LINAC2022 - List of Keywords (damping)

Paper	Title	Other Keywords	Page
THPOJO21	Higher Order Modes Investigation in the PERLE Superconducting RF Cavity	HOM, cavity, impedance, dipole	731
	C. Barbagallo, P. Duchesne, W. Kaabi, G. Olry, Z.F. Zomer Université Paris-Saclay, CNRS/IN2P3, IJCLab, Orsay, France R.A. Rimmer, H. Wang JLab, Newport News, Virginia, USA
	The regenerative Beam Break Up (BBU) excited by the dipole Higher Order Modes (HOMs) in superconducting RF (SRF) cavities is a crucial issue for continuous-wave high-current energy recovery linacs. Beam-induced monopole HOMs can increase the cryogenic losses of the linac also. One of the ways to limit these effects is to use HOM couplers on the beam tubes of cavities to absorb and untrap cavity eigenmodes. These couplers feature antennas designed to damp dangerous HOMs and adequately reject the fundamental mode. This study illustrates an investigation of the HOMs of a 5-cell 801.58 MHz elliptical SRF cavity designed for PERLE (Powerful Energy Recovery Linac for Experiments), a multi-turn energy recovery linac (ERL) currently under study and later to be hosted at IJCLab in Orsay. Time-domain wakefield and frequency-domain eigenmode simulations have been used to calculate the cavity broadband HOM impedance spectra and identify the dangerous BBU HOMs. The transmission characteristics of several coaxial HOM couplers have been studied. The efficiencies of several HOM-damping schemes have been compared to propose a HOM endgroup to be fabricated and added to the existing bare SRF cavity.
	Poster THPOJO21 [2.090 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-THPOJO21
About •	Received ※ 24 August 2022 — Revised ※ 27 August 2022 — Accepted ※ 01 September 2022 — Issue date ※ 23 September 2022
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPOJO25	HOM Damping in Multi-Cell Superconducting Cavities for the Future Electron Source BriXSinO	HOM, cavity, linac, impedance	739
	S. Samsam, A. Bacci, C. Curatolo, I. Drebot, D. Giove, V. Petrillo, M. Rossetti Conti, A.R. Rossi, L. Serafini INFN-Milano, Milano, Italy A. Bosotti, D. Giove, L. Monaco, R. Paparella, D. Sertore INFN/LASA, Segrate (MI), Italy M.R. Masullo, A. Passarelli INFN-Napoli, Napoli, Italy V. Petrillo Universita’ degli Studi di Milano, Milano, Italy
	High order modes (HOMs) in multi-cell superconducting cavities are of particular concern in beam dynamics of linear accelerators, mainly those operating in CW mode with high current and high repetition rate. These undesired modes may invoke beam instabilities, beam breakup and increase the energy spread if not correctly pulled out and damped. The study reported in this paper is applied for damping the HOMs in the main Linac of BriXSinO, an ongoing project of an Energy Recovery Linac at LASA INFN laboratory. We developed a numerical model to study the interaction of monopole HOMs with the beam in long timescale. The presented model, named HOMEN (High Order Modes Evolution based on eNergy budget), allows the evaluation of the loss factor Kloss, crucial for evaluating the perturbing modes. At the same time, electromagnetic simulations of the standing wave multicell cavity, highlighted the dangerous modes and revealed a tolerable beam energy spread induced by HOMs. This method allows us to distinguish all dangerous modes of our interest for implementing the necessary damping mechanisms.
	Poster THPOJO25 [1.111 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-THPOJO25
About •	Received ※ 22 August 2022 — Revised ※ 17 August 2022 — Accepted ※ 29 August 2022 — Issue date ※ 15 September 2022
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

Paper

Title

Other Keywords

Page

THPOJO21

Higher Order Modes Investigation in the PERLE Superconducting RF Cavity

HOM, cavity, impedance, dipole

731

C. Barbagallo, P. Duchesne, W. Kaabi, G. Olry, Z.F. Zomer
Université Paris-Saclay, CNRS/IN2P3, IJCLab, Orsay, France
R.A. Rimmer, H. Wang
JLab, Newport News, Virginia, USA

The regenerative Beam Break Up (BBU) excited by the dipole Higher Order Modes (HOMs) in superconducting RF (SRF) cavities is a crucial issue for continuous-wave high-current energy recovery linacs. Beam-induced monopole HOMs can increase the cryogenic losses of the linac also. One of the ways to limit these effects is to use HOM couplers on the beam tubes of cavities to absorb and untrap cavity eigenmodes. These couplers feature antennas designed to damp dangerous HOMs and adequately reject the fundamental mode. This study illustrates an investigation of the HOMs of a 5-cell 801.58 MHz elliptical SRF cavity designed for PERLE (Powerful Energy Recovery Linac for Experiments), a multi-turn energy recovery linac (ERL) currently under study and later to be hosted at IJCLab in Orsay. Time-domain wakefield and frequency-domain eigenmode simulations have been used to calculate the cavity broadband HOM impedance spectra and identify the dangerous BBU HOMs. The transmission characteristics of several coaxial HOM couplers have been studied. The efficiencies of several HOM-damping schemes have been compared to propose a HOM endgroup to be fabricated and added to the existing bare SRF cavity.

Poster THPOJO21 [2.090 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-THPOJO21

About •

Received ※ 24 August 2022 — Revised ※ 27 August 2022 — Accepted ※ 01 September 2022 — Issue date ※ 23 September 2022

Cite •

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

THPOJO25

HOM Damping in Multi-Cell Superconducting Cavities for the Future Electron Source BriXSinO

HOM, cavity, linac, impedance

739

S. Samsam, A. Bacci, C. Curatolo, I. Drebot, D. Giove, V. Petrillo, M. Rossetti Conti, A.R. Rossi, L. Serafini
INFN-Milano, Milano, Italy
A. Bosotti, D. Giove, L. Monaco, R. Paparella, D. Sertore
INFN/LASA, Segrate (MI), Italy
M.R. Masullo, A. Passarelli
INFN-Napoli, Napoli, Italy
V. Petrillo
Universita’ degli Studi di Milano, Milano, Italy

High order modes (HOMs) in multi-cell superconducting cavities are of particular concern in beam dynamics of linear accelerators, mainly those operating in CW mode with high current and high repetition rate. These undesired modes may invoke beam instabilities, beam breakup and increase the energy spread if not correctly pulled out and damped. The study reported in this paper is applied for damping the HOMs in the main Linac of BriXSinO, an ongoing project of an Energy Recovery Linac at LASA INFN laboratory. We developed a numerical model to study the interaction of monopole HOMs with the beam in long timescale. The presented model, named HOMEN (High Order Modes Evolution based on eNergy budget), allows the evaluation of the loss factor Kloss, crucial for evaluating the perturbing modes. At the same time, electromagnetic simulations of the standing wave multicell cavity, highlighted the dangerous modes and revealed a tolerable beam energy spread induced by HOMs. This method allows us to distinguish all dangerous modes of our interest for implementing the necessary damping mechanisms.

Poster THPOJO25 [1.111 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-THPOJO25

About •

Received ※ 22 August 2022 — Revised ※ 17 August 2022 — Accepted ※ 29 August 2022 — Issue date ※ 15 September 2022

Cite •

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