SAP2023 - List of Authors (Xu, H.S.)

Paper	Title	Page
MOCXA01	Simulation Studies of Collective Beam Instabilities in the HEPS
	H.S. Xu IHEP, Beijing, People’s Republic of China
	Collective beam instabilities are among the key limiting factors of the design performance of synchrotron light sources, and study of collective beam instabilities is generally necessary throughout the "whole life cycle" of synchrotron light sources, from design to operation. In recent years, the 4th generation synchrotron light sources have attracted worldwide attention for their higher brightness and better coherence. The High Energy Photon Source (HEPS), currently under construction in the Huairou Science City, Beijing, China, is the first 4th generation synchrotron light source in China and one of the brightest synchrotron light sources in the world. Compared with the existing 3rd generation light source, due to larger impedance of the storage ring, the collective beam instabilities are more challenging in the 4th generation synchrotron light sources. To investigate whether HEPS can achieve the target beam current and to evaluate the full-current beam parameters, we have carried out systematic studies of the main instabilities in HEPS via simulations. Here, we will present the simulation results of the main instabilities in HEPS and the effectiveness of the suppression methods.
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MOPB014	Development of a Vlasov Solver for Arbitrary Sub-optimal Lengthening Conditions in Double-RF System	34
	J.Y. Xu, N. Wang, H.S. Xu, Y. Zhang IHEP, Beijing, People’s Republic of China C.T. Lin IASF, Shenzhen, Guangdong, People’s Republic of China
	Solving Vlasov equation is a classic method for analyzing collective beam instabilities. Considering longitudinal impedance and the nonlinear longitudinal potential well, we developed a new Vlasov solver which can be used to study the transverse mode-coupling instability under the arbitrary sub-optimal lengthening and the optimal lengthening conditions in a double-RF system. Several different techniques to deal with the radial direction of longitudinal phase space have been tested. Numerical discretization method is selected in this paper. The development of the solver is presented in details here. Benchmarks and crosscheck of the solver have been made and presented as well.
DOI •	reference for this paper ※ doi:10.18429/JACoW-SAP2023-MOPB014
About •	Received ※ 30 June 2023 — Revised ※ 08 July 2023 — Accepted ※ 11 July 2023 — Issued ※ 21 August 2024
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MOPB021	Energy Stabilization of High-charge Laser Plasma Accelerator Electron Beams via Hybrid Plasma Dechirper
	X.Y. Shi, D.Z. Li, J. Wang, H.S. Xu, M. Zeng IHEP, Beijing, People’s Republic of China
	As the beam quality of laser plasma accelerators (LPAs) improves, potential application of an LPA as the injector of a booster of a synchrotron light source becomes more and more realistic. Even though, it is still very challenging because the energy jitter and energy spread of the-state-of-the-art LPAs are not small enough. There have been proposals, which are successful to suppress the energy jitter and energy spread simultaneously by implementing magnetic chicane together with active dechirper, for relatively low charge conditions (e.g., tens of pC). However, this method is not very effectivewhen the bunch charge becomes an order of magnitude higher due to the heavy beam loading. In this paper, we present a novel method which can suppress the energy jitter and reduce the energy spread simultaneously even with heavy beam loading. Preliminary particle-in-cell (PIC) simulations showed that such a design can reduce the energy jitter and energy spread of the 500 pC bunches from ±2% and 2.39% to less than 0.33% and 0.8%, respectively, with high transmission efficiency (>89%).
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TUPB028	Studies of Ion Effects in the Heps Storage Ring
	S.K. Tian, C.C. Du, J.Q. Wang, N. Wang, H.S. Xu IHEP, Beijing, People’s Republic of China
	In the fourth generation synchrotron radiation light source, the accelerator design aims to deliver low-emittance electron beams¿to maximize the brightness of the photon beams. This brings new challenges to maintain low emittance with potential collective instabilities. One particular source of concern is the ion-driven instability, which can be induced by ionization of the residual gas by the circulating electron beam. The ion effects in the HEPS storage ring are estimated by both analytical formula and macro-particle simulations. More detailed simulations considering actual filling patterns and vacuum conditions are performed. The results indicate that at the design beam current, the ions will be over-focused due to the very high beam densities, and the beam will not be perturbed by the ions. This is somewhat different from widely accepted understanding that the coupled motion between the beam and the ions is inversely proportional to the beam size and is typically proportional to the average beam current and residual gas pressure. In this paper the results of the instability amplitude and beam emittance growth, the variation process of trapped ion density is presented.
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Paper

