LINAC2022 - List of Keywords (impedance)

Paper	Title	Other Keywords	Page
MOPOGE04	Cell Geometry Optimization for Dipole Kick Correction in a High-Frequency IH Structure	dipole, cavity, linac, DTL	146
	R. López López, P. Calvo, D. Gavela, J. Giner Navarro, G. Moreno, C. Oliver, J.M. Pérez Morales CIEMAT, Madrid, Spain M.C. Battaglia, J.M. Carmona AVS, Elgoibar, Spain A.M. Lombardi CERN, Meyrin, Switzerland
	Funding: CIEMAT Given the asymmetry in the stem configuration of an IH-DTL structure, an electric dipole component is always present between drift tubes, and it is especially significant for reduced dimensions in high-frequency regimes. Here we study the effect of different modifications of the drift tubes geometry of a 750 MHz IH-DTL to eliminate the impact of the dipole component in the transverse beam dynamics. Tracking simulations through a single cell are also performed to assess the outcomes in particle’s trajectory offset and angle.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-MOPOGE04
About •	Received ※ 24 August 2022 — Revised ※ 27 August 2022 — Accepted ※ 31 August 2022 — Issue date ※ 04 September 2022
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPOGE05	Effect of High-Magnetic Field Region Geometry on the Efficiency of a 750 MHz IH Structure	cavity, linac, simulation, software	150
	G. Moreno, P. Calvo, D. Gavela, J. Giner Navarro, R. López López, C. Oliver, J.M. Pérez Morales CIEMAT, Madrid, Spain M.C. Battaglia, J.M. Carmona AVS, Elgoibar, Spain A.M. Lombardi CERN, Meyrin, Switzerland
	Funding: CIEMAT High frequency structures generally translate to high efficiency performances thanks to reduced surfaces of the inner cavity. Two round-profiles geometry and some variations of two important parameters of a 750 MHz IH-DTL are proposed in this paper in order to improve shunt impedance performance regarding an existing solution with flat-walled cavity developed by CERN. The proposed designs are shaped such that they guarantee an easy connection of RF and vacuum auxiliaries. Electromagnetic simulations are checked with CST Microwave Studio.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-MOPOGE05
About •	Received ※ 20 August 2022 — Revised ※ 22 August 2022 — Accepted ※ 27 August 2022 — Issue date ※ 13 October 2022
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPOGE13	Acceleration Efficiency of TE-Mode Structures for Proton Linacs	DTL, cavity, proton, simulation	177
	J. Tamura, Y. Kondo, T. Morishita JAEA/J-PARC, Tokai-mura, Japan F. Naito, M. Otani KEK, Tokai, Ibaraki, Japan
	Various types of cavity structures are typically used in hadron linacs, depending on the energy range of the beam particle. This is especially the case in a normal-conducting linac, because the cavity’s acceleration efficiency varies with the velocity of the synchronous particle. For low-energy proton acceleration, while Alvarez drift-tube linacs (DTLs) are the most prevalent, TE-mode accelerating structures, which could also be called H-mode structures, are also widely used immediately after an initial radiofrequency quadrupole linac (RFQ). At present, the representative structures of TE modes are interdigital H-mode (IH) DTL and crossbar H-mode (CH) DTL, which are based on the TE11-mode pillbox cavity and TE21-mode pillbox cavity, respectively. In this presentation, acceleration efficiency of TE-mode structures including higher-order TE-modes such as TE31 and TE41 was comparatively reviewed with Alvarez DTL. This study shows that IH-DTL and CH-DTL have a larger shunt impedance than Alvarez DTL for proton acceleration below 10 MeV, and furthermore for the TEm1-mode structures, the rotational symmetry of the electric field improves with increasing angular index m.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-MOPOGE13
About •	Received ※ 30 August 2022 — Revised ※ 06 September 2022 — Accepted ※ 14 September 2022 — Issue date ※ 26 September 2022
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPOJO17	High Efficiency High Power Resonant Cavity Amplifier For PIP-II	cavity, coupling, network, electron	384
	R.E. Simpson, N. Butler, D.B. Cope, M.P.J. Gaudreau, M.K. Kempkes Diversified Technologies, Inc., Bedford, Massachusetts, USA
	An advanced high-power, high power density, solid state power amplifier (SSPA) was developed to replace Vacuum Electron Devices (VEDs). Diversified Technologies, Inc. (DTI) developed and integrated a resonant-cavity combiner with solid state amplifiers for the Proton Improvement Plan-II (PIP-II) at Fermilab. The architecture combines the power of N-many RF power transistors into a single resonant cavity that are surface-mounted and -cooled. The system is designed so that failure of individual transistors has negligible performance impact. Due to the electrical and mechanical simplicity, maintenance and logistics are simplified. DTI demonstrated the basic feasibility of a 50-100 kW class amplifier resonant cavity combiner system at 650 MHz. A single-cavity system reached 15 kW at 66% power-added efficiency with ten of 12 slots filled on only 1 of 2 cavities faces. The system further demonstrated the expected graceful degradation; an intermittent fault occurred on 1 of the 10 modules and the only observable effect was a reduction in output power to 13.3 kW with a slight reduction in efficiency. Combining of multiple cavities was also demonstrated at low power.
	Poster TUPOJO17 [0.790 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-TUPOJO17
About •	Received ※ 16 August 2022 — Revised ※ 25 August 2022 — Accepted ※ 28 August 2022 — Issue date ※ 15 September 2022
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPOJO08	RF Design of Traveling-Wave Accelerating Structures for the FCC-ee Pre-injector Complex	linac, positron, electron, klystron	707
	H.W. Pommerenke, A. Grudiev, A. Latina CERN, Meyrin, Switzerland S. Bettoni, P. Craievich, J.-Y. Raguin, M. Schaer PSI, Villigen PSI, Switzerland
	Funding: This project received funding from the EU’s Horizon 2020 research program (grant No 951754), and was done under the auspices of CHART (Swiss Accelerator Research and Technology Collaboration). The linacs of the FCCee (Future Circular Electron-Positron Collider) injector complex will both provide the drive beam for positron production and accelerate nominal electron and positron beams up to 6 GeV. Several linacs comprise different traveling-wave (TW) accelerating structures fulfilling the beam dynamics and rf constraints. Notably, high-phase advance large-aperture structures accelerate the positron beam at low energies. All TW structures are rotationally symmetric for easier production. Long-range wakes are damped by HOM detuning. Operating mode and HOM parameters were calculated based on lookup tables and analytic formulas, allowing for rapidly scanning large parameter spaces. In this paper, we present both methodology and realization of the rf design of the TW structures including their pulse compressors.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-THPOJO08
About •	Received ※ 24 August 2022 — Accepted ※ 08 September 2022 — Issue date ※ 15 September 2022
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPOJO21	Higher Order Modes Investigation in the PERLE Superconducting RF Cavity	HOM, cavity, damping, 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, damping	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

