Vacuum furnace for degassing stainless-steel vacuum components

Fedchak, James A.; Scherschligt, Julia; Barker, Daniel S.; Eckel, Stephen; Farrell, Alex; Sefa, Makfir

doi:10.1116/1.5016181

Cited by 13 publications

(12 citation statements)

References 14 publications

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“…Before use, the CDGs were fired inside a custom-built vacuum furnace 7 for 33 days at approximately 425 • C to reduce hydrogen outgassing, following procedures developed in references 8 and 9. The gauges were not tested prior to this hightemperature bake.…”

Section: Apparatusmentioning

confidence: 99%

Stability of bakeable capacitance diaphragm gauges

Scherschligt¹,

Barker²,

Eckel³

et al. 2021

Preprint

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Here, we study the stability of bakeable capacitance diaphragm gauges. We focus on their stability before and after a controlled series of bakes. We find that baking results in appreciable shifts of the zero offset, but note that these can easily be corrected at time of use. Linearity however cannot be corrected at time of use, so it is essential to understand its effect if one wishes to use similar gauges in a system that requires baking. For the gauges in this study, we find that baking introduces a minimal additional uncertainty, and that the total uncertainty can be kept to below about 0.3 % at the k = 2 confidence level (95%).

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Section: Apparatusmentioning

confidence: 99%

Stability of bakeable capacitance diaphragm gauges

Scherschligt¹,

Barker²,

Eckel³

et al. 2021

Preprint

Self Cite

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“…The SCE is made from sintered stainless steel powder [15] with approximately 25 nL/s conductance for N 2 near 300 K. The variable volume is constructed from welded bellows made from titanium, which minimizes H 2 outgassing [10]. All stainless steel components except the SCE were baked at 450 °C for at least 20 days in a vacuum furnace to minimize hydrogen outgassing [13].…”

Section: Component Quantificationmentioning

confidence: 99%

“…Such exposure is possible, for example, from contamination in the gas used to fill the flowmeter, and thus a low-outgassing flowmeter must be designed for repeated bakes. Hydrogen outgassing can be more difficult to minimize, requiring either a low hydrogen-outgassing material, like titanium or aluminum [10], or a process of baking the vacuum components at higher temperatures [11,12,13].…”

Section: Introductionmentioning

confidence: 99%

A constant pressure flowmeter for extremely high vacuum

Eckel,

Barker,

Fedchak

et al. 2021

Preprint

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We demonstrate operation of a constant-pressure flowmeter capable of generating and accurately measuring flows as low as 1 × 10 −13 mol/s. Generation of such small flows is accomplished by using a small conductance element with C ≈ 25 nL/s. Accurate measurement then requires both low outgassing materials (< 10 −15 mol/s) and small volume changes (≈ 70 µL). We outline the present flowmeter's construction, detail its operation, and quantify its uncertainty, which is < 1 % over the entire operating range and better than 0.3 % over a majority. In particular, we present an analysis of its hydraulic system, and quantify the shift and uncertainty due to the slightly compressible oil. Finally, we compare our flowmeter against a NIST standard flowmeter, and find agreement to within 0.61 % (k = 2). Future modifications could achieve a k = 2 uncertainty of 0.2 %.

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“…We characterize light-induced atomic desorption process by loading a Li MOT within a stainless-steel vacuum chamber. All steel components of the chamber were vacuum baked at 425 • C for 21 days to reduce hydrogen outgassing [35,36]. We did not bake the chamber after assembly to remove H 2 O.…”

Section: Apparatusmentioning

confidence: 99%

Light-induced atomic desorption of lithium

et al. 2018

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We demonstrate loading of a Li magneto-optical trap using light-induced atomic desorption. The magnetooptical trap confines up to approximately 4 × 104 7Li atoms with loading rates up to approximately 4 × 103 atoms per second. We study the Li desorption rate as a function of the desorption wavelength and power. The extracted wavelength threshold for desorption of Li from fused silica is approximately 470 nm. In addition to desorption of lithium, we observe light-induced desorption of background gas molecules. The vacuum pressure increase due to the desorbed background molecules is ≲ 50 % and the vacuum pressure decreases back to its base value with characteristic timescales on the order of seconds when we extinguish the desorption light. By examining both the loading and decay curves of the magneto-optical trap, we are able to disentangle the trap decay rates due to background gases and desorbed lithium. Our results show that light-induced atomic desorption can be a viable Li vapor source for compact devices and sensors.

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Vacuum furnace for degassing stainless-steel vacuum components

Cited by 13 publications

References 14 publications

Stability of bakeable capacitance diaphragm gauges

Stability of bakeable capacitance diaphragm gauges

A constant pressure flowmeter for extremely high vacuum

Light-induced atomic desorption of lithium

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