Title

Page

MOCXA01

Simulation Studies of Collective Beam Instabilities in the HEPS

H.S. Xu
IHEP, Beijing, People’s Republic of China

Collective beam instabilities are among the key limiting factors of the design performance of synchrotron light sources, and study of collective beam instabilities is generally necessary throughout the "whole life cycle" of synchrotron light sources, from design to operation. In recent years, the 4th generation synchrotron light sources have attracted worldwide attention for their higher brightness and better coherence. The High Energy Photon Source (HEPS), currently under construction in the Huairou Science City, Beijing, China, is the first 4th generation synchrotron light source in China and one of the brightest synchrotron light sources in the world. Compared with the existing 3rd generation light source, due to larger impedance of the storage ring, the collective beam instabilities are more challenging in the 4th generation synchrotron light sources. To investigate whether HEPS can achieve the target beam current and to evaluate the full-current beam parameters, we have carried out systematic studies of the main instabilities in HEPS via simulations. Here, we will present the simulation results of the main instabilities in HEPS and the effectiveness of the suppression methods.

Cite •

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

MOPB014

Development of a Vlasov Solver for Arbitrary Sub-optimal Lengthening Conditions in Double-RF System

34

J.Y. Xu, N. Wang, H.S. Xu, Y. Zhang
IHEP, Beijing, People’s Republic of China
C.T. Lin
IASF, Shenzhen, Guangdong, People’s Republic of China

Solving Vlasov equation is a classic method for analyzing collective beam instabilities. Considering longitudinal impedance and the nonlinear longitudinal potential well, we developed a new Vlasov solver which can be used to study the transverse mode-coupling instability under the arbitrary sub-optimal lengthening and the optimal lengthening conditions in a double-RF system. Several different techniques to deal with the radial direction of longitudinal phase space have been tested. Numerical discretization method is selected in this paper. The development of the solver is presented in details here. Benchmarks and crosscheck of the solver have been made and presented as well.

DOI •

reference for this paper ※ doi:10.18429/JACoW-SAP2023-MOPB014

About •

Received ※ 30 June 2023 — Revised ※ 08 July 2023 — Accepted ※ 11 July 2023 — Issued ※ 21 August 2024

Cite •

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

MOPB021

Energy Stabilization of High-charge Laser Plasma Accelerator Electron Beams via Hybrid Plasma Dechirper

X.Y. Shi, D.Z. Li, J. Wang, H.S. Xu, M. Zeng
IHEP, Beijing, People’s Republic of China

As the beam quality of laser plasma accelerators (LPAs) improves, potential application of an LPA as the injector of a booster of a synchrotron light source becomes more and more realistic. Even though, it is still very challenging because the energy jitter and energy spread of the-state-of-the-art LPAs are not small enough. There have been proposals, which are successful to suppress the energy jitter and energy spread simultaneously by implementing magnetic chicane together with active dechirper, for relatively low charge conditions (e.g., tens of pC). However, this method is not very effectivewhen the bunch charge becomes an order of magnitude higher due to the heavy beam loading. In this paper, we present a novel method which can suppress the energy jitter and reduce the energy spread simultaneously even with heavy beam loading. Preliminary particle-in-cell (PIC) simulations showed that such a design can reduce the energy jitter and energy spread of the 500 pC bunches from ±2% and 2.39% to less than 0.33% and 0.8%, respectively, with high transmission efficiency (>89%).

Cite •

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

TUPB028

Studies of Ion Effects in the Heps Storage Ring

S.K. Tian, C.C. Du, J.Q. Wang, N. Wang, H.S. Xu
IHEP, Beijing, People’s Republic of China

In the fourth generation synchrotron radiation light source, the accelerator design aims to deliver low-emittance electron beams¿to maximize the brightness of the photon beams. This brings new challenges to maintain low emittance with potential collective instabilities. One particular source of concern is the ion-driven instability, which can be induced by ionization of the residual gas by the circulating electron beam. The ion effects in the HEPS storage ring are estimated by both analytical formula and macro-particle simulations. More detailed simulations considering actual filling patterns and vacuum conditions are performed. The results indicate that at the design beam current, the ions will be over-focused due to the very high beam densities, and the beam will not be perturbed by the ions. This is somewhat different from widely accepted understanding that the coupled motion between the beam and the ions is inversely proportional to the beam size and is typically proportional to the average beam current and residual gas pressure. In this paper the results of the instability amplitude and beam emittance growth, the variation process of trapped ion density is presented.

Cite •

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