MOPOGE04

Cell Geometry Optimization for Dipole Kick Correction in a High-Frequency IH Structure

dipole, cavity, linac, DTL

146

R. López López, P. Calvo, D. Gavela, J. Giner Navarro, G. Moreno, C. Oliver, J.M. Pérez Morales
CIEMAT, Madrid, Spain
M.C. Battaglia, J.M. Carmona
AVS, Elgoibar, Spain
A.M. Lombardi
CERN, Meyrin, Switzerland

Funding: CIEMAT
Given the asymmetry in the stem configuration of an IH-DTL structure, an electric dipole component is always present between drift tubes, and it is especially significant for reduced dimensions in high-frequency regimes. Here we study the effect of different modifications of the drift tubes geometry of a 750 MHz IH-DTL to eliminate the impact of the dipole component in the transverse beam dynamics. Tracking simulations through a single cell are also performed to assess the outcomes in particle’s trajectory offset and angle.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-MOPOGE04

About •

Received ※ 24 August 2022 — Revised ※ 27 August 2022 — Accepted ※ 31 August 2022 — Issue date ※ 04 September 2022

Cite •

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

MOPOGE05

Effect of High-Magnetic Field Region Geometry on the Efficiency of a 750 MHz IH Structure

cavity, linac, simulation, software

150

G. Moreno, P. Calvo, D. Gavela, J. Giner Navarro, R. López López, C. Oliver, J.M. Pérez Morales
CIEMAT, Madrid, Spain
M.C. Battaglia, J.M. Carmona
AVS, Elgoibar, Spain
A.M. Lombardi
CERN, Meyrin, Switzerland

Funding: CIEMAT
High frequency structures generally translate to high efficiency performances thanks to reduced surfaces of the inner cavity. Two round-profiles geometry and some variations of two important parameters of a 750 MHz IH-DTL are proposed in this paper in order to improve shunt impedance performance regarding an existing solution with flat-walled cavity developed by CERN. The proposed designs are shaped such that they guarantee an easy connection of RF and vacuum auxiliaries. Electromagnetic simulations are checked with CST Microwave Studio.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-MOPOGE05

About •

Received ※ 20 August 2022 — Revised ※ 22 August 2022 — Accepted ※ 27 August 2022 — Issue date ※ 13 October 2022

