HB2023 - List of Keywords (feedback)

Paper	Title	Other Keywords	Page
WEC4I1	RF Systems of J-PARC Proton Synchrotrons for High-Intensity Longitudinal Beam Optimization and Handling	cavity, operation, controls, acceleration	305
	F. Tamura, R. Miyakoshi, M. Nomura, H. Okita, T. Shimada, M. Yamamoto JAEA/J-PARC, Tokai-mura, Japan K. Hara, K. Hasegawa, C. Ohmori, K. Seiya, Y. Sugiyama, M. Yoshii KEK, Tokai, Ibaraki, Japan
	The application of magnetic alloy (MA) cores to the accelerating rf cavities in high intensity proton synchrotrons was pioneered for the J-PARC synchrotrons, the RCS and MR. The MA loaded cavities can generate high accelerating voltages. The wideband frequency response of the MA cavity enables the frequency sweep to follow the velocity change of protons without the tuning loop. The dual harmonic operation, where a single cavity is driven by the superposition of the fundamental and second harmonic rf voltages, is indispensable for the longitudinal bunch shaping to alleviate the space charge effects in the RCS. These advantages of the MA cavity are also disadvantages when looking at them from a different perspective. Since the wake voltage consists of several harmonics, which can cause bucket distortion or coupled-bunch instabilities, the beam loading compensation must be multiharmonic. The operation of tubes in the final stage amplifier is not trivial when accelerating very high intensity beams; the output current is high and the anode voltageis also multiharmonic. We summarize our effort against these issues in the operation of the RCS and MR for more than 10 years.
	Slides WEC4I1 [6.932 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-HB2023-WEC4I1
About •	Received ※ 29 September 2023 — Revised ※ 07 October 2023 — Accepted ※ 10 October 2023 — Issued ※ 29 October 2023
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEC4I2	Development of Dual-harmonic RF System for CSNS-II	cavity, controls, LLRF, impedance	312
	X. Li, X. Li, W. Long, W.J. Wu, C.L. Zhang IHEP, Beijing, People’s Republic of China Y. Liu DNSC, Dongguan, People’s Republic of China B. Wu IHEP CSNS, Guangdong Province, People’s Republic of China
	The upgrade of the China Spallation Neutron Source (CSNS-II) encompasses the development of a dual har-monic RF system for the Rapid Cycling Synchrotron (RCS). The objective of this system is to achieve a maxi-mum second harmonic voltage of 100 kV. To meet this requirement, a high gradient cavity is being used in place of the traditional ferrite loaded cavity. Magnetic alloy (MA) loaded cavities, which can attain very high field gradients, have demonstrated their suitability for high-intensity proton synchrotrons. As a result, designing an RF system with MA-loaded cavities has emerged as a primary focus. Over the past decade, substantial ad-vancements have been made in the development of MA-loaded cavities at CSNS. This paper provides an overview of the RF system that incorporates the MA-loaded cavity and presents the high-power test results of the system.
	Slides WEC4I2 [6.449 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-HB2023-WEC4I2
About •	Received ※ 28 September 2023 — Revised ※ 07 October 2023 — Accepted ※ 10 October 2023 — Issued ※ 22 October 2023
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THBP40	Mitigation Strategies for the Instabilities Induced by the Fundamental Mode of the HL-LHC Crab Cavities	cavity, impedance, betatron, optics	571
	L. Giacomel, P. Baudrenghien, X. Buffat, R. Calaga, N. Mounet CERN, Meyrin, Switzerland
	The transverse impedance is one of the potentially limiting effects for the performance of the High-Luminosity Large Hadron Collider (HL-LHC). In the current LHC, the impedance is dominated by the resistive-wall contribution of the collimators at typical bunch-spectrum frequencies, and is of broad-band nature. Nevertheless, the fundamental mode of the crab cavities, that are a vital part of the HL-LHC baseline, adds a strong and narrow-band contribution. The resulting coupled-bunch instability, which contains a strong head-tail component, requires dedicated mitigation measures, since the efficiency of the transverse damper is limited against such instabilities, and Landau damping from octupoles would not be sufficient. The efficiency and implications of various mitigation strategies, based on RF feedbacks and optics changes, are discussed, along with first measurements using crab cavity prototypes at the Super Proton Synchrotron (SPS).
	Poster THBP40 [0.461 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-HB2023-THBP40
About •	Received ※ 30 September 2023 — Revised ※ 08 October 2023 — Accepted ※ 11 October 2023 — Issued ※ 19 October 2023
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

