SAP2023 - List of Keywords (electron)

Paper	Title	Other Keywords	Page
MOCXA02	Beam-Beam Interaction with Longitudinal Impedance and Its Application in TMCI Study	impedance, coupling, synchrotron, simulation	1
	C.T. Lin IASF, Shenzhen, Guangdong, People’s Republic of China K. Ohmi KEK, Ibaraki, Japan Y. Zhang IHEP, Beijing, People’s Republic of China
	Simulations have showed a novel coherent head-tail instability induced by beam-beam interaction with a large Piwinski angle. The localized cross-wake force has been introduced to explain the instability. The longitudinal impedance would cause coherent and incoherent synchrotron tune shift and distort the particle¿s trajectories in longitudinal phase space. Further beam-beam simulation revealed that the longitudinal impedance has strong impacts on the beam stability, squeezing the horizontal stable tune area seriously. The instability has become an important issue during the designs of CEPC and FCC-ee. In this paper, we develop a transverse mode coupling analysis method that could be used to study beam-beam instability with and without longitudinal impedance. This method can also be applied in synchrotron light sources to study transverse mode coupling instability (TMCI) with longitudinal impedance and harmonic cavity. Some preliminary results at Shenzhen Innovation Light Source (SILF) are also shown.
DOI •	reference for this paper ※ doi:10.18429/JACoW-SAP2023-MOCXA02
About •	Received ※ 30 June 2023 — Accepted ※ 11 July 2023 — Issued ※ 23 September 2024
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPB001	Terahertz-Driven MeV Electron Bunch Compression and Streaking	FEM, simulation, timing, laser	14
	Y. Xu, K. Fan, Z. Liu, Y. Song, C.-Y. Tsai, J. Wang HUST, Wuhan, People’s Republic of China
	Electron bunches with ultra-short bunch length and ultra-high timing stability are crucial for various applications. To achieve these desired characteristics, there is a growing interest in employing Terahertz-driven techniques to manipulate and diagnose electron bunches. This paper presents a method capable of compressing and measuring electron bunch lengths. Theoretical and simulation results demonstrate that the bunch length of 54 is reduced to 4 fs by utilizing THz-driven resonant cavity compression, achieving a compression ratio of 13. Furthermore, we also verify the bunch compression using a terahertz-driven streak camera.
DOI •	reference for this paper ※ doi:10.18429/JACoW-SAP2023-MOPB001
About •	Received ※ 28 June 2023 — Revised ※ 09 July 2023 — Accepted ※ 11 July 2023 — Issued ※ 26 February 2024
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MOPB004	Lowest Longitudinal and Transverse Resistive-wall Wake and Impedance for Nonultra-relativistic Beams	wakefield, dipole, impedance, space-charge	21
	J.Z. Tang TUB, Beijing, People’s Republic of China
	With the development of the steady-state microbunch(SSMB) storage ring, its parameters reveal that the ultra-relativistic assumption which is wildly used is not valid for the electron beam bunch train. For a bunch train with a length in the 100nm range, spacing of 1um, and energy in the hundred MeV range, the action angle of the space charge force is estimated by {r/γ}. The space charge effect of the mirror current loop formed in the wall with a scale of 1cm will have a sustained effect on approximately dozens of microbunches behind the source particle. The strength of the interaction between such bunches and the potential instability it may cause needs careful evaluation. At the same time, the effect of the space charge inside a single bunch due to space charge effect also needs to be considered. We reorganized the lowest-order longitudinal wakefield under non-extreme relativistic conditions, and modified the inconsistent part in the theoretical derivation in some essays of the lowest-order transverse wakefield. We present the modified theoretical results and analysis. The action area are then divided into three parts. It lays foundation in future research.
	Poster MOPB004 [1.278 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-SAP2023-MOPB004
About •	Received ※ 30 June 2023 — Revised ※ 08 July 2023 — Accepted ※ 11 July 2023 — Issued ※ 22 November 2023
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MOPB008	Approximation of Space Charge Effect in the Presence of Longitudinal Magnetic Fields	space-charge, simulation, controls, emittance	27
	H.Y. Li, H.B. Chen, Q. Gao, W.H. Gu, J.R. Shi, H. Zha TUB, Beijing, People’s Republic of China
	The space charge effect plays a significant role in the evolution of phase space during beam transport. Applying an external longitudinal magnetic field has been shown to effectively reduce beam expansion through the mechanism of beam rotation. In this article, we present a fast approximation algorithm for estimating the impact of an external magnetic field on beam expansion. The algorithm enables efficient computations and provides insights into controlling the phase space dynamics of the beam in the presence of longitudinal magnetic fields.
	Poster MOPB008 [0.447 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-SAP2023-MOPB008
About •	Received ※ 30 June 2023 — Revised ※ 11 July 2023 — Accepted ※ 12 July 2023 — Issued ※ 30 April 2024
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MOPB016	Matching Section Optics Design for the MeV Ultrafast Electron Beam Experimental Facility	sextupole, quadrupole, dipole, simulation	37
	H. Qi, K. Fan, Z. Liu, C.-Y. Tsai, J. Wang HUST, Wuhan, People’s Republic of China
	This paper introduces the design and optimization of the matching section beamline for the ultrafast electron research platform at Huazhong University of Science and Technology (HUST). The matching section serves as a connection between the main beamline and the beam physics research beamline, aiming to achieve efficient and precise control over the electron beam trajectory and parameters. To evaluate its performance, particle tracking simulations using GPT software were conducted. When the beam is set at 3 MeV and 1 pC charge, the matching section is capable of compressing the bunch length to approximately 50 fs. This level of compression is crucial for ultrafast electron research applications, as it enables the study of phenomena that occur on extremely short time scales, demonstrating its effectiveness in achieving precise beam control and compression.