Cite •

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

MOPOGE13

Acceleration Efficiency of TE-Mode Structures for Proton Linacs

DTL, cavity, proton, simulation

177

J. Tamura, Y. Kondo, T. Morishita
JAEA/J-PARC, Tokai-mura, Japan
F. Naito, M. Otani
KEK, Tokai, Ibaraki, Japan

Various types of cavity structures are typically used in hadron linacs, depending on the energy range of the beam particle. This is especially the case in a normal-conducting linac, because the cavity’s acceleration efficiency varies with the velocity of the synchronous particle. For low-energy proton acceleration, while Alvarez drift-tube linacs (DTLs) are the most prevalent, TE-mode accelerating structures, which could also be called H-mode structures, are also widely used immediately after an initial radiofrequency quadrupole linac (RFQ). At present, the representative structures of TE modes are interdigital H-mode (IH) DTL and crossbar H-mode (CH) DTL, which are based on the TE11-mode pillbox cavity and TE21-mode pillbox cavity, respectively. In this presentation, acceleration efficiency of TE-mode structures including higher-order TE-modes such as TE31 and TE41 was comparatively reviewed with Alvarez DTL. This study shows that IH-DTL and CH-DTL have a larger shunt impedance than Alvarez DTL for proton acceleration below 10 MeV, and furthermore for the TEm1-mode structures, the rotational symmetry of the electric field improves with increasing angular index m.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-MOPOGE13

About •

Received ※ 30 August 2022 — Revised ※ 06 September 2022 — Accepted ※ 14 September 2022 — Issue date ※ 26 September 2022

Cite •

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

TUPOJO17

High Efficiency High Power Resonant Cavity Amplifier For PIP-II

cavity, coupling, network, electron

384

R.E. Simpson, N. Butler, D.B. Cope, M.P.J. Gaudreau, M.K. Kempkes
Diversified Technologies, Inc., Bedford, Massachusetts, USA

An advanced high-power, high power density, solid state power amplifier (SSPA) was developed to replace Vacuum Electron Devices (VEDs). Diversified Technologies, Inc. (DTI) developed and integrated a resonant-cavity combiner with solid state amplifiers for the Proton Improvement Plan-II (PIP-II) at Fermilab. The architecture combines the power of N-many RF power transistors into a single resonant cavity that are surface-mounted and -cooled. The system is designed so that failure of individual transistors has negligible performance impact. Due to the electrical and mechanical simplicity, maintenance and logistics are simplified. DTI demonstrated the basic feasibility of a 50-100 kW class amplifier resonant cavity combiner system at 650 MHz. A single-cavity system reached 15 kW at 66% power-added efficiency with ten of 12 slots filled on only 1 of 2 cavities faces. The system further demonstrated the expected graceful degradation; an intermittent fault occurred on 1 of the 10 modules and the only observable effect was a reduction in output power to 13.3 kW with a slight reduction in efficiency. Combining of multiple cavities was also demonstrated at low power.

Poster TUPOJO17 [0.790 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-TUPOJO17

About •

Received ※ 16 August 2022 — Revised ※ 25 August 2022 — Accepted ※ 28 August 2022 — Issue date ※ 15 September 2022

Cite •

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

THPOJO08

RF Design of Traveling-Wave Accelerating Structures for the FCC-ee Pre-injector Complex

linac, positron, electron, klystron

707

H.W. Pommerenke, A. Grudiev, A. Latina
CERN, Meyrin, Switzerland
S. Bettoni, P. Craievich, J.-Y. Raguin, M. Schaer
PSI, Villigen PSI, Switzerland

Funding: This project received funding from the EU’s Horizon 2020 research program (grant No 951754), and was done under the auspices of CHART (Swiss Accelerator Research and Technology Collaboration).
The linacs of the FCCee (Future Circular Electron-Positron Collider) injector complex will both provide the drive beam for positron production and accelerate nominal electron and positron beams up to 6 GeV. Several linacs comprise different traveling-wave (TW) accelerating structures fulfilling the beam dynamics and rf constraints. Notably, high-phase advance large-aperture structures accelerate the positron beam at low energies. All TW structures are rotationally symmetric for easier production. Long-range wakes are damped by HOM detuning. Operating mode and HOM parameters were calculated based on lookup tables and analytic formulas, allowing for rapidly scanning large parameter spaces. In this paper, we present both methodology and realization of the rf design of the TW structures including their pulse compressors.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-THPOJO08

About •

Received ※ 24 August 2022 — Accepted ※ 08 September 2022 — Issue date ※ 15 September 2022

Cite •

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

THPOJO21

Higher Order Modes Investigation in the PERLE Superconducting RF Cavity

HOM, cavity, damping, 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, damping

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)