Development of a vacuum pump without a moving part with the aid of thermal transpiration flow of a rarefied gas

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The subject that we proposed is studied in the following two directions.1. Flows induced in a rarefied gas by its temperature fieldThe comprehensive study of flows induced by temperature fields is made in order to find the possibility of constructing a pump without any moving part with the aid of the flow.(1) It is experimentally observed for the first time that a flow is induced around the edge of a uniformly heated plate.(2) Flows induced between two coaxial elliptic cylinders with different temperatures are studied numerically on the basis of kinetic theory for the whole range of the Knudsen number. The configuration of the flow is found to be considerably affected by the global geometry of the system except in the case of small Knudsen numbers.(3) One-way flows induced in a circular pipe with a periodic temperature distribution and with ditches periodically dug are studied numerically in details. The pumping effect is found to be several times larger than that of the channel flows … More studied previously by Sone et al.(4) It is experimentally observed that a one-way flow is induced in a pipe without average pressure and temperature gradients, as in item (3). The experiment shows that the shape of the pipe is essential to inducing a one-way flow.(5) The results obtained, combined with those of our previous research, are formed into a systematic survey of flows induced by temperature fields.These studies show that a pumping system without a moving part is not difficult to be realized with the aid of the thermal transpiration.2. Flows with evaporation or condensation in relation to a cryo-pumping system(1) Weak evaporation from or condensation onto a spherical condensed phase are studied analytically and numerically on the basis of kinetic theory, and the detailed behavior of the flow is clarified for the whole range of the Knudsen number. Further, Onsager's relation is shown to hold for arbitrary Knudsen numbers.(2) Transonic condensing flows onto a plane condensed phase are studied analytically. The analytic structure of the solution, especially, the discontinuous change of the range of existence of a solution across the sonic point is clarified.(3) Cylindrical Couette flows between two axial circular cylindrical condensed phases are studied in details. New type of bifurcation is found to exist, and the range of the parameters where the bifurcation takes place and its physical mechanism etc. are clarified. Less