Review of papers regarding vacuum system and
materials
M. Wong, 21-Mar-02
This review summarizes the
outgassing rates of various materials:
·
Aluminum
·
Epoxies
·
Kapton
·
Plastics
Also described are the
results of various cleaning methods.
Chart 1
summarizes the outgassing rates of aluminum.
Note the different methods of measurement and treatment of samples.
|
Material |
Treatment |
Outgassing rate (torr-L/sec-cm2) |
Time meas. (hours) |
Test method |
Reference |
Year |
|
Aluminum |
None |
1x10-6 |
1h |
|
Schamus (ref Markley, et al) |
1999 |
|
Aluminum |
Degassed |
1.7x10-7 |
1h |
|
Schmaus (ref Markley, et al) |
1999 |
|
Aluminum |
Degassed |
2.7x10-8 |
10h |
|
Schmaus (ref Markley, et al) |
1999 |
|
Aluminum 6061-T6 |
Baked 13.5h @ 300°C |
1.4x10-8 |
10h |
|
Schmaus (ref Das) |
1999 |
|
Aluminum |
Cleaned |
8x10-9 |
10h |
|
Schmaus (ref Blears, et al) |
1999 |
|
Aluminum |
Fresh, degreased w/ trichloroethylene & cleaned w/
ethyl alcohol |
6.3x10-9 |
1h |
conductance |
Elsey (ref Schram) |
1975 (1963) |
|
Aluminum |
Degassed |
4.6x10-9 |
100h |
|
Schmaus (ref Markley, et al) |
1999 |
|
Aluminum 6061-T6 |
Baked @ 200°C |
4.5x10-9 |
10h |
|
Schmaus (ref Das) |
1999 |
|
Aluminum |
Degassed 24h, degreased w/ trichloroethylene & cleaned
w/ ethyl alcohol |
4.14x10-9 |
1h |
conductance |
Elsey (ref Schram) |
1975 (1963) |
|
Aluminum 6061-T6 |
None |
2.5x10-9 |
10h |
|
Schmaus (ref Das) |
1999 |
|
Aluminum 5083-O |
Bell jar, as received, room temp. |
2.18x10-9 |
10.3h |
Rate-of-rise |
Schrank, et al |
1964 |
|
Aluminum 5083-O |
Bell jar, as received, room temp. |
1.27x10-9 |
8h |
Conductance |
Schrank, et al |
1964 |
|
Aluminum 5083-O |
Bell jar, as received, room temp. |
6.6x10-10 |
24h |
Conductance |
Schrank, et al |
1964 |
|
Aluminum 5083-O |
Bell jar, as received, room temp. after baking @ 220°C |
4.6x10-10 |
50h (baked @27-31h) |
Conductance |
Schrank, et al |
1964 |
|
Aluminum 6061-T6 |
Baked 15h @ 300°C |
1.6x10-10 |
10h |
|
Schmaus (ref Das) |
1999 |
|
Aluminum |
Degassed 24h, degreased w/ trichloroethylene & cleaned
w/ ethyl alcohol |
3.06x10-10 |
1h |
conductance |
Elsey (ref Schram) |
1975 (1963) |
|
Aluminum 5083-O |
Bell jar, no. 4 finish (lapped), room temp. |
2.87x10-10 |
6.0h |
Rate-of-rise |
Schrank, et al |
1964 |
|
Aluminum |
Fresh, degreased w/ trichloroethylene & cleaned w/
ethyl alcohol |
6.0x10-10 |
10h |
conductance |
Elsey (ref Schram) |
1975 (1963) |
|
Aluminum, type 1100 |
Cleaned w/ detergent, rinsed w/ acetone, pumped 24 hours |
~10-10 |
0 |
conductance |
Young |
1968 |
|
Aluminum |
LEP vacuum chamber, chem.. clean, baked in situ @ 150°C |
2.3x10-11 |
24h |
|
Mathewson, et al |
1988 |
|
Aluminum 6061-T4 |
Degreased in acetone w/ methanol rinse; baked 100°C |
6x10-12 |
24h |
Rate-of-rise & conductance |
Halama, Herrera |
1976 |
|
Aluminum 6061-T4 |
Degreased in acetone w/ methanol rinse, chem polished,
baked 100°C |
3x10-12 |
24h |
Rate-of-rise & conductance |
Halama, Herrera |
1976 |
|
Aluminum 6061-T4 |
Degreased in acetone w/ methanol rinse, chem polished,
glow discharge in Ar, baked 100°C |
5x10-13 |
24h |
Rate-of-rise & conductance |
Halama, Herrera |
1976 |
|
Aluminum, type 1100 |
Above plus baked 15h @ 250°C under vacuum |
4x10-13 |
24h @ room temperature |
conductance |
Young |
1968 |
|
Aluminum |
PETRA vacuum chamber, glow discharge@145°C |
1x10-13 |
Up to 200h |
In situ glow discharge, conductance |
Mathewson, et al |
1977 |
Chart 2 summarizes
the outgassing rates of stainless steels, along with the surface treatment and
pumping time.
