SRF2017 - List of Authors (Zheng, H.J.)

Paper	Title	Page
MOPB028	HOM Coupler Design for CEPC Cavities	115
	H.J. Zheng, F. Meng, J.Y. Zhai IHEP, Beijing, People's Republic of China
	Funding: This study was supported by National Key Programme for S&T Research and Development (Grant NO.: 2016YFA0400400) In this paper，it will be presented the higher order mode (HOM) coupler design for the Circular Electron-Positron Collider (CEPC) 650 MHz 2-cell cavity. The higher order modes excited by the intense beam bunches must be damped to avoid additional cryogenic loss and multi-bunch instabilities. To keep the beam stable, the impedance budget and the HOM damping requirement are given. A double notch coaxial HOM coupler, which will be mounted on the beam pipe, is planned to extract the HOM power below the cut-off frequency of the beam pipe. This paper summarizes the RF design of the HOM coupler, tolerance analysis, thermal analysis as well as mechanical structures.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-MOPB028
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MOPB071	The Recent Research of HOM Damper for Superconducting Cavity in IHEP	223
	F. Meng, T.M. Huang, H.Y. Lin, Q. Ma, W.M. Pan, J.Y. Zhai, P. Zhang, H.J. Zheng IHEP, Beijing, People's Republic of China
	Funding: This study was supported by National Key Programme for S&T Research and Development (Grant NO.: 2016YFA0400400) For high current accelerator, the efficient higher-order mode (HOM) damping is always an important issue. HOM damper with microwave absorbing material is a key component for high power and broadband HOM damping application. To pursue the high damping efficiency, some ideal material with good microwave absorbing capacity is essential during the RF design and fabrication phase. Sometimes the selection and test of material is the first step and also a long step. This paper will present the recent work on HOM dampers for BEPCII 500MHz cavity and CEPC 650MHz cavity in IHEP.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-MOPB071
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TUXAA01	CEPC SRF System Design and Challenges	332
	J.Y. Zhai, Y.L. Chi, J. Dai, J. Gao, R. Ge, D.J. Gong, R. Han, T.M. Huang, S. Jin, Z.Q. Li, B. Liu, Z.C. Liu, Q. Ma, F. Meng, Z.H. Mi, G. Pei, Q. Qin, P. Sha, Q.Y. Wang, T.X. Zhao, H.J. Zheng IHEP, Beijing, People's Republic of China C. Pagani Università degli Studi di Milano & INFN, Segrate, Italy
	Funding: Work supported by National Key Programme for S&T Research and Development of China (Grant NO.: 2016YFA0400400) CEPC is a 100 km circular electron positron collider operating at 90-240 GeV center-of-mass energy of Z, W and Higgs bosons. CEPC and its successor SPPC, a 100 TeV center-of-mass super proton-proton collider, will ensure the elementary particle physics a vibrant field for decades to come. The conceptual design report (CDR) of CEPC will be completed in the end of 2017 as an important step to move the project forward. In this contribution, CEPC SRF system CDR design and challenges will be introduced, including the system layout and parameter choices, configuration at different operation energies, transient beam loading and its compensation, cavity fundamental mode (FM) and higher order mode (HOM) induced coupled bunch instabilities (CBI) and the beam feedback requirement, etc. The SRF technology R&D plan and progress as well as the SRF infrastructure and industrialization plan are discussed at last.
	Slides TUXAA01 [9.124 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-TUXAA01
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TUPB032	Study on 650MHz 5-cell Prototype Cavities at IHEP	448
	S. Jin, J. Gao, D.J. Gong, Z.C. Liu, P. Sha, J.Y. Zhai, T.X. Zhao, H.J. Zheng IHEP, Beijing, People's Republic of China
	CEPC Pre CDR pointed that the 650 MHz 5-cell SRF cavity could be a candidate for the main ring of the single-ring pretzel scheme at the Higgs energy in 2015. Then EM design of 5-cell cavities were published later. So, the study on the fabrication of a 5-cell prototype cavity with waveguide HOM couplers were carried on at IHEP. In the paper, we will mainly report the mechanical design and fabrication progress of the 5-cell prototype. Besides, fabrication of a bare 2-cell prototype cavity was also carried on according to the further study after Pre-CDR. Challenges and possible solutions for the prototypes development will also be discussed.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-TUPB032
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TUPB033	Tests of the High Current Slotted Superconducting Cavity with Extremely Low Impedance	451
	Z.C. Liu, J. Gao, F.S. He, S. Jin, Z.H. Mi, T.X. Zhao, H.J. Zheng IHEP, Beijing, People's Republic of China F. Wang, D.H. Zhuang PKU, Beijing, People's Republic of China
	Slotted superconducting cavity is a novel structure with extremely low impedance and high BBU threshold. It can be used in various high current applications. A 1.3 GHz 3-cell slotted superconducting cavity was designed and tested. The room temperature test results show the cavity has an extremely low impedance. The vertical test results show the cavity gradient can reach several MV/m, but it was limited by the test end group made of steel.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-TUPB033
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TUPB036	R&D of CEPC Cavity	463
	P. Sha Institute of High Energy Physics (IHEP), Chinese Academy of Sciences, Beijing, People's Republic of China B. Liu, Z.H. Mi, J.Y. Zhai, X.Y. Zhang, H.J. Zheng IHEP, Beijing, People's Republic of China
	Funding: This study was supported by National Key Programme for S&T Research and Development (Grant NO.: 2016YFA0400400) and National Natural Science Foundation of China (Grant NO.: 11505197) CEPC will use 650 MHz cavities for the collider (Main Ring) and 1.3 GHz cavities for the Booster. Each booster cryomodule contains eight 1.3 GHz 9-cell cavities, which is similar as LCLS-II. Each collider cryomodule contains six 650 MHz 2-cell cavities, which is totally new. So our R&D of CEPC cavity mainly focuses on the 650 MHz 2-cell cavity. A cryomodule which consists of two 650 MHz 2-cell cavities has began in early 2017. In this thesis, the RF and mechanical design is displayed with Helium Vessel. Besides, multipacting is analyzed. In order to achieve high Q, N-doping is also studied.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-TUPB036
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Paper

