mean free path 

Statements about this table:
when vacuum range be medium vacuum the mean free path be 0.1 mm - 100 mm
in a medium vacuum the pressure be 1 - 10 - 3 hpa (mbar)
in a medium vacuum the mean free path be 0.1 - 100 mm
a mean free path of 0.1 - 100 km will occur when vacuum range be medium
vacuum range
pressure in hpa (mbar)
molecules / cm 3
molecules / m 3
mean free path
ambient pressure
1013
2.7 10 19
2.7 10 25
68 nm
low vacuum
300 - 1
10 19 - 10 16
10 25 - 10 22
0.1 - 100 μm
medium vacuum
1 - 10 3
10 16 - 10 13
10 22 - 10 19
0.1 - 100 mm
vacuum range
pressure in hpa (mbar)
molecules / cm 3
molecules / m 3
mean free path
high vacuum
10 3 - 10 7
10 13 - 10 9
10 19 - 10 15
10 cm - 1 km
ultra high vacuum
10 7 - 10 12
10 9 - 10 4
10 15 - 10 10
1 km - 10 5 km
extremely high vacuum
<10 12
<10 4
<10 10
>10 5 km