DOI •	reference for this paper ※ doi:10.18429/JACoW-SAP2023-MOPB016
About •	Received ※ 29 June 2023 — Revised ※ 08 July 2023 — Accepted ※ 11 July 2023 — Issued ※ 20 January 2024
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MOPB026	Physical Design for EEHG Beamlines at S3FEL	FEL, undulator, radiation, simulation	55
	X.F. Wang Institute of Advanced Science Facilities, Shenzhen, People’s Republic of China C. Feng, Z. Wang SARI-CAS, Pudong, Shanghai, People’s Republic of China X.M. Li, J.T. Sun, Y. Yu DICP, Dalian, Liaoning, People’s Republic of China Y.F. Liang, X.M. Yang, H. Yi, L. Zeng, W.Q. Zhang IASF, Shenzhen, Guangdong, People’s Republic of China
	Funding: Work supported by the National Key R&D Program of China (Grant No.2018YFE0203000) and the National Natural Science Foundation of China (Grant No.22288201). The proposed Shenzhen Superconducting Soft X-Ray Free-electron Laser (S3FEL) aims at generating FEL pulses from 1 nm to 30 nm. At phase-I, two undulator beamlines work at ehco-enable harmonic generation (EEHG) principle. The two undulators will cover the spectral ranges 2.3-15 nm (~83-539 eV) and 5-30 nm (~41-248 eV), respectively, when receiving electrons from 2.5 GeV superconducting linac. However, the generated FEL radiation is sensitive to various electron beam properties, e.g., its energy profile influenced by collective effects such as Coherent Synchroton Radiation (CSR), especially at high harmonics. To generate intense full coherent FEL radiation at ultra-short wavelength, a novel technique of EEHG cascaded harmonic lasing method is also considered. Physical design and FEL performance are described in this paper.
DOI •	reference for this paper ※ doi:10.18429/JACoW-SAP2023-MOPB026
About •	Received ※ 10 July 2023 — Revised ※ 11 July 2023 — Accepted ※ 18 July 2023 — Issued ※ 04 October 2024
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MOPB027	A Scheme of Fully Coherent X-Ray Free Electron Laser for the Shine Based on Fresh-Slices	FEL, radiation, undulator, simulation	59
	YX. Liu SINAP, Shanghai, People’s Republic of China T. Liu SARI-CAS, Pudong, Shanghai, People’s Republic of China
	In this paper, the fresh-slice self-seeding free electron laser scheme is studied, and the feasibility of its application in the SHINE project is analyzed. The scheme used the fresh-slice method to generate the beam with adjustable spatial distribution, which can effectively improve the longitudinal coherence and stability of the self-seeding output radiation. Through the FEL simulation, we demonstrated that this scheme can produce a highly stable, narrow bandwidth pulse output under the SHINE’s parametric conditions, which will be beneficial to further improve the performance of this device in the future.
	Poster MOPB027 [1.524 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-SAP2023-MOPB027
About •	Received ※ 10 July 2023 — Revised ※ 11 July 2023 — Accepted ※ 12 July 2023 — Issued ※ 02 November 2023
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MOPB029	Multi-bunch Operation Mode for Simultaneously Serving SASE and Seeding FEL Beamlines	FEL, acceleration, undulator, laser	66
	X.F. Wang Institute of Advanced Science Facilities, Shenzhen, People’s Republic of China X.M. Li, J.T. Sun, X.M. Yang, Y. Yu, W.Q. Zhang DICP, Dalian, Liaoning, People’s Republic of China Y.F. Liang, X.M. Yang, H. Yi, L. Zeng, W.Q. Zhang IASF, Shenzhen, Guangdong, People’s Republic of China
	Modern free-electron laser (FEL) facilities are de-signed to simultaneously serve multiple undulator lines to provide x-ray pulses with high peak power and tunable wavelengths. To satisfy different scientific demands, it is preferred to make the separate undulator lines work under different FEL schemes, such as the self-amplified spontaneous emission (SASE) scheme and the echo-enabled harmonic generation (EEHG) scheme. However, different FEL schemes have differ-ent requirements on the beam longitudinal distribu-tion. Here, we propose to use multiple bunches to sim-ultaneously serve the undulator lines and put the bunches at different acceleration phase to change the bunch length with two compressor chicanes. The ac-celeration phase for each bunch is varied by adjusting the time delays of the photocathode drive laser pulses with the accelerator settings unchanged. The start-to-end simulation demonstrates that a fs bunch with high peak current can be produced to serve the SASE line while a bunch with hundred-of-fs length and uniform current distribution can be produced to serve the EEHG line. The FEL performances are simulated and discussed.
DOI •	reference for this paper ※ doi:10.18429/JACoW-SAP2023-MOPB029
About •	Received ※ 25 June 2023 — Revised ※ 10 July 2023 — Accepted ※ 11 July 2023 — Issued ※ 07 September 2024
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MOPB030	Physical Design of an S-Band Cold Cathode RF Gun	gun, cavity, cathode, coupling	70
	T.H. He, H. Xu, K. Zhou, Z. Zhou CAEP/IAE, Mianyang, Sichuan, People’s Republic of China
	In recent years, the properties of new field emission materials have been gradually improved with the advancement of materials research fields, which have provided the possibility for the research and realization of cold cathode RF guns. A 0.32+1 cell S-band RF gun was designed based on the emission properties of carbon nanotube films and ultra nano diamond films. This article mainly introduces the selection of electron gun cavity, RF design and corresponding thermal analysis. The physical design results basically meet the design requirements.
