SAP2023 - List of Keywords (acceleration)

Paper	Title	Other Keywords	Page
MOPB005	Design of Beam Dynamics for a High-Power DC Proton Accelerator at the MeV Level	focusing, space-charge, proton, neutron	24
	Z.-F. He, M.H. Zhao SINAP, Shanghai, People’s Republic of China W. Wan ShanghaiTech University, Shanghai, People’s Republic of China
	This paper aims to design the beam dynamics of a MeV-level high-power DC proton accelerator for use in high-voltage accelerators. The high-power proton accelerator has essential applications such as ion implantation equipment, neutron therapy equipment, and accelerator-based neutron source equipment. With the increasing use of high-voltage generators due to their stable and reliable operation, these accelerators have gained significant popularity in the field. The paper discusses the design considerations of the accelerator equipment, including the functions and requirements of the acceleration tube, electric field distribution, and voltage holding issues. Additionally, the paper focuses on the design aspects of beam optics, encompassing topics such as electric field distribution, beam focusing, beam transmission, divergence, and the impact of space charge effects on beam quality. Calculations and optimizations are performed based on the parameters and requirements specific to high-voltage accelerators. Finally, the paper presents and analyzes the results of the accelerator tube and beam optics design.
DOI •	reference for this paper ※ doi:10.18429/JACoW-SAP2023-MOPB005
About •	Received ※ 30 June 2023 — Revised ※ 09 July 2023 — Accepted ※ 11 July 2023 — Issued ※ 04 October 2024
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPB029	Multi-bunch Operation Mode for Simultaneously Serving SASE and Seeding FEL Beamlines	FEL, electron, 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
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPB010	Dynamics Design on 70-250Mev Proton Linac	proton, linac, lattice, radiation	102
	Y.F. Yang, Z. Li, P.T. Lin, Z.Q. Ren, X.M. Wan SCU, Chengdu, People’s Republic of China
	Charged proton beams have broad application prospects, and research on compact S-band proton linear accelerators is increasingly heating up in recent years. For radiation therapy, to achieve the conventional penetration range of water-equivalent tissues, protons with energy of 70 to 230MeV are required. The design of electromagnetic structure is closely related to particle dynamics design. A flexible and controllable particle dynamic tracking code (PDT) through both traveling wave and standing wave acceleration has been compiled to simulate particle trajectory and satisfy automatic tuning of the various components in the entire acceleration chain. The linac with a total length of approximately 8.2m composed of 16 tanks of backward traveling wave structures and permanent magnet quadrupole lenses was designed, operating at an RF frequency of 2.856GHz with a target acceleration gradient of 30MV/m, and accelerating proton beam from 70MeV to 250MeV while maintaining low emittance and high transmission efficiency.
DOI •	reference for this paper ※ doi:10.18429/JACoW-SAP2023-TUPB010
About •	Received ※ 09 July 2023 — Accepted ※ 12 July 2023 — Issued ※ 11 August 2023
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPB013	Multipole Field Optimization of X-Band High Gradient Structure	multipole, quadrupole, cavity, simulation	108
	B.Y. Feng, H.B. Chen, Q. Gao, X. Lin, J.R. Shi, H. Zha TUB, Beijing, People’s Republic of China
	The X-band constant gradient acceleration structure plays a crucial role in the VIGAS project. However, the presence of a multipole field component in the struc-ture’s coupler leads to an increase in ray bandwidth and a decrease in yield, ultimately affecting the quality of the generated rays. Through calculations, it has been determined that the quadrupole field component is particularly prominent in the original structure, ac-counting for 29.5% of the fundamental mode strength. Therefore, it is necessary to modify the cavity struc-ture of the coupler. By altering the shape of the cavity to two staggered circles, the objective of reducing the quadrupole field is achieved. The optimized quadru-pole field component now accounts for approximately 0.3% of the fundamental mode strength. Subsequently, the non-resonant perturbation method was employed to simulate and experimentally measure the magnitude of the multipole field component in the actual acceler-ation cavity.
	Poster TUPB013 [0.350 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-SAP2023-TUPB013
About •	Received ※ 30 June 2023 — Accepted ※ 11 July 2023 — Issued ※ 27 September 2024
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPB019	Beam Dynamics in Superconducting Proton Linac	focusing, quadrupole, simulation, resonance	126
	X.M. Wan, Z. Li, W.L. Liao, P.T. Lin, X.B. Luo, X.J. Pu, Z.Q. Ren, Y.F. Yang SCU, Chengdu, People’s Republic of China
	Funding: This work was supported by the National Natural Science Foundation of China (Grant Nos. 11375122 and 11875197). Beam loss control is a crucial research direction in high-current superconducting linear accelerators (SCL). The research findings include firstly, for continuous beams, when tune depression eta > 0.7, zero current periodic phase advance (σ0t) can partially exceed 90° during transport in solenoid and quadrupole doublet periodic focusing channels. Different results occur when eta < 0.7. Secondly, in the solenoid system, σ0t can partially exceed 90° without significant impact on beam quality. In the quadrupole doublet focusing system, the partial breakdown of 90° affects beam quality. Thirdly, Similar conclusions hold for acceleration effects. Fourthly, numerical analysis shows that double-period structures have more stringent design criteria than fully period structures. The double-period structure can cause envelope instability even if σ0t < 90°. Fifthly, the primary factor causing halo is the 2:1 resonance. Additionally, when eta is small, higher-order resonances can also cause halo.
DOI •	reference for this paper ※ doi:10.18429/JACoW-SAP2023-TUPB019
About •	Received ※ 09 July 2023 — Revised ※ 11 July 2023 — Accepted ※ 12 July 2023 — Issued ※ 08 April 2024
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

