Outgassing base

unbaked austenitic stainless steel

Table 3, measured at room temperature. The 10 h row is credited in Table 3 to Benvenuti, Extreme Vacua, Physica Scripta T22 (1988). CERN design rule for all metal alloys, Eq. 13 of the source: qH2O of about 3e-9 divided by t in hours, mbar l per s per cm2. The source states that without the pumping time any value of qH2O is meaningless.

Methodthroughput

Pumping timethe abscissa of the curve below

304L stainless steel, no heat treatment

Table III, published in Pa L/s/cm2 at 2e3, 1e4 and 1e5 s, converted at build by the exact definition of the units, times converted to hours. Power law fit alpha 1.3. Uncertainty 33 percent. Assumes all outgassing products are H2O. Chamber exposed to atmosphere at least several days before pumpdown.

Methodthroughput

Pumping timethe abscissa of the curve below

316L stainless steel, no heat treatment

Table III run 316L no. 1, converted at build by the exact definition of the units. Alpha 0.89. A repeat run more than one year later gave 4.1e-9, 7.7e-10 and 6.9e-11 at the same three times. Uncertainty 33 percent.

Methodthroughput

Pumping timethe abscissa of the curve below

316LN electroslag re-melt stainless steel, no heat treatment

Table III, converted at build by the exact definition of the units. Alpha 1.2. Uncertainty 33 percent. The source notes 316LN and 316LN-XHV hold their improvement over 304L across the whole pumpdown.

Methodthroughput

Pumping timethe abscissa of the curve below

316L stainless steel, vacuum fired

Table III run 316L-XHV no. 1, converted at build by the exact definition of the units. Alpha 0.83. The source states vacuum firing does not significantly affect water outgassing. Repeat run about nine months later: 2.6e-9, 5.3e-10 and 5.4e-11.

Methodthroughput

Pumping timethe abscissa of the curve below

316LN electroslag re-melt stainless steel, vacuum fired

Table III, converted at build by the exact definition of the units. Alpha 1.3. Uncertainty 33 percent.

Methodthroughput

Pumping timethe abscissa of the curve below

austenitic stainless steel

Tables 3 and 4. Pumping time marked N.A. by the source: hydrogen outgassing rate does not depend on the duration of pumping. Measured at CERN by Ivo Wevers, Geraldine Chuste and the author.

Bake150 C, 24 h

Methodthroughput

Pumping timenot applicable, the source states the rate independent of pumping time

austenitic stainless steel

Table 4, bakeout for 24 h. Measured at CERN by Ivo Wevers, Geraldine Chuste and the author.

Bake300 C, 24 h

Methodthroughput

Pumping timenot applicable, the source states the rate independent of pumping time

304L stainless steel, 2 mm thick, corrugated walls (VIRGO arm modules)

Section 5.3 of the source: after in situ bakeout at 150 C for several days, outgassing rates in the low 1e-15 range were reproducibly measured. Underlying references named by the source: Bernardini et al., JVST A 16, 188-193 (1998) and Brisson et al., Vacuum 60, 9-14 (2001). In situ bake duration given as several days, no number published.

Bake150 C, duration not stated

Methodthroughput

Pumping timenot applicable, the source states the rate independent of pumping time

304L stainless steel, no heat treatment

Table IV, published as 9.4e-10 Pa L/s/cm2 at 298.15 K, converted at build by the exact definition of the units. Rate-of-rise with spinning rotor gauge, SI traceable. Bake stated as 125 to 150 C for a minimum of 72 h, midpoint written here, range verbatim. Activation energy ED 0.59 eV. Uncertainty 24 percent, k equals 2. Chamber 3 mm walls, composition from supplier certificates in Table I.

Bake137 C, 72 h

Methodaccumulation

Pumping timenot applicable, the source states the rate independent of pumping time

316L stainless steel, no heat treatment

Table IV, published as 6.5e-10 Pa L/s/cm2 at 298.15 K, converted at build by the exact definition of the units. Bake range 125 to 150 C for at least 72 h. ED 0.66 eV. Uncertainty 24 percent.

Bake137 C, 72 h

Methodaccumulation

Pumping timenot applicable, the source states the rate independent of pumping time

316LN electroslag re-melt stainless steel, no heat treatment

Table IV, published as 7.0e-10 Pa L/s/cm2 at 298.15 K, converted at build by the exact definition of the units. ED 0.64 eV. Uncertainty 24 percent. The source concludes no improvement of 316LN ESR over 316L without heat treatment.

Bake137 C, 72 h

Methodaccumulation

Pumping timenot applicable, the source states the rate independent of pumping time

SAE 304L stainless steel chamber VAC1, before heat treatment

Chamber VAC1, row published as before heat treatment. The only thermal condition applied is the standard bake at 150 C for 72 h that precedes every measurement. Table II of the source. Four nominally identical chambers assembled from standard DN40CF components in SAE 304L, UNS S30403, inner surface area 348 cm2 and volume 0.291 l, cleaned with a commercial detergent in a warm ultrasonic bath, rinsed in deionized water, then in isopropyl alcohol, and blown dry with nitrogen. Copper gaskets of oxygen free high purity copper, about 5 percent of the chamber area. Before every outgassing measurement all chambers were exposed to laboratory air, evacuated and baked at 150 C for 72 h, and the outgassing fluxes were measured for chamber temperatures between 20 and 21 C, a range the source states without a single number, so the measurement temperature is recorded as absent. The method is a rate of rise on a spinning rotor gauge, SI traceable through a NIST calibration of the accommodation coefficient. The total combined uncertainty is about 20 percent at k equal to 2. Published in Pa l/s/cm2 and converted to the canonical unit at build by the exact definition of the units. The source states no pumping time for these readings, only that measurements began once the system had reached a pressure below 1e-7 Pa after the bake.

Bake150 C, 72 h, vacuum

Methodaccumulation

Pumping timeNOT STATED by the source

austenitic stainless steels, vacuum fired

Order of magnitude stated by the source for vacuum chambers with up to a few mm thick walls. Fig. 24 of the source reports measured values lower than 1e-14 for a vacuum fired 316LN chamber, 2 m long, 2 mm thick, after bakeout at 200 C for 20 h.

Methodthroughput

Pumping timenot applicable, the source states the rate independent of pumping time

316L stainless steel, vacuum fired 950 C for at least 24 hours

Table IV, published as 5.1e-12 Pa L/s/cm2 at 298.15 K, converted at build by the exact definition of the units. ED 0.68 eV. Uncertainty 72 percent for rates below 1e-11 Pa L/s/cm2, reproducibility dominated.

Bake137 C, 72 h

Methodaccumulation

Pumping timenot applicable, the source states the rate independent of pumping time

316LN electroslag re-melt stainless steel, vacuum fired 950 C for at least 24 hours

Table IV, published as 9.9e-12 Pa L/s/cm2 at 298.15 K, converted at build by the exact definition of the units. ED 0.53 eV. Uncertainty 72 percent.

Bake137 C, 72 h

Methodaccumulation

Pumping timenot applicable, the source states the rate independent of pumping time

Stainless Steels, the row covering 18-8, 17-4PH, 301, 302, 304, 304L, 304LN, 316, 316L, 316LN, 317, 317L, ferritic and martensitic grades, A286 and Nitronic 60

Table 1, row H21, condition column reads unbaked. Published in torr-liter/s/cm2 and converted to the canonical unit at build by the exact definition of the units: Jtotal 1.8e-08 torr-liter/s/cm2, JH2O 1.8e-08 torr-liter/s/cm2. No pumping time and no measurement temperature are given anywhere in the table. Footnote 8 of the source states the entries are representative of material sample measurements and provided as a design guideline for working up a gas budget. Table references: 1, Dayton, Trans. 6th Nat. Vacuum Congress (1960) p 101. The values are annotated in the table as applying to 304 and 304L only, although the row lists twelve grades.

Methodstated

Pumping timeNOT STATED by the source

Stainless Steel 18/9/1 (electro polished)

Table 4 of the source. Published in torr l per s per cm2 with the column multiplier 1e-10, converted to the canonical unit at build by the exact definition of the units. Published values K10 2 x 1e-10. Slopes of the log log plot as printed, alpha1 not printed and alpha10 not printed. The table credits this row to reference 15 of the source, R S Barton and R P Govier, Proc 4th Int Vac Cong, p 775, 1968, and Vacuum, 20, 1970, 1. The tables of this source state neither a measurement temperature nor a gas species, and the source states in section 3.1 that the evolved gas is in general a mixture of water vapour, hydrogen, carbon monoxide and other gases treated as though it were air or nitrogen. The source prints no value at the other pumping time of this table.

Methodstated

Pumping time10 h

Stainless Steel 18/9/1 (vapour degreased)

Table 4 of the source. Published in torr l per s per cm2 with the column multiplier 1e-10, converted to the canonical unit at build by the exact definition of the units. Published values K10 1 x 1e-10. Slopes of the log log plot as printed, alpha1 not printed and alpha10 not printed. The table credits this row to reference 15 of the source, R S Barton and R P Govier, Proc 4th Int Vac Cong, p 775, 1968, and Vacuum, 20, 1970, 1. The tables of this source state neither a measurement temperature nor a gas species, and the source states in section 3.1 that the evolved gas is in general a mixture of water vapour, hydrogen, carbon monoxide and other gases treated as though it were air or nitrogen. The source prints no value at the other pumping time of this table.

Methodstated

Pumping time10 h

Stainless Steel 18/9/1 (diversey cleaned)

Table 4 of the source. Published in torr l per s per cm2 with the column multiplier 1e-10, converted to the canonical unit at build by the exact definition of the units. Published values K10 3 x 1e-10. Slopes of the log log plot as printed, alpha1 not printed and alpha10 not printed. The table credits this row to reference 15 of the source, R S Barton and R P Govier, Proc 4th Int Vac Cong, p 775, 1968, and Vacuum, 20, 1970, 1. The tables of this source state neither a measurement temperature nor a gas species, and the source states in section 3.1 that the evolved gas is in general a mixture of water vapour, hydrogen, carbon monoxide and other gases treated as though it were air or nitrogen. The source prints no value at the other pumping time of this table.