Title

Page

HOM Coupler Design for CEPC Cavities

115

H.J. Zheng, F. Meng, J.Y. Zhai
IHEP, Beijing, People's Republic of China

Funding: This study was supported by National Key Programme for S&T Research and Development (Grant NO.: 2016YFA0400400)
In this paper，it will be presented the higher order mode (HOM) coupler design for the Circular Electron-Positron Collider (CEPC) 650 MHz 2-cell cavity. The higher order modes excited by the intense beam bunches must be damped to avoid additional cryogenic loss and multi-bunch instabilities. To keep the beam stable, the impedance budget and the HOM damping requirement are given. A double notch coaxial HOM coupler, which will be mounted on the beam pipe, is planned to extract the HOM power below the cut-off frequency of the beam pipe. This paper summarizes the RF design of the HOM coupler, tolerance analysis, thermal analysis as well as mechanical structures.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-MOPB028

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPB071

The Recent Research of HOM Damper for Superconducting Cavity in IHEP

223

F. Meng, T.M. Huang, H.Y. Lin, Q. Ma, W.M. Pan, J.Y. Zhai, P. Zhang, H.J. Zheng
IHEP, Beijing, People's Republic of China

Funding: This study was supported by National Key Programme for S&T Research and Development (Grant NO.: 2016YFA0400400)
For high current accelerator, the efficient higher-order mode (HOM) damping is always an important issue. HOM damper with microwave absorbing material is a key component for high power and broadband HOM damping application. To pursue the high damping efficiency, some ideal material with good microwave absorbing capacity is essential during the RF design and fabrication phase. Sometimes the selection and test of material is the first step and also a long step. This paper will present the recent work on HOM dampers for BEPCII 500MHz cavity and CEPC 650MHz cavity in IHEP.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-MOPB071