Paper

Title

Other Keywords

Page

WEC4I1

RF Systems of J-PARC Proton Synchrotrons for High-Intensity Longitudinal Beam Optimization and Handling

cavity, operation, controls, acceleration

305

F. Tamura, R. Miyakoshi, M. Nomura, H. Okita, T. Shimada, M. Yamamoto
JAEA/J-PARC, Tokai-mura, Japan
K. Hara, K. Hasegawa, C. Ohmori, K. Seiya, Y. Sugiyama, M. Yoshii
KEK, Tokai, Ibaraki, Japan

The application of magnetic alloy (MA) cores to the accelerating rf cavities in high intensity proton synchrotrons was pioneered for the J-PARC synchrotrons, the RCS and MR. The MA loaded cavities can generate high accelerating voltages. The wideband frequency response of the MA cavity enables the frequency sweep to follow the velocity change of protons without the tuning loop. The dual harmonic operation, where a single cavity is driven by the superposition of the fundamental and second harmonic rf voltages, is indispensable for the longitudinal bunch shaping to alleviate the space charge effects in the RCS. These advantages of the MA cavity are also disadvantages when looking at them from a different perspective. Since the wake voltage consists of several harmonics, which can cause bucket distortion or coupled-bunch instabilities, the beam loading compensation must be multiharmonic. The operation of tubes in the final stage amplifier is not trivial when accelerating very high intensity beams; the output current is high and the anode voltageis also multiharmonic. We summarize our effort against these issues in the operation of the RCS and MR for more than 10 years.

Slides WEC4I1 [6.932 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-HB2023-WEC4I1

About •

Received ※ 29 September 2023 — Revised ※ 07 October 2023 — Accepted ※ 10 October 2023 — Issued ※ 29 October 2023

Cite •

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

WEC4I2

Development of Dual-harmonic RF System for CSNS-II

cavity, controls, LLRF, impedance

312

X. Li, X. Li, W. Long, W.J. Wu, C.L. Zhang
IHEP, Beijing, People’s Republic of China
Y. Liu
DNSC, Dongguan, People’s Republic of China
B. Wu
IHEP CSNS, Guangdong Province, People’s Republic of China

The upgrade of the China Spallation Neutron Source (CSNS-II) encompasses the development of a dual har-monic RF system for the Rapid Cycling Synchrotron (RCS). The objective of this system is to achieve a maxi-mum second harmonic voltage of 100 kV. To meet this requirement, a high gradient cavity is being used in place of the traditional ferrite loaded cavity. Magnetic alloy (MA) loaded cavities, which can attain very high field gradients, have demonstrated their suitability for high-intensity proton synchrotrons. As a result, designing an RF system with MA-loaded cavities has emerged as a primary focus. Over the past decade, substantial ad-vancements have been made in the development of MA-loaded cavities at CSNS. This paper provides an overview of the RF system that incorporates the MA-loaded cavity and presents the high-power test results of the system.

Slides WEC4I2 [6.449 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-HB2023-WEC4I2

About •

Received ※ 28 September 2023 — Revised ※ 07 October 2023 — Accepted ※ 10 October 2023 — Issued ※ 22 October 2023

Cite •

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

THBP40

Mitigation Strategies for the Instabilities Induced by the Fundamental Mode of the HL-LHC Crab Cavities

cavity, impedance, betatron, optics

571

L. Giacomel, P. Baudrenghien, X. Buffat, R. Calaga, N. Mounet
CERN, Meyrin, Switzerland

The transverse impedance is one of the potentially limiting effects for the performance of the High-Luminosity Large Hadron Collider (HL-LHC). In the current LHC, the impedance is dominated by the resistive-wall contribution of the collimators at typical bunch-spectrum frequencies, and is of broad-band nature. Nevertheless, the fundamental mode of the crab cavities, that are a vital part of the HL-LHC baseline, adds a strong and narrow-band contribution. The resulting coupled-bunch instability, which contains a strong head-tail component, requires dedicated mitigation measures, since the efficiency of the transverse damper is limited against such instabilities, and Landau damping from octupoles would not be sufficient. The efficiency and implications of various mitigation strategies, based on RF feedbacks and optics changes, are discussed, along with first measurements using crab cavity prototypes at the Super Proton Synchrotron (SPS).

Poster THBP40 [0.461 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-HB2023-THBP40

About •

Received ※ 30 September 2023 — Revised ※ 08 October 2023 — Accepted ※ 11 October 2023 — Issued ※ 19 October 2023

Cite •

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