Methodstated

Pumping time10 h

Stainless steel

Table 4 of the source. Published in torr l per s per cm2 with the column multiplier 1e-10, converted to the canonical unit at build by the exact definition of the units. Published values K1 1750 x 1e-10 and K10 210 x 1e-10. Slopes of the log log plot as printed, alpha1 1.1 and alpha10 0.75. The table credits this row to reference 13 of the source, B B Dayton, Trans 6th AVS Symp, p 101, 1959. The tables of this source state neither a measurement temperature nor a gas species, and the source states in section 3.1 that the evolved gas is in general a mixture of water vapour, hydrogen, carbon monoxide and other gases treated as though it were air or nitrogen.

Methodstated

Pumping timethe abscissa of the curve below

Type 304 stainless steel test chamber, inner surface electropolished, 1 m long and 15 cm in diameter, internal area 4747 cm2, oxide layer about 60 angstrom thick

Throughput method on a type 304 stainless steel chamber, inner surface electropolished, 1 m long and 15 cm in diameter, internal area 4747 cm2, oxide layer about 60 angstrom thick. Pumping speed throttled to 4.7 litre per s, chamber volume 16.7 litre, ambient temperature 25 C. Time zero is defined when the system pressure crosses 17 torr, the vapour pressure of water at 20 C. H2O absorbed 7.8 monolayers. Venting gas, ambient air. The rate is a water equivalent, and mass scans indicate that about 10 percent of the total outgassing comes from H2, CH4, CO and CO2 with less than 1 percent from any other species, which is why the species of this entry is total and not H2O. One monolayer is taken as about 5e19 molecules on the geometrical area of this chamber. The two fits are published in torr litre per cm2 per s with t in seconds and are NOT converted to the canonical unit of this corpus, because converting the coefficients of a fit would republish a fit nobody made.

Methodthroughput

Pumping timethe abscissa of the law below

304 Stainless Steel (electro polished)

Table 5 of the source, metals vacuum baked. Published K 300 x 1e-14 torr l per s per cm2, converted to the canonical unit at build by the exact definition of the units. The column head of this table carries NO pumping time subscript, unlike tables 4, 6, 7 and 8 where K1, K4 and K10 name theirs, so the pumping time at which this rate was read is not published. The table credits this row to reference 17 of the source, J R Young, J Vac Sci Technol, 6, 1969, 398. Treatment as printed, 30 h at 250 C.

Bake250 C, 30 h, vacuum

Methodstated

Pumping timeNOT STATED by the source

Stainless steel, reference sample of table 3

Table 3 of the source publishes one stainless steel reading, at 1 day in vacuum, in the same table as the PMMA samples. The source states no grade, no surface treatment and no measurement temperature for this reference, so the state is recorded as not stated. Published in l Torr/(s cm2) and converted to the canonical unit at build by the exact definition of the units.

Methodthroughput

Pumping time24 h

Stainless steel, empty test volume of the apparatus

Not a table value. The setup section states in prose that the measured background outgassing of the empty stainless steel volume was 3.3e-11 Torr l/s/cm2 at 100 C. The source states no pumping time for this number and no surface treatment. Converted to the canonical unit at build by the exact definition of the units.

Methodthroughput

Pumping timeNOT STATED by the source

Type 304 stainless steel, electropolished, as a function of water vapour exposure during venting

Pump down to the base pressure of 5e-8 torr is reached in less than 2 h when the chamber is vented with dry nitrogen and takes more than 200 h after exposure to moist air. Integrating the desorbed water gives 16.8 monolayers for the 600 monolayer exposure and 0.017 monolayers for the highly dry nitrogen venting.

A power law exponent is not an outgassing rate. It is carried because it is the quantity that makes any single rate meaningless without its pumping time.

Water on a type 304 stainless steel surface

Measured during the 800 monolayer water exposure trial. The chamber was pumped to 1.3e-5 torr, then the whole system was heated from room temperature 28 C to 60 C within 20 min. The pressure at 60 C was 1.2e-4 torr, almost ten times the pressure at 28 C. The source states the result is in good agreement with previous estimates and measurements.

A desorption activation energy is not a diffusion coefficient and does not belong in the diffusion block, whose Arrhenius form describes a diffusion law. It is carried as a declaration so that no field misnames it.

SAE 304L stainless steel chamber DAIR3, dry air bake at 415 C for 48 h

Not a reading problem. The cell was read twice, in the text layer and on a 400 dpi raster, and both give 1.0e-11 Pa l/s/cm2 against 3.8e-10 for hydrogen on the same row. The six other rows of table II give a hydrogen over nitrogen equivalent ratio between 3.67 and 3.83, and this row gives 38.0, ten times higher. The value is written into the base exactly as printed, and this declaration records the arithmetic so that a reader who compares the columns sees what the table does. Only the source can say whether the printed exponent is the one intended.

Austenitic stainless steel, 316LN ESR

Seven austenitic stainless steels studied by thermal desorption spectroscopy on two setups, S1 and S2. The grades are 316L ARC plus AOD, 316L ARC plus AOD plus ESR, 316LN ARC plus AOD plus ESR, 316Ti ARC plus AOD, 318 ARC plus AOD, 318 ARC plus AOD plus ESR and X20MDW ARC plus AOD plus ESR. Mean grain sizes as received are 62, 44, 44, 31, 31, 31 and 22 micrometres in the same order. The total hydrogen content measured by argon carrier fusion is between 1 and 7 wt.ppm. Sample roughness Ra was 1.6 micrometres of N7 type. The accuracy of the outgassing rate measurements is stated as plus or minus 20 percent and of the temperature as plus or minus 10 C.

The source publishes its hydrogen outgassing rates as desorption spectra against temperature in figures 3, 4, 5, 9, 10, 11 and 12, and tabulates none of them. Reading a number off a plotted curve is not reading a published value, so no value field is filled. Tables I and II of the source carry chemical compositions and grain sizes, which are not outgassing rates and have no field in this corpus.

Austenitic stainless steel, 316Ti ARC plus AOD

Seven austenitic stainless steels studied by thermal desorption spectroscopy on two setups, S1 and S2. The grades are 316L ARC plus AOD, 316L ARC plus AOD plus ESR, 316LN ARC plus AOD plus ESR, 316Ti ARC plus AOD, 318 ARC plus AOD, 318 ARC plus AOD plus ESR and X20MDW ARC plus AOD plus ESR. Mean grain sizes as received are 62, 44, 44, 31, 31, 31 and 22 micrometres in the same order. The total hydrogen content measured by argon carrier fusion is between 1 and 7 wt.ppm. Sample roughness Ra was 1.6 micrometres of N7 type. The accuracy of the outgassing rate measurements is stated as plus or minus 20 percent and of the temperature as plus or minus 10 C.

A trapping energy is not a diffusion coefficient and not an outgassing rate. The diffusion block of this corpus holds an Arrhenius law for a diffusion coefficient or a coefficient measured at one temperature, and neither form carries a detrapping energy, so the number is recorded verbatim in this text and no block is filled with it. The source publishes its hydrogen outgassing rates as desorption spectra against temperature in figures 3, 4, 5, 9, 10, 11 and 12, and tabulates none of them. Reading a number off a plotted curve is not reading a published value, so no value field is filled. Tables I and II of the source carry chemical compositions and grain sizes, which are not outgassing rates and have no field in this corpus.

Austenitic stainless steel, 316LN ESR

Seven austenitic stainless steels studied by thermal desorption spectroscopy on two setups, S1 and S2. The grades are 316L ARC plus AOD, 316L ARC plus AOD plus ESR, 316LN ARC plus AOD plus ESR, 316Ti ARC plus AOD, 318 ARC plus AOD, 318 ARC plus AOD plus ESR and X20MDW ARC plus AOD plus ESR. Mean grain sizes as received are 62, 44, 44, 31, 31, 31 and 22 micrometres in the same order. The total hydrogen content measured by argon carrier fusion is between 1 and 7 wt.ppm. Sample roughness Ra was 1.6 micrometres of N7 type. The accuracy of the outgassing rate measurements is stated as plus or minus 20 percent and of the temperature as plus or minus 10 C.

A residual hydrogen content is not an outgassing rate. The source publishes a depletion factor and the spectra that produce it, and no rate per unit area for the fired samples. Writing this fact as a value would need a conversion from a content to a rate that the source does not make and this corpus does not invent. The source publishes its hydrogen outgassing rates as desorption spectra against temperature in figures 3, 4, 5, 9, 10, 11 and 12, and tabulates none of them. Reading a number off a plotted curve is not reading a published value, so no value field is filled. Tables I and II of the source carry chemical compositions and grain sizes, which are not outgassing rates and have no field in this corpus.

Austenitic stainless steel, 316LN ESR

Seven austenitic stainless steels studied by thermal desorption spectroscopy on two setups, S1 and S2. The grades are 316L ARC plus AOD, 316L ARC plus AOD plus ESR, 316LN ARC plus AOD plus ESR, 316Ti ARC plus AOD, 318 ARC plus AOD, 318 ARC plus AOD plus ESR and X20MDW ARC plus AOD plus ESR. Mean grain sizes as received are 62, 44, 44, 31, 31, 31 and 22 micrometres in the same order. The total hydrogen content measured by argon carrier fusion is between 1 and 7 wt.ppm. Sample roughness Ra was 1.6 micrometres of N7 type. The accuracy of the outgassing rate measurements is stated as plus or minus 20 percent and of the temperature as plus or minus 10 C.

A percentage of hydrogen removed is not an outgassing rate, and the source tabulates no rate for these samples. The source publishes its hydrogen outgassing rates as desorption spectra against temperature in figures 3, 4, 5, 9, 10, 11 and 12, and tabulates none of them. Reading a number off a plotted curve is not reading a published value, so no value field is filled. Tables I and II of the source carry chemical compositions and grain sizes, which are not outgassing rates and have no field in this corpus.

