FLS2023 - List of Keywords (impedance)

Paper	Title	Other Keywords	Page
MO3B2	Beam Dynamics Using Superconducting Passive Harmonic Cavities with High Current per Bunch	cavity, dipole, synchrotron, emittance	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)

MO4B3	Development of a Pulsed Injection Stripline for Diamond-II	injection, simulation, kicker, storage-ring	38
	R.T. Fielder, A. Lueangaramwong, A.F.D. Morgan DLS, Oxfordshire, United Kingdom
	Diamond-II will use a single bunch aperture sharing injection scheme. This applies a strong kick to both the injected and the targeted stored bunch with a very short duration (ideally <3 ns, if disturbance to the adjacent bunches is to be avoided). We have developed a design for the stripline kickers that can meet these requirements while minimising internal reflections and beam impedance. We show an analysis of the electric and magnetic fields produced by the stripline and simulations of the effects on injected and stored beam, and analysis of the wakefields and impedance of the structure.
	Slides MO4B3 [2.164 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-FLS2023-MO4B3
About •	Received ※ 21 August 2023 — Revised ※ 24 August 2023 — Accepted ※ 30 August 2023 — Issued ※ 02 December 2023
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TU3D4	Compact HOM-damped RF Cavity for a Next Generation Light Source	cavity, HOM, damping, operation	74
	H. Ego KEK, Ibaraki, Japan T. Asaka, N. Nishimori QST, Sendai, Miyagi, Japan T. Inagaki, H. Tanaka RIKEN SPring-8 Center, Hyogo, Japan T. Ohshima, T. Tomai, H. Yamaguchi JASRI, Hyogo, Japan
	A beam-accelerating RF cavity with a new HOM-damping structure was designed in order to suppress coupled-bunch instabilities in a next generation light source with an ultra-low emittance and supplying X-rays approaching their diffraction limits. The TM020 mode at 509 MHz is selected as a beam-accelerating mode because it has a high Q-value of 60,000 and a shunt impedance sufficient for beam acceleration and brings a compact HOM-damping structure to the cavity differently from massive types of cavities with waveguides or pipes extracting HOM power. Two shallow slots are cut on the cavity inner-wall and materials absorbing RF waves are directly fitted into them. They work as HOM dampers without affecting the RF properties of the beam-accelerating mode. A prototype cavity of OFHC copper was fabricated to demonstrate the HOM-damping and generating an accelerating voltage of 900 kV in the cavity. Since the cavity was successful in operation up to 135 kW, the feasibility of both the high-power operation and the damping structure was proved. Four actual cavities were produced and installed to the new 3-GeV synchrotron radiation facility, NanoTerasu in Japan.
	Slides TU3D4 [8.581 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-FLS2023-TU3D4
About •	Received ※ 22 August 2023 — Revised ※ 23 August 2023 — Accepted ※ 31 August 2023 — Issued ※ 02 December 2023
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TU4P19	Evolution of Equilibrium Parameters Ramp Including Collective Effects in the Diamond-II Booster	booster, emittance, simulation, extraction	120
	R. Husain, R.T. Fielder, I.P.S. Martin DLS, Oxfordshire, United Kingdom P. Burrows Oxford University, Physics Department, Oxford, Oxon, United Kingdom
	Efficient top-up injection into the Diamond-II storage ring will require upgrading the booster lattice for a beam emittance of <20 nm rad and a bunch length of <40 ps, including when operating with high single-bunch charge. The small vacuum chamber dimensions will drive the resistive wall instability and may adversely affect equilibrium parameters along the beam energy ramp. In addition, various diagnostic and vacuum chamber components will generate geometric impedances which may further disrupt the equilibrium parameters. Based on the detailed engineering designs, impedance models of the major components have been simulated using CST Studio and included in ELEGANT tracking simulations of the booster. In addition, the effects of synchrotron radiation emission and intra-beam scattering on the equilibrium parameters during the ramp are studied.
DOI •	reference for this paper ※ doi:10.18429/JACoW-FLS2023-TU4P19
About •	Received ※ 22 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)

WE4P33	Design of a 166.6 MHz HOM Damped Copper Cavity for the Southern Advanced Photon Source	cavity, HOM, damping, photon	207
	J.Y. Zhu, X. Li, Z.J. Lu IHEP, Beijing, People’s Republic of China J.B. Yu IHEP CSNS, Guangdong Province, People’s Republic of China
	Funding: This work was supported by the National Natural Science Foundation of China (12205168). The Southern Advanced Photon Source (SAPS) aims to achieve ultra-low emittances and is expected to adopt low-frequency cavities (< 200 MHz) to accommodates on-axis injection. This paper focuses on the design of a 166.6 MHz HOM-damped normal conducting (NC) cavity for the SAPS. We propose a novel approach to achieve efficient HOM damping by optimizing the lowest frequency HOM and implementing a beam-line absorber in a coaxial resonant NC cavity. Notably, unlike beam-line absorbers for conventional NC cavities, the presence of a large beam tube in a coaxial resonant cavity does not affect the accelerating performance. This enables effective HOM damping while maintaining a high shunt impedance in a NC cavity. The numerical simulation results show that a compact copper cavity with effective HOM damping and excellent RF properties has been achieved.
DOI •	reference for this paper ※ doi:10.18429/JACoW-FLS2023-WE4P33
About •	Received ※ 23 August 2023 — Revised ※ 30 August 2023 — Accepted ※ 01 September 2023 — Issued ※ 02 December 2023
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

