| Paper | Title | Page |
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| TUYAA01 | High Currents Effects in DAΦNE | 82 |
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| DAΦNE, the Italian lepton collider, operates routinely with high intensity electron and positron colliding beams. The high current multi-bunch beams are stored in two independent rings, each of them 97 m long, and are distributed in 100 ’ 110 contiguous buckets out of the 120 available, spaced by only 2.7 ns. Since its construction, DAΦNE has been operated in different configurations which, overall, allowed to store current up to 1.4 A and 2.45 A in the positron and in the electron beam respectively. Still today DAΦNE holds the record for the highest electron beam current ever stored in particle factories and modern synchrotron radiation sources. The DAΦNE experience in terms of beam dynamics optimization aimed at achieving the high intensity beams is presented, with special emphasis on the e-cloud related issues, which represent the dominant effect limiting the positron beam current. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-eeFACT2018-TUYAA01 | |
| About • | paper received ※ 24 October 2018 paper accepted ※ 19 February 2019 issue date ※ 21 April 2019 | |
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| TUYAA03 | Impedances and Collective Effects for JLEIC | 90 |
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Funding: This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics under contract DE-AC05-06OR23177. JLEIC is the high luminosity and high polarization electron-ion collider (EIC) currently under design at Jefferson Lab. Its luminosity performance relies on the beam stability under high-intensity electron and ion beam operation. The impedance budget analysis and the estimations of beam instabilities are currently underway. In this paper, we present the update status of our back-of-envelope estimations for these collective instabilities, and identify area or parameter regimes where special attentions for instability mitigations are required. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-eeFACT2018-TUYAA03 | |
| About • | paper received ※ 22 October 2018 paper accepted ※ 08 March 2019 issue date ※ 21 April 2019 | |
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| TUYAA04 | Study to Mitigate Electron Cloud Effect in SuperKEKB | 95 |
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| During Phase-1 commissioning of the SuperKEKB from February to June 2016, electron cloud effects (ECE) were observed in the positron ring. The electron clouds were considered to exist in the beam pipes in the drift spaces of the ring, where the beam pipes have antechambers and titanium nitride (TiN) coating as countermeasures against ECE. Following this, permanent magnets and solenoids were attached to the beam pipes as additional countermeasures. Consequently, during Phase-2 commissioning from March to July 2018, experiments showed that the threshold beam current for exciting ECE increased by a factor of at least two relative to that during Phase-1 commissioning. While the countermeasures were strengthened, the effectiveness of the antechambers and TiN film coating was re-evaluated. From various simulations and experiments during Phase-2 commissioning, the antechamber was found to be less effective than expected with regard to reducing the number of photoelectrons in the beam channel. The TiN film coating, on the other hand, was considered to have a low secondary electron yield as expected. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-eeFACT2018-TUYAA04 | |
| About • | paper received ※ 27 September 2018 paper accepted ※ 19 February 2019 issue date ※ 21 April 2019 | |
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