What is an ultra high vacuum?

Ultra high vacuum applies to pressures less than 10

--7 Pascal or 100 nanopascals (one ten million Pascal). By comparison, atmospheric pressure is 101.3 kPa (kilopascals), which is more than billions higher, the pressure inside the bulb is about 1 pascal and the pressure in the walls of the thermos is about 0.1 passcals. Even the universe around the Earth is not an ultra -high vacuum, because it has a pressure of about 100 micropascals, a thousand times larger than in an ultra -high vacuum. In an ultra -high vacuum, the average free path of each gas molecule is 40 km, so these molecules collide many times with the walls of their chamber before they collide each other.

Ultra high vacuum is primarily used for surface analytical techniques such as anger electron spectroscopy, X -ray photoelectron spectroscopy, secondary ion mass spectrometry, thermal desorption spectroscopy, angle distinguished spectroscopy and thin film growth thin film growth techniques andThin film techniques and thin film growth techniques and thin film growth techniques and thin film growth techniques and thin film growth techniques and thin film growth techniques and thin film growth techniques and thin film growth techniques and thin film growth Molecular beam and UHV Chemical deposition of steam. The ultra high vacuum is also used in particle accelerators to create an empty beam path.

Creating an ultra high vacuum requires extraordinary measures. Special chambers constructions minimize the surface area, high -speed pumps, including parallel pumps, are used for pumps with high conductivity, pits of captured gas (as in the thread of the screw) must be eliminated, to be cooled to cryogenic temperatures to be used to KRyogenic temperature to be used as low those that must be used as low those to be used as low bodies that must be used as low bodies that must be used as low bodies that must be captured as columns that must be captured in nanoscopic liquids to be captured in nanoscopic liquids, which must be captured in nanoscopic liquids, which must be captured in nanoscopic liquids that must be captured. The system must be baked at 250 ° C to 400 ° C (482 ° F to 752 ° F) to remove hydrocarbon or water tracks. Outgassing - a slow intrusion of gas molecules with small cracks in the chamber - can be the main problem. Some chambers may be unable to produce an ultra -high vacuum due to the way they were made and the hardware must be fired and replaced. For all these reasons, it may be to achieve an ultra -high vacuum dRahé and difficult.

Although ultra high vacuum may seem extreme, some environments are even better vacuum, including the surface of the moon and interstellar space. Some areas of space, such as Boötes void, are so rare that there are only one atom per cubic meter.