| Paper | Title | Page |
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| WEPML055 | Simulation Study of Parasitic-Mode Damping Methods for a 1.5-GHz TM020-Mode Harmonic Cavity | 2822 |
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Design study of parasitic-mode (PM) damped structures has been conducted for the purpose to realize a normal conducting 1.5 GHz harmonic cavity which is based on the TM020 resonant mode*. We have investigated the performances of two PM-damping mechanisms, that are, rod-type antennas** and annular slots. The rod-type antennas locate at the node of electric field of the TM020 mode while the annular slots locate at the node of magnetic field. As a result of 3D electromagnetic simulations, suitable performances of PMs were confirmed by employing either of the PM-damping mechanisms. It was also shown that the slot-type structure is superior in PM-damping performance and in the unloaded Q of the TM020 mode.
* N. Yamamoto et al., IPAC'17, paper THOPIK037; N. Yamamoto Phys. Rev. Accel. Beams, 21, 1, 012001. ** T. Takahashi et al., IPAC'17, paper THPIK036. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPML055 | |
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| THPAK001 | Impedance Evaluation of In-Vacuum Undulator at KEK Photon Factory | 3200 |
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| The estimate of impedance and kick factors of the recently installed at KEK Photon Factory (PF) four In-Vacuum Undulators (IVU) is currently a very important issue, because they could be considerable contributors to the total impedance of PF. Moreover, the coupling impedance of the IVUs could lead to the beam energy loss, changes in the bunch shape, betatron tune shifts and, finally, to the various beam instabilities. Using the simulation tool (CST Particle Studio), longitudinal and transverse impedances of the IVUs were evaluated and compared to analytical formulas and measurement results. The study provides guidelines for mitigation of unwanted impedance, for the accurate estimate of its effects on the beam quality and beam instabilities and also for the impedance budget of a newly designed next-generation machine which has many IVUs and small-aperture beam pipes. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK001 | |
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