LINAC2022 - List of Authors (Grudiev, A.)

Paper	Title	Page
MOPOJO09	A Compact Inverse Compton Scattering Source Based on X-Band Technology and Cavity-Enhanced High Average Power Ultrafast Lasers	44
	A. Latina, R. Corsini, L.A. Dyks, E. Granados, A. Grudiev, V. Musat, S. Stapnes, W. Wuensch CERN, Meyrin, Switzerland E. Cormier CELIA, Talence, France L.A. Dyks Oxford University, Physics Department, Oxford, Oxon, United Kingdom G. Santarelli ILE, Palaiseau Cedex, France
	A high-pulse-current injector followed by a short high-gradient X-band linac is considered as a driver for a compact Inverse Compton Scattering source. We show that using a high-power ultrashort pulse laser operating in burst mode and a Fabry-Pérot enhancement cavity, X-rays with flux values over 10¹³ ph/s and photon energies up to MeV are achievable. The resulting high-intensity and high-energy X-rays allow for various applications, including cancer therapy, tomography, and nuclear waste management. A preliminary conceptual design of such a compact ICS source is presented, together with simulations of the expected performance.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-MOPOJO09
About •	Received ※ 19 August 2022 — Revised ※ 30 August 2022 — Accepted ※ 01 September 2022 — Issue date ※ 06 September 2022
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPORI23	High-Power Testing Results of X-Band RF-Window and 45 Degrees Spiral Load	279
	M. Boronat, H. Bursali, N. Catalán Lasheras, A. Grudiev, G. McMonagle, I. Syratchev CERN, Meyrin, Switzerland
	The X-Band test facilities at CERN have been running for some years now qualifying CLIC structure prototypes but also developing and testing high power general-purpose X-Band components, used in a wide range of applications. Driven by operational needs, several components have been redesigned and tested aiming to optimize the reliability and the compactness of the full system and therefore enhancing the accessibility of this technology inside and outside CERN. To this extent, a new high-power RF-window has been designed and tested aiming to avoid unnecessary venting of high-power sections already conditioned, easing the interventions, and protecting the klystrons. A new spiral load prototype has also been designed, built, and tested, optimizing the compactness, and improving the fabrication process. In these pages, the design and manufacturing for each component will be shortly described, along with the last results on the high-power testing.
	Poster MOPORI23 [2.275 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-MOPORI23
About •	Received ※ 24 August 2022 — Revised ※ 29 August 2022 — Accepted ※ 29 August 2022 — Issue date ※ 31 August 2022
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPOPA06	Microscopy Investigation on Different Materials After Pulsed High Field Conditioning and Low Energy H-Irradiation	422
SUPCJO06	use link to see paper's listing under its alternate paper code
	C.F. Da Palma Serafim, G. Bellodi, S. Calatroni, A. Grudiev, A.M. Lombardi, R.C. Peacock, A.T. Perez Fontenla, S. Ramberger, E. Sargsyan, S. Sgobba, W. Wuensch CERN, Meyrin, Switzerland F. Djurabekova HIP, University of Helsinki, Finland
	During operation the LINAC4 RFQ (Radio-Frequency-Quadrupole) is exposed to high electric fields which can lead to vacuum breakdown. It is also subject to beam loss that can cause surface modification, including blistering, which can result in reduced electric field handling and an increased breakdown rate. An experimental study has been made to identify materials with high electric field capability and robustness to low-energy irradiation. In this paper we briefly discuss the selection criteria and we analyze these materials investigating their metallurgical properties using advanced microscopic techniques such as Scanning Electron Microscope, Electron Back Scattered Diffraction, Energy-dispersive X-ray Spectroscopy and conventional optical microscopy. These allow to observe and characterize the different materials on aμand a nano-scale, allowing us to compare results before and after irradiation and breakdown testing.
	Poster TUPOPA06 [2.771 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-TUPOPA06
About •	Received ※ 14 August 2022 — Revised ※ 23 August 2022 — Accepted ※ 29 August 2022 — Issue date ※ 31 August 2022
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPOPA09	RF Measurements and Tuning of the CERN 750 MHz ELISA-RFQ for Public Exhibition	426
	M. Marchi, A. Grudiev, S.J. Mathot, H.W. Pommerenke CERN, Meyrin, Switzerland