Austenitic stainless steel, 316LN ESR, 1 mm thick

Seven austenitic stainless steels studied by thermal desorption spectroscopy on two setups, S1 and S2. The grades are 316L ARC plus AOD, 316L ARC plus AOD plus ESR, 316LN ARC plus AOD plus ESR, 316Ti ARC plus AOD, 318 ARC plus AOD, 318 ARC plus AOD plus ESR and X20MDW ARC plus AOD plus ESR. Mean grain sizes as received are 62, 44, 44, 31, 31, 31 and 22 micrometres in the same order. The total hydrogen content measured by argon carrier fusion is between 1 and 7 wt.ppm. Sample roughness Ra was 1.6 micrometres of N7 type. The accuracy of the outgassing rate measurements is stated as plus or minus 20 percent and of the temperature as plus or minus 10 C.

A percentage of hydrogen removed is not an outgassing rate, and the source publishes the corresponding fractions as a figure. The source publishes its hydrogen outgassing rates as desorption spectra against temperature in figures 3, 4, 5, 9, 10, 11 and 12, and tabulates none of them. Reading a number off a plotted curve is not reading a published value, so no value field is filled. Tables I and II of the source carry chemical compositions and grain sizes, which are not outgassing rates and have no field in this corpus.

Stainless steel, including Invar

Section 13.10. Prescribed clean and bake condition, not a measurement. The document states the procedures are consistent with baking a material at the maximum temperature possible and with meeting the summed mass pressure limit, and that vacuum baking is preferred over air baking because it allows an RGA scan of the load.

304 stainless steel vacuum components

Table I of the source, column at 150 C. Calculated times in DAYS to reduce the hydrogen concentration in 304 stainless steel by 99 percent, five characteristic diffusion times: 72 for a 1.6 mm plate, 290 for a 3.2 mm plate, 1700 for a DN 16 flange 0.76 cm thick, 4600 for a DN 40 flange 1.3 cm thick, 8500 for a DN 63 flange 1.7 cm thick, 11000 for a DN 100 flange 2 cm thick, 14000 for a DN 150 flange 2.24 cm thick, 17000 for a DN 200 flange 2.5 cm thick and 23000 for a DN 250 flange 2.84 cm thick. These are calculated from the diffusion coefficient with D0 1.22e-6 m2/s and an activation energy of 0.57 eV taken from Grant and colleagues, not measured, and they hold in the diffusion limited regime only. The source states that below a certain outgassing rate the process becomes recombination limited and the characteristic time is then longer than the formula predicts. The flange designations are those of ISO 3669. Similar degas times are stated for 316 stainless steel. The bake duration is left absent because the column publishes nine different durations, one per thickness, and picking one of them would be a choice the source does not make.

304 stainless steel vacuum components

Table I of the source, column at 375 C. Calculated times in DAYS to reduce the hydrogen concentration in 304 stainless steel by 99 percent, five characteristic diffusion times: 0.30, 1.3, 7.4, 21, 38, 50, 64, 77 and 100 for the same nine components in the same order. These are calculated from the diffusion coefficient with D0 1.22e-6 m2/s and an activation energy of 0.57 eV taken from Grant and colleagues, not measured, and they hold in the diffusion limited regime only. The source states that below a certain outgassing rate the process becomes recombination limited and the characteristic time is then longer than the formula predicts. The flange designations are those of ISO 3669. Similar degas times are stated for 316 stainless steel. The bake duration is left absent because the column publishes nine different durations, one per thickness, and picking one of them would be a choice the source does not make.

304 stainless steel vacuum components

Table I of the source, column at 400 C. Calculated times in DAYS to reduce the hydrogen concentration in 304 stainless steel by 99 percent, five characteristic diffusion times: 0.20, 0.90, 5.1, 14, 26, 34, 44, 53 and 71 for the same nine components in the same order. These are calculated from the diffusion coefficient with D0 1.22e-6 m2/s and an activation energy of 0.57 eV taken from Grant and colleagues, not measured, and they hold in the diffusion limited regime only. The source states that below a certain outgassing rate the process becomes recombination limited and the characteristic time is then longer than the formula predicts. The flange designations are those of ISO 3669. Similar degas times are stated for 316 stainless steel. The bake duration is left absent because the column publishes nine different durations, one per thickness, and picking one of them would be a choice the source does not make.

304 stainless steel vacuum components

Table I of the source, column at 425 C. Calculated times in DAYS to reduce the hydrogen concentration in 304 stainless steel by 99 percent, five characteristic diffusion times: 0.20, 0.60, 3.6, 9.9, 18, 24, 31, 37 and 50 for the same nine components in the same order. These are calculated from the diffusion coefficient with D0 1.22e-6 m2/s and an activation energy of 0.57 eV taken from Grant and colleagues, not measured, and they hold in the diffusion limited regime only. The source states that below a certain outgassing rate the process becomes recombination limited and the characteristic time is then longer than the formula predicts. The flange designations are those of ISO 3669. Similar degas times are stated for 316 stainless steel. The bake duration is left absent because the column publishes nine different durations, one per thickness, and picking one of them would be a choice the source does not make.

6061-T651 aluminum, no heat treatment

Table III, published in Pa L/s/cm2 at 2e3, 1e4 and 1e5 s, converted at build by the exact definition of the units, times converted to hours. Power law fit alpha 1.0. Uncertainty 33 percent. The source finds the aluminium chamber a factor 2.5 higher than 304L at 1e5 s, the worst of the seven for water.

Methodthroughput

Pumping timethe abscissa of the curve below

6061-T651 aluminum, no heat treatment

Table IV, published as 5.5e-12 Pa L/s/cm2 at 298.15 K, converted at build by the exact definition of the units. Rate-of-rise with spinning rotor gauge, SI traceable. Bake stated as 125 to 150 C for a minimum of 72 h, midpoint written in the field. Uncertainty 72 percent, k equals 2, for rates below 1e-11 Pa L/s/cm2. Chamber 3 mm walls, aluminium gasket and aluminium orifice. Composition from supplier certificates in Table I.

Bake137 C, 72 h

Methodaccumulation

Pumping timenot applicable, the source states the rate independent of pumping time

Al alloys

Table 3, bakeout at 100 C to 200 C for about 20 h, midpoint written in the field, range verbatim here. The source credits this row to Benvenuti Physica Scripta T22 (1988), Moraw and Dobrozemsky Jpn. J. Appl. Phys. 13 (1974) 264, Halama JVST 16 (1979) 717, and Suemitsu et al. JVST A 5 (1987) 37. Alloy not named at this row.

Bake150 C, 20 h

Methodstated

Pumping timenot applicable, the source states the rate independent of pumping time

AA 6060 Al alloys

Table 4, bakeout for 24 h, published as at most 1e-13. The source credits this row to Benvenuti, Bojon, Chiggiato and Losch, Ultimate pressures of the LEP vacuum system, Vacuum 44 (1993) 507-509. AA 6060 is a different alloy from the 6061-T651 measured by S-FEDCHAK-2021 on this card.

Bake150 C, 24 h

Methodstated

Pumping timenot applicable, the source states the rate independent of pumping time

Aluminium and aluminium alloys, 2000, 4000, 5000 and 6000 series, wrought form

Table 1, row H1, condition column reads unbaked. Published in torr-liter/s/cm2 and converted to the canonical unit at build by the exact definition of the units: Jtotal 7.6e-09 torr-liter/s/cm2, JH2O 7.6e-09 torr-liter/s/cm2. No pumping time and no measurement temperature are given anywhere in the table. Footnote 8 of the source states the entries are representative of material sample measurements and provided as a design guideline for working up a gas budget. Table references: 1, Dayton (1960), 8, Coyne, LIGO-L070132-00. The 7000 series is excluded by the source because of its zinc content.

Methodstated

Pumping timeNOT STATED by the source

Aluminium (fresh)

Table 4 of the source. Published in torr l per s per cm2 with the column multiplier 1e-10, converted to the canonical unit at build by the exact definition of the units. Published values K1 63 x 1e-10 and K10 6.0 x 1e-10. Slopes of the log log plot as printed, alpha1 1.0 and alpha10 1.0. The table credits this row to reference 9 of the source, A Schram, Le Vide, No 103, 1963, 55. The tables of this source state neither a measurement temperature nor a gas species, and the source states in section 3.1 that the evolved gas is in general a mixture of water vapour, hydrogen, carbon monoxide and other gases treated as though it were air or nitrogen.

Methodstated

Pumping timethe abscissa of the curve below

Aluminium (degassed 24 h)

Table 4 of the source. Published in torr l per s per cm2 with the column multiplier 1e-10, converted to the canonical unit at build by the exact definition of the units. Published values K1 41.4 x 1e-10 and K10 3.06 x 1e-10. Slopes of the log log plot as printed, alpha1 3.2 and alpha10 0.9. The table credits this row to reference 9 of the source, A Schram, Le Vide, No 103, 1963, 55. The tables of this source state neither a measurement temperature nor a gas species, and the source states in section 3.1 that the evolved gas is in general a mixture of water vapour, hydrogen, carbon monoxide and other gases treated as though it were air or nitrogen.

Methodstated

Pumping timethe abscissa of the curve below

Aluminium (3 h in air)

Table 4 of the source. Published in torr l per s per cm2 with the column multiplier 1e-10, converted to the canonical unit at build by the exact definition of the units. Published values K1 66.5 x 1e-10 and K10 4.75 x 1e-10. Slopes of the log log plot as printed, alpha1 1.9 and alpha10 0.9. The table credits this row to reference 9 of the source, A Schram, Le Vide, No 103, 1963, 55. The tables of this source state neither a measurement temperature nor a gas species, and the source states in section 3.1 that the evolved gas is in general a mixture of water vapour, hydrogen, carbon monoxide and other gases treated as though it were air or nitrogen.

