Design study of distributed pumping system using multilayer NEG strips for particle accelerators

Suetsugu, Y.; Shibata, K.; Shirai, Mitsuru

doi:10.1016/j.nima.2008.09.023

Cited by 20 publications

(8 citation statements)

References 41 publications

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“…The vacuum system of the collider is designed to effectively mitigate i) higher order mode (HOM) power losses, ii) heat and gas loads due to the large SR power and photon density, iii) the electron cloud and fast ion effects in the LER and HER, respectively. A distributed pumping system based on multilayer non-evaporable getter (NEG) strips [11] is used to keep the vacuum pressure at the level of 1 × 10 −7 Pa, which is required to achieve an hours-long beam-gas lifetime. To monitor the vacuum level in the beam pipe, cold cathode gauges (CCGs) are placed approximately every 10 m along each ring.…”

Section: Superkekb and Belle IImentioning

confidence: 99%

Beam background expectations for Belle II at SuperKEKB

Natochii¹,

Browder²,

Cao³

et al. 2022

Preprint

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The Belle II experiment at the SuperKEKB electron-positron collider aims to collect an unprecedented data set of 50 ab −1 to study CP -violation in the Bmeson system and to search for Physics beyond the Standard Model (BSM). SuperKEKB is already the world's highest-luminosity collider. In order to collect the planned data set within approximately one decade, the target is to reach a peak luminosity of 6.3 × 10 35 cm −2 s −1 by further increasing the beam currents and reducing the beam-size at the interaction point by squeezing the betatron function down to β * y = 0.3 mm. Beam backgrounds are a key challenge in this context. We estimate the expected background evolution in the next ten years and discuss potential challenges and background mitigation strategies. We find that backgrounds will remain high but acceptable until a luminosity of at least 2.8 × 10 35 cm −2 s −1 is reached at β * y = 0.6 mm. Beyond this luminosity, predictions are highly uncertain, owing to a planned redesign of the interaction region. Improved background estimates with reduced uncertainties for the final, maximum-luminosity operation will require completion of this redesign.

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Section: Superkekb and Belle IImentioning

confidence: 99%

Beam background expectations for Belle II at SuperKEKB

Natochii¹,

Browder²,

Cao³

et al. 2022

Preprint

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show abstract

“…3 and 4, respectively, during the Phase-1 commissioning, which lasted for approximately five months. In the activation process, the NEG strips were heated up to approximately 400°C by sheath heaters [23]. The maximum temperatures on the outside surfaces of the antechambers were approximately 80°C and 28°C with and without water flowing in the cooling channels of the beam pipes, respectively.…”

Section: Status Of the New Vacuum Componentsmentioning

confidence: 99%

“…Nonevaporable getter (NEG) strips (St707, SAES Getters Co. Ltd.) were used as a main pump. They were installed in one of the antechambers and generate a uniformly distributed pumping system along the beam pipes at arc sections [23,24]. To counteract the ECE in the LER, antechamber structures were adopted as described above to suppress the effects of photoelectrons [11][12][13].…”

Section: Introductionmentioning

confidence: 99%

First commissioning of the SuperKEKB vacuum system

Suetsugu

Shibata

Ishibashi

et al. 2016

Phys. Rev. Accel. Beams

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The first (Phase-1) commissioning of SuperKEKB, an asymmetric-energy electron-positron collider at KEK, began in February 2016, after more than five years of upgradation work on KEKB and successfully ended in June 2016. A major task of the Phase-1 commissioning was the vacuum scrubbing of new beam pipes in anticipation of a sufficiently long beam lifetime and low background noise in the next commissioning, prior to which a new particle detector will be installed. The pressure rise per unit beam current decreased steadily with increasing beam dose, as expected. Another important task was to check the stabilities of various new vacuum components at high beam currents of approximately 1 A. The temperature increases of the bellows chambers, gate valves, connection flanges, and so on were less than several degrees at 1 A, and no serious problems were found. The effectiveness of the antechambers and TiN coating in suppressing the electron-cloud effect (ECE) in the positron ring was also confirmed. However, the ECE in the Al-alloy bellows chambers was observed where TiN had not been coated. The use of permanent magnets to create an axial magnetic field of approximately 100 G successfully suppressed this effect. Pressure bursts accompanying beam losses were also frequently observed in the positron ring. This phenomenon is still under investigation, but it is likely caused by collisions between the circulating beams and dust particles, especially in the dipole magnet beam pipes.

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“…4. 22 The number of NEG strips was optimized by calculating the pressure distribution inside the pump channel; as a result, three strips were used. Indirect heating with sheath heaters was considered instead of direct Joule heating in order to safely activate the NEG strips in the narrow space.…”

Section: B Pump Systemmentioning

confidence: 99%

“…The total length of the assemblies to be fitted within the beam pipes ranged from 0.6 to 2.7 m. The effect of sheath heaters on the magnetic field was checked using a real bending magnet, and found to be negligible. The effective area of the NEG surface in an assembly is approximately 0.1 m 2 per 1 m. 22 The linear pumping speed of the assembly for nitrogen (N 2 ) just after an activation was approximately 0.2 m 3 s À1 m À1 (i.e., 2.0 m 3 s À1 m À2 for the NEG surface). Therefore, according to the data in the ST707 Catalogue, 23 the pumping speed for carbon monoxide (CO), which is a main gas component in the photodesorption process, was expected to be approximately 2.0 m 3 s À1 m À1 (i.e., 20 m 3 s À1 m À2 for the NEG surface) just after an activation.…”

Section: B Pump Systemmentioning

confidence: 99%

Design and construction of the SuperKEKB vacuum system

Suetsugu

Kanazawa

Shibata

et al. 2012

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

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Development of planar x-ray source using gated carbon nanotube emitter J. Vac. Sci. Technol. B 31, 02B110 (2013) Tungstate formation in a model scandate thermionic cathode J. Vac. Sci. Technol. B 31, 011210 (2013) Influence of gun design on Coulomb interactions in a field emission gun J. Vac. Sci. Technol. B 29, 06F605 (2011) Model scandate cathodes investigated by thermionic-emission microscopyA two-ring electron-positron collider with asymmetric energies-called the SuperKEKB-has been designed by the High Energy Accelerator Research Organization (KEK) as an upgrade of the KEKB B-factory (KEKB), which completed 12 years of operation in 2010. It is anticipated that the SuperKEKB will reach a luminosity of 8 Â 10 35 cm À2 s À1 , which is approximately 40 times larger than that of the original KEKB. The upgrade of the vacuum system is a key factor that will allow the SuperKEKB to achieve unprecedented high performance. Most of the beam pipes, especially in the positron ring, are newly manufactured to manage the electron cloud effect, and to reduce beam impedance, which is essential to keep the low-emittance beam stable. Our design of the vacuum system implements recent technologies and draws on various experiences and studies during the operation of the original KEKB. The basic design is near completion, and manufacturing of beam pipes and the major vacuum components, such as bellows chambers, gate valves and supports, are in progress. The installation of these components will start in 2013 with the aim of commissioning the SuperKEKB in

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Design study of distributed pumping system using multilayer NEG strips for particle accelerators

Cited by 20 publications

References 41 publications

Beam background expectations for Belle II at SuperKEKB

Beam background expectations for Belle II at SuperKEKB

First commissioning of the SuperKEKB vacuum system

Design and construction of the SuperKEKB vacuum system

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