|
Material |
Treatment |
Outgassing rate (torr-L/sec-cm2) |
Time meas. (hours) |
Test method |
Reference |
Year |
|
Stainless steel |
None |
6.4x10-7 |
1h |
|
Schamus (ref Markley, et al) |
1999 |
|
Stainless steel |
degreased |
4x10-7 |
1h |
|
Schamus (ref Markley, et al) |
1999 |
|
Stainless steel |
None |
2x10-7 |
1h |
|
Schamus (ref Blears, et al) |
1999 |
|
Stainless steel |
None |
2x10-8 |
10h |
|
Schamus (ref Blears, et al) |
1999 |
|
Stainless steel NS22S |
Fresh |
1.4x10-8 |
1h |
Conductance |
Elsey (ref Schram) |
1975 |
|
Stainless steel ICN 472 |
fresh |
1.3x10-8 |
1h |
Conductance |
Elsey (ref Schram) |
1975 |
|
Stainless steel |
None |
1.2x10-8 |
10h |
|
Schamus (ref Das, et al) |
1999 |
|
Stainless steel ICN 472 |
sanded |
8.3x10-9 |
1h |
Conductance |
Elsey (ref Schram) |
1975 |
|
Stainless steel NS22S |
electro polished |
4.3x10-9 |
1h |
Conductance |
Elsey (ref Schram) |
1975 |
|
Stainless steel NS22S |
mechanically polished |
1.7x10-9 |
1h |
Conductance |
Elsey (ref Schram) |
1975 |
|
Stainless steel |
fresh |
1.5x10-9 |
10h |
Conductance |
Elsey (ref Schram) |
1975 |
|
Stainless steel ICN 472 |
Polished & vapor degreased |
1.4x10-9 |
10h |
|
Schamus (ref Dayton, et al) |
1999 |
|
Stainless steel |
None |
1.4x10-9 |
10h |
|
Schamus (ref Das, et al) |
1999 |
|
Stainless steel NS22S |
fresh |
1.3x10-9 |
10h |
Conductance |
Elsey (ref Schram) |
1975 |
|
Stainless steel ICN 472 |
sanded |
1.0x10-9 |
10h |
Conductance |
Elsey (ref Schram) |
1975 |
|
Stainless steel |
None |
7.6x10-10 |
1h |
|
Schamus (ref Das, et al) |
1999 |
|
Stainless steel NS22S |
mechanically polished |
4.6x10-10 |
10h |
Conductance |
Elsey (ref Schram) |
1975 |
|
Stainless steel NS22S |
electro polished |
4.3x10-10 |
10h |
Conductance |
Elsey (ref Schram) |
1975 |
|
Stainless steel |
Baked 24h @ 200°C |
1.5x10-10 |
1h |
|
Schamus (ref Das, et al) |
1999 |
|
Stainless steel |
None |
1.1x10-10 |
100h |
|
Schamus (ref Das, et al) |
1999 |
|
Stainless steel 304 |
Degrease + water rinse |
4.0x10-11 |
40h |
Conductance |
Strausser |
1973 |
|
Stainless steel U15C |
Baked 25h @ 300ºC |
4.5x10-12 |
|
|
Elsey (ref Calder, et al) |
1975 |
|
Stainless steel 304 |
Degrease + water rinse, baked in vacuum 150ºC for 12h |
4.0x10-12 |
5h after bakeout |
Conductance |
Strausser |
1967 |
|
Stainless steel 304 |
Electropolished, baked 30h @ 250ºC |
3.0x10-12 |
|
|
Elsey (ref Young) |
1975 |
|
Stainless steel U15C |
Baked 45h @ 360ºC |
2.6x10-12 |
|
|
Elsey (ref Calder, et al) |
1975 |
|
Stainless steel |
Baked 24h @ 200°C |
9.3x10-13 |
100h |
|
Schamus (ref Das, et al) |
1999 |
|
Stainless steel U15C |
Baked 3h in vacuum @ 1000ºC + 25h in situ @ 360°C |
1.6x10-14 |
|
|
Elsey (ref Calder, et al) |
1975 |
Other
cleaning methods are listed in Chart 3, although outgassing rates are not
measured:
|
Material |
Treatment |
Results |
