Keyword: distributed
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MOPO066 Simulation of the Transitional Process in Accelerating Sections by Equivalent Circuit Method coupling, operation, MMI, interface 145
  • S.V. Matsievskiy, V.I. Kaminskiy, Ya.V. Shashkov
    MEPhI, Moscow, Russia
  Nowadays linac accelerating RF systems design is usually done by the finite difference method. It provides high accuracy of calculations and freedom in topology choosing, but may draw considerable amounts of computer resources with long calculation times. Alternative to this method, equivalent circuit method exists. The basic idea of this method is to build a lumped element circuit, which with certain approximation acts as an original accelerating cell. It drastically reduces the number of equations to solve. This method is long known but usually only used for the particular accelerating structures when speed of calculation is a key-factor. Present paper describes a way to numerically simulate transition processes in arbitrary coupled accelerating cells using the equivalent circuit method. This approach allows simulating transitional processes in accelerating structures significantly faster and allows doing so for structures with high quality factor and many cells - a hard task for conventional transient solvers based on the finite difference method.  
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About • paper received ※ 23 August 2018      issue date ※ 18 January 2019  
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TUPO031 Investigation of the Surface Resistance of Niobium Between 325 MHz and 1300 MHz Using a Coaxial Half-wave Cavity cavity, niobium, SRF, electromagnetic-fields 395
  • H. Park, S.U. De Silva, J.R. Delayen
    ODU, Norfolk, Virginia, USA
  The Center for Accelerator Science at Old Dominion University has built a half-wave coaxial cavity (*) to measure the surface resistance of niobium as a function of frequency, temperature, rf field, preparation techniques, over a wide range of frequencies of interest for particle accelerators. The characteristics of the half-wave coaxial cavity provide these information on a same surface. The preliminary results showed clearly the frequency dependence of residual surface resistance (**). After establishing baseline, we have conducted a study of low temperature baking effect on the surface resistance under controlled environment. This paper will describe the details of the test procedure, results and we will explore underlying physics of the phenomenon.
* H. Park et al., MOPB003, Proc. SRF2015,
** H. Park et al., THPB080, Proc. SRF2017,
slides icon Slides TUPO031 [0.966 MB]  
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About • paper received ※ 17 September 2018      issue date ※ 18 January 2019  
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TUPO051 Design Considerations of a Balloon-shaped SSR Superconducting Cavity cavity, simulation, electron, multipactoring 448
  • H.J. Cha, S.W. Jang, E.-S. Kim, K.R. Kim, S. H. Park, J.Y. Yoon
    Korea University Sejong Campus, Sejong, Republic of Korea
  A single spoke resonator (SSR, β = 0.51 and f = 325 MHz) is being developed at Korea University. It is well-known that a traditional spoke cavity having flat or round end walls has broad multipacting ranges in acceleration gradient, sometimes including operation region. In general, quite long conditioning time is consumed to overcome such multipacting barriers. In this study, we introduce a balloon-shaped SSR superconducting cavity for the multipacting mitigation due to structural simplicity. The electromagnetic modeling of the SSR was made based on the RF parameter optimization. The simulation results show much narrower multipacting bandwidth, compared to those for the traditional spoke cavity. Mechanical analyses with stiffening structure at maximum allowable working pressures indicate acceptable stresses at the SSR cavity wall. In addition, the resonant frequency shifts due to fabrication and processing for cold tests are predicted and power coupling and tuning mechanism are also investigated.  
DOI • reference for this paper ※  
About • paper received ※ 10 September 2018      issue date ※ 18 January 2019  
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