| Paper | Title | Other Keywords | Page |
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| WEPEC008 | HOM Spectrum and Q-factor Estimations of the High-Beta CERN-SPL-Cavities | cavity, resonance, HOM, coupling | 2905 |
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Beam energy deposited in Higher-Order-Modes may affect both beam stability and cryo power requirements of the planned CERN Superconducting Proton Linac SPL. We report on numerical studies of the high-beta cavity type, analyzing it's HOM spectrum. The most dangerous modes are identified and different possibilities of appropriate damping are discussed. |
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| WEPEC009 | Designing of 9 Cell Reduced Beta Elliptical Cavity for High Intensity Proton Linac | cavity, coupling, linac, proton | 2908 |
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A superconducting rf cavity is designed for acceleration of particles travelling at 81% the speed of light. The cavity will operate at 1.3 GHz & is to be used in SILC section of the proposed high intensity proton linac at Fermilab. At present cavity will serve to accelerate the particles for energy range 466 MeV to 1.2 GeV. The cavity will be shorter than 9 cell beta =1 cavity but nearly same ratio of surface magnetic field to surface electric field. Cell to cell coupling coefficient is also optimized to get the good field flatness. The cavity is studied for monopole modes and higher order modes. The shapes of end cells are optimized to avoid dangerous modes with keeping same field flatness & same operating frequency. |
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| WEPEC010 | Optimization of End Cells of Low Beta Cavity of Higher Energy Part of Project X | cavity, HOM, impedance, linac | 2911 |
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Eleven cell elliptical cavity is designed for acceleration of particles traveling at 81 % of the speed of light. It will operate at 1.3 GHz and will be used to accelerate the particles from 0.4 GeV to 1.2 GeV. The cavity is studied for higher order mode (HOM) and trapped modes. The shapes of end cells of cavity is optimized to increase the field amplitude in end cells so that coupling of trapped modes may increase with HOM coupler and they can be extracted easily but keeping the field flatness & operating frequency undisturbed. |
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| WEPEC063 | Using a Resistive Material for HOM Damping | HOM, cavity, damping, impedance | 3037 |
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Ferrites and lossy ceramics used in HOM (higher order mode) load for superconducting accelerators, have shortcomings such as poor batch-to-batch reproducibility of electromagnetic properties, extremely low electric conductivity at cryogenic temperatures leading to accumulation of charge on the material surface, brittleness, which may cause contamination of the nearby SRF cavities by lossy dust, etc. A proposal to use a resistive material free of these shortcomings is presented. |
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| THPEA025 | HOM Characteristics Measurement of Mini-LIA Cavity | cavity, HOM, simulation, induction | 3732 |
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Mini-LIA was a miniature linear induction accelerator designed and manufactured by China Academy of Engineering Physics and Tsinghua University. To investigate the higher order mode (HOM) of Mini-LIA cavity, especially the frequency and quality factor Q of the TM110 and TM120 in it, both numerical simulation and experiments were performed. Several models of the cavity were established and calculated by using E module of MAFIA code. Network analyzer was applied to measure the frequency and Q in cavity. Both the simulation results and the experiment results are presented in this paper. The results of the experiments were coincident with the calculated results. Finally, The HOM characteristic of Mini-LIA cavity with metglass core in it was explored, and some interesting results was obtained. |
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| THPEC021 | Coaxial Coupling Scheme for TESLA/ILC-type Cavities | coupling, cavity, HOM, niobium | 4089 |
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This paper reports about our efforts to develop a flangeable coaxial coupler for both HOM and fundamental coupling for 9-cell TESLA/ILC-type cavities. The cavities were designed in early 90‘s for pulsed operation with a low duty factor, less than 1 %. The proposed design of the coupler has been done in a way, that the magnetic flux B at the flange connection is minimized and only a field of <5 mT would be present at the accelerating field Eacc of ~ 36 MV/m (B =150 mT in the cavity). Even though we achieved reasonably high Q-values at low field, the cavity/coupler combination was limited in the cw mode to only ~ 7 MV/m, where a thermally initiated degradation occurred. We have improved the cooling conditions by initially drilling radial channels every 30 degrees, then every 15 degrees into the shorting plate. The modified prototype performed well up to 9 MV/m in cw mode. This paper reports about our experiences with the further modified coaxial coupler and about test results in cw and low duty cycle pulsed mode, similar to the TESLA/ILC operation conditions. |