Methodstated

Pumping timethe abscissa of the curve below

Aluminium (bright rolled)

Table 4 of the source. Published in torr l per s per cm2 with the column multiplier 1e-10, converted to the canonical unit at build by the exact definition of the units. Published values K10 75 x 1e-10. Slopes of the log log plot as printed, alpha1 not printed and alpha10 1. The table credits this row to reference 13 of the source, B B Dayton, Trans 6th AVS Symp, p 101, 1959. The tables of this source state neither a measurement temperature nor a gas species, and the source states in section 3.1 that the evolved gas is in general a mixture of water vapour, hydrogen, carbon monoxide and other gases treated as though it were air or nitrogen. The source prints no value at the other pumping time of this table.

Methodstated

Pumping time10 h

Aluminium

Table 5 of the source, metals vacuum baked. Published K 40 x 1e-14 torr l per s per cm2, converted to the canonical unit at build by the exact definition of the units. The column head of this table carries NO pumping time subscript, unlike tables 4, 6, 7 and 8 where K1, K4 and K10 name theirs, so the pumping time at which this rate was read is not published. The table credits this row to reference 17 of the source, J R Young, J Vac Sci Technol, 6, 1969, 398. Treatment as printed, 15 h at 250 C.

Bake250 C, 15 h, vacuum

Methodstated

Pumping timeNOT STATED by the source

Aluminium 6061-T6

Section 13.6. Prescribed clean and bake condition, not a measurement. The document states the procedures are consistent with baking a material at the maximum temperature possible and with meeting the summed mass pressure limit, and that vacuum baking is preferred over air baking because it allows an RGA scan of the load. The document states tempered aluminium is very sensitive to reheat and can lose significant yield strength with excessive bake temperature or time, and that this cycle keeps strength losses below 5 percent. All other aluminium alloys are baked at 120 C for 48 hours.

titanium, ASTM grade 2 (unalloyed), no heat treatment

Table III, converted at build by the exact definition of the units, times converted to hours. Alpha 1.0. Uncertainty 33 percent. At 1e5 s the titanium chamber is about 10 percent above 304L, which the source states is within the measurement uncertainty: the best hydrogen material of the study has no water advantage.

Methodthroughput

Pumping timethe abscissa of the curve below

titanium, ASTM grade 2 (unalloyed), no heat treatment

Table IV, published as 2.5e-12 Pa L/s/cm2, converted at build by the exact definition of the units. This value is the average of all titanium measurements, not a fit: the source states the temperature dependence of the titanium chamber did not follow the Arrhenius relationship, so no activation energy is given. The measured rate decreased over time after the bake, which the source attributes to hydrogen depleting from the surface layer down to the noise floor. The source also states that re-adsorption of outgassed hydrogen on the titanium surface is possible and that the true rate may therefore be larger. Uncertainty 72 percent. Lowest H2 rate of the seven chambers, a factor of about 300 better than 304L.

Bake137 C, 72 h

Methodaccumulation

Pumping timenot applicable, the source states the rate independent of pumping time

Titanium

Table 4 of the source. Published in torr l per s per cm2 with the column multiplier 1e-10, converted to the canonical unit at build by the exact definition of the units. Published values K1 113 x 1e-10 and K10 18.4 x 1e-10. Slopes of the log log plot as printed, alpha1 0.6 and alpha10 1.1. The table credits this row to reference 9 of the source, A Schram, Le Vide, No 103, 1963, 55. The tables of this source state neither a measurement temperature nor a gas species, and the source states in section 3.1 that the evolved gas is in general a mixture of water vapour, hydrogen, carbon monoxide and other gases treated as though it were air or nitrogen.

Methodstated

Pumping timethe abscissa of the curve below

Beryllium

Table 4, bakeout for 24 h, published as below 1e-14. Measured at CERN by Ivo Wevers, Geraldine Chuste and the author. A bound, not a measured value: the rate is below the sensitivity reported at this row.

Bake150 C, 24 h

Methodthroughput

Pumping timenot applicable, the source states the rate independent of pumping time

OFS copper (oxygen-free silver-bearing)

Table 3, measured at room temperature, pumping time marked N.A. by the source. Measured at CERN by Ivo Wevers, Geraldine Chuste and the author. The material is silver-bearing oxygen-free copper, not plain OFE.

Bake200 C, 24 h

Methodthroughput

Pumping timenot applicable, the source states the rate independent of pumping time

Copper Silver added (OFS)

Table 4, typical H2 outgassing rates after bakeout of metals used in particle accelerators, bakeout T for 24 h. Published as approximately 1e-14. Measured at CERN by Ivo Wevers, Geraldine Chuste and the author.

Bake200 C, 24 h

Methodthroughput

Pumping timenot applicable, the source states the rate independent of pumping time

Copper Silver added (OFS)

Table 4, bakeout for 24 h. Same value as austenitic stainless steel at the same bakeout temperature in the same table: the advantage of copper appears only at 200 C. Measured at CERN by Ivo Wevers, Geraldine Chuste and the author.

Bake150 C, 24 h

Methodthroughput

Pumping timenot applicable, the source states the rate independent of pumping time

copper and aluminium alloys

Section 5 of the source, verbatim: for copper and aluminium alloys, a few bakeout at 150-200 C for 24 hours are sufficient to reduce the hydrogen-outgassing rate to less than 1e-13 mbar l per s per cm2. The bake temperature is a range of 150 to 200 C, midpoint written in the field, range verbatim here. The statement covers several bakeout cycles, not one.

Bake175 C, 24 h

Methodstated

Pumping timenot applicable, the source states the rate independent of pumping time

Copper (elemental and OFHC)

Table 1, row H6, condition column reads unbaked. Published in torr-liter/s/cm2 and converted to the canonical unit at build by the exact definition of the units: Jtotal 4.2e-09 torr-liter/s/cm2, JH2O 4.2e-09 torr-liter/s/cm2. No pumping time and no measurement temperature are given anywhere in the table. Footnote 8 of the source states the entries are representative of material sample measurements and provided as a design guideline for working up a gas budget. Table references: 2, Schram, Le Vide No 103 (1963) p 55, 6, Coyne, Allowable Bake Temperature for UHV Processing of Copper Alloys, LIGO-T0900368-v2.

Methodstated

Pumping timeNOT STATED by the source

Copper (fresh)

Table 4 of the source. Published in torr l per s per cm2 with the column multiplier 1e-10, converted to the canonical unit at build by the exact definition of the units. Published values K1 400 x 1e-10 and K10 41.5 x 1e-10. Slopes of the log log plot as printed, alpha1 1.0 and alpha10 1.0. The table credits this row to reference 9 of the source, A Schram, Le Vide, No 103, 1963, 55. The tables of this source state neither a measurement temperature nor a gas species, and the source states in section 3.1 that the evolved gas is in general a mixture of water vapour, hydrogen, carbon monoxide and other gases treated as though it were air or nitrogen.

Methodstated

Pumping timethe abscissa of the curve below

Copper (mech. polished)

Table 4 of the source. Published in torr l per s per cm2 with the column multiplier 1e-10, converted to the canonical unit at build by the exact definition of the units. Published values K1 35 x 1e-10 and K10 3.56 x 1e-10. Slopes of the log log plot as printed, alpha1 1.0 and alpha10 1.0. The table credits this row to reference 9 of the source, A Schram, Le Vide, No 103, 1963, 55. The tables of this source state neither a measurement temperature nor a gas species, and the source states in section 3.1 that the evolved gas is in general a mixture of water vapour, hydrogen, carbon monoxide and other gases treated as though it were air or nitrogen.

Methodstated

Pumping timethe abscissa of the curve below

OFHC copper (fresh)

Table 4 of the source. Published in torr l per s per cm2 with the column multiplier 1e-10, converted to the canonical unit at build by the exact definition of the units. Published values K1 188 x 1e-10 and K10 12.6 x 1e-10. Slopes of the log log plot as printed, alpha1 1.3 and alpha10 1.3. The table credits this row to reference 9 of the source, A Schram, Le Vide, No 103, 1963, 55. The tables of this source state neither a measurement temperature nor a gas species, and the source states in section 3.1 that the evolved gas is in general a mixture of water vapour, hydrogen, carbon monoxide and other gases treated as though it were air or nitrogen.

Methodstated

Pumping timethe abscissa of the curve below

OFHC copper (mech. polished)

Table 4 of the source. Published in torr l per s per cm2 with the column multiplier 1e-10, converted to the canonical unit at build by the exact definition of the units. Published values K1 19 x 1e-10 and K10 1.63 x 1e-10. Slopes of the log log plot as printed, alpha1 1.1 and alpha10 1.1. The table credits this row to reference 9 of the source, A Schram, Le Vide, No 103, 1963, 55. The tables of this source state neither a measurement temperature nor a gas species, and the source states in section 3.1 that the evolved gas is in general a mixture of water vapour, hydrogen, carbon monoxide and other gases treated as though it were air or nitrogen.

Methodstated

Pumping timethe abscissa of the curve below

Copper

Table 5 of the source, metals vacuum baked. Published K 110 x 1e-14 torr l per s per cm2, converted to the canonical unit at build by the exact definition of the units. The column head of this table carries NO pumping time subscript, unlike tables 4, 6, 7 and 8 where K1, K4 and K10 name theirs, so the pumping time at which this rate was read is not published. The table credits this row to reference 14 of the source, G Moraw, Vacuum, 24, 1974, 125. Treatment as printed, 20 h at 100 C.

Bake100 C, 20 h, vacuum

Methodstated

Pumping timeNOT STATED by the source

Copper and copper alloys, including OFHC, beryllium copper and aluminium bronze, excluding phosphor bronze

Section 13.13. Prescribed clean and bake condition, not a measurement. The document states the procedures are consistent with baking a material at the maximum temperature possible and with meeting the summed mass pressure limit, and that vacuum baking is preferred over air baking because it allows an RGA scan of the load. Phosphor bronze is baked in air at 200 C for 24 hours. If any other copper alloy must be air baked rather than vacuum baked, the document limits it to 175 C for 48 hours. All parts must be wrought, not cast.