	Poster MOPB030 [1.010 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-SAP2023-MOPB030
About •	Received ※ 28 June 2023 — Revised ※ 09 July 2023 — Accepted ※ 11 July 2023 — Issued ※ 21 November 2023
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MOPB034	Start to End Simulation for A Compact THz-FEL	undulator, cavity, radiation, FEL	76
	R.Y. Luo, Q.S. Chen HUST, Wuhan, People’s Republic of China
	Funding: This work is supported by the National Natural Science Foundation of China(No.12175077) An oscillator type terahertz free electron laser (THz-FEL) is under construction at Huazhong University of Science and Technology (HUST). The designed electron beam energy ranges from 8 MeV to 14 MeV, and the radiation frequency ranges from 3 THz to 10 THz. FEL requires high quality electron beams of emittance, energy spread, bunch charge etc. To know the overall facility performance, a start to end simulation (from electron gun to the end of the oscillator) of the THz-FEL is performed. The simulation of the electron gun to the exit of the linac is performed using PARMELA, where the effect of space charge effects is considered. In addition, the effect of beam loading effect is considered for the linac. The transport line is matched and simulated using ELEGANT. GENESIS 1.3 and OPC is used for the lasing process. Results of the simulation are presented and discussed in this paper.
DOI •	reference for this paper ※ doi:10.18429/JACoW-SAP2023-MOPB034
About •	Received ※ 30 June 2023 — Revised ※ 08 July 2023 — Accepted ※ 11 July 2023 — Issued ※ 18 October 2024
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MOPB039	Low-Alpha Storage Ring Design for Steady-State Microbunching to Generate EUV Radiation	storage-ring, radiation, lattice, coupling	88
	Z. Pan, A. Chao, X.J. Deng, W.-H. Huang, Z.Z. Li, C.-X. Tang TUB, Beijing, People’s Republic of China
	A new concept is proposed for minimizing the longitudinal emittance of a low momentum compaction factor (low-alpha) storage ring which has the capability to stably store sub-femtosecond electron bunches for the first time. This storage ring is designed for Steady-State microbunching (SSMB) to generate kW level average power EUV radiation. The proposed design approach can be applied to any quasi-isochronous storage rings to yield very high radiation power due to longitudinal coherence of the radiation. We obtain an optimal lattice design by minimizing global and local momentum compaction factors simultaneously and the result of single-particle tracking shows that the electron beam with equilibrium rms bunch length of about 40 nm can be stored in this ring. Nonlinear dynamics is studied for this lattice.
DOI •	reference for this paper ※ doi:10.18429/JACoW-SAP2023-MOPB039
About •	Received ※ 03 July 2023 — Revised ※ 08 July 2023 — Accepted ※ 11 July 2023 — Issued ※ 31 December 2023
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TUPB024	Electron Cooling for Future High-energy Hadron Accelerators	wiggler, emittance, hadron, proton	133
	H. Zhao IMP/CAS, Lanzhou, People’s Republic of China
	Funding: National Natural Science Foundation of China (No. 12275323) Electron cooling is an important method to reduce the emittance and momentum spread of hadron beams, and it has been successfully applied in several facilities around the world. In 2019, the world¿s first RF-based electron cooler (LEReC) was commissioned at BNL for the RHIC BES-II project, and the integrated luminosity of RHIC is finally doubled. In addition, electron cooling is also a must for the future Electron-Ion Collider (BNL EIC). However, the high energy requirement of the electron beam (150 MeV) is far beyond what all present coolers can achieve (<4.3 MeV). For that, an electron ring cooler with strong radiation damping is proposed and designed, in which the non-magnetized and dispersive cooling techniques are applied. In this talk, I will introduce the experimental and simulation results of the two facilities. Mainly, I will introduce several new phenomena that were first observed in LEReC, such as the beam heating effect and the ion beam focusing effect. Besides, some new theories that were developed for the ring cooler will also be discussed.
	Poster TUPB024 [1.769 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-SAP2023-TUPB024
About •	Received ※ 04 July 2023 — Revised ※ 09 July 2023 — Accepted ※ 11 July 2023 — Issued ※ 14 December 2023
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TUPB025	Influence of Transverse Distribution of Electron Beam on the Distribution of Proton Beam in the Process of Electron Cooling	proton, simulation, storage-ring, scattering	137
	X.D. Yang IMP/CAS, Lanzhou, People’s Republic of China
	Funding: National Natural Science Foundation of China No.12275325 The electron cooling process of 20GeV proton beam in EicC was simulated for the eight transverse distribution of electron beam with the help of electron cooling simulation code. The transverse cooling time was obtained in the different transverse distribution of electron beam. The final transverse distribution of proton beam was demonstrated. The simulated results reveal that the transverse distribution of electron beam influences the distribution of proton beam in the process of electron cooling. In the future, this idea was expected to apply to the longitudinal distribution of electron beam. The longitudinal distribution of proton beam was attempted to be controlled by the longitudinally modulated electron beam. As a result, the peak current and longitudinal distribution of proton beam will be controlled by the electron beam. The loss of proton beams will be reduced, and the stored lifetime of proton beam in the storage ring will be extended. The intensity of the proton beam will be maintained for a longer time.
	Poster TUPB025 [2.048 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-SAP2023-TUPB025
About •	Received ※ 28 June 2023 — Revised ※ 09 July 2023 — Accepted ※ 12 July 2023 — Issued ※ 06 June 2024