Paper

Title

Other Keywords

Page

MO3B2

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

cavity, dipole, synchrotron, emittance

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)

MO4B3

Development of a Pulsed Injection Stripline for Diamond-II

injection, simulation, kicker, storage-ring

38

R.T. Fielder, A. Lueangaramwong, A.F.D. Morgan
DLS, Oxfordshire, United Kingdom

Diamond-II will use a single bunch aperture sharing injection scheme. This applies a strong kick to both the injected and the targeted stored bunch with a very short duration (ideally <3 ns, if disturbance to the adjacent bunches is to be avoided). We have developed a design for the stripline kickers that can meet these requirements while minimising internal reflections and beam impedance. We show an analysis of the electric and magnetic fields produced by the stripline and simulations of the effects on injected and stored beam, and analysis of the wakefields and impedance of the structure.

Slides MO4B3 [2.164 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-FLS2023-MO4B3

About •

Received ※ 21 August 2023 — Revised ※ 24 August 2023 — Accepted ※ 30 August 2023 — Issued ※ 02 December 2023

Cite •

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

TU3D4

Compact HOM-damped RF Cavity for a Next Generation Light Source

cavity, HOM, damping, operation

74

H. Ego
KEK, Ibaraki, Japan
T. Asaka, N. Nishimori
QST, Sendai, Miyagi, Japan
T. Inagaki, H. Tanaka
RIKEN SPring-8 Center, Hyogo, Japan
T. Ohshima, T. Tomai, H. Yamaguchi
JASRI, Hyogo, Japan

A beam-accelerating RF cavity with a new HOM-damping structure was designed in order to suppress coupled-bunch instabilities in a next generation light source with an ultra-low emittance and supplying X-rays approaching their diffraction limits. The TM020 mode at 509 MHz is selected as a beam-accelerating mode because it has a high Q-value of 60,000 and a shunt impedance sufficient for beam acceleration and brings a compact HOM-damping structure to the cavity differently from massive types of cavities with waveguides or pipes extracting HOM power. Two shallow slots are cut on the cavity inner-wall and materials absorbing RF waves are directly fitted into them. They work as HOM dampers without affecting the RF properties of the beam-accelerating mode. A prototype cavity of OFHC copper was fabricated to demonstrate the HOM-damping and generating an accelerating voltage of 900 kV in the cavity. Since the cavity was successful in operation up to 135 kW, the feasibility of both the high-power operation and the damping structure was proved. Four actual cavities were produced and installed to the new 3-GeV synchrotron radiation facility, NanoTerasu in Japan.

Slides TU3D4 [8.581 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-FLS2023-TU3D4

About •

Received ※ 22 August 2023 — Revised ※ 23 August 2023 — Accepted ※ 31 August 2023 — Issued ※ 02 December 2023

Cite •

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

TU4P19

Evolution of Equilibrium Parameters Ramp Including Collective Effects in the Diamond-II Booster

booster, emittance, simulation, extraction

120

R. Husain, R.T. Fielder, I.P.S. Martin
DLS, Oxfordshire, United Kingdom
P. Burrows
Oxford University, Physics Department, Oxford, Oxon, United Kingdom

Efficient top-up injection into the Diamond-II storage ring will require upgrading the booster lattice for a beam emittance of <20 nm rad and a bunch length of <40 ps, including when operating with high single-bunch charge. The small vacuum chamber dimensions will drive the resistive wall instability and may adversely affect equilibrium parameters along the beam energy ramp. In addition, various diagnostic and vacuum chamber components will generate geometric impedances which may further disrupt the equilibrium parameters. Based on the detailed engineering designs, impedance models of the major components have been simulated using CST Studio and included in ELEGANT tracking simulations of the booster. In addition, the effects of synchrotron radiation emission and intra-beam scattering on the equilibrium parameters during the ramp are studied.

DOI •

reference for this paper ※ doi:10.18429/JACoW-FLS2023-TU4P19

About •

Received ※ 22 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)

WE4P33

Design of a 166.6 MHz HOM Damped Copper Cavity for the Southern Advanced Photon Source

cavity, HOM, damping, photon

207

J.Y. Zhu, X. Li, Z.J. Lu
IHEP, Beijing, People’s Republic of China
J.B. Yu
IHEP CSNS, Guangdong Province, People’s Republic of China

Funding: This work was supported by the National Natural Science Foundation of China (12205168).
The Southern Advanced Photon Source (SAPS) aims to achieve ultra-low emittances and is expected to adopt low-frequency cavities (< 200 MHz) to accommodates on-axis injection. This paper focuses on the design of a 166.6 MHz HOM-damped normal conducting (NC) cavity for the SAPS. We propose a novel approach to achieve efficient HOM damping by optimizing the lowest frequency HOM and implementing a beam-line absorber in a coaxial resonant NC cavity. Notably, unlike beam-line absorbers for conventional NC cavities, the presence of a large beam tube in a coaxial resonant cavity does not affect the accelerating performance. This enables effective HOM damping while maintaining a high shunt impedance in a NC cavity. The numerical simulation results show that a compact copper cavity with effective HOM damping and excellent RF properties has been achieved.

DOI •

reference for this paper ※ doi:10.18429/JACoW-FLS2023-WE4P33

About •

Received ※ 23 August 2023 — Revised ※ 30 August 2023 — Accepted ※ 01 September 2023 — Issued ※ 02 December 2023

Cite •

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