One step in the manufacture of optical fibers is the chemical vapor deposition of silane (SiH4) on the inside surface of a hollow glass fiber to form a very thin cladding of solid silicon as shown in Figure below. Typically, the process is carried out at high temperature and very low total system pressure. Optical fibers for high bandwidth data transmission have very small inner pore diameters, typically less than 20m. If the inner diameter of the Si-coated hollow glass fiber is 10m, assess the importance of Knudsen diffusion for SiH4 inside the fiber lumen at 900K and 100Pa total system pressure. And estimate the diffusivity coefficient. Silane is diluted to 1.0mol% in the inert carrier gas helium (He). The binary gas phase diffusivity of silane in helium at 25C and 1.0atm total system pressure is 0.571cm2/s, with SiH4=4.08A and SiH4/k=207.6K. The molecular weight of silane is 32g/mol