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TUPB027	New Progress of the Miniaturized Microwave Ion Source at Peking University	plasma, MMI, ion-source, ECR	144
	S.X. Peng, J.E. Chen, B.J. Cui, Z.Y. Guo, Y.X. Jiang, T.H. Ma, W.B. Wu PKU, Beijing, People’s Republic of China A.L. Zhang USTC, Hefei, Anhui, People’s Republic of China
	The generation of plasma in a microwave ion source involves confining electrons using a static magnetic field and energizing them with an electromagnetic field that transmitted into the plasma chamber. However, according to electromagnetics theory, there is always a cut-off size in circular wave guides for a given frequency. For a 2.45 GHz microwave, this dimension is 72 mm, which should theoretically prevent transmission of the microwave into the discharge chamber and no plasma can be generated. Since 2006 Peking University(PKU) has successfully developed a series of permanent magnet 2.45 GHz microwave ion sources (PKU PMECRs¿ with a discharge chamber less than 50 mm, capable of delivering tens of mA beams for accelerators. To explain this anomalous phenomenon, a hybrid discharge heating (HDH) mode that combines surface wave plasma (SWP) and electron cyclotron heating (ECH) has been proposed. This HDH mode not only successfully explains PKU PMECRs, but also predicts that the optimized inner diameter of the plasma chamber is 24 mm, which is confirmed by experiments involving different liners in the miniaturized microwave ion source.
DOI •	reference for this paper ※ doi:10.18429/JACoW-SAP2023-TUPB027
About •	Received ※ 27 June 2023 — Revised ※ 10 July 2023 — Accepted ※ 12 July 2023 — Issued ※ 15 June 2024
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TUPB029	Wakefield Studies for the Step Structure and the Skin Depth of Coated Dielectric Tubes	wakefield, impedance, FEL, simulation	147
	H. Liu SINAP, Shanghai, People’s Republic of China S. Chen, H.X. Deng, B. Liu, Y.M. Wen SARI-CAS, Pudong, Shanghai, People’s Republic of China J.J. Guo Zhangjiang Lab, Shanghai, People’s Republic of China
	Funding: This work was supported by YSBR-042, 12125508, 11935020, 21XD1404100 and JCYJ-SHFY-2021-010. Wakefield issues are always important research objects in free electron laser (FEL) facilities. Since the wakefield in free electron laser facilities usually leads to a decrease of FEL performance, the research of the wakefield impacts is of great significance. Step structures are almost ubiquitous in the overall undulator section of an FEL facility, which always generate critical wakefields. In this paper, we systematically analyze and summarize the wakefield characteristics of step structures including the step-in structure and the step-out structure. In addition, the skin depth issue of the wakefield is still controversial. We study the skin depth of the wakefield field in the vacuum chamber of the kicker in the SHINE, which is made of the dielectric pipe. We proposed the conception of ¿effective skin depth¿ from two different perspectives and wrote simulation codes to calculate the ¿effective skin depth¿. We hope these methods could provide new mentalities for related research in the future.
	Poster TUPB029 [0.392 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-SAP2023-TUPB029
About •	Received ※ 30 June 2023 — Revised ※ 09 July 2023 — Accepted ※ 12 July 2023 — Issued ※ 21 September 2023
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TUPB033	Heating Estimation of Undulator Vacuum Chamber at S3FEL	wakefield, vacuum, undulator, impedance	151
	H. Yi IASF, Shenzhen, Guangdong, People’s Republic of China X.F. Wang Institute of Advanced Science Facilities, Shenzhen, People’s Republic of China X.M. Yang, W.Q. Zhang DICP, Dalian, Liaoning, People’s Republic of China
	Heating of the vacuum chambers are unavoidable when electron beams pass through the chamber channels at relativistic speeds. In the undulator vacuum chambers, such effects might lead to temperature increase of the magnets and eventually cause degradations in the FEL lasing process. Thus, in this paper, the heating of the undulator vacuum chambers at S3FEL due to wake field effects and spontaneous synchrotron radiation are estimated using an analytical approach. For the wake field effects, the contribution from finite conductivity of the vacuum chamber material and from the inner surface roughness are considered. A electron beam profile from a start-to-end simulation is used to calculate the total wake field and the induced heat. For the synchrotron radiation, a simple analytical expression is used.
DOI •	reference for this paper ※ doi:10.18429/JACoW-SAP2023-TUPB033
About •	Received ※ 05 July 2023 — Revised ※ 09 July 2023 — Accepted ※ 12 July 2023 — Issued ※ 26 September 2024
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TUPB035	Recent Progress of the Beam Background Experiment in the BEPCII	background, experiment, simulation, positron	155
	B. Wang, H.Y. Shi, C.H. Yu IHEP, Beijing, People’s Republic of China
	The Beijing Electron Positron Collider II will upgrade to extend the beam energy and the luminosity by increasing the beam current and slightly compressing the beam size, where the beam energy will be extended from 2.3 GeV to 2.8 GeV and the peak luminosity will be up to 1.1×10³³\rm{cm}^-2\rm{s}^-1 at the optimizing beam energy of 2.35 GeV. The BEPCII upgrade is expected to result in challenging levels of beam related background in the interaction region. An precise simulating and mitigating beam background is necessary to protect the BESIII detector and increase the beam current and peak luminosity. The beam related background at BEPCII is mainly from the Touschek effect and the beam gas effect, this paper presents the recent progress of the beam background simulation and experiment.
DOI •	reference for this paper ※ doi:10.18429/JACoW-SAP2023-TUPB035
About •	Received ※ 06 July 2023 — Revised ※ 09 July 2023 — Accepted ※ 11 July 2023 — Issued ※ 22 July 2024
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Paper