Tungsten

Table 1, row H25, condition column reads unbaked. Published in torr-liter/s/cm2 and converted to the canonical unit at build by the exact definition of the units: Jtotal 1.95e-07 torr-liter/s/cm2, JH2O 1.95e-07 torr-liter/s/cm2. No pumping time and no measurement temperature are given anywhere in the table. Footnote 8 of the source states the entries are representative of material sample measurements and provided as a design guideline for working up a gas budget. Table references: 3, Holland, Steckelmacher, Yarwood, Vacuum Manual (1974).

Methodstated

Pumping timeNOT STATED by the source

Tungsten plates

Row at 25 C of the tungsten column, published as less than 2.7 times 1e-13, an upper estimate obtained by assuming an outgassing of 50 percent of the background. Table 15 of the thesis. Four tungsten plates of total surface area 216 cm2 in the accumulation system, baked 24 h at 250 C and 22 h at 150 C. Rates are published in hPa l/(s cm2), the canonical unit under another spelling, and are nitrogen equivalent. The thesis publishes no elapsed pumping time for the readings. At 60 C and 100 C only tentative tests were made and the thesis states the measurements were cancelled because the outgassing was too low to distinguish.

Bake250 C, 24 h, vacuum

Methodaccumulation

Pumping timeNOT STATED by the source

Molybdenum

Table 1, row H11, condition column reads unbaked. Published in torr-liter/s/cm2 and converted to the canonical unit at build by the exact definition of the units: Jtotal 6.8e-07 torr-liter/s/cm2, JH2O 6.8e-07 torr-liter/s/cm2. No pumping time and no measurement temperature are given anywhere in the table. Footnote 8 of the source states the entries are representative of material sample measurements and provided as a design guideline for working up a gas budget. Table references: 3, Holland, Steckelmacher, Yarwood, Vacuum Manual (1974).

Methodstated

Pumping timeNOT STATED by the source

Molybdenum

Table 4 of the source. Published in torr l per s per cm2 with the column multiplier 1e-10, converted to the canonical unit at build by the exact definition of the units. Published values K1 52 x 1e-10 and K10 3.67 x 1e-10. Slopes of the log log plot as printed, alpha1 1.0 and alpha10 1. The table credits this row to reference 9 of the source, A Schram, Le Vide, No 103, 1963, 55. The tables of this source state neither a measurement temperature nor a gas species, and the source states in section 3.1 that the evolved gas is in general a mixture of water vapour, hydrogen, carbon monoxide and other gases treated as though it were air or nitrogen.

Methodstated

Pumping timethe abscissa of the curve below

Pyrex glass

Table 1, row F4, condition column reads unbaked. Published in torr-liter/s/cm2 and converted to the canonical unit at build by the exact definition of the units: Jtotal 1.6e-10 torr-liter/s/cm2, JH2O 1.6e-10 torr-liter/s/cm2. No pumping time and no measurement temperature are given anywhere in the table. Footnote 8 of the source states the entries are representative of material sample measurements and provided as a design guideline for working up a gas budget. Table references: 2, Schram, Le Vide No 103 (1963).

Methodstated

Pumping timeNOT STATED by the source

Pyrex (fresh)

Table 8 of the source. Published in torr l per s per cm2 with the column multiplier 1e-10, converted to the canonical unit at build by the exact definition of the units. Published values K1 73.5 x 1e-10 and K10 5.5 x 1e-10. Slopes of the log log plot as printed, alpha1 1.1 and alpha10 1.7. The table credits this row to reference 9 of the source, A Schram, Le Vide, No 103, 1963, 55. The tables of this source state neither a measurement temperature nor a gas species, and the source states in section 3.1 that the evolved gas is in general a mixture of water vapour, hydrogen, carbon monoxide and other gases treated as though it were air or nitrogen.

Methodstated

Pumping timethe abscissa of the curve below

Pyrex (1 month in air)

Table 8 of the source. Published in torr l per s per cm2 with the column multiplier 1e-10, converted to the canonical unit at build by the exact definition of the units. Published values K1 11.6 x 1e-10 and K10 1.6 x 1e-10. Slopes of the log log plot as printed, alpha1 0.9 and alpha10 0.7. The table credits this row to reference 9 of the source, A Schram, Le Vide, No 103, 1963, 55. The tables of this source state neither a measurement temperature nor a gas species, and the source states in section 3.1 that the evolved gas is in general a mixture of water vapour, hydrogen, carbon monoxide and other gases treated as though it were air or nitrogen.

Methodstated

Pumping timethe abscissa of the curve below

Viton A (fresh)

Table 7 of the source. Published in torr l per s per cm2 with the column multiplier 1e-8, converted to the canonical unit at build by the exact definition of the units. Published values K1 114 x 1e-8. Slopes of the log log plot as printed, alpha1 0.8 and alpha4 not printed. The table credits this row to reference 9 of the source, A Schram, Le Vide, No 103, 1963, 55. The tables of this source state neither a measurement temperature nor a gas species, and the source states in section 3.1 that the evolved gas is in general a mixture of water vapour, hydrogen, carbon monoxide and other gases treated as though it were air or nitrogen. The source prints no value at the other pumping time of this table.

Methodstated

Pumping time1 h

3M/Dyneon Fluorel FC2180, processed per LIGO-E970130-A

Row I9 of Table 1. Same column alignment problem as row A14. The pair is worth reading for the ratio it shows, a factor of about 4.6 gained by baking, but the species is not written without certainty.

Fluoroelastomer molded castings, Fluorel and Viton, manufactured per E970130

Section 13.17.2.1. Prescribed clean and bake condition, not a measurement. The document states the procedures are consistent with baking a material at the maximum temperature possible and with meeting the summed mass pressure limit, and that vacuum baking is preferred over air baking because it allows an RGA scan of the load. Ramp from room temperature at no more than 2.5 C per minute, hold 182 C plus or minus 1 C at a pressure not exceeding 1e-6 torr for 48 hours, cool in vacuum at no more than 3 C per minute. Free fluorine extraction, five pressure-cook cycles in DI water at 15 psi for 2 hours, precedes the bake. The document warns these parts can emit a large amount of hydrocarbon material and asks that surface exposure be maximised and surface contact minimised during the bake.

PEEK disks, 2 mm thick

Section 6.3, combined accumulation-throughput method. Two reservations published by the source and carried here: accumulation methods cannot give valid results for water outgassing, especially on polymers, and the figure is described as a rough estimation in the low 1e-8. Water was still the leading gas after the bake, the 18 amu peak more than ten times the peaks at 2, 28 and 44 amu.

Bake125 C, 20 h

Methodaccumulation

Pumping timenot applicable, the source states the rate independent of pumping time

PEEK, Semitron ESd 480 from Boedeker Plastics, a static dissipative reinforced PEEK

Table 1, row I6, condition column reads cleaned and baked. Published in torr-liter/s/cm2 and converted to the canonical unit at build by the exact definition of the units: Jtotal 7.2e-12 torr-liter/s/cm2, JH2O 3.5e-13 torr-liter/s/cm2, JH2 8.9e-14 torr-liter/s/cm2, JHC 1.8e-13 torr-liter/s/cm2. No pumping time and no measurement temperature are given anywhere in the table. Footnote 8 of the source states the entries are representative of material sample measurements and provided as a design guideline for working up a gas budget. Table references: 25, B. Taylor and D. Coyne, Material Qualification RGA Test Results: Semitron ESD 480 PEEK, LIGO-E1000298-v1.

Methodstated

Pumping timeNOT STATED by the source

PEEK disks, 2 mm thick

Section 6.3, combined accumulation-throughput method with a calibrated RGA. Activation energy 0.33 eV per molecule from the Arrhenius plot of accumulations lasting about 6 h at each measurement temperature. The 28 amu signal is attributed to N2 by the ratio of the 28 to 14 amu peaks.

Bake125 C, 20 h

Methodaccumulation

Pumping timenot applicable, the source states the rate independent of pumping time

PEEK disks, 2 mm thick

The source states that the very high partial pressure of water made the 2 amu peak mainly due to the fragmentation pattern of the water molecule, so the hydrogen rate could not be extracted. This is a measurement limit reported by the source, not a missing entry.

PEEK disks, 2 mm thick

Section 6.3 publishes an argon outgassing rate alongside the N2 and CO2 values, but the exponent did not survive text extraction of the source and reads as 8e-1, which is physically impossible for this quantity. The activation energy for argon, 0.27 eV per molecule, is legible and stated here. The value itself waits for a reading of the figure or of the typeset article. Nothing approximate is written.

Kapton HN foils, 0.0125 mm to 0.125 mm thick

Section 6.4 gives q(t) for several thicknesses in Fig. 34 only. The behaviour is stated: the rate follows the inverse square root of pumping time at short times, then falls much faster, with tails most likely going as t to the power minus three rather than the exponential predicted by the slab diffusion model, which the source attributes to water dissolved in the micro-voids of the amorphous phase. The time at which the regime changes increases with sample thickness. Underlying study: S.G. Sammartano, Outgassing rates of PEEK, Kapton and Vespel polymers, Master Thesis, Arcada, Helsinki, 2020. Measurements at CERN by Sergio Giacomo Sammartano, Ivo Wevers and Giuseppe Bregliozzi.

PEEK connectors, Kapton cabling and wire harnesses

Section 13.26.1. Prescribed clean and bake condition, not a measurement. The document states the procedures are consistent with baking a material at the maximum temperature possible and with meeting the summed mass pressure limit, and that vacuum baking is preferred over air baking because it allows an RGA scan of the load. Preceded by ultrasonic cleaning in methanol for 10 minutes.

Indium, pure

Section 13.14. Prescribed clean and bake condition, not a measurement. The document states the procedures are consistent with baking a material at the maximum temperature possible and with meeting the summed mass pressure limit, and that vacuum baking is preferred over air baking because it allows an RGA scan of the load. The document restricts this temperature to pure indium, melting point 156 C, and not to low temperature indium solders. Ultrasonic cleaning in acetone precedes the bake.

Magnetron sputtered TiZrV thin films after activation

Table 3 and section 3.3. Measured by the combined accumulation-throughput method on a TiZrV coated chamber of standard LHC long straight section geometry, 7 m long, 8 cm diameter. The source states this method works only for gases that are not readsorbed on the walls of the system. About 20 molecules per second per square centimetre. Lowest value published in the source, thirteen orders of magnitude below unbaked stainless steel water at 10 h.

