Rarefied Gas Flow through Long Rectangular Channel with Very Small Gap-to-Width Ratio: Experiments and DSMC Calculations

A non-destructive, fast 2D profile monitor for an ion beam accelerator can be achieved by creating a high-density gas-sheet target in vacuum. It is known that gas flow through long rectangular channel with very small gap-to-width ratio effectual forming sheet. To obtain sheet the desired performance, spatial distribution of emitted molecules candidate should examined more detail. As part development, load also investigated to maintain tubes ultra-high For efficient investigation, we explored possibility using direct simulation Monte Carlo (DSMC) method instead experiments. We measured (N2 and Ar) gap = 0.1 mm, width b 50 length L 100 mm derived vacuum conductance C Knudsen number (Kn) range 0.03–104. Then, comparing Kn dependence conductance, DSMC was used calculate transmission probability (the Clausing factor Ck) passing infinite width. The changes Ck are similar. decreases from ∼103, begin decrease rapidly reach minimum when between 1 0.5. Then they increase as further <0.5. Furthermore, successfully simulated ejected molecular collisions occur increasing inlet pressure.