| condition |
pressure in mbar |
applications/matter density |
| normal pressure |
1000 |
respiration / at 20 C, 5 X 1019 molecules/cm3 |
| rough vacuum |
1000-100 |
vacuum cleaner, milking devices, vacuum packaging |
| intermediate vacuum |
1-10-3 |
simple chemical procedures, metal coating, metallurgy |
| high vacuum |
10-3 |
as above; light bulbs, picture tubes |
| ultrahigh vacuum |
below 10-6 |
chip manufacture, elementary particle acceleration below 1010 molecules / cm3 |
| Earth's atmosphere at 250 km |
10-7 |
109 molecules / cm3 at about 20° C |
Earth's atmosphere at 400 km
Vacuum tube of LEP rings
|
10-9 |
107 molecules / cm3 |
| Best vacuum reached today |
10-13 |
103 molecules /cm3 |
| matter density in interstellar space |
|
1 hydrogen atom / cm3 |
| "critical matter density" |
|
10-7 hydrogen atoms / cm3 |
| average matter density of visible matter in the universe |
|
10-9 hydrogen atoms / cm3 |