Methodaccumulation

Pumping timenot applicable, the source states the rate independent of pumping time

non-evaporable getter coatings and strips

The source states that a vacuum chamber sputter-coated with a getter film may be transformed from a gas source to a pump by activating the coating during standard in situ bakeout. It also states that methane is not pumped by getters, and that the ultimate pressure of the LEP NEG pump is set by the outgassing of CH4 and Ar, gases not pumped by NEGs, divided by the pumping speed of a sputter-ion pump. A base that carries only a magnitude for these surfaces loses the sign and the species boundary, which are the two facts that matter in design.

TiZrV coating, magnetron sputtered from intertwisted Ti, Zr and V wires

The source states that TiZrV is practically fully activated after 24 h baking at 200 C, and that adding vanadium to TiZr shifts activation about 50 C lower for all degassing products, H2, CO, CO2 and CH4. Ultimate pressures after 24 h baking and H2 sticking coefficients are published as curves, on chambers 2 m long, 10 cm diameter, with 25 L/s applied for H2. Later literature from the same group is reported to give 180 C for 24 h, that value is not written here because the document publishing it has not been read on the page. Reading it is on the library list.

equiatomic TiZr coating on stainless steel

Section 3 of the source, from electron stimulated desorption measurements at 20 C after 2 h heating, electron energy 500 eV, current 1 mA, without intermediate air venting. For elemental Ti, Zr and Hf coatings no degassing variation is noticeable up to 200 C. The source gives the conversion between heating times: extending from 2 h to 24 h roughly corresponds to increasing the 2 h temperature by 50 C. Desorption yields are published as curves, no static outgassing rate is tabulated.

Sputter deposited TiZrV thin film, composition Ti 30 percent, Zr 20 percent, V 50 percent atomic, from intertwisted elemental wires

Measured on a 58 mm inner diameter chamber, not vented to air between baking cycles, by the variation of the ultimate pressure as a function of the baking temperature.

The document publishes an activation temperature and not an outgassing rate, so no value field is filled. The abstract, section 2 and the caption of figure 1 all give 180 C for 24 h. Section 2 states that the same coating was found to display full activation after 24 h heating at 200 C in the earlier work of reference 3, and that the interval between 150 and 200 C was then explored to obtain a more precise value.

TiZrV and other getter coatings after complete activation

The spread closely corresponds to that reported in the literature for titanium films deposited in situ by sublimation, so the source states it cannot be imputed to the chemical composition or to variable surface cleanliness of the coatings. Composition of the coating, stated by the source, Ti 30 percent, Zr 20 percent and V 50 percent atomic, sputtered from a cathode of intertwisted elemental wires of the same diameter. It is this coating that activates at 180 C and that traps about 3500 ppm of argon.

A sticking factor is a dimensionless capture probability, not an outgassing rate, so no value field is filled. The corpus carries it because it is the quantity that decides whether a getter surface is a pump or a source.

TiZrV film 5 micrometre thick, repeatedly activated and vented to air

During activation the oxygen present in the surface passivation layer diffuses inside the getter film, which for a film of micrometre thickness raises the film oxygen concentration and may reduce pumping speed and capacity and raise the activation temperature. Preliminary measurements indicate that film ageing may be reduced by dry air venting. Composition of the coating, stated by the source, Ti 30 percent, Zr 20 percent and V 50 percent atomic, sputtered from a cathode of intertwisted elemental wires of the same diameter. It is this coating that activates at 180 C and that traps about 3500 ppm of argon.

The document publishes an ageing behaviour and not an outgassing rate. The activation is initially carried out at 200 C and the activation temperature is progressively increased as the H2 sticking factor decreases.

TiZrV coated chambers 2 m long, diameters 34, 58 and 100 mm

Chambers connected to a vacuum system pumped by a sputter ion and a titanium sublimation pump through an orifice of 25 l per s for H2, with a CERN type Helmer gauge. Larger chambers of 160 mm were also measured but the source states the measuring uncertainty then becomes larger. Ultimate pressures in the 1e-14 Torr range reported a few years earlier are described as substantiated by these conclusions. Composition of the coating, stated by the source, Ti 30 percent, Zr 20 percent and V 50 percent atomic, sputtered from a cathode of intertwisted elemental wires of the same diameter. It is this coating that activates at 180 C and that traps about 3500 ppm of argon.

An ultimate system pressure is not a surface outgassing rate and never converts to one without the pumping speed and the area, so no value field is filled. The source itself declares these pressures instrument limited.

TiZrV coating produced by sputtering from an intertwisted wire cathode

Measured by laser ablating or melting a known amount of getter film and measuring the total amount of rare gas evolved. For comparison the source reports that sputter grown niobium films contain about 400 ppm of argon and that using krypton as the discharge gas the trapped amount decreases to a few ppm. Composition of the coating, stated by the source, Ti 30 percent, Zr 20 percent and V 50 percent atomic, sputtered from a cathode of intertwisted elemental wires of the same diameter. It is this coating that activates at 180 C and that traps about 3500 ppm of argon.

A trapped gas content in ppm is not an outgassing rate. It is carried because rare gases are not pumped by getters, so their release sets a floor the getter cannot lower.

TiZrV coating in a 58 mm inner diameter chamber, not vented to air between baking cycles

Chamber of 58 mm inner diameter, 2 m long, not vented to air between the baking cycles. The axes read Ultimate Pressure in Torr against 24 Hours Heating Temperature in degrees C. The source states elsewhere that the measured ultimate pressures are an instrumental artefact consequent to the degassing of the measuring gauge, so this plateau is a floor of the instrument and not of the coating. Composition of the coating, stated by the source, Ti 30 percent, Zr 20 percent and V 50 percent atomic, sputtered from a cathode of intertwisted elemental wires of the same diameter. It is this coating that activates at 180 C and that traps about 3500 ppm of argon.

THESE THREE NUMBERS ARE READ FROM A GRAPH, not from a table. The source tabulates none of them. They are carried as a declaration and never as a measurement, and their uncertainty is that of a reading on a logarithmic axis, of the order of the size of a plotted point, so about 20 percent on the mantissa. A system ultimate pressure is in any case not a surface outgassing rate and does not convert to one without the pumping speed and the area.

St 101 NEG strip, Zr84-Al16 powder on constantan, 30 mm wide, 100 micron coating both sides (SAES Getters)

Section 1 of the source, LEP vacuum system, about 23 of the 27 km. Pumping speed for H2 about 2000 L/s per linear metre. Ultimate pressure about 2e-12 Torr in a LEP dipole chamber after 24 h baking at 150 C, set by the outgassing of CH4 and Ar divided by the pumping speed of a sputter-ion pump of about 50 L/s nominal for a 12 m chamber, with six such pumps on the same chamber, about 5e-13 Torr. Porosity raised from 7 to 13 percent for the LEP delivery. These are pumping speeds and system pressures, not specific outgassing rates. Card assignment to be checked at integration: this strip may belong to a card other than st707-zao.

St 707 NEG strip (SAES Getters)

Section 1 of the source: pumping curves very similar to those of St 101 are obtained after heating at 350 to 400 C. Covering the inner surface of a chamber entirely with St 707 strip, a total NEG pump, gives pumping speeds above 1e4 L/s per linear metre after a 350 C bakeout and pressures below 1e-13 Torr, measured in a 3 m stainless steel tube and stated by the source to be extrapolable to any length because the pump is modular.

Brass (wave-guide)

Table 4 of the source. Published in torr l per s per cm2 with the column multiplier 1e-10, converted to the canonical unit at build by the exact definition of the units. Published values K1 4000 x 1e-10 and K10 100 x 1e-10. Slopes of the log log plot as printed, alpha1 2.0 and alpha10 1.2. The table credits this row to reference 13 of the source, B B Dayton, Trans 6th AVS Symp, p 101, 1959. The tables of this source state neither a measurement temperature nor a gas species, and the source states in section 3.1 that the evolved gas is in general a mixture of water vapour, hydrogen, carbon monoxide and other gases treated as though it were air or nitrogen.

Methodstated

Pumping timethe abscissa of the curve below

Zinc

Table 4 of the source. Published in torr l per s per cm2 with the column multiplier 1e-10, converted to the canonical unit at build by the exact definition of the units. Published values K1 2210 x 1e-10 and K10 322 x 1e-10. Slopes of the log log plot as printed, alpha1 1.4 and alpha10 0.8. The table credits this row to reference 9 of the source, A Schram, Le Vide, No 103, 1963, 55. The tables of this source state neither a measurement temperature nor a gas species, and the source states in section 3.1 that the evolved gas is in general a mixture of water vapour, hydrogen, carbon monoxide and other gases treated as though it were air or nitrogen.

Methodstated

Pumping timethe abscissa of the curve below

Mild steel

Table 4 of the source. Published in torr l per s per cm2 with the column multiplier 1e-10, converted to the canonical unit at build by the exact definition of the units. Published values K1 5400 x 1e-10 and K10 500 x 1e-10. Slopes of the log log plot as printed, alpha1 1 and alpha10 1. The table credits this row to reference 13 of the source, B B Dayton, Trans 6th AVS Symp, p 101, 1959. The tables of this source state neither a measurement temperature nor a gas species, and the source states in section 3.1 that the evolved gas is in general a mixture of water vapour, hydrogen, carbon monoxide and other gases treated as though it were air or nitrogen.

Methodstated

Pumping timethe abscissa of the curve below

Mild steel (slightly rusty)

Table 4 of the source. Published in torr l per s per cm2 with the column multiplier 1e-10, converted to the canonical unit at build by the exact definition of the units. Published values K1 6000 x 1e-10 and K10 130 x 1e-10. Slopes of the log log plot as printed, alpha1 3.1 and alpha10 1. The table credits this row to reference 13 of the source, B B Dayton, Trans 6th AVS Symp, p 101, 1959. The tables of this source state neither a measurement temperature nor a gas species, and the source states in section 3.1 that the evolved gas is in general a mixture of water vapour, hydrogen, carbon monoxide and other gases treated as though it were air or nitrogen. Internal inconsistency of the source, signalled and not corrected. The two published rates give a log log slope of 1.66 over the interval, while the printed slopes are 3.1 and 1. Both rates were read twice, from the text layer and from a 400 dpi raster, and agree. A slope is a local quantity and need not equal the average, but here it differs from both printed values.