Title

Other Keywords

Page

MOCXA02

Beam-Beam Interaction with Longitudinal Impedance and Its Application in TMCI Study

impedance, coupling, synchrotron, simulation

1

C.T. Lin
IASF, Shenzhen, Guangdong, People’s Republic of China
K. Ohmi
KEK, Ibaraki, Japan
Y. Zhang
IHEP, Beijing, People’s Republic of China

Simulations have showed a novel coherent head-tail instability induced by beam-beam interaction with a large Piwinski angle. The localized cross-wake force has been introduced to explain the instability. The longitudinal impedance would cause coherent and incoherent synchrotron tune shift and distort the particle¿s trajectories in longitudinal phase space. Further beam-beam simulation revealed that the longitudinal impedance has strong impacts on the beam stability, squeezing the horizontal stable tune area seriously. The instability has become an important issue during the designs of CEPC and FCC-ee. In this paper, we develop a transverse mode coupling analysis method that could be used to study beam-beam instability with and without longitudinal impedance. This method can also be applied in synchrotron light sources to study transverse mode coupling instability (TMCI) with longitudinal impedance and harmonic cavity. Some preliminary results at Shenzhen Innovation Light Source (SILF) are also shown.

DOI •

reference for this paper ※ doi:10.18429/JACoW-SAP2023-MOCXA02

About •

Received ※ 30 June 2023 — Accepted ※ 11 July 2023 — Issued ※ 23 September 2024

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

MOPB001

Terahertz-Driven MeV Electron Bunch Compression and Streaking

FEM, simulation, timing, laser

14

Y. Xu, K. Fan, Z. Liu, Y. Song, C.-Y. Tsai, J. Wang
HUST, Wuhan, People’s Republic of China

Electron bunches with ultra-short bunch length and ultra-high timing stability are crucial for various applications. To achieve these desired characteristics, there is a growing interest in employing Terahertz-driven techniques to manipulate and diagnose electron bunches. This paper presents a method capable of compressing and measuring electron bunch lengths. Theoretical and simulation results demonstrate that the bunch length of 54 is reduced to 4 fs by utilizing THz-driven resonant cavity compression, achieving a compression ratio of 13. Furthermore, we also verify the bunch compression using a terahertz-driven streak camera.

DOI •

reference for this paper ※ doi:10.18429/JACoW-SAP2023-MOPB001

About •

Received ※ 28 June 2023 — Revised ※ 09 July 2023 — Accepted ※ 11 July 2023 — Issued ※ 26 February 2024

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MOPB004

Lowest Longitudinal and Transverse Resistive-wall Wake and Impedance for Nonultra-relativistic Beams

wakefield, dipole, impedance, space-charge

21

J.Z. Tang
TUB, Beijing, People’s Republic of China

With the development of the steady-state microbunch(SSMB) storage ring, its parameters reveal that the ultra-relativistic assumption which is wildly used is not valid for the electron beam bunch train. For a bunch train with a length in the 100nm range, spacing of 1um, and energy in the hundred MeV range, the action angle of the space charge force is estimated by {r/γ}. The space charge effect of the mirror current loop formed in the wall with a scale of 1cm will have a sustained effect on approximately dozens of microbunches behind the source particle. The strength of the interaction between such bunches and the potential instability it may cause needs careful evaluation. At the same time, the effect of the space charge inside a single bunch due to space charge effect also needs to be considered. We reorganized the lowest-order longitudinal wakefield under non-extreme relativistic conditions, and modified the inconsistent part in the theoretical derivation in some essays of the lowest-order transverse wakefield. We present the modified theoretical results and analysis. The action area are then divided into three parts. It lays foundation in future research.

Poster MOPB004 [1.278 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-SAP2023-MOPB004

About •

Received ※ 30 June 2023 — Revised ※ 08 July 2023 — Accepted ※ 11 July 2023 — Issued ※ 22 November 2023

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MOPB008

Approximation of Space Charge Effect in the Presence of Longitudinal Magnetic Fields

space-charge, simulation, controls, emittance

27

H.Y. Li, H.B. Chen, Q. Gao, W.H. Gu, J.R. Shi, H. Zha
TUB, Beijing, People’s Republic of China

The space charge effect plays a significant role in the evolution of phase space during beam transport. Applying an external longitudinal magnetic field has been shown to effectively reduce beam expansion through the mechanism of beam rotation. In this article, we present a fast approximation algorithm for estimating the impact of an external magnetic field on beam expansion. The algorithm enables efficient computations and provides insights into controlling the phase space dynamics of the beam in the presence of longitudinal magnetic fields.

Poster MOPB008 [0.447 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-SAP2023-MOPB008

About •

Received ※ 30 June 2023 — Revised ※ 11 July 2023 — Accepted ※ 12 July 2023 — Issued ※ 30 April 2024

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MOPB016

Matching Section Optics Design for the MeV Ultrafast Electron Beam Experimental Facility

sextupole, quadrupole, dipole, simulation

37

H. Qi, K. Fan, Z. Liu, C.-Y. Tsai, J. Wang
HUST, Wuhan, People’s Republic of China

This paper introduces the design and optimization of the matching section beamline for the ultrafast electron research platform at Huazhong University of Science and Technology (HUST). The matching section serves as a connection between the main beamline and the beam physics research beamline, aiming to achieve efficient and precise control over the electron beam trajectory and parameters. To evaluate its performance, particle tracking simulations using GPT software were conducted. When the beam is set at 3 MeV and 1 pC charge, the matching section is capable of compressing the bunch length to approximately 50 fs. This level of compression is crucial for ultrafast electron research applications, as it enables the study of phenomena that occur on extremely short time scales, demonstrating its effectiveness in achieving precise beam control and compression.

