Laser pulses with energy of -10μJ are generated at 46.9 nm on the 3p-3s transition of the Ne-like Ar by a fast capillary discharge setup in both 3-and 4-mm channels. The dependence of the laser output pulse energy on...Laser pulses with energy of -10μJ are generated at 46.9 nm on the 3p-3s transition of the Ne-like Ar by a fast capillary discharge setup in both 3-and 4-mm channels. The dependence of the laser output pulse energy on the pressure of Ar gas is measured for 3-mm-diameter capillaries at currents of 25, 30, and 35 kA. Under the same discharge conditions used in 3-mm capillaries, experiments indicate that higher and faster current pulses are required to produce soft X-ray amplification in 4-mm-diamater capillaries.展开更多
文摘The penetration of water during water flooding has been observed over many years using several methods. A microfocused X-ray computed tomography scanner can be used to directly observe 3D water flooding in a nondestructive manner. To eliminate the possibility of false images being produced because of X-ray broadening effects, we developed a visualization method by arranging the brightness distribution of all phases involved. Water flooding experiments were conducted using oil-wet and water-wet porous media. The water phase was injected upward into packed glass beads containing an oil phase, and the process was scanned every minute until steady state was reached. Using this scheme, real-time, the water invasion pattern and oil trapping process in clusters of pores and individual pores can be observed clearly. By eliminating false images, the boundary of each phase could be identified with high precision, even in a single pore. Porelevel phenomena, including snap off (which has never before been captured in a real 3D porous medium), piston-like displacement, and the curvature of the interface, were also observed. Direct measurement of the pore throat radius and the contact angle between the wetting and nonwetting phases gave an approximation of the capillary pressure during the piston-like displacement and snap-off processes.
文摘Research activities in Japan relevant to particle beam inertial fusion are briefly reviewed.These activities can be ascended to the 1980s.During the past three decades,significant progress in particle beam fusion,pulsed power systems,accelerator schemes for intense beams,target physics,and high-energy-density physics research has been made by a number of research groups at universities and accelerator facilities in Japan.High-flux ions have been extracted from laser ablation plasmas.Controllability of the ion velocity distribution in the plasma by an axial magnetic and/or electric field has realized a stable high-flux low-emittance beam injector.Beam dynamics have been studied both theoretically and experimentally.The efforts have been concentrated on the beam behavior during the final compression stage of intense beam accelerators.A novel accelerator scheme based on a repetitive induction modulator has been proposed as a cost-effective particle-beam driver scheme.Beam-plasma interaction and pulse-powered plasma experiments have been investigated as relevant studies of particle beam inertial fusion.An irradiation method to mitigate the instability in imploding target has been proposed using oscillating heavy-ion beams.The new irradiation method has reopened the exploration of direct drive scheme of particle beam fusion.
基金supported by National Key Technology R&D Program of China (Grant No. 2012BAC22B01)Natural Science Foundation of China (Grant Nos. 10902116, 40805045, and 41175095)Grants-in-Aid for Scientific Research, Japan Society for the Promotion of Science (Grant No. 24560187)
文摘A global transport model is proposed in which a multimoment constrained finite volume （MCV） scheme is applied to a Yin-Yang overset grid. The MCV scheme defines 16 degrees of freedom （DOFs） within each element to build a 2D cubic reconstruction polynomial. The time evolution equations for DOFs are derived from constraint conditions on moments of line-integrated averages （LIA）, point values （PV）, and values of first-order derivatives （DV）. The Yin-Yang grid eliminates polar singularities and results in a quasi-uniform mesh. A limiting projection is designed to remove nonphysical oscillations around discontinuities. Our model was tested against widely used benchmarks; the competitive results reveal that the model is accurate and promising for developing general circulation models.
文摘A new cavitating model by using bubble size distribution based on mass of bubbles is proposed. Liquid phase is treated with Eulerian framework as a mixture containing minute cavitating bubbles. Vapor phase consists of various sizes of minute vapor bubbles, which is distributed to classes based on their mass. The change of bubble number density for each class was solved by considering the change of bubble mass due to phase change as well as generation of new bubbles due to heterogeneous nucleation. In this method the mass of bubbles is treated as an independent variable, in other word, a new coordinate, and dependant variables are solved in Eulerian framework for spatial coordinates and bubble-mass coordinate. The present method is applied to a cavitating flow in a convergent-divergent nozzle, and the two-phase flow with bubble size distribution and phase change was successfully predicted.
文摘Laser pulses with energy of -10μJ are generated at 46.9 nm on the 3p-3s transition of the Ne-like Ar by a fast capillary discharge setup in both 3-and 4-mm channels. The dependence of the laser output pulse energy on the pressure of Ar gas is measured for 3-mm-diameter capillaries at currents of 25, 30, and 35 kA. Under the same discharge conditions used in 3-mm capillaries, experiments indicate that higher and faster current pulses are required to produce soft X-ray amplification in 4-mm-diamater capillaries.