Reference |
Year |
|
Aluminum |
Quench a hot aluminum extrusion in an Ar-O2
atmosphere |
Dense, thin (~20Å thick) oxide layer |
Sasaki, Y.T. |
1990 |
|
Aluminum 6063 |
Clean with an alkaline detergent (Almeco 18) |
Removes MgO, C, and Al2O3 |
Sasaki, Y.T. |
1990 |
|
Aluminum |
Vapor degreasing, pump for 120h before and after bake |
Dominant residual gases: H2O, H2,
CO, CO2, & CH4; after baking @ 150°C and
pumping, H2O & CH4 gone, outgassing rates of other gases
reduced 1 order of magnitude except H2 |
Mathewson, A.G., et al |
1989 |
|
Aluminum |
Vapor degreasing, then light alkaline etch (CERN basic
procedure), pump for 120h before and after bake |
Dominant residual gases: H2O, H2,
CO, & CO2; after baking @ 150°C and pumping, only H2
exists |
Mathewson A.G., et al |
1989 |
|
Aluminum |
Strong alkaline etching in NaOH, pump for 120h before and
after bake |
Dominant residual gases: H2O, H2,
CO, CO2, & CH4; after baking @ 150°C and
pumping, only H2 exists |
Mathewson A.G., et al |
1989 |
|
Aluminum |
Vapor degreasing, Ar glow discharge @ 150°C |
On initiation of discharge, large pressure increase
(normal in Ar glow discharge) was too large for accurate measurement |
Mathewson A.G., et al |
1989 |
|
Aluminum |
Vapor degreasing, then light alkaline etch (CERN basic
procedure), Ar glow discharge @ 150°C |
H2, CO dominant gases desorbing from surface
during discharge cleaning |
Mathewson A.G., et al |
1989 |
|
Aluminum |
Strong alkaline etching in NaOH, Ar glow discharge @ 150°C |
H2, CO dominant gases desorbing from surface
during discharge cleaning at order of magnitude less than light alkaline etch |
Mathewson A.G., et al |
1989 |
|
SS |
H2 glow discharge - 22°C |
Dominant residual gases:
CH4, CO, & C2H4; water production
insignificant; frequent arcing on all exposed surface noted during initial
discharge period |
Dylla, H.F. |
1988 |
|
SS |
H2 glow discharge – 150°C |
Dominant residual gases: CH4, CO, & C2H4,
and H2O; frequent arcing on all exposed surface noted during
initial discharge period |
Dylla, H.F. |
1988 |
|
SS |
Ar glow discharge – ambient temp |
Dominant residual gases that were significantly removed:
CO2, H2 |
Dylla, H.F. |
1988 |
|
SS |
Ar/O2 glow discharge |
Improved removal of CO and CO2; minor amts of implanted Ar
that can be removed by baking @ 350°C |
Dylla, H.F. |
1988 |
|
|
Ar/O2 glow discharge 2h, exposed to air, then
Ar/O2 glow discharge 2h |
Some degree of passivation: residual gases were removed
with 1st cleaning & did not show up during the 2nd
cleaning |
Dylla, H.F. |
1988 |
|
|
O2 glow discharge |
Rapid removal of carbon, not of hydrocarbons (which can be
baked out initially), increased surf. Oxidation, sputtering of the base
metal, and possible enhanced outgassing of O2-containing molec. |
Dylla, H.F. |
1988 |
Chart 4
shows different outgassing measurements of epoxies.
