Influence of Adsorption at Endothermic Surface Sites on the Pumping and Outgassing Rate for Ion Gauges, Residual Gas Analyzers, and other Similar Devices

1970 ◽  
Vol 7 (1) ◽  
pp. 262-266 ◽  
Author(s):  
Harold F. Winters
Keyword(s):  
Surface Sites ◽  
Residual Gas ◽  
Outgassing Rate

scholarly journals Commissioning and operation status of the MAX IV 3 GeV storage ring vacuum system

2021 ◽  
Vol 28 (3) ◽  
Author(s):  
Marek Grabski ◽  
Eshraq Al-Dmour
Keyword(s):  
Storage Ring ◽  
Vacuum System ◽  
Vacuum Chambers ◽  
The World ◽  
Beam Lifetime ◽  
Residual Gas ◽  
Outgassing Rate ◽  
Almost All ◽  
Operation Status ◽  
Better Than

The 3 GeV electron storage ring of the MAX IV laboratory is the first storage-ring-based synchrotron radiation facility with the inner surface of almost all the vacuum chambers along its circumference coated with non-evaporable getter (NEG) thin film. The coating provides a low dynamic outgassing rate and pumping of active gases. As the NEG coating was applied on an unprecedented scale, there were doubts concerning the storage ring performance. Fast conditioning of the vacuum system and over five years of reliable accelerator operation have demonstrated that the chosen design proved to be good and does not impose limits on the operation. The vacuum system performance is comparable with or better than that of other similar facilities around the world, where conventional designs were implemented. Observed pressure levels are low, and the electron beam lifetime is long and not limited by residual gas density. A summary of the vacuum performance is presented.

Residual Gas Reactions in the Electron Microscope: I. Qualitative Observations on the Water Gas Reaction

1968 ◽  
Vol 26 ◽  
pp. 292-293
Author(s):  
Richard E. Hartman ◽  
Roberta S. Hartman ◽  
Peter L. Ramos
Keyword(s):  
Electron Beam ◽  
Electron Microscope ◽  
Gas Phase ◽  
Absolute Temperature ◽  
Residual Gas ◽  
Gas Reactions ◽  
Image Position ◽  
The Right ◽  
Water Gas ◽  
Thinning Rate

The action of water and the electron beam on organic specimens in the electron microscope results in the removal of oxidizable material (primarily hydrogen and carbon) by reactions similar to the water gas reaction .which has the form:The energy required to force the reaction to the right is supplied by the interaction of the electron beam with the specimen.The mass of water striking the specimen is given by:where u = gH2O/cm2 sec, PH2O = partial pressure of water in Torr, & T = absolute temperature of the gas phase. If it is assumed that mass is removed from the specimen by a reaction approximated by (1) and that the specimen is uniformly thinned by the reaction, then the thinning rate in A/ min iswhere x = thickness of the specimen in A, t = time in minutes, & E = efficiency (the fraction of the water striking the specimen which reacts with it).

Recent Progress In High-Resolution Shadowing For Biological Transmission Electron Microscopy

1990 ◽  
Vol 48 (1) ◽  
pp. 510-511 ◽  
Author(s):  
Heinz Gross ◽  
Katarina Krusche ◽  
Peter Tittmann
Keyword(s):  
Heavy Metal ◽  
High Resolution ◽  
Freeze Drying ◽  
Atmospheric Conditions ◽  
Vacuum Equipment ◽  
Transmission Electron ◽  
Gas Atmosphere ◽  
Gas Molecules ◽  
Residual Gas ◽  
Backing Layer

Freeze-drying followed by heavy metal shadowing is a long established and straight forward approach to routinely study the structure of dehydrated macromolecules. Very thin specimens such as isolated membranes or single macromolecules are directly adsorbed on C-coated grids. After rapid freezing the grids are transferred into a suitable vacuum equipment for freeze-drying and heavy metal shadowing.To improve the resolution power of shadowing films we introduced shadowing at very low specimen temperature (−250°C). To routinely do that without the danger of contamination we developed in collaboration with Balzers an UHV (p≤10-9 mbar) machine (BAF500K, Fig.2). It should be mentioned here that at −250°C the specimen surface acts as effective cryopump for practically all impinging residual gas molecules from the residual gas atmosphere.Common high resolution shadowing films (Pt/C, Ta/W) have to be protected from alterations due to air contact by a relatively thick C-backing layer, when transferred via atmospheric conditions into the TEM. Such an additional C-coat contributes disturbingly to the contrast at high resolution.

