Photon‐stimulated desorption yields from stainless steel and copper‐plated beam tubes with various pretreatments

Foerster, C. L.; Halama, H. J.; Lanni, C.

doi:10.1116/1.576638

Cited by 32 publications

(6 citation statements)

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“…This is consistent with the heavy dose given even after a few seconds of WL irradiation. Such doses have been shown to be sufficient to affect the desorption yield of the surface (hence its composition) [14,15]. It can be speculated that the WL exposure is, rather than cleaning the surface, changing it by cracking chemisorbed molecules to smaller units which can then no longer be photodesorbed.…”

Section: Photoemission With Monochromatic Light: Cumentioning

confidence: 99%

VUV photoemission studies of candidate Large Hadron Collider vacuum chamber materials

Cimino

Collins

Baglin

1999

Phys. Rev. ST Accel. Beams

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In the context of future accelerators and, in particular, the beam vacuum of the Large Hadron Collider (LHC), a 27 km circumference proton collider to be built at CERN, VUV synchrotron radiation (SR) has been used to study both qualitatively and quantitatively candidate vacuum chamber materials. Emphasis is given to show that angle and energy resolved photoemission is an extremely powerful tool to address important issues relevant to the LHC, such as the emission of electrons that contributes to the creation of an electron cloud which may cause serious beam instabilities and unmanageable heat loads on the cryogenic system. Here we present not only the measured photoelectron yields from the proposed materials, prepared on an industrial scale, but also the energy and in some cases the angular dependence of the emitted electrons when excited with either a white light (WL) spectrum, simulating that in the arcs of the LHC, or monochromatic light in the photon energy range of interest. The effects on the materials examined of WL irradiation and /or ion sputtering, simulating the SR and ion bombardment expected in the LHC, were investigated. The studied samples exhibited significant modifications, in terms of electron emission, when exposed to the WL spectrum from the BESSY Toroidal Grating Monochromator beam line. Moreover, annealing and ion bombardment also induce substantial changes to the surface thereby indicating that such surfaces would not have a constant electron emission during machine operation. Such characteristics may be an important issue to define the surface properties of the LHC vacuum chamber material and are presented in detail for the various samples analyzed. It should be noted that all the measurements presented here were recorded at room temperature, whereas the majority of the LHC vacuum system will be maintained at temperatures below 20 K. The results cannot therefore be directly applied to these sections of the machine until measurements at cryogenic temperatures, i.e., in the presence of cryosorbed gas layers, are obtained. However, these results are directly relevant to all the warm regions of the LHC vacuum system, such as the experimental vacuum chambers and warm element vacuum chambers in the insertion regions. [S1098-4402(99)

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Section: Photoemission With Monochromatic Light: Cumentioning

confidence: 99%

VUV photoemission studies of candidate Large Hadron Collider vacuum chamber materials

Cimino

Collins

Baglin

1999

Phys. Rev. ST Accel. Beams

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“…ii) Short wavelength UV-irradiation is known to be efficient in photon induced desorption of various molecular species 7,8 including water, H 2 and O 2 . In the treatment system a deuterium lamp with maximum emission between 160 and 300 nm allows irradiation of the chip surface and PCB.…”

Section: In-situ Surface Treatmentsmentioning

confidence: 99%

Ultrahigh Vacuum Packaging and Surface Cleaning for Quantum Devices

Mergenthaler,

Paredes,

Müller

et al. 2020

Preprint

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We describe design, implementation and performance of an ultra-high vacuum (UHV) package for superconducting qubit chips or other surface sensitive quantum devices. The UHV loading procedure allows for annealing, ultra-violet light irradiation, ion milling and surface passivation of quantum devices before sealing them into a measurement package. The package retains vacuum during the transfer to cryogenic temperatures by active pumping with a titanium getter layer. We characterize the treatment capabilities of the system and present measurements of flux tunable qubits with an average T 1 = 84 µs and T echo 2 = 134 µs after vacuum-loading these samples into a bottom loading dilution refrigerator in the UHV-package.

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“…There are a number of experimental results published in the literature for photodesorption yields, η, measured as function of accumulated photon dose, D, for different materials and measured up to certain photon doses (for example, see [1,2,3]). Schematically, a typical behaviour of the desorption yield as a function of photon dose is shown in Figure 1.…”

Section: Psd Yield As a Function Of Photon Dosementioning

confidence: 99%

Vacuum systems for the ILC helical undulator

Malyshev

Scott

Bailey

et al. 2007

Journal of Vacuum Science &Amp; Technology A: Vacuum, Surfaces, and Films

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The International Linear Collider (ILC) positron source uses a helical undulator to generate polarised photons of ~10 MeV at the first harmonic. Unlike many undulators used in synchrotron radiation sources, the ILC helical undulator vacuum chamber will be bombarded by photons, generated by undulator, with energies mostly below that of the 1 st harmonic. Achieving the vacuum specification, of ~100 nTorr, in a narrow chamber, of 4 to 6 mm inner diameter, with a long length, of 100 -200 m, makes the design of the vacuum system challenging. This paper describes the vacuum specifications, calculations of the flux and energy of photons irradiating the undulator vacuum chamber and considers possible vacuum system design solutions for two cases: cryogenic and room temperature.

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Photon‐stimulated desorption yields from stainless steel and copper‐plated beam tubes with various pretreatments

Cited by 32 publications

References 0 publications

VUV photoemission studies of candidate Large Hadron Collider vacuum chamber materials

VUV photoemission studies of candidate Large Hadron Collider vacuum chamber materials

Ultrahigh Vacuum Packaging and Surface Cleaning for Quantum Devices

Vacuum systems for the ILC helical undulator

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