|
Material |
Treatment |
Outgassing rate (torr-L/sec-cm2) |
Time meas. (hours) |
Test method |
Reference |
Year |
|
NMA w/ solid alumina filler |
Cured 300°F |
1.6x10-7 |
|
|
Hanson, Patel |
1970 |
|
Polyimide polymer |
Thermosetting; measured @ 40°C |
~1.1x10-7 |
4h+9min |
conductance |
Kendall, Zabielski |
1965 |
|
Polyimide polymer |
Thermosetting; measured @ 155°C |
~5x10-8 |
4.5h increase temp + 6h |
conductance |
Kendall, Zabielski |
1965 |
|
Silicone resin |
Needs dicumyl peroxide catalyst; thermosetting, measured @
35°C |
~5x10-8 |
4h |
conductance |
Kendall, Zabielski |
1965 |
|
Araldite epoxies |
Cured ~150°C for
15h |
~10-8 |
51h pumping |
conductance |
Barton, Govier |
1965 |
Kapton is
a newer material and little data exists about its outgassing rate. Below are three references.
|
Material |
Treatment |
Outgassing rate (torr-L/sec-cm2) |
Time meas. (hours) |
Test method |
Reference |
Year |
|
Kapton cable |
|
1.0x10-5 |
0h |
conductance |
Postma |
1999 |
|
Kapton foil |
|
1.0x10-7 |
40h |
|
Ferro-Luzzi |
1999 |
|
Polyimide |
Bake @ 300°C |
4.0x10-8 |
12h |
|
Weston |
1970 |
|
Kapton cable |
|
2.4x10-8 |
168h |
conductance |
Postma |
1999 |
|
Kapton cable |
|
2.7x10-9 |
336h |
conductance |
Postma |
1999 |
|
Kapton cable |
|
6.5x10-10 |
504h |
conductance |
Postma |
1999 |
Chart 6
shows the outgassing rates of several types of plastics.
|
Material |
Treatment |
Outgassing rate (torr-L/sec-cm2) |
Time meas. (hours) |
Test method |
Reference |
Year |
|
Nylon |
|
1.2x10-5 |
1h |
|
Elsey (ref Power, et al) |
1975 |
|
Nylon |
|
6.0x10-6 |
1h |
|
Elsey (ref Power, et al) |
1975 |
|
PVC |
24h @ 95% relative humidity |
8.5x10-7 |
1h |
conductance |
Elsey (ref Santler) |
1975 |
|
PTFE |
Fresh |
1.7x10-7 |
1h |
conductance |
Elsey (ref Santler) |
1975 |
|
Teflon |
|
6.5x10-8 |
1h |
conductance |
Elsey (ref Santler) |
1975 |
|
PTFE |
Fresh |
3.3x10-8 |
10h |
conductance |
Elsey (ref Santler) |
1975 |
|
Teflon |
|
2.5x10-8 |
10h |
conductance |
Elsey (ref Santler) |
1975 |
|
PVC |
24h @ 95% relative humidity |
2.0x10-8 |
10h |
conductance |
Elsey (ref Santler) |
1975 |
|
G-10 |
|
~10-8 |
|
|
Beams Division - FNAL |
2001 |