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reference for this paper ※ doi:10.18429/JACoW-SAP2023-MOPB016

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Received ※ 29 June 2023 — Revised ※ 08 July 2023 — Accepted ※ 11 July 2023 — Issued ※ 20 January 2024

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MOPB026

Physical Design for EEHG Beamlines at S3FEL

FEL, undulator, radiation, simulation

55

X.F. Wang
Institute of Advanced Science Facilities, Shenzhen, People’s Republic of China
C. Feng, Z. Wang
SARI-CAS, Pudong, Shanghai, People’s Republic of China
X.M. Li, J.T. Sun, Y. Yu
DICP, Dalian, Liaoning, People’s Republic of China
Y.F. Liang, X.M. Yang, H. Yi, L. Zeng, W.Q. Zhang
IASF, Shenzhen, Guangdong, People’s Republic of China

Funding: Work supported by the National Key R&D Program of China (Grant No.2018YFE0203000) and the National Natural Science Foundation of China (Grant No.22288201).
The proposed Shenzhen Superconducting Soft X-Ray Free-electron Laser (S3FEL) aims at generating FEL pulses from 1 nm to 30 nm. At phase-I, two undulator beamlines work at ehco-enable harmonic generation (EEHG) principle. The two undulators will cover the spectral ranges 2.3-15 nm (~83-539 eV) and 5-30 nm (~41-248 eV), respectively, when receiving electrons from 2.5 GeV superconducting linac. However, the generated FEL radiation is sensitive to various electron beam properties, e.g., its energy profile influenced by collective effects such as Coherent Synchroton Radiation (CSR), especially at high harmonics. To generate intense full coherent FEL radiation at ultra-short wavelength, a novel technique of EEHG cascaded harmonic lasing method is also considered. Physical design and FEL performance are described in this paper.

DOI •

reference for this paper ※ doi:10.18429/JACoW-SAP2023-MOPB026

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Received ※ 10 July 2023 — Revised ※ 11 July 2023 — Accepted ※ 18 July 2023 — Issued ※ 04 October 2024

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MOPB027

A Scheme of Fully Coherent X-Ray Free Electron Laser for the Shine Based on Fresh-Slices

FEL, radiation, undulator, simulation

59

YX. Liu
SINAP, Shanghai, People’s Republic of China
T. Liu
SARI-CAS, Pudong, Shanghai, People’s Republic of China

In this paper, the fresh-slice self-seeding free electron laser scheme is studied, and the feasibility of its application in the SHINE project is analyzed. The scheme used the fresh-slice method to generate the beam with adjustable spatial distribution, which can effectively improve the longitudinal coherence and stability of the self-seeding output radiation. Through the FEL simulation, we demonstrated that this scheme can produce a highly stable, narrow bandwidth pulse output under the SHINE’s parametric conditions, which will be beneficial to further improve the performance of this device in the future.

Poster MOPB027 [1.524 MB]

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reference for this paper ※ doi:10.18429/JACoW-SAP2023-MOPB027

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Received ※ 10 July 2023 — Revised ※ 11 July 2023 — Accepted ※ 12 July 2023 — Issued ※ 02 November 2023

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MOPB029

Multi-bunch Operation Mode for Simultaneously Serving SASE and Seeding FEL Beamlines

FEL, acceleration, undulator, laser

66

X.F. Wang
Institute of Advanced Science Facilities, Shenzhen, People’s Republic of China
X.M. Li, J.T. Sun, X.M. Yang, Y. Yu, W.Q. Zhang
DICP, Dalian, Liaoning, People’s Republic of China
Y.F. Liang, X.M. Yang, H. Yi, L. Zeng, W.Q. Zhang
IASF, Shenzhen, Guangdong, People’s Republic of China

Modern free-electron laser (FEL) facilities are de-signed to simultaneously serve multiple undulator lines to provide x-ray pulses with high peak power and tunable wavelengths. To satisfy different scientific demands, it is preferred to make the separate undulator lines work under different FEL schemes, such as the self-amplified spontaneous emission (SASE) scheme and the echo-enabled harmonic generation (EEHG) scheme. However, different FEL schemes have differ-ent requirements on the beam longitudinal distribu-tion. Here, we propose to use multiple bunches to sim-ultaneously serve the undulator lines and put the bunches at different acceleration phase to change the bunch length with two compressor chicanes. The ac-celeration phase for each bunch is varied by adjusting the time delays of the photocathode drive laser pulses with the accelerator settings unchanged. The start-to-end simulation demonstrates that a fs bunch with high peak current can be produced to serve the SASE line while a bunch with hundred-of-fs length and uniform current distribution can be produced to serve the EEHG line. The FEL performances are simulated and discussed.

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reference for this paper ※ doi:10.18429/JACoW-SAP2023-MOPB029

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Received ※ 25 June 2023 — Revised ※ 10 July 2023 — Accepted ※ 11 July 2023 — Issued ※ 07 September 2024

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MOPB030

Physical Design of an S-Band Cold Cathode RF Gun

gun, cavity, cathode, coupling

70

T.H. He, H. Xu, K. Zhou, Z. Zhou
CAEP/IAE, Mianyang, Sichuan, People’s Republic of China

In recent years, the properties of new field emission materials have been gradually improved with the advancement of materials research fields, which have provided the possibility for the research and realization of cold cathode RF guns. A 0.32+1 cell S-band RF gun was designed based on the emission properties of carbon nanotube films and ultra nano diamond films. This article mainly introduces the selection of electron gun cavity, RF design and corresponding thermal analysis. The physical design results basically meet the design requirements.

