| Paper | Title | Other Keywords | Page |
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| MOPMW023 | Optimization of the RF Cavity of a Low-energy Storage Ring for Thomson Scattering X-Ray Source | cavity, HOM, storage-ring, coupling | 438 |
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| Results of optimization of the RF cavity of a low-energy storage ring for Thomson scattering X-ray source are presented. The geometry of 714 MHz RF cavity was optimized to provide maximum shunt impedance taking into account position of higher order modes (HOMs). The number and position of cooling channels were adjusted to minimize frequency shift due to cavity thermal deformations. The waveguide coupler and frequency tuner were calculated. Special attention was paid to detailed calculations of the HOMs parameter and to study of methods to minimize their influence on the storage ring beam dynamics. | |||
| DOI • | reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMW023 | ||
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| WEPMB045 | Measurement of Higher Order Modes Electrodynamic Characteristics for Array of Two 2400 MHz Cavities | HOM, cavity, damping, simulation | 2214 |
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Funding: *Work supported by Ministry of Education and Science grant 3.245.2014/r and the EU FP7 HiLumi LHC ' Grant Agreement 284404 In the frameworks of the High Luminosity Large hadron collider (HL-LHC) upgrade program an application of additional superconducting harmonic cavities operating at 800 MHz is currently under discussion. As a candidate, the two cavities with grooved beam pipes connected by the drift tube were suggested. In this article of measurements of Qload are performed for the aluminum model of array of two cavities connected by drift tube. Field distribution of Fundamental Mode (FM) and Higher Order Modes (HOM) were measured for aluminum prototype with a frequency of the operational mode of 2400 MHz, and their comparison with the simulation results. Higher order modes |
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| DOI • | reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPMB045 | ||
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| WEPMB048 | Macros for Identification of Higher Order Modes Types, Their Transverse Shunt Impedance and Kick Factor | HOM, cavity, damping, interface | 2220 |
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Funding: *Work supported by Ministry of Education and Science grant 3.245.2014/r During the design studies of accelerating cavities one of the most time-consuming tasks is classification of the higher order modes (HOM) types. To automate the process of identification of HOM types special macros for CST Microwave studio was written. This article describes the programs algorithm of mode recognition and the results of the analysis on the example of single cell and 9 cell cavities. Macros for the calculation of the HOM transverse shunt impedance upon Q-factor values and kick-factor was also written. Higher order modes, electrodynamic characteristics, macros |
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| DOI • | reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPMB048 | ||
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| WEPMB058 | LHC Crab Cavity Coupler Test Boxes | HOM, cavity, luminosity, operation | 2248 |
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| The LHC double quarter wave (DQW) crab cavities have two different types of Higher Order Mode (HOM) couplers in addition to a fundamental power coupler (FPC). The FPC requires conditioning, so to achieve this we have designed a radio-frequency (RF) quarter wave resonator to provide high transmission between two opposing FPCs. For the HOM couplers we must ensure that the stop-band filter is positioned at the cavity frequency and that peak transmission occurs at the same frequencies as the strongest HOMs. We have designed two test boxes which preserve the cavity spectral response in order to test the couplers. | |||
| DOI • | reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPMB058 | ||
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| THPMY002 | Fabrication of Ferrite-Copper Block by Spark Plasma Sintering (SPS) | HOM, vacuum, cavity, plasma | 3654 |
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| A ferrite has been well known as an effective material for absorbing electromagnetic waves. Various types of the ferrite blocks have been actually used in accelerator fields as the higher-order modes (HOMs) absorbers in the vacuum beam pipes. However, one of difficulties in using the ferrite is to bond it to the beam pipes with a sufficient adhesive force, and to assure the contact with a high thermal conductivity in vacuum. The brazing or Hot Isostatic Pressing (HIP) is not so easy owing to a low thermal expansion rate and a relatively low tensile strength of the ferrite. We established a method of fabricating a ferrite block bonded to copper by spark plasma sintering (SPS). The ferrite powders are directly sintered on a copper block in the SPS process together with some metals to relax the thermal stress between them. The sintered ferrite-copper block can be brazed or welded to other metal blocks, or directly on the beam pipes. Here reported are R&D results of the fabrication method, and some experimental results on the properties of the ferrite-copper block. | |||
| DOI • | reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPMY002 | ||
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