Knudsen cell A piece of apparatus, consisting of a crucible (made of pyrolytic boron nitride, quartz, tungsten or graphite), heating filaments, a water cooling system, which is used to measure very low vapor pressures by measuring the mass of vapor which escapes when the vessel contains a liquid in equilibrium with its vapor. It is also used as a source evaporator during crystal growth e.g. during molecular-beam epitaxy. 2009-09-29T06:39:36Z CHMO:0002473 https://orcid.org/0000-0001-5985-7429 device