Pressure Distribution and Pumping Delay Time in Short-Spacing Parallel Planes

The two-dimensional pressure distribution and pump-down performance between two parallel planes having a short-distance were simulated by a Monte-Carlo method, assuming the cosine-law for desorbing molecules. The distribution results were compared with those calculated by a diffusion model. The surface hitting number per molecule was also counted, and the delay time of the pumping process was evaluated by multiplying the hitting number and the surface sojourn time. The experimental observation for the delay time was compared with the calculated ones