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUXAA01

CEPC SRF System Design and Challenges

332

J.Y. Zhai, Y.L. Chi, J. Dai, J. Gao, R. Ge, D.J. Gong, R. Han, T.M. Huang, S. Jin, Z.Q. Li, B. Liu, Z.C. Liu, Q. Ma, F. Meng, Z.H. Mi, G. Pei, Q. Qin, P. Sha, Q.Y. Wang, T.X. Zhao, H.J. Zheng
IHEP, Beijing, People's Republic of China
C. Pagani
Università degli Studi di Milano & INFN, Segrate, Italy

Funding: Work supported by National Key Programme for S&T Research and Development of China (Grant NO.: 2016YFA0400400)
CEPC is a 100 km circular electron positron collider operating at 90-240 GeV center-of-mass energy of Z, W and Higgs bosons. CEPC and its successor SPPC, a 100 TeV center-of-mass super proton-proton collider, will ensure the elementary particle physics a vibrant field for decades to come. The conceptual design report (CDR) of CEPC will be completed in the end of 2017 as an important step to move the project forward. In this contribution, CEPC SRF system CDR design and challenges will be introduced, including the system layout and parameter choices, configuration at different operation energies, transient beam loading and its compensation, cavity fundamental mode (FM) and higher order mode (HOM) induced coupled bunch instabilities (CBI) and the beam feedback requirement, etc. The SRF technology R&D plan and progress as well as the SRF infrastructure and industrialization plan are discussed at last.

Slides TUXAA01 [9.124 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-TUXAA01

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPB032

Study on 650MHz 5-cell Prototype Cavities at IHEP

448

S. Jin, J. Gao, D.J. Gong, Z.C. Liu, P. Sha, J.Y. Zhai, T.X. Zhao, H.J. Zheng
IHEP, Beijing, People's Republic of China

CEPC Pre CDR pointed that the 650 MHz 5-cell SRF cavity could be a candidate for the main ring of the single-ring pretzel scheme at the Higgs energy in 2015. Then EM design of 5-cell cavities were published later. So, the study on the fabrication of a 5-cell prototype cavity with waveguide HOM couplers were carried on at IHEP. In the paper, we will mainly report the mechanical design and fabrication progress of the 5-cell prototype. Besides, fabrication of a bare 2-cell prototype cavity was also carried on according to the further study after Pre-CDR. Challenges and possible solutions for the prototypes development will also be discussed.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-TUPB032

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPB033

Tests of the High Current Slotted Superconducting Cavity with Extremely Low Impedance

451

Z.C. Liu, J. Gao, F.S. He, S. Jin, Z.H. Mi, T.X. Zhao, H.J. Zheng
IHEP, Beijing, People's Republic of China
F. Wang, D.H. Zhuang
PKU, Beijing, People's Republic of China

Slotted superconducting cavity is a novel structure with extremely low impedance and high BBU threshold. It can be used in various high current applications. A 1.3 GHz 3-cell slotted superconducting cavity was designed and tested. The room temperature test results show the cavity has an extremely low impedance. The vertical test results show the cavity gradient can reach several MV/m, but it was limited by the test end group made of steel.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-TUPB033

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPB036

R&D of CEPC Cavity

463

P. Sha
Institute of High Energy Physics (IHEP), Chinese Academy of Sciences, Beijing, People's Republic of China
B. Liu, Z.H. Mi, J.Y. Zhai, X.Y. Zhang, H.J. Zheng
IHEP, Beijing, People's Republic of China

Funding: This study was supported by National Key Programme for S&T Research and Development (Grant NO.: 2016YFA0400400) and National Natural Science Foundation of China (Grant NO.: 11505197)
CEPC will use 650 MHz cavities for the collider (Main Ring) and 1.3 GHz cavities for the Booster. Each booster cryomodule contains eight 1.3 GHz 9-cell cavities, which is similar as LCLS-II. Each collider cryomodule contains six 650 MHz 2-cell cavities, which is totally new. So our R&D of CEPC cavity mainly focuses on the 650 MHz 2-cell cavity. A cryomodule which consists of two 650 MHz 2-cell cavities has began in early 2017. In this thesis, the RF and mechanical design is displayed with Helium Vessel. Besides, multipacting is analyzed. In order to achieve high Q, N-doping is also studied.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-TUPB036

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)