FLS2023 - List of Authors (Nagaoka, R.)

Paper	Title	Page
MO3B2	Beam Dynamics Using Superconducting Passive Harmonic Cavities with High Current per Bunch	14
	A. Gamelin, V. Gubaidulin, A. Loulergue, P. Marchand, L.S. Nadolski, R. Nagaoka SOLEIL, Gif-sur-Yvette, France N. Yamamoto KEK, Ibaraki, Japan
	In 4th generation synchrotron light sources, harmonic cavities (HCs) are critical components needed to achieve the required performance. They provide longer bunches, which helps to reduce statistical effects (intra-beam scattering and Touschek effect). In "timing" modes, where the bunch spacing is larger than in conventional modes and the number of particles per bunch is higher, this need is even greater. In this article, we present the beam dynamics in the high current per bunch regime and how it interacts with the single bunch collective effects. In particular, a dipole-quadrupole instability is observed above the microwave threshold and a coupling between the dipole and cavity modes is shown to limit bunch lengthening at low current. The effective gain from the use of HCs in terms of lifetime, emittance, and energy spread is also discussed.
	Slides MO3B2 [1.529 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-FLS2023-MO3B2
About •	Received ※ 13 August 2023 — Revised ※ 15 August 2023 — Accepted ※ 31 August 2023 — Issued ※ 02 December 2023
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TU1B4	Minimizing the Fluctuation of Resonance Driving Terms for Analyzing and Optimizing the Storage Ring Dynamic Aperture	66
	Z.H. Bai, B.F. Wei USTC/NSRL, Hefei, Anhui, People’s Republic of China A. Loulergue, L.S. Nadolski, R. Nagaoka SOLEIL, Gif-sur-Yvette, France
	Minimization of resonance driving terms (RDTs) of nonlinear magnets such as sextupoles and octupoles is an essential condition for enlarging the dynamic aperture (DA) of a storage ring. We recently studied the correlation between minimizing the fluctuation or variation of RDTs along the ring and enlarging the DA. It was found that minimizing the RDT fluctuations is much more effective than minimizing the commonly-used one-turn RDTs in enlarging the DA, and that reducing low-order RDT fluctuations can also help reduce both higher-order RDT fluctuations and higher-order one-turn RDTs. In this paper, DA analysis based on minimizing RDT fluctuations is further extended. By considering the RDT fluctuations including low- and high-frequency fluctuations, some nonlinear dynamics issues can be explained. DA optimization is also studied based on numerically minimizing RDT fluctuations using genetic algorithms. Large DA can be obtained, and the optimization is performed very fast.
	Slides TU1B4 [3.118 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-FLS2023-TU1B4
About •	Received ※ 23 August 2023 — Revised ※ 28 August 2023 — Accepted ※ 30 August 2023 — Issued ※ 02 December 2023
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

Paper

Title

Page

Beam Dynamics Using Superconducting Passive Harmonic Cavities with High Current per Bunch

14

A. Gamelin, V. Gubaidulin, A. Loulergue, P. Marchand, L.S. Nadolski, R. Nagaoka
SOLEIL, Gif-sur-Yvette, France
N. Yamamoto
KEK, Ibaraki, Japan

In 4th generation synchrotron light sources, harmonic cavities (HCs) are critical components needed to achieve the required performance. They provide longer bunches, which helps to reduce statistical effects (intra-beam scattering and Touschek effect). In "timing" modes, where the bunch spacing is larger than in conventional modes and the number of particles per bunch is higher, this need is even greater. In this article, we present the beam dynamics in the high current per bunch regime and how it interacts with the single bunch collective effects. In particular, a dipole-quadrupole instability is observed above the microwave threshold and a coupling between the dipole and cavity modes is shown to limit bunch lengthening at low current. The effective gain from the use of HCs in terms of lifetime, emittance, and energy spread is also discussed.

Slides MO3B2 [1.529 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-FLS2023-MO3B2

About •

Received ※ 13 August 2023 — Revised ※ 15 August 2023 — Accepted ※ 31 August 2023 — Issued ※ 02 December 2023

Cite •

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

TU1B4

Minimizing the Fluctuation of Resonance Driving Terms for Analyzing and Optimizing the Storage Ring Dynamic Aperture

66

Z.H. Bai, B.F. Wei
USTC/NSRL, Hefei, Anhui, People’s Republic of China
A. Loulergue, L.S. Nadolski, R. Nagaoka
SOLEIL, Gif-sur-Yvette, France

Minimization of resonance driving terms (RDTs) of nonlinear magnets such as sextupoles and octupoles is an essential condition for enlarging the dynamic aperture (DA) of a storage ring. We recently studied the correlation between minimizing the fluctuation or variation of RDTs along the ring and enlarging the DA. It was found that minimizing the RDT fluctuations is much more effective than minimizing the commonly-used one-turn RDTs in enlarging the DA, and that reducing low-order RDT fluctuations can also help reduce both higher-order RDT fluctuations and higher-order one-turn RDTs. In this paper, DA analysis based on minimizing RDT fluctuations is further extended. By considering the RDT fluctuations including low- and high-frequency fluctuations, some nonlinear dynamics issues can be explained. DA optimization is also studied based on numerically minimizing RDT fluctuations using genetic algorithms. Large DA can be obtained, and the optimization is performed very fast.

Slides TU1B4 [3.118 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-FLS2023-TU1B4

About •

Received ※ 23 August 2023 — Revised ※ 28 August 2023 — Accepted ※ 30 August 2023 — Issued ※ 02 December 2023

Cite •

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