Methodstated

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Gaflon (PTFE) (fresh)

Table 6 of the source. Published in torr l per s per cm2 with the column multiplier 1e-8, converted to the canonical unit at build by the exact definition of the units. Published values K1 16.6 x 1e-8 and K10 3.31 x 1e-8. Slopes of the log log plot as printed, alpha1 0.8 and alpha10 0.9. The table credits this row to reference 9 of the source, A Schram, Le Vide, No 103, 1963, 55. The tables of this source state neither a measurement temperature nor a gas species, and the source states in section 3.1 that the evolved gas is in general a mixture of water vapour, hydrogen, carbon monoxide and other gases treated as though it were air or nitrogen.

Methodstated

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PTFE

Table 6 of the source. Published in torr l per s per cm2 with the column multiplier 1e-8, converted to the canonical unit at build by the exact definition of the units. Published values K1 30 x 1e-8 and K10 15 x 1e-8. Slopes of the log log plot as printed, alpha1 0.45 and alpha10 0.56. The table credits this row to reference 13 of the source, B B Dayton, Trans 6th AVS Symp, p 101, 1959. The tables of this source state neither a measurement temperature nor a gas species, and the source states in section 3.1 that the evolved gas is in general a mixture of water vapour, hydrogen, carbon monoxide and other gases treated as though it were air or nitrogen.

Methodstated

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Teflon

Table 6 of the source. Published in torr l per s per cm2 with the column multiplier 1e-8, converted to the canonical unit at build by the exact definition of the units. Published values K1 6.5 x 1e-8 and K10 2.5 x 1e-8. Slopes of the log log plot as printed, alpha1 0.5 and alpha10 0.2. The table credits this row to reference 36 of the source, G Thieme, Vacuum, 13, 1963, 55. The tables of this source state neither a measurement temperature nor a gas species, and the source states in section 3.1 that the evolved gas is in general a mixture of water vapour, hydrogen, carbon monoxide and other gases treated as though it were air or nitrogen.

Methodstated

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Silicone

Table 7 of the source. Published in torr l per s per cm2 with the column multiplier 1e-8, converted to the canonical unit at build by the exact definition of the units. Published values K1 1800 x 1e-8 and K4 440 x 1e-8. Slopes of the log log plot as printed, alpha1 1.0 and alpha4 1.2. The table credits this row to reference 32 of the source, R Jaeckel and F J Schitto, Gas Evolution from Materials in Vacuum, West Germany Ministry Research Report. The tables of this source state neither a measurement temperature nor a gas species, and the source states in section 3.1 that the evolved gas is in general a mixture of water vapour, hydrogen, carbon monoxide and other gases treated as though it were air or nitrogen.

Methodstated

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Neoprene

Table 3, measured at room temperature. The source credits this row to R.N. Peacock, Practical selection of elastomer materials for vacuum seals, J. Vac. Sci. Technol. 17 (1980) 330. Five orders of magnitude above unbaked austenitic stainless steel at the same pumping time. The source works out the consequence: a 1 cm2 piece of a few mm thick Neoprene inside a 1 m2 stainless vessel, 0.01 percent of the area, raises the pressure after 10 h of pumping by one order of magnitude.

Methodstated

Pumping time10 h

Neoprene

Table 7 of the source. Published in torr l per s per cm2 with the column multiplier 1e-8, converted to the canonical unit at build by the exact definition of the units. Published values K1 3000 x 1e-8 and K4 1800 x 1e-8. Slopes of the log log plot as printed, alpha1 0.4 and alpha4 0.4. The table credits this row to reference 31 of the source, J Blears et al, Trans 1st IOVST Symp, 1960. The tables of this source state neither a measurement temperature nor a gas species, and the source states in section 3.1 that the evolved gas is in general a mixture of water vapour, hydrogen, carbon monoxide and other gases treated as though it were air or nitrogen.

Methodstated

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Methyl methacrylate

Table 6 of the source. Published in torr l per s per cm2 with the column multiplier 1e-8, converted to the canonical unit at build by the exact definition of the units. Published values K1 420 x 1e-8 and K10 140 x 1e-8. Slopes of the log log plot as printed, alpha1 0.9 and alpha10 0.57. The table credits this row to reference 31 of the source, J Blears et al, Trans 1st IOVST Symp, 1960. The tables of this source state neither a measurement temperature nor a gas species, and the source states in section 3.1 that the evolved gas is in general a mixture of water vapour, hydrogen, carbon monoxide and other gases treated as though it were air or nitrogen.

Methodstated

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Nylon

Table 6 of the source. Published in torr l per s per cm2 with the column multiplier 1e-8, converted to the canonical unit at build by the exact definition of the units. Published values K1 1200 x 1e-8 and K10 600 x 1e-8. Slopes of the log log plot as printed, alpha1 0.5 and alpha10 0.5. The table credits this row to reference 35 of the source, B D Power and D J Crawley, Advances in Vacuum Science and Technology, Vol 1, p 206, Pergamon Press, Oxford, 1960. The tables of this source state neither a measurement temperature nor a gas species, and the source states in section 3.1 that the evolved gas is in general a mixture of water vapour, hydrogen, carbon monoxide and other gases treated as though it were air or nitrogen.

Methodstated

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Plexiglas

Table 6 of the source. Published in torr l per s per cm2 with the column multiplier 1e-8, converted to the canonical unit at build by the exact definition of the units. Published values K1 72 x 1e-8 and K10 27 x 1e-8. Slopes of the log log plot as printed, alpha1 0.44 and alpha10 0.44. The table credits this row to reference 36 of the source, G Thieme, Vacuum, 13, 1963, 55. The tables of this source state neither a measurement temperature nor a gas species, and the source states in section 3.1 that the evolved gas is in general a mixture of water vapour, hydrogen, carbon monoxide and other gases treated as though it were air or nitrogen.

Methodstated

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Polyamid

Table 6 of the source. Published in torr l per s per cm2 with the column multiplier 1e-8, converted to the canonical unit at build by the exact definition of the units. Published values K1 460 x 1e-8 and K10 230 x 1e-8. Slopes of the log log plot as printed, alpha1 0.5 and alpha10 0.5. The table credits this row to reference 32 of the source, R Jaeckel and F J Schitto, Gas Evolution from Materials in Vacuum, West Germany Ministry Research Report. The tables of this source state neither a measurement temperature nor a gas species, and the source states in section 3.1 that the evolved gas is in general a mixture of water vapour, hydrogen, carbon monoxide and other gases treated as though it were air or nitrogen.

Methodstated

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PVC (24 h at 95 percent RH)

Table 6 of the source. Published in torr l per s per cm2 with the column multiplier 1e-8, converted to the canonical unit at build by the exact definition of the units. Published values K1 85 x 1e-8 and K10 2 x 1e-8. Slopes of the log log plot as printed, alpha1 1.0 and alpha10 not printed. The table credits this row to reference 34 of the source, D J Santeler, Trans 5th AVS Symp, 1958. The tables of this source state neither a measurement temperature nor a gas species, and the source states in section 3.1 that the evolved gas is in general a mixture of water vapour, hydrogen, carbon monoxide and other gases treated as though it were air or nitrogen. Internal inconsistency of the source, signalled and not corrected. The two published rates give a log log slope of 1.63 over the interval, while the printed slopes are 1.0. Both rates were read twice, from the text layer and from a 400 dpi raster, and agree. A slope is a local quantity and need not equal the average, but here it differs from both printed values.

Methodstated

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Ultrahigh molecular weight polymethylmethacrylate, sample number 2, obtained by frontal polymerization at 60 C for 5 days, molecular weight about 1e7 g per mole

Third block of table 3, after an air vent that follows the bakeout at 120 C. The state is recorded as unbaked because the surface saw atmosphere again after the bakeout, and the history is stated here rather than folded into a single word. Table 3 of the source, published in l Torr/(s cm2) and converted to the canonical unit at build by the exact definition of the units. The table publishes no gas species and no measurement temperature. The samples were purified by film evaporation under reduced pressure with a rotary vaporizer, polymerized by electron flux from the ILU-6 linear accelerator, mechanically treated and polished, then annealed at 110 C for 1 day. The source states that usual PMMA has a molecular weight of about 1e6 g per mole and that usual PMMA and sample number 1 showed no difference in outgassing rate.

Methodthroughput

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Ultrahigh molecular weight polymethylmethacrylate, sample number 2, obtained by frontal polymerization at 60 C for 5 days, molecular weight about 1e7 g per mole

First block of table 3, seven readings from 1 to 11 days in vacuum after the anneal and before any in situ bakeout. Table 3 of the source, published in l Torr/(s cm2) and converted to the canonical unit at build by the exact definition of the units. The table publishes no gas species and no measurement temperature. The samples were purified by film evaporation under reduced pressure with a rotary vaporizer, polymerized by electron flux from the ILU-6 linear accelerator, mechanically treated and polished, then annealed at 110 C for 1 day. The source states that usual PMMA has a molecular weight of about 1e6 g per mole and that usual PMMA and sample number 1 showed no difference in outgassing rate.

Bake110 C, 24 h

Methodthroughput

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Aluminium (anodised-2 um pores)

Table 4 of the source. Published in torr l per s per cm2 with the column multiplier 1e-10, converted to the canonical unit at build by the exact definition of the units. Published values K1 2760 x 1e-10 and K10 322 x 1e-10. Slopes of the log log plot as printed, alpha1 0.9 and alpha10 0.9. The table credits this row to reference 9 of the source, A Schram, Le Vide, No 103, 1963, 55. The tables of this source state neither a measurement temperature nor a gas species, and the source states in section 3.1 that the evolved gas is in general a mixture of water vapour, hydrogen, carbon monoxide and other gases treated as though it were air or nitrogen.

