| Paper | Title | Other Keywords | Page |
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| MOPME003 | Radio Frequency Quadrupole Surrogate Field Models Based on 3D Electromagnetic Field Simulation Results | rfq, simulation, multipole, quadrupole | 379 |
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Funding: This research is funded by grant ”KUL 3E100118” ”Electromagnetic Field Simulation for Future Particle Accelerators”, Project FP7-Euratom No. 269565 and the Belgian Nuclear Research Centre (SCK•CEN) Surrogate field models for the different sections of a Radio Frequency Quadrupole (RFQ) are developed, identified on the basis of finite element (FE) simulation and embedded in a moment method beam dynamics simulation code. The models are validated for both theoretical and realistic RFQ designs. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-MOPME003 | ||
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| MOPME009 | Numerical Calculation of Electromagnetic Fields in Acceleration Cavities under Precise Consideration of Coupler Structures | cavity, dipole, HOM, impedance | 394 |
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Funding: Work supported by BMBF under contract 05H12RD5 During the design phase of superconducting radio frequency (RF) accelerating cavities a challenging and difficult task is to determine the electromagnetic field distribution inside the structure with the help of proper computer simulations. Although dissipation due to lossy materials is neglected in the current work, in reality, because energy transfer appears due to the design of the superconducting cavities, the numerical eigenmode analysis based on real-valued variables is no longer suitable to describe the dissipative acceleration structure. Dissipation can appear with the help of dedicated higher order mode (HOM) couplers, the power coupler as well as the beam tube once the resonance frequency is above the cutoff frequency of the corresponding waveguide. At the Computational Electromagnetics Laboratory (TEMF) a robust parallel eigenmode solver based on complex-valued finite element analysis is available. The eigenmode solver has been applied to the TESLA 1.3 GHz and the third harmonic 3.9 GHz nine-cell cavities to determine the resonance frequency, the quality factor and the corresponding field distribution of eigenmodes. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-MOPME009 | ||
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| MOPME019 | Study of a Fast Convolution Method for Solving the Space Charge Fields of Charged Particle Bunches | simulation, space-charge, electron, ion | 418 |
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The kernel of beam dynamics simulations using the particle-in-cell (PIC) model is the solution of Poisson's equation for the electric potential. A very common way to solve Poisson's equation is to use the convolution of charge density and Green's function, the so-called Green's function method. Additionally, the integrated Green's function method* is being used in order to achieve a higher accuracy. For both methods, the convolutions are done using fast Fourier transform based on the convolution theorem. However, the construction of the integrated Green's function and the further convolution is still very time-consuming. The computation can be accelerated without loosing precision if the calculation of Green’s function values is limited to that part of the computational domain with non-zero grid charge density. In this paper we present a general numerical study of these Green's function methods for computing the potential of different bunches: The results can also be used in other simulation codes to improve efficiency.
* J. Qiang, S. Lidia, R. D. Ryne, and C. Limborg-Deprey, “A Three-Dimensional Quasi-Static Model for High Brightness Beam Dynamics simulation,” Phys. Rev. ST Accel. Beams, vol 9, 044204 (2006). |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-MOPME019 | ||
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| TUPME054 | Influence of a Vacuum Gap on a Bunch Wakefield in a Circular Waveguide Filled up with Dielectric | vacuum, wakefield, cavity, radiation | 1489 |
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Analysis of electromagnetic field of a particle bunch intersecting several boundaries in a dielectric waveguide is important for the wakefield acceleration technique and other problems of accelerator physics. In previous works we investigated the case of a single boundary in a waveguide*. Now we study the electromagnetic field of the bunch moving in a dielectric circular waveguide and crossing a vacuum cavity. The main attention is given to the case when wakefield (Cherenkov radiation) is generated in dielectric. The behavior of the total field depending on distance and time is explored numerically. Analytical estimations are made as well. Influence of the vacuum gap on the wakefield is considered for different lengths of the gap. It is clarified conditions when the vacuum gap does not practically influence on the wakefield. It is noted that the quasi monochromatic wave (the Cherenkov transition radiation) generated in the vacuum region can be used for restoration of the field in the area after the gap. This effect can be achieved for some optimal parameters of the problem.
* T.Yu. Alekhina, A.V. Tyukhtin, Phys. Rev. ST-AB, v.15, 091302 (2012); T.Yu. Alekhina, A.V. Tyukhtin, Phys. Rev. ST-AB, v.16, 081301 (2013). |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-TUPME054 | ||
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| THPME096 | Goubau Line Beam Instrumentation Testing, The Benefits | instrumentation, resonance, impedance, electronics | 3462 |
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| At JLab and Bergoz Instrumentation Goubau lines are used for beam instrumentation testing. A Goubau line differs fundamentally from standard bench testing techniques in the way it produces the electromagnetic fields which interact with the DUT. This allows to acquire complementary information about DUT characteristics. Consequently, we improve our knowledge about the DUT. At JLab BPM responses have been successfully mapped and at Bergoz Instrumentation high frequency behavior of current transformers is under study. We present results, highlight benefits and outline ideas for future studies of additional accelerator components. | |||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THPME096 | ||
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| THPRI053 | Ferrite Material Characterization in a Static Bias Field for the Design of a Tunable Cavity | simulation, impedance, cavity, solenoid | 3890 |
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| During the development of ferrite-loaded accelerating cavities, the electromagnetic properties of the dispersive ferrite material need to be known. We describe a coaxial short-circuit measurement technique to measure the complex permeability of toroidal-shaped samples (127mm outer and 70mm inner diameter) that are exposed to an external magnetic bias field. The external magnetic bias field is applied perpendicular to the RF magnetic field. With this method it is possible to characterize the frequency dependence of the permeability for a frequency range of 1-100MHz. The dependence of the permeability on the external magnetic bias is presented for the ferrite G-510 from Trans-Tech Inc. and the material characterization is shown in the same frequency range. The measurement results are verified by simulations of the measurement set-up. | |||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THPRI053 | ||
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