| Paper | Title | Other Keywords | Page |
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| TUPLM11 | Beam-Beam Damping of the Ion Instability | electron, simulation, storage-ring, feedback | 391 |
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Funding: Work Supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. Beam-Beam damping of the Ion Instability The electron storage ring of the proposed electron ion collider at BNL has bunch charges as large as 50 nC and bunch spacings as small as 10 ns. For molecules like CO a dangerous buildup of positive ions is possible and a significant fraction of these ions can survive allowable clearing gaps. The instability is thus multi-turn and the weak damping required to stop the ion instabilty with an ideal clearing gap is ineffective here. The beam-beam force is highly nonlinear and a potent source of tune spread. Simulations employing several macro-particles per electron bunch and several ion macroparticles are used to estimate maximum gas densities for some common molecules. A simplified model is introduced and compared with simulations. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-TUPLM11 | ||
| About • | paper received ※ 26 August 2019 paper accepted ※ 02 September 2019 issue date ※ 08 October 2019 | ||
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| TUPLM13 | Two-Energy Storage-Ring Electron Cooler for Relativistic Ion Beams | cavity, storage-ring, electron, emittance | 399 |
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| An electron beam based cooling system for the ion beam is one of the commonly used approaches. The proposed two’energy storage-ring electron cooler consists of damping and cooling sections at markedly different energies connected by an energy recovering superconducting RF structure. The parameters in the cooling and damping sections are adjusted for optimum cooling of a stored ion beam and for optimum damping of the electron beam respectively. This paper briefly describes a two cavities model along with a third cavity model to accelerate and decelerate the electron beam in two energy storage ring. Based on our assumed value of equilibrium emittance shows that these models give a bunch length of the order of cm and energy spread of the order of 〖10〗-5 in the cooling section which are required parameters for the better cooling. Numerical calculations along with elegant simulation are presented. | |||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-TUPLM13 | ||
| About • | paper received ※ 28 August 2019 paper accepted ※ 03 September 2019 issue date ※ 08 October 2019 | ||
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| TUPLM24 | Electron Heating by Ions in Cooling Rings | electron, radiation, proton, scattering | 426 |
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Hadron beam cooling at high energy is a critical technique for Electron-Ion Colliders (EIC). We consider using an electron storage ring for the EIC at BNL. For such a cooler, the electron beam quality plays an important role since it directly determines the cooling rate. Besides the effects of IBS, space charge and synchrotron damping, which are calculable with well known methods, the heating effect by ions also needs to be carefully considered in electron beam dynamics. In this paper, we present an analytical model to calculate the heating rate by ions and give some example calculations. In addition, this model was benchmarked by applying it on the IBS calculation.
* Work supported by States Department of Energy |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-TUPLM24 | ||
| About • | paper received ※ 26 August 2019 paper accepted ※ 02 September 2019 issue date ※ 08 October 2019 | ||
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| WEPLM04 | Precision Cavity Higher-Order Mode Tuning Scheme for Stabilizing the Stored Beam in the Advanced Photon Source Upgrade | cavity, HOM, impedance, resonance | 670 |
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Funding: Work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357 The Advanced Photon Source Upgrade will suffer longitudinal multi-bunch instability because of the presence of several monopole higher-order mode (HOMs) of the 12 352-MHz rf cavities. Even with a feedback system, it would be good to mitigate any driving terms with conventional means such as tuning HOM frequencies with temperature. However the latter is problematic because there will be 90 or so HOMs that are potentially harmful. A scheme is developed, utilizing the measured spectrum of HOMs, to find the best temperature setting for each cavity. We present measurements of 30 or so HOMs, and a thermal model of HOM frequencies using cavity wall power and cooling water temperature as inputs to maintain the optimum tuning condition with sufficient accuracy. The newly acquired Dimtel iGp12 processor box is central to the HOM frequency measurements. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-WEPLM04 | ||
| About • | paper received ※ 29 August 2019 paper accepted ※ 05 September 2019 issue date ※ 08 October 2019 | ||
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