Beam Induced Pressure Rise in RHIC

Zhang, S.Y.; Alessi, J.; Bai, Mei; Blaskiewicz, M.; Cameron, P.; Fischer, W.; Gullotta, J.; He, P.; Hseuh, H.C.; Huang, H.; Iriso, Ubaldo; Lee, R.; Litvinenko, Vladimir; MacKay, W. W.; Nicoletti, A.; Oerter, B.; Peggs, S.; Pilat, F.; Ptitsyn, V.; Roser, T.; Satogata, T.; Smart, L.; Snydstrup, L.; Thieberger, P.; Trbojević, D.; Wang, L.; Jiang, Wei; Zeno, K.

doi:10.1109/pac.2005.1591804

Cited by 10 publications

(11 citation statements)

References 1 publication

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“…Copious gas desorption can result from ions striking beam tubes in accelerators. The desorption is much larger from heavy ions than from protons, in fact, pressure rises limit or threaten to limit the beam current in a number of heavy-ion accelerators [20]. Large desorption coefficients (number of molecules desorbed by each ion) of ≤20,000 were measured at CERN for 800 MeV lead ions (4.2 MeV/u where u ≡ nucleon mass) [21] and ≤37,000 for 158 GeV/u indium ions [22] impinging on stainless steel targets that were chemically cleaned and baked-in-situ in ultra-high vacuum chambers.…”

Section: Smooth Roughmentioning

confidence: 99%

Electron Production and Collective Field Generation in Intense Particle Beams

Molvik¹,

Vay²,

Cohen³

et al. 2006

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Electron cloud effects (ECEs) are increasingly recognized as important, but incompletely understood, dynamical phenomena, which can severely limit the performance of present electron colliders, the next generation of high-intensity rings, such as PEP-II upgrade, LHC, and the SNS, the SIS 100/200, or future high-intensity heavy ion accelerators such as envisioned in Heavy Ion Inertial Fusion (HIF). Deleterious effects include ion-electron instabilities, emittance growth, particle loss, increase in vacuum pressure, added heat load at the vacuum chamber walls, and interference with certain beam diagnostics. Extrapolation of present experience to significantly higher beam intensities is uncertain given the present level of understanding. With coordinated LDRD projects at LLNL and LBNL, we undertook a comprehensive R&D program including experiments, theory and simulations to better understand the phenomena, establish the essential parameters, and develop mitigating mechanisms. This LDRD project laid the essential groundwork for such a program. We developed insights into the essential processes, modeled the relevant physics, and implemented these models in computational production tools that can be used for self-consistent study of the effect on ion beams. We validated the models and tools through comparison with experimental data, including data from new diagnostics that we developed as part of this work and validated on the High-Current Experiment (HCX) at LBNL. We applied these models to High-Energy Physics (HEP) and other advanced accelerators. This project was highly successful, as evidenced by the two paragraphs above, and six paragraphs following that are taken from our 2003 proposal with minor editing that mostly consisted of changing the tense. Further benchmarks of outstanding performance are: we had 13 publications with 8 of them in refereed journals, our work was recognized by the accelerator and plasma physics communities by 8 invited papers and we have 5 additional invitations for invited papers at upcoming conferences, we attracted collaborators who had SBIR funding, we are collaborating with scientists at CERN and

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Section: Smooth Roughmentioning

confidence: 99%

Electron Production and Collective Field Generation in Intense Particle Beams

Molvik¹,

Vay²,

Cohen³

et al. 2006

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“…Itb expressed at lo* Au charge equivalent for different species and running modes at IR12 (IP) and BO11 (Single)..NEG coated beam pipes were installed and activated in these re ' 2005 vs p-110 in 2003 for the single beam section). The magnitude of pressure rise at w m sections with NEG coated beam pipes is also lower than that of un-coated sections [4]. However, the magnitude of the pressure reduction is not as dramatic as one would expect based on pumping speed along.…”

Section: Pressure Rise Vs In-situ Bakementioning

confidence: 80%

“…It has limited the Au intensity for 55-bunch injection, and prevented the 110bunch mode operation. The second type of pressure rise occurred at the transition and rebucketing [4], and is proportional to the total beam intensity, but not sensitive to the bunch intensity and spacing. This type of pressure rise has caused high detector background and hampers further luminosity improvement.…”

Section: Pressure Rise Vs In-situ Bakementioning

confidence: 93%

Upgrade of RHIC Vacuum Systems for High Luminosity Operation

Hseuh

Mapes²,

Smart³

et al.

Proceedings of the 2005 Particle Accelerator Conference

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With increasing ion beam intensity during recent RHIC operations, rapid pressure rises of several decades were observed at most warm sections and at a few cold sections. The pressure rises are associated with electron multi-pacting, electron stimulated desorption and beam ion induced desorptiok and have been one of the major intensity and luminosity limiting factors for RHIC. Improvement of the warm sections has been carried out in the last few years. Extensive in-situ bakes, additional UHV pumping and anti-grazing ridges have been implemented. Several hundred meters of NEG coated beam pipes have been installed and activated. Vacuum monitoring and logging were enhanced. Preventive measures, such as pumping before cool down to reduce monolayer condensates, were also taken to suppress the pressure rises in the cold sections. The effectiveness of these measures in reducing the pressure rises during machine studies and during physics runs are discussed and summarized.

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“…The main areas of the evaluation here are electron cloud and pressure rise problems, which have been observed already at the existing intensities in most warm and a few cold sections of the rings. Possible remedies have been under intensive testing, like NEG vacuum chamber coating, in-situ baking, using solenoids, and antigrazing ridges on vacuum pipe [4]. This year, beam experiments demonstrated real advantages of pipe sections with NEG coating against the pressure rise.…”

Section: Ion Ring Upgradesmentioning

confidence: 99%

The eRHIC Ring-Ring Collider Design

Wang

Farkhondeh

Franklin

et al.

Proceedings of the 2005 Particle Accelerator Conference

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The eRHIC ring-ring collider is the main design option for the future lepton-ion collider at Brookhaven National Laboratory. The baseline design is presented in the eRHIC Zero th -Order Design Report (ZDR) [1]. We report on progress made during the past year including possible interaction region design changes, upgrade efforts on RHIC (the ion ring), and results of a new design study on the e-ring. The interaction region revision is based on a new scheme for the main detector design. RHIC upgrades are being pursued to ensure luminosity and ion polarization goals of the ring-ring option in the baseline design will be met. Higher current operation of the lepton storage ring is under serious consideration as a result of better understanding of beam-beam interaction effects.

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Beam Induced Pressure Rise in RHIC

Cited by 10 publications

References 1 publication

Electron Production and Collective Field Generation in Intense Particle Beams

Electron Production and Collective Field Generation in Intense Particle Beams

Upgrade of RHIC Vacuum Systems for High Luminosity Operation

The eRHIC Ring-Ring Collider Design

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