A novel route to extreme vacua: the non-evaporable getter thin film coatings

Benvenuti, C.; Cazeneuve, J.M.; Chiggiato, Paolo; Cicoira, Fabio; Santana, Antonio; Johánek, Viktor; Ruzinov, V.L.; Fraxedas, Jordi

doi:10.1016/s0042-207x(98)00377-7

Cited by 117 publications

(49 citation statements)

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“…In that case, the samples investigated were all crystalline bulk materials. On TiZrV coatings produced by a cathode made by intertwisted wires at CERN, the reduction of the surface oxide layer has already been observed by XPS after heating at 250 qC during 2 hours 3 . For an identical thermal treatment, the reduction was less effective for TiZr, in agreement with the present findings.…”

Section: Discussionmentioning

confidence: 96%

“…Many coatings composed of various elements have been produced and tested, which all exhibited activation temperature below 400 °C 1,2 . The lowest activation temperature, 200 qC for a 24-hour heating, has been obtained with a TiZrV alloy thin film 3 . A complete review of the results obtained with this coating is presented separately at this conference 4 .…”

Section: Introductionmentioning

confidence: 97%

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Lowering the activation temperature of TiZrV non-evaporable getter films

Prodromides

Scheuerlein

Taborelli

2001

Vacuum

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In order to reduce the activation temperature of the TiZrV alloy, thin films of various compositions were produced by three-cathode magnetron sputtering on stainless steel substrates. For the characterisation of the activation behaviour the surface chemical composition has been monitored by Auger Electron Spectroscopy (AES) during specific in situ thermal cycles. The volume elemental composition of the film has been measured by Energy Dispersive X-ray spectroscopy (EDX) and the morphology (crystal structure and size of the crystallites) has been investigated by X-ray diffraction (XRD). The criteria indicating the sample quality and its dependence on film structure and chemical composition are presented and discussed.Keywords: getter, activation, NEG, titanium alloy, vanadium alloy, zirconium alloy, ternary alloys, thin film Paper presented at the 6th European Vacuum Conference University Lyon 1, Campus La Doua/IPNL, Lyon, France 7-10 December 1999 To be published in "Vacuum" Geneva, SwitzerlandDécembre 1999 -2 - INTRODUCTIONIn the context of the technical developments for the construction of the Large Hadron Collider (LHC) at CERN, a systematic study has been undertaken in order to produce suitable non-evaporable getter films (NEG). Many coatings composed of various elements have been produced and tested, which all exhibited activation temperature below 400 °C 1,2 . The lowest activation temperature, 200 qC for a 24-hour heating, has been obtained with a TiZrV alloy thin film 3 . A complete review of the results obtained with this coating is presented separately at this conference 4 .In the present study, thin films of titanium-zirconium-vanadium ternaries with various compositions have been produced and characterised by structural and chemical analyses in order to possibly further decrease the activation temperature. Characterisation by surface analytical techniques has been chosen, namely Auger Electron Spectroscopy (AES). It was preferred to other techniques because it results in faster sample production and characterisation. EXPERIMENTAL Coating deposition methodNEG thin films are produced by sputtering, because this deposition method provides an easy way to deposit an uniform coating on complex and narrow access chambers, and it can be applied to most metals and their alloys. The initially adopted sputtering system makes use of a composite cathode obtained by twisting together wires of different materials 1 . However, this configuration limits the range of achievable elemental compositions. In order to have a wider choice of compositions a three magnetron sputtering system has been adopted, in which the three cathodes are independently supplied. All our samples have been produced using the same parameters: a total base pressure after bake-out in the 10 -7 Pa range, an argon discharge pressure of 7 x 10 -1 Pa, non heated substrates (T d 90 qC), water cooled cathodes, constant magnetic fields due to two SmCo magnets (a central Sm 2 Co 17 circular magnet surrounded by a SmCo 5 toroidal magnet).The powe...

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Section: Discussionmentioning

confidence: 96%

Section: Introductionmentioning

confidence: 97%

Lowering the activation temperature of TiZrV non-evaporable getter films

Prodromides

Scheuerlein

Taborelli

2001

Vacuum

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“…Non-evaporable getter (NEG) thin ®lm coatings are currently being developed at CERN for use in the ultra-high vacuum (UHV) system of the Large Hadron Collider (LHC) [3]. These NEG coatings can be passively activated during a vacuum chamber bakeout.…”

Section: Introductionmentioning

confidence: 99%

The secondary electron yield of TiZr and TiZrV non-evaporable getter thin film coatings

Henrist

Hilleret

Scheuerlein

et al. 2001

Applied Surface Science

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The secondary electron yield (SEY) of two different non-evaporable getter (NEG) samples has been measured`as received' and after thermal treatment. The investigated NEGs are TiZr and TiZrV thin ®lm coatings of 1 mm thickness, which are sputter deposited onto copper substrates. The maximum SEY d max of the air exposed TiZr and TiZrV coating decreases from above 2.0 to below 1.1 during a 2 h heat treatment at 250 and 2008C, respectively.Saturating an activated TiZrV surface under vacuum with the gases typically present in ultra-high vacuum systems increases d max by about 0.1. Changes in elemental surface composition during the applied heat treatments were monitored by Auger electron spectroscopy (AES). After activation carbon, oxygen and chlorine were detected on the NEG surfaces. The potential of AES for detecting the surface modi®cations which cause the reduction of SE emission during the applied heat treatments is critically discussed. #

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“…Experimental data from Benvenuti et al [29,30,[54][55] showing the pressure of the vacuum system during activation of several NEG coatings.…”

Section: Oxidation and Bakingmentioning

confidence: 99%

A Review of Outgassing and Methods for its Reduction

Grinham

Chew

2017

Appl. Sci. Converg. Technol.

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There are several contributions to the gas load of a system of which often the most important is outgassing. Adsorption occurs via two main processes, physisorption and chemisorption, and can be described using five (or six) classifying isotherms. Outgassing is the result of desorption of previously adsorbed molecules, bulk diffusion, permeation and vapourisation. Looking at the desorption rate, pumping speed and readsorption on surfaces, the net outgassing of the system can be calculated. There is significant variation in measured outgassing rates between different materials but also between published rates for the same materials, in part due to the number of different methods used to measure outgassing. This article aims to review the outgassing process, outgassing rates, measurement methods and techniques that can be used to reduce the outgassing of a system.

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A novel route to extreme vacua: the non-evaporable getter thin film coatings

Cited by 117 publications

References 0 publications

Lowering the activation temperature of TiZrV non-evaporable getter films

Lowering the activation temperature of TiZrV non-evaporable getter films

The secondary electron yield of TiZr and TiZrV non-evaporable getter thin film coatings

A Review of Outgassing and Methods for its Reduction

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