Thermal soak compatibility test and residual gas analysis on 4130 steel and methanol thermosyphons

1997 ◽  
Author(s):  
Q. He ◽  
Pon Ponnappan ◽  
J. Brown ◽  
Q. He ◽  
Pon Ponnappan ◽  
...  
Keyword(s):  
Gas Analysis ◽  
Compatibility Test ◽  
Residual Gas

Mercury Removal from Wastewater by Steamed Hoof Powder

1999 ◽  
Vol 40 (7) ◽  
pp. 109-116 ◽  
Author(s):  
M. H. Ansari ◽  
A. M. Deshkar ◽  
P. S. Kelkar ◽  
D. M. Dharmadhikari ◽  
M. Z. Hasan ◽  
...  
Keyword(s):  
Heavy Metals ◽  
Adsorption Capacity ◽  
Adsorption Process ◽  
Adsorption Equilibrium ◽  
Light Metal ◽  
Mercury Removal ◽  
High Adsorption ◽  
Surface Sites ◽  
Ph Values ◽  
High Adsorption Capacity

Steamed Hoof Powder (SHP), size < 53μ, was observed to have high adsorption capacity for Hg(II) with >95% removal from a solution containing 100 mg/L of Hg(II) with only 0.1% (W/V) concentration of SHP. The SHP has good settling properties and gives clear and odour free effluent. Studies indicate that pH values between 2 and 10 have no effect on the adsorption of Hg(II) on SHP. Light metal ions like Na+, K+, Ca2+ and Mg2+ up to concentrations of 500 mg/L and heavy metals like Cu2+, Zn2+, Cd2+, Co2+, Pb2+, Ni2+, Mn2+, Cr3+, Cr6+, Fe2+ and Fe3+ up to concentrations of 100 mg/L do not interfere with the adsorption process. Anions like sulphate, acetate and phosphate up to concentrations of 200 mg/L do not interfere. Chloride interferes in the adsorption process when Hg(II) concentration is above 9.7 mg/L. The adsorption equilibrium was established within two hours. Studies indicate that adsorption occurs on the surface sites of the adsorbent.

Work function studies of propylene, acetylene, hydrogen and nitrogen chemisorption on molybdenum

1982 ◽  
Vol 47 (11) ◽  
pp. 2996-3003
Author(s):  
Zdeněk Bastl
Keyword(s):  
Work Function ◽  
Surface Topography ◽  
Surface Coverage ◽  
Dissociative Chemisorption ◽  
Complete Coverage ◽  
Surface Sites ◽  
Function Change ◽  
Work Function Change

The work function changes of vacuum deposited molybdenum films caused by the chemisorption of propylene, acetylene, hydrogen and nitrogen were measured using the Kelvin vibrating capacitor method. During the hydrocarbon chemisorption, the work function increased in a low surface coverage region but decreased at the higher surface coverages. The saturation values of the work function changes corresponding to complete coverage of the surface by chemisorbed propylene and acetylene equal -0.08 eV and -0.42 eV, respectively. The observed dependences of the work function change on surface coverage are interpreted by the dissociative chemisorption of hydrocarbons on a limited number of surface sites which are simultaneously the sites of preferred adsorption. The extent of dissociation decreases in the adsorption with the increasing surface coverage. The results of the study of the work function changes induced by the hydrogen and nitrogen chemisorption enabled to draw several conclusions on the surface topography of the used films.

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