Methodstated

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Steel (nickel plated fresh)

Table 4 of the source. Published in torr l per s per cm2 with the column multiplier 1e-10, converted to the canonical unit at build by the exact definition of the units. Published values K1 42.4 x 1e-10 and K10 4.94 x 1e-10. Slopes of the log log plot as printed, alpha1 0.9 and alpha10 0.9. The table credits this row to reference 9 of the source, A Schram, Le Vide, No 103, 1963, 55. The tables of this source state neither a measurement temperature nor a gas species, and the source states in section 3.1 that the evolved gas is in general a mixture of water vapour, hydrogen, carbon monoxide and other gases treated as though it were air or nitrogen.

Methodstated

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Steel (nickel plated)

Table 4 of the source. Published in torr l per s per cm2 with the column multiplier 1e-10, converted to the canonical unit at build by the exact definition of the units. Published values K1 27.6 x 1e-10 and K10 2.33 x 1e-10. Slopes of the log log plot as printed, alpha1 1.1 and alpha10 1.1. The table credits this row to reference 9 of the source, A Schram, Le Vide, No 103, 1963, 55. The tables of this source state neither a measurement temperature nor a gas species, and the source states in section 3.1 that the evolved gas is in general a mixture of water vapour, hydrogen, carbon monoxide and other gases treated as though it were air or nitrogen.

Methodstated

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Steel (chemically nickel plated fresh)

Table 4 of the source. Published in torr l per s per cm2 with the column multiplier 1e-10, converted to the canonical unit at build by the exact definition of the units. Published values K1 83 x 1e-10 and K10 7.05 x 1e-10. Slopes of the log log plot as printed, alpha1 1 and alpha10 1. The table credits this row to reference 9 of the source, A Schram, Le Vide, No 103, 1963, 55. The tables of this source state neither a measurement temperature nor a gas species, and the source states in section 3.1 that the evolved gas is in general a mixture of water vapour, hydrogen, carbon monoxide and other gases treated as though it were air or nitrogen.

Methodstated

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Steel (chemically nickel plated polished)

Table 4 of the source. Published in torr l per s per cm2 with the column multiplier 1e-10, converted to the canonical unit at build by the exact definition of the units. Published values K1 52.2 x 1e-10 and K10 4.6 x 1e-10. Slopes of the log log plot as printed, alpha1 1 and alpha10 1. The table credits this row to reference 9 of the source, A Schram, Le Vide, No 103, 1963, 55. The tables of this source state neither a measurement temperature nor a gas species, and the source states in section 3.1 that the evolved gas is in general a mixture of water vapour, hydrogen, carbon monoxide and other gases treated as though it were air or nitrogen.

Methodstated

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Macor machinable glass ceramic rods

Row at 25 C of the Macor column, published as less than 5.2 times 1e-13. Table 15 of the thesis. Five Macor rods of total surface area 110 cm2 in the accumulation system, baked 24 h at 250 C and 21 h at 150 C. Because the outgassing sits so close to the background, the thesis states that it is more reasonable to estimate maximum possible outgassing rates, obtained by assuming an outgassing of 50 percent of the background, since samples outgassing more than half the background would have been surely distinct in the tests. The value is therefore a bound and stays a bound. Rates are published in hPa l/(s cm2), the canonical unit under another spelling, and are nitrogen equivalent. The thesis publishes no elapsed pumping time for the readings.

Bake250 C, 24 h, vacuum

Methodaccumulation

Pumping timeNOT STATED by the source

Vitreous Carbon, Beckwith Carbon Corp., Van Nuys, California

Table I of the source, vacuum characteristics of carbons. The first four columns give the gas evolved on outgassing to 2000 K in monolayers evolved, and the last four give adsorption probabilities at 300 K. Samples were initially outgassed above 2000 K, exposed to laboratory air for several hours at room temperature, then tested in ultrahigh vacuum near 1e-10 Torr following a normal 24 hour bake at 300 C. Heating was by electrical conduction in increments of about 100 K up to 2000 K, with flashes of 4 s. The source defines one monolayer as 5e14 molecules/cm2 in a footnote on page 11.

A quantity of gas evolved in monolayers is not a rate per unit area. It has no time in it, and it cannot be converted into the canonical unit of this corpus by any factor. The corpus carries no field for a quantity of gas evolved on heating, so the numbers are recorded verbatim in the text of this declaration and no value field is filled. Converting them would invent a pumping time that the source never published.

Pyrolytic Graphite, Super Temp, Santa Fe Springs, California

Table I of the source, vacuum characteristics of carbons. The first four columns give the gas evolved on outgassing to 2000 K in monolayers evolved, and the last four give adsorption probabilities at 300 K. Samples were initially outgassed above 2000 K, exposed to laboratory air for several hours at room temperature, then tested in ultrahigh vacuum near 1e-10 Torr following a normal 24 hour bake at 300 C. Heating was by electrical conduction in increments of about 100 K up to 2000 K, with flashes of 4 s. The source defines one monolayer as 5e14 molecules/cm2 in a footnote on page 11.

A quantity of gas evolved in monolayers is not a rate per unit area. It has no time in it, and it cannot be converted into the canonical unit of this corpus by any factor. The corpus carries no field for a quantity of gas evolved on heating, so the numbers are recorded verbatim in the text of this declaration and no value field is filled. Converting them would invent a pumping time that the source never published.

Grafoil, Union Carbide, New York, New York

Table I of the source, vacuum characteristics of carbons. The first four columns give the gas evolved on outgassing to 2000 K in monolayers evolved, and the last four give adsorption probabilities at 300 K. Samples were initially outgassed above 2000 K, exposed to laboratory air for several hours at room temperature, then tested in ultrahigh vacuum near 1e-10 Torr following a normal 24 hour bake at 300 C. Heating was by electrical conduction in increments of about 100 K up to 2000 K, with flashes of 4 s. The source defines one monolayer as 5e14 molecules/cm2 in a footnote on page 11.

A quantity of gas evolved in monolayers is not a rate per unit area. It has no time in it, and it cannot be converted into the canonical unit of this corpus by any factor. The corpus carries no field for a quantity of gas evolved on heating, so the numbers are recorded verbatim in the text of this declaration and no value field is filled. Converting them would invent a pumping time that the source never published.

All carbon triode gauge, collector, grid and supports in Grafoil and pyrolytic graphite

Section on gauge testing, page 21 of the report. Read on a 400 dpi raster of the scanned page, where the unit is printed as torr l/cm2 with no per second.

The printed unit has no time in it. A rate per unit area is torr l per second per cm2 and the source prints torr l/cm2, so the reading is certain and the unit is not. The rule of this campaign is that a value whose unit is not certain is not written, and this one is not. The operating condition is also not a material condition, since the source expects the 37 W to raise the grid and collector to about 750 K, 130 K above the bake-out temperature.

Graphite grade R 8500 from SGL Carbon, isostatically pressed

Throughput system, 100 hours of pumping measured at each of 30, 60, 100, 150 and 200 C. The same holds for the PEEK sample of 103 cm2 and for the unbaked Vespel SP-1 sample of 48.5 cm2 measured on the same system, whose rates are published as curves only.

The outgassing rates of both graphite samples are published as curves against time in figures 32 and 36 and are tabulated nowhere. Reading a number off a plotted curve is not reading a published value, so no value field is filled.

Boron carbide ceramic

Column at 100 C of table 1, eight readings of the same samples over 23 months in vacuum. Table 1 of the source, published in Torr l/s/cm2 and converted to the canonical unit at build by the exact definition of the units. The table publishes no gas species, so the value is recorded as a total rate. Elapsed times in months are converted with the mean Gregorian month of 730.5 h, and the verbatim column reads 5 hours, 24 hours, 29 hours, 8 months, 12 months, 20 months, 22 months and 23 months. Samples cleaned with isopropyl alcohol, ultrasonically treated in distilled water, and baked at 1000 C in vacuum. The baking cycle before the outgassing test was a ramp from room temperature to 320 C in 10 h, 24 h at 320 C, a ramp back to room temperature in 10 h, 36 h at room temperature, a ramp to 100 C in 3 h, then steady 100 C for testing. The area of the ceramic was more than ten times the area of the empty test volume. Dynamic flow method. The pressure drop across an element of known molecular conductivity is measured, and the gas release of the empty test volume is compared with the volume filled with samples. Pressure read by a hot cathode gauge, partial pressures by an SRS quadrupole. The measured background outgassing of the empty stainless steel volume was 3.3e-11 Torr l/s/cm2 at 100 C. The source states that the rate meets the ITER Vacuum Handbook requirement of not more than 1e-10 Torr l/s/cm2 for hydrogen and not more than 1e-12 Torr l/s/cm2 for all other impurities, with a large reserve.

Bake320 C, 24 h, vacuum

Methodthroughput

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MasterBond EP30-2 epoxy

Table 1, row A12, condition column reads not stated. Published in torr-liter/s/cm2 and converted to the canonical unit at build by the exact definition of the units: Jtotal 5.6e-11 torr-liter/s/cm2, JH2O 2.2e-12 torr-liter/s/cm2, JH2 1.2e-12 torr-liter/s/cm2, JHC 5e-13 torr-liter/s/cm2. No pumping time and no measurement temperature are given anywhere in the table. Footnote 8 of the source states the entries are representative of material sample measurements and provided as a design guideline for working up a gas budget. Table references: 23, B. Taylor and D. Coyne, LIGO-E1000386-v1, 24, Optical Contamination Test Results, LIGO-E1000479-v1.

Methodstated

Pumping timeNOT STATED by the source

Epo-Tek 353ND epoxy

Row A14 of Table 1 carries one number across four species columns, JTotal, Jwater, JH2 and JHC, and the column alignment did not survive text extraction of the source. Nothing is written rather than guessing the species. Underlying qualification documents named by the table: LIGO-E1300653-v1 and LIGO-E1300654-v1.