From constructional reasons we accept distance from processable details up to wall of the chamber of 80 mm. Thus, we accept length of the chamber - 3,72 m, height - 2,755 m, width - 0,9 m. Volume of the chamber 5,66 м3.
For clearing accelerators with the anode layer, located on flanges which fasten to the mouths welded to VC are used. Length of flanges - 730 mm.
Thickness of a wall of the chamber - 10 mm, doors - 15 mm. Doors fasten with the help of folding bolts.
Walls and covers of the chamber are made of stainless steel Х18Н10Т. Thickness of VC shell 10 mm, cover 15 mm. For condensation we use rubber ИРП-1368.
As the vacuum system assumes three lines of spilling, working in parallel, we shall accept making elements and lengths of pipelines in these lines identical and we shall execute calculation of one of them.
For calculation of vacuum system in the given work the technique stated in [24] is used.
The gas stream which is pumped out by the pump during the steady-state mode of vacuum system is defined:
Q=Qс+Qт, (4.1)
Qc=Qг+Qн, (4.2)
where Qс – total gas evolution and leakage in vacuum installation, Qг – gas evolution from constructional materials, Qн – leakage through the casing of the chamber, Qт – technological leakage.
Gas evolution from constructional materials occurs due to following processes: adsorptive gas evolutions, diffusion gas evolutions, gas permeability.
Leakage through the casing of the chamber happens as on folding and not folding connections which cannot provide absolute tightness, and on continuous metal.
For the approached definition of total gas evolution in the vacuum chamber it is possible to take advantage of specific gas evolution of materials and define Qг as:
, (4.3)
where qi·и Wi·- specific gas evolution and gas permeability of materials, Si – the areas of surfaces of corresponding materials, p1 – external pressure, p2 – pressure inside of the chamber, δi – wall thickness of the vacuum chamber element executed from the given material.
Factor of specific gas evolution of chamber walls material steel Х18Н10Т: 
, gas permeability of
steel is not considered because of it smallness.
Factors of specific gas evolution and gas permeability of consolidation
material are equal: 
and 
accordingly. At
calculation we consider rubber consolidation of the essential size, i.e. consolidation
on the chamber covers, on plasma ionic installations flanges.
After transformations the formula (4.3) will become:
, (4.4)
where
Sст и Sрез – the sum of the areas of
surfaces of the walls material, covers and rubber consolidation accordingly;
– consolidation
thickness, mm; pнар – external pressure, we
accept pнар=760 torr; pраб – pressure inside of the chamber.
.
We shall define technological leakage. At the steady-state mode of vacuum installation in working gas 1 % of other gases impurity is supposed, means:
, (4.5)
.
Total leakage under the formula (5.1):
.
The choice of vacuum pumps is made at the steady-state mode of pumps at the set gas stream and working pressure. Thus a condition of the steady-state mode is equality of pump speed and gas evolutions:
, (4.6)
where SQ – gas evolution speed, Sэф – effective pump speed.
For creation of operating vacuum the pump with operating ratio 
was chosen; working pressure 
torr, limiting pressure
torr. The pump was selected from pump
speed S:
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