Paper

Title

Other Keywords

Page

MOPB005

Design of Beam Dynamics for a High-Power DC Proton Accelerator at the MeV Level

focusing, space-charge, proton, neutron

24

Z.-F. He, M.H. Zhao
SINAP, Shanghai, People’s Republic of China
W. Wan
ShanghaiTech University, Shanghai, People’s Republic of China

This paper aims to design the beam dynamics of a MeV-level high-power DC proton accelerator for use in high-voltage accelerators. The high-power proton accelerator has essential applications such as ion implantation equipment, neutron therapy equipment, and accelerator-based neutron source equipment. With the increasing use of high-voltage generators due to their stable and reliable operation, these accelerators have gained significant popularity in the field. The paper discusses the design considerations of the accelerator equipment, including the functions and requirements of the acceleration tube, electric field distribution, and voltage holding issues. Additionally, the paper focuses on the design aspects of beam optics, encompassing topics such as electric field distribution, beam focusing, beam transmission, divergence, and the impact of space charge effects on beam quality. Calculations and optimizations are performed based on the parameters and requirements specific to high-voltage accelerators. Finally, the paper presents and analyzes the results of the accelerator tube and beam optics design.

DOI •

reference for this paper ※ doi:10.18429/JACoW-SAP2023-MOPB005

About •

Received ※ 30 June 2023 — Revised ※ 09 July 2023 — Accepted ※ 11 July 2023 — Issued ※ 04 October 2024

Cite •

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

MOPB029

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

FEL, electron, 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

Cite •

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

TUPB010

Dynamics Design on 70-250Mev Proton Linac

proton, linac, lattice, radiation

102

Y.F. Yang, Z. Li, P.T. Lin, Z.Q. Ren, X.M. Wan
SCU, Chengdu, People’s Republic of China

Charged proton beams have broad application prospects, and research on compact S-band proton linear accelerators is increasingly heating up in recent years. For radiation therapy, to achieve the conventional penetration range of water-equivalent tissues, protons with energy of 70 to 230MeV are required. The design of electromagnetic structure is closely related to particle dynamics design. A flexible and controllable particle dynamic tracking code (PDT) through both traveling wave and standing wave acceleration has been compiled to simulate particle trajectory and satisfy automatic tuning of the various components in the entire acceleration chain. The linac with a total length of approximately 8.2m composed of 16 tanks of backward traveling wave structures and permanent magnet quadrupole lenses was designed, operating at an RF frequency of 2.856GHz with a target acceleration gradient of 30MV/m, and accelerating proton beam from 70MeV to 250MeV while maintaining low emittance and high transmission efficiency.

DOI •

reference for this paper ※ doi:10.18429/JACoW-SAP2023-TUPB010

About •

Received ※ 09 July 2023 — Accepted ※ 12 July 2023 — Issued ※ 11 August 2023

Cite •

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

TUPB013

Multipole Field Optimization of X-Band High Gradient Structure

multipole, quadrupole, cavity, simulation

108

B.Y. Feng, H.B. Chen, Q. Gao, X. Lin, J.R. Shi, H. Zha
TUB, Beijing, People’s Republic of China

The X-band constant gradient acceleration structure plays a crucial role in the VIGAS project. However, the presence of a multipole field component in the struc-ture’s coupler leads to an increase in ray bandwidth and a decrease in yield, ultimately affecting the quality of the generated rays. Through calculations, it has been determined that the quadrupole field component is particularly prominent in the original structure, ac-counting for 29.5% of the fundamental mode strength. Therefore, it is necessary to modify the cavity struc-ture of the coupler. By altering the shape of the cavity to two staggered circles, the objective of reducing the quadrupole field is achieved. The optimized quadru-pole field component now accounts for approximately 0.3% of the fundamental mode strength. Subsequently, the non-resonant perturbation method was employed to simulate and experimentally measure the magnitude of the multipole field component in the actual acceler-ation cavity.

Poster TUPB013 [0.350 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-SAP2023-TUPB013

About •

Received ※ 30 June 2023 — Accepted ※ 11 July 2023 — Issued ※ 27 September 2024

Cite •

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

TUPB019

Beam Dynamics in Superconducting Proton Linac

focusing, quadrupole, simulation, resonance

126

X.M. Wan, Z. Li, W.L. Liao, P.T. Lin, X.B. Luo, X.J. Pu, Z.Q. Ren, Y.F. Yang
SCU, Chengdu, People’s Republic of China

Funding: This work was supported by the National Natural Science Foundation of China (Grant Nos. 11375122 and 11875197).
Beam loss control is a crucial research direction in high-current superconducting linear accelerators (SCL). The research findings include firstly, for continuous beams, when tune depression eta > 0.7, zero current periodic phase advance (σ0t) can partially exceed 90° during transport in solenoid and quadrupole doublet periodic focusing channels. Different results occur when eta < 0.7. Secondly, in the solenoid system, σ0t can partially exceed 90° without significant impact on beam quality. In the quadrupole doublet focusing system, the partial breakdown of 90° affects beam quality. Thirdly, Similar conclusions hold for acceleration effects. Fourthly, numerical analysis shows that double-period structures have more stringent design criteria than fully period structures. The double-period structure can cause envelope instability even if σ0t < 90°. Fifthly, the primary factor causing halo is the 2:1 resonance. Additionally, when eta is small, higher-order resonances can also cause halo.

DOI •

reference for this paper ※ doi:10.18429/JACoW-SAP2023-TUPB019

About •

Received ※ 09 July 2023 — Revised ※ 11 July 2023 — Accepted ※ 12 July 2023 — Issued ※ 08 April 2024

Cite •

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