Poster MOPB030 [1.010 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-SAP2023-MOPB030

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Received ※ 28 June 2023 — Revised ※ 09 July 2023 — Accepted ※ 11 July 2023 — Issued ※ 21 November 2023

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MOPB034

Start to End Simulation for A Compact THz-FEL

undulator, cavity, radiation, FEL

76

R.Y. Luo, Q.S. Chen
HUST, Wuhan, People’s Republic of China

Funding: This work is supported by the National Natural Science Foundation of China(No.12175077)
An oscillator type terahertz free electron laser (THz-FEL) is under construction at Huazhong University of Science and Technology (HUST). The designed electron beam energy ranges from 8 MeV to 14 MeV, and the radiation frequency ranges from 3 THz to 10 THz. FEL requires high quality electron beams of emittance, energy spread, bunch charge etc. To know the overall facility performance, a start to end simulation (from electron gun to the end of the oscillator) of the THz-FEL is performed. The simulation of the electron gun to the exit of the linac is performed using PARMELA, where the effect of space charge effects is considered. In addition, the effect of beam loading effect is considered for the linac. The transport line is matched and simulated using ELEGANT. GENESIS 1.3 and OPC is used for the lasing process. Results of the simulation are presented and discussed in this paper.

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reference for this paper ※ doi:10.18429/JACoW-SAP2023-MOPB034

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Received ※ 30 June 2023 — Revised ※ 08 July 2023 — Accepted ※ 11 July 2023 — Issued ※ 18 October 2024

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MOPB039

Low-Alpha Storage Ring Design for Steady-State Microbunching to Generate EUV Radiation

storage-ring, radiation, lattice, coupling

88

Z. Pan, A. Chao, X.J. Deng, W.-H. Huang, Z.Z. Li, C.-X. Tang
TUB, Beijing, People’s Republic of China

A new concept is proposed for minimizing the longitudinal emittance of a low momentum compaction factor (low-alpha) storage ring which has the capability to stably store sub-femtosecond electron bunches for the first time. This storage ring is designed for Steady-State microbunching (SSMB) to generate kW level average power EUV radiation. The proposed design approach can be applied to any quasi-isochronous storage rings to yield very high radiation power due to longitudinal coherence of the radiation. We obtain an optimal lattice design by minimizing global and local momentum compaction factors simultaneously and the result of single-particle tracking shows that the electron beam with equilibrium rms bunch length of about 40 nm can be stored in this ring. Nonlinear dynamics is studied for this lattice.

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reference for this paper ※ doi:10.18429/JACoW-SAP2023-MOPB039

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Received ※ 03 July 2023 — Revised ※ 08 July 2023 — Accepted ※ 11 July 2023 — Issued ※ 31 December 2023

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TUPB024

Electron Cooling for Future High-energy Hadron Accelerators

wiggler, emittance, hadron, proton

133

H. Zhao
IMP/CAS, Lanzhou, People’s Republic of China

Funding: National Natural Science Foundation of China (No. 12275323)
Electron cooling is an important method to reduce the emittance and momentum spread of hadron beams, and it has been successfully applied in several facilities around the world. In 2019, the world¿s first RF-based electron cooler (LEReC) was commissioned at BNL for the RHIC BES-II project, and the integrated luminosity of RHIC is finally doubled. In addition, electron cooling is also a must for the future Electron-Ion Collider (BNL EIC). However, the high energy requirement of the electron beam (150 MeV) is far beyond what all present coolers can achieve (<4.3 MeV). For that, an electron ring cooler with strong radiation damping is proposed and designed, in which the non-magnetized and dispersive cooling techniques are applied. In this talk, I will introduce the experimental and simulation results of the two facilities. Mainly, I will introduce several new phenomena that were first observed in LEReC, such as the beam heating effect and the ion beam focusing effect. Besides, some new theories that were developed for the ring cooler will also be discussed.

Poster TUPB024 [1.769 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-SAP2023-TUPB024

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Received ※ 04 July 2023 — Revised ※ 09 July 2023 — Accepted ※ 11 July 2023 — Issued ※ 14 December 2023

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TUPB025

Influence of Transverse Distribution of Electron Beam on the Distribution of Proton Beam in the Process of Electron Cooling

proton, simulation, storage-ring, scattering

137

X.D. Yang
IMP/CAS, Lanzhou, People’s Republic of China

Funding: National Natural Science Foundation of China No.12275325
The electron cooling process of 20GeV proton beam in EicC was simulated for the eight transverse distribution of electron beam with the help of electron cooling simulation code. The transverse cooling time was obtained in the different transverse distribution of electron beam. The final transverse distribution of proton beam was demonstrated. The simulated results reveal that the transverse distribution of electron beam influences the distribution of proton beam in the process of electron cooling. In the future, this idea was expected to apply to the longitudinal distribution of electron beam. The longitudinal distribution of proton beam was attempted to be controlled by the longitudinally modulated electron beam. As a result, the peak current and longitudinal distribution of proton beam will be controlled by the electron beam. The loss of proton beams will be reduced, and the stored lifetime of proton beam in the storage ring will be extended. The intensity of the proton beam will be maintained for a longer time.

