Experimental and numerical investigation in flow configurations related to the vacuum systems of fusion reactors

Vacuum flows in various configurations, which are related to fusion reactors are simulated using linear kinetic theory and the direct simulation Monte Carlo method (DSMC), in the whole range of the Knudsen number. In the case of flows through channels of infinite length, even for large pressure differences, the flow is linear (fully developed) and linearized kinetic theory has been applied with considerable success. In the case of flows through channels of finite length, the flow is strongly non-equilibrium and has to be tackled by the DSMC method. In the present work we present a comparative study between experimental and computational results for the case of circular channels of finite length. Experimental data and corresponding computational results are provided for the conductance of channels with different lengths and several downstream to upstream pressure ratios, covering a wide range of the Knudsen number. In addition, a brief review of some recent work related to the case of long channels is presented and general remarks related to the overall flow conditions and characteristics for flows through channels of various lengths and cross sections are stated.