meta data for this page
Differences
This shows you the differences between two versions of the page.
| Both sides previous revisionPrevious revisionNext revision | Previous revision | ||
| groups:mg:project_ptb-cavity:vacuum:bake_out [2017/05/09 13:33] – ssauer | groups:mg:project_ptb-cavity:vacuum:bake_out [2024/03/20 09:36] (current) – Admin: Syntax-Update (Migration from deprecated "fontcolor" plugin to "color" plugin) klaus | ||
|---|---|---|---|
| Line 1: | Line 1: | ||
| - | ====== Bake out ====== | + | ====== Bake out list ====== |
| - | * We use the temperature monitoring design, made by E. Wodey, for the out of loop measurements during the out baking. | ||
| - | * Talk by E. Wodey for the explanation of the monitoring system:{{ : | ||
| - | * Box-design made by S. Sauer: {{: | ||
| - | |||
| - | |||
| - | ==== Bake out list ==== | ||
| - | |||
| - | ^ Item ^ Material | ||
| - | | Mounting for the spacer | ||
| - | | Zerodur rods | Zerodur | ||
| - | | Viton balls | Viton | 280 | Wikipedia | ||
| - | | Glas balls | Borosilikatglas | ||
| - | | Heat shields | ||
| - | | Screws from the mounting and hield shield | ||
| - | | Windows | ||
| - | What is the maximum (continuous) temperature which the AR coatings are able to withstand? What is the maximum temperature gradient that can be applied (continuously) between the two faces of the 1/2" 3mm BK7 and fused silica windows?\\ Response from Jeremy at Thorlabs:\\ | ||
| - | The maximum temperature will be around 200°C or so. We do not spec a maximum temperature gradient since it can depend on the thermal boundary conditions and geometrical boundary conditions of the window. However, I would recommend UVFS over N-BK7 because of its much lower coefficient of thermal coefficient. | ||
| - | | Window holder | ||
| - | | Vacuum chamber | ||
| - | | CF Cupper ring | Cupper | ||
| - | | CF Flanschkit | ||
| - | | IGP | | 350 | | | ||
| - | | IGP cable | | < 220 | | | ||
| - | | Vacuum pressure sensor | ||
| - | | Vacuum pressure sensor cable | ||
| - | | Angle valve | | < = 300 | | | ||
| - | | Gate valve | ||
| - | | Sub-D Socket | ||
| - | | Sub-D Feedthrough | ||
| - | | Sub-D Kabel 37FXRR-500 | ||
| - | | CF-Kreuz | ||
| - | | Lead wire | Lead | 327 | | | ||
| - | | Indium wire | Indium | ||
| - | | Indium foil | Indium | ||
| - | | Capton wires | Kupferdraht versilbert\\ Kaptonband-isoliert | ||
| - | | Crimp pins | Cu vergoldet | ||
| - | | Peltier-elements | ||
| - | | NTC Sensors | ||
| - | | Vacuum glue [Torrseal] | ||
| + | ^ Item ^ Material | ||
| + | | CF Cupper ring | Cupper | ||
| + | | Mounting for the spacer | ||
| + | | Zerodur rods | Zerodur | ||
| + | | Heat shields | ||
| + | | Window holder | ||
| + | | Vacuum chamber | ||
| + | | CF Flanschkit | ||
| + | | Glas balls | Borosilikatglas | ||
| + | | IGP | | 350 | | | ||
| + | | Lead wire | Lead | 327 | | | ||
| + | | Teflon rings (Windows) | ||
| + | | NTC Sensors | ||
| + | | Angle valve | | < = 300 | | | ||
| + | | Viton balls | Viton | 280 | Wikipedia | ||
| + | | Sub-D Kabel 37FXRR-500 | ||
| + | | Vacuum pressure sensor | ||
| + | | Gate valve | ||
| + | | Sub-D Socket | ||
| + | | Sub-D Feedthrough | ||
| + | | Crimp pins | Cu vergoldet | ||
| + | | Capton wires | Kupferdraht versilbert\\ Kaptonband-isoliert | ||
| + | | IGP cable | | < 220 | | | ||
| + | | Peltier-elements | ||
| + | | Windows | ||
| + | | Vacuum glue [Torrseal] | ||
| + | | Indium wire | Indium | ||
| + | | Indium foil | Indium | ||
| + | | Vacuum pressure sensor cable | ||
| + | | CF-Kreuz | ||
| + | | Screws from the mounting and hield shield | ||
| | ULE Spacer| | | ULE Spacer| | ||
| Line 47: | Line 39: | ||
| | Faraday rotator | | | | | Faraday rotator | | | | ||
| | Glue from faraday rotator | | | | | Glue from faraday rotator | | | | ||
| - | |||
| - | ==== Bake out tips ==== | ||
| - | |||
| - | http:// | ||
| - | |||
| - | |||
| - | 3.3 Baking\\ | ||
| - | Early workers baked systems only to about 200C which was effective in removing weakly bound surface water and hydrocarbon molecules. It was not long before it was discovered that baking to higher temperatures was required to remove more tightly bound species and the hydrogen diffusing from the bulk, both of which had the effect of limiting the ultimate system vacuum. The effectiveness of high temperature bakes is amply demonstrated | ||
| - | Santeler (1991), quotes early work by Aero Vac Corporation which gives valuable data on the effect of baking to different temperatures which is reproduced here below:\\ | ||
| - | **Outgassing rates in Torr l/s cm2**\\ | ||
| - | |||
| - | |||
| - | === BAKING TIME === | ||
| - | |||
| - | ^ BAKING TEMP ^ 20 hrs ^ 40 hrs ^ 100 hrs ^ 200hrs ^ | ||
| - | | 150C | 6.3E-11 | 5.3E-11 | 2.8E-11 | 2.0E-11 | | ||
| - | | 250C | 6.3E-12 | 5.3E-12 | 2.8E-12 | 2.0E-12 | | ||
| - | | 400C | 4.0E-13 | 1.7E-13 | 1.0E-13 | 1.0E-13 | | ||
| - | | 500C | 8.0E-15 | 8.0E-16 | 4.0E-17 | 8.0E-19 | | ||
| - | |||
| - | The data above bring home clearly the benefits of high baking temperatures and the diminishing returns from increasing baking time much beyond 20 hrs for baking temperatures up to 400C; at 500C the table shows that it is worthwhile to bake for as long as 200 hrs although one might legitimately question the unusually low value of 8.0E-19 torr l/s cm2 that is quoted. Recent work (Ishikawa, 1995; Ishikawa et al 1991; and Ishikawa and Odaka1990), confirms the values above for lower temperatures but indicates that surface treatments and raw material quality can improve these figures substantially, | ||
| - | |||
| - | ==== Bake out Protocol ==== | ||
| - | |||