Poster TUPB025 [2.048 MB]

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reference for this paper ※ doi:10.18429/JACoW-SAP2023-TUPB025

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Received ※ 28 June 2023 — Revised ※ 09 July 2023 — Accepted ※ 12 July 2023 — Issued ※ 06 June 2024

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TUPB027

New Progress of the Miniaturized Microwave Ion Source at Peking University

plasma, MMI, ion-source, ECR

144

S.X. Peng, J.E. Chen, B.J. Cui, Z.Y. Guo, Y.X. Jiang, T.H. Ma, W.B. Wu
PKU, Beijing, People’s Republic of China
A.L. Zhang
USTC, Hefei, Anhui, People’s Republic of China

The generation of plasma in a microwave ion source involves confining electrons using a static magnetic field and energizing them with an electromagnetic field that transmitted into the plasma chamber. However, according to electromagnetics theory, there is always a cut-off size in circular wave guides for a given frequency. For a 2.45 GHz microwave, this dimension is 72 mm, which should theoretically prevent transmission of the microwave into the discharge chamber and no plasma can be generated. Since 2006 Peking University(PKU) has successfully developed a series of permanent magnet 2.45 GHz microwave ion sources (PKU PMECRs¿ with a discharge chamber less than 50 mm, capable of delivering tens of mA beams for accelerators. To explain this anomalous phenomenon, a hybrid discharge heating (HDH) mode that combines surface wave plasma (SWP) and electron cyclotron heating (ECH) has been proposed. This HDH mode not only successfully explains PKU PMECRs, but also predicts that the optimized inner diameter of the plasma chamber is 24 mm, which is confirmed by experiments involving different liners in the miniaturized microwave ion source.

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reference for this paper ※ doi:10.18429/JACoW-SAP2023-TUPB027

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Received ※ 27 June 2023 — Revised ※ 10 July 2023 — Accepted ※ 12 July 2023 — Issued ※ 15 June 2024

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TUPB029

Wakefield Studies for the Step Structure and the Skin Depth of Coated Dielectric Tubes

wakefield, impedance, FEL, simulation

147

H. Liu
SINAP, Shanghai, People’s Republic of China
S. Chen, H.X. Deng, B. Liu, Y.M. Wen
SARI-CAS, Pudong, Shanghai, People’s Republic of China
J.J. Guo
Zhangjiang Lab, Shanghai, People’s Republic of China

Funding: This work was supported by YSBR-042, 12125508, 11935020, 21XD1404100 and JCYJ-SHFY-2021-010.
Wakefield issues are always important research objects in free electron laser (FEL) facilities. Since the wakefield in free electron laser facilities usually leads to a decrease of FEL performance, the research of the wakefield impacts is of great significance. Step structures are almost ubiquitous in the overall undulator section of an FEL facility, which always generate critical wakefields. In this paper, we systematically analyze and summarize the wakefield characteristics of step structures including the step-in structure and the step-out structure. In addition, the skin depth issue of the wakefield is still controversial. We study the skin depth of the wakefield field in the vacuum chamber of the kicker in the SHINE, which is made of the dielectric pipe. We proposed the conception of ¿effective skin depth¿ from two different perspectives and wrote simulation codes to calculate the ¿effective skin depth¿. We hope these methods could provide new mentalities for related research in the future.

Poster TUPB029 [0.392 MB]

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reference for this paper ※ doi:10.18429/JACoW-SAP2023-TUPB029

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Received ※ 30 June 2023 — Revised ※ 09 July 2023 — Accepted ※ 12 July 2023 — Issued ※ 21 September 2023

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TUPB033

Heating Estimation of Undulator Vacuum Chamber at S3FEL

wakefield, vacuum, undulator, impedance

151

H. Yi
IASF, Shenzhen, Guangdong, People’s Republic of China
X.F. Wang
Institute of Advanced Science Facilities, Shenzhen, People’s Republic of China
X.M. Yang, W.Q. Zhang
DICP, Dalian, Liaoning, People’s Republic of China

Heating of the vacuum chambers are unavoidable when electron beams pass through the chamber channels at relativistic speeds. In the undulator vacuum chambers, such effects might lead to temperature increase of the magnets and eventually cause degradations in the FEL lasing process. Thus, in this paper, the heating of the undulator vacuum chambers at S3FEL due to wake field effects and spontaneous synchrotron radiation are estimated using an analytical approach. For the wake field effects, the contribution from finite conductivity of the vacuum chamber material and from the inner surface roughness are considered. A electron beam profile from a start-to-end simulation is used to calculate the total wake field and the induced heat. For the synchrotron radiation, a simple analytical expression is used.

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reference for this paper ※ doi:10.18429/JACoW-SAP2023-TUPB033

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Received ※ 05 July 2023 — Revised ※ 09 July 2023 — Accepted ※ 12 July 2023 — Issued ※ 26 September 2024

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TUPB035

Recent Progress of the Beam Background Experiment in the BEPCII

background, experiment, simulation, positron

155

B. Wang, H.Y. Shi, C.H. Yu
IHEP, Beijing, People’s Republic of China

The Beijing Electron Positron Collider II will upgrade to extend the beam energy and the luminosity by increasing the beam current and slightly compressing the beam size, where the beam energy will be extended from 2.3 GeV to 2.8 GeV and the peak luminosity will be up to 1.1×10³³\rm{cm}^-2\rm{s}^-1 at the optimizing beam energy of 2.35 GeV. The BEPCII upgrade is expected to result in challenging levels of beam related background in the interaction region. An precise simulating and mitigating beam background is necessary to protect the BESIII detector and increase the beam current and peak luminosity. The beam related background at BEPCII is mainly from the Touschek effect and the beam gas effect, this paper presents the recent progress of the beam background simulation and experiment.

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reference for this paper ※ doi:10.18429/JACoW-SAP2023-TUPB035

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Received ※ 06 July 2023 — Revised ※ 09 July 2023 — Accepted ※ 11 July 2023 — Issued ※ 22 July 2024

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