@phdthesis{oai:tsukuba.repo.nii.ac.jp:00008689,
 author = {Nakai, Hirotaka and 仲井, 浩孝},
 month = {},
 note = {Cooling systems in space using superfluid helium require some important devices to accomplish their roles, because there is very small gravitational force. One of them is a phase separator which separates superfluid helium from its vapor. Another device is a thermomechanical pump which tranfers and circulates suprefluid helium in a cooling system. Thermomechanical effect (fountain effect) of superfluid helium with a porous medium gives a simple but effective working principle to such devices. Unfortunately, however, not all situations of the superfluid helium flow through a porous medium are ideal, i. e. , predicted theoretically on the basis of two-fluid equations without appreciable dissipation effects. This study has an objective to understand experimentally the superfluid helium flow through a porous medium, i. e. , a common phenomenon for both porous plug phase separators and thermomechanical pumps. In this experimental study, flow characteristics of superfluid helium through a porous element of a thermomechanical pump are measured precisely with the special emphasis on the observation of a transition from the ideal state to the superfluid turbulent one. It is found that the critical heat input depends on the temperature of superfluid helium. Its temperature dependence is also quantitatively clarified. General flow characteristics of superfluid helium through a porous medium are proposed, concerning with properties of the porous medium, based on the experimental data on the suprefluid helium flows through both porous plug phase separators and porous elements of thermomechanical pumps. They may be a great help to understand the flow of suprefluid helium through a porous medium., 1994},
 school = {筑波大学, University of Tsukuba},
 title = {Superfluid helium flow through porous medium},
 year = {1995}
}