2005 Fiscal Year Final Research Report Summary
Research on higher-order-mode (HOM) damping of superconducting cavities for the next-generation synchrotron light sources.
| Project/Area Number |
15540300
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Particle/Nuclear/Cosmic ray/Astro physics
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| Research Institution | High Energy Accelerator Research Organization (2004-2005)
The High Energy Accelerator Research Organization (2003) |
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Principal Investigator |
SAKANAKA Shogo High Energy Accelerator Research Organization (KEK), Institute of Material Structure Science (IMSS), Associate Professor, 物理構造科学研究所, 助教授 (20178560)
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| Co-Investigator(Kenkyū-buntansha) |
ISAWA Masaaki High Energy Accelerator Research Organization (KEK), IMSS, Professor, 物理構造科学研究所, 教授 (10168164)
SAITO Kenji High Energy Accelerator Research Organization (KEK), Associate Professor, 加速器研究施設, 助教授 (10178478)
UMEMORI Kensei High Energy Accelerator Research Organization (KEK), IMSS, Research Assistant, 物理構造科学研究所, 助手 (60353364)
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| Project Period (FY) |
2003 – 2005
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| Keywords | Superconducting cavity / Energy Recovery Linac / ERL / higher order modes / beam instabilities / BBU / damping method / HOM coupler |
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| Research Abstract |
The superconducting (SC) linear accelerator (linac) is one of the key technologies for the next-generation synchrotron light sources. We investigated method of higher-order-mode (HOM) damping for superconducting cavities, that is, one of the important issues for the SC-linacs for preventing beam breakup (BBU) instabilities.
We applied the HOM damping method using radial-transmission lines to the 9-cell 1.3-GHz cavities. We investigated the Q-values of the principal HOMs by computer simulations, as well as by rf measurements of model copper cavity. The Q-values of HOMs depended strongly on the distance between the radial line and the end of the cavity. For the monopole modes, such as TM011-like and TM020-like modes, typical external Q-values of about 10,000 were obtained. For the dipole modes, typical Q-values were about 10,000 and about 10,000-100,000 for the TE111-like and the TM110-like modes, respectively. The HOM damping due to this method was good on the whole, however, further improvements are desirable for the TM110-like modes. We are trying to improve this point by such method as enlarging the beam-pipe radius from 39 mm (present) to larger ones.
From FY2005,the development of the energy recovery linac (ERL) for the next-generation synchrotron light sources started by collaboration between the High Energy Accelerator Research Organization (KEK) and the Japan Atomic Energy Agency (JAEA). A team for developing the SC cavities for this purpose was organized, and they started their research. The basic research results from our research are fully used for this purpose.
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