Methane outgassing from a Ti sublimation pump
A Ti sublimation pump together with a small 20 l/s ion pump is typically used as the pump for UHV systems. It is well known that the Ti surface will not pump methane and that the ion pump pumping speed for CH/sub 4/ is only 1 l/s in the low 10/sup -11/ Torr range. Thus it is important to identify and if possible reduce the sources of CH/sub 4/ outgassing. In this study we report the first quantitative measurements of the methane outgassing rate from a 1500 cm/sup 2/ Ti sublimation chamber both before and after the Ti evaporation. The contrast to the very low CH/sub 4/ outgassing rate from the chamber before the Ti is flashed (<10/sup -12/ Torr l/s) the CH/sub 4/ outgassing rate after the Ti evaporation is considerable (4 x 10/sup -11/ Torr l/s) with a very slow decrease with repect to time, and has been found to be significant in terms of the ISABELLE requirements. To essentially eliminate the methane outgassing from the Ti getter chamber, it has been determined sufficient to heat the Ti chamber for four hours at 100 C after the Ti evaporation has been completed. Using a similar procedure a reasonably rapid processing of the ISABELLE vacuum system to an ultrahigh vacuum condition should be possible after an atmospheric exposure.
- Research Organization:
- Brookhaven National Laboratory, Upton, New York 11973
- OSTI ID:
- 5326512
- Journal Information:
- J. Vac. Sci. Technol.; (United States), Vol. 17:1
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
METHANE
SUBLIMATION
TITANIUM
SORPTIVE PROPERTIES
VACUUM PUMPS
GETTERS
ISABELLE STORAGE RINGS
MASS SPECTROMETERS
STAINLESS STEEL-304
ULTRAHIGH VACUUM
VACUUM SYSTEMS
ALKANES
ALLOYS
CHROMIUM ALLOYS
CHROMIUM STEELS
CHROMIUM-NICKEL STEELS
CORROSION RESISTANT ALLOYS
CRYOGENIC FLUIDS
ELEMENTS
EVAPORATION
FLUIDS
HEAT RESISTANT MATERIALS
HEAT RESISTING ALLOYS
HYDROCARBONS
IRON ALLOYS
IRON BASE ALLOYS
LABORATORY EQUIPMENT
MATERIALS
MEASURING INSTRUMENTS
METALS
NICKEL ALLOYS
ORGANIC COMPOUNDS
PHASE TRANSFORMATIONS
PUMPS
SPECTROMETERS
STAINLESS STEELS
STEELS
STORAGE RINGS
SURFACE PROPERTIES
TRANSITION ELEMENTS
430400* - Particle Accelerators- Storage Rings