	Over the last few years CERN has successfully designed, built and commissioned the smallest RFQ to date, the one meter long PIXE-RFQ operating at 750 MHz. Its compactness offers a unique opportunity for education and public presentation of the accelerator community: A duplicate machine called ELISA-RFQ (Experimental Linac for Surface Analysis) will be exhibited in the Science Gateway, CERN’s upcoming scientific education and outreach center. It will allow the public to approach within a few centimeters a live proton beam injected into air, which is visible to the naked eye. The construction of the ELISA-RFQ has been completed in 2022. In this paper, we present the results of low-power RF measurements as well as field and frequency tuning.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-TUPOPA09
About •	Received ※ 14 August 2022 — Revised ※ 18 August 2022 — Accepted ※ 30 August 2022 — Issue date ※ 01 September 2022
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPOPA10	Beam Dynamics and RF Design Studies for the New RFQ for CERN Linac4 Upgrade	430
	H.W. Pommerenke, G. Bellodi, A. Grudiev, S. Kumar, A.M. Lombardi CERN, Meyrin, Switzerland
	The 352 MHz Linac4-RFQ is the first rf accelerating structure of the CERN accelerator complex, accelerating an H⁻ beam to 3 MeV. After successful commissioning in 2013, superficial vane damage has been observed in 2020. In view that the RFQ is a single point of failure, in parallel to the production of a near identical spare (RFQ2), design studies on a longer-term upgrade have been launched: Linac4-RFQ3. Main goals are to achieve a design with higher beam acceptance, reduced beam losses, and reduced RF breakdown rate. Two versions of RFQ are under study: a conventional RFQ built by brazing copper, as well as an RFQ with titanium vane tips (brazed on copper). High-gradient experiments suggest that titanium vane tips support higher surface fields compared to copper, up to 40 MV/m, and are more resistant against beam irradiation. In this paper, we present beam dynamics and rfdesign of both variants of RFQ3.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-TUPOPA10
About •	Received ※ 12 August 2022 — Revised ※ 19 August 2022 — Accepted ※ 29 August 2022 — Issue date ※ 02 September 2022
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPOPA13	Pulsed DC High Field Measurements of Irradiated and Non-Irradiated Electrodes of Different Materials	441
SUPCJO07	use link to see paper's listing under its alternate paper code
	R.C. Peacock, G. Burt Lancaster University, Lancaster, United Kingdom G. Bellodi, S. Calatroni, C.F. Da Palma Serafim, A. Grudiev, A.M. Lombardi, A.T. Perez Fontenla, S. Ramberger, E. Sargsyan, S. Sgobba, W. Wuensch CERN, Meyrin, Switzerland
	Beam loss occurs in Radio Frequency Quadrupoles (RFQ), and has been observed in the H⁻ linear accelerator Linac4 (L4) at CERN. To determine if beam loss can induce breakdowns, and to compare the robustness of different materials, tests have been done using pulsed high-voltage DC systems. Electrical breakdown phenomena and conditioning processes have been studied using these systems. Cathodes of different materials were irradiated with 1.2x10¹⁹ H⁻ p/cm², the estimated beam loss of the L4 RFQ over 10 days. The irradiated electrodes were installed in a system to observe if the irradiated area coincided with the breakdown locations, with pulsing parameters similar to the RFQ. Tests of irradiated and non-irradiated electrodes of the same material were done for comparison. The main difference observed was an increase in the number of breakdowns during the initial conditioning that returned to non-irradiated sample values with further running. Visual observations after irradiation show the beam centre and a halo the same diameter of the beam pipe. Breakdown clusters occur in the centre and halo regions, suggesting irradiation is not the only factor determining the breakdown probability.
	Poster TUPOPA13 [3.845 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-TUPOPA13
About •	Received ※ 23 August 2022 — Revised ※ 29 August 2022 — Accepted ※ 01 September 2022 — Issue date ※ 07 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	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)

Paper

Title

Page

A Compact Inverse Compton Scattering Source Based on X-Band Technology and Cavity-Enhanced High Average Power Ultrafast Lasers

44

A. Latina, R. Corsini, L.A. Dyks, E. Granados, A. Grudiev, V. Musat, S. Stapnes, W. Wuensch
CERN, Meyrin, Switzerland
E. Cormier
CELIA, Talence, France
L.A. Dyks
Oxford University, Physics Department, Oxford, Oxon, United Kingdom
G. Santarelli
ILE, Palaiseau Cedex, France

A high-pulse-current injector followed by a short high-gradient X-band linac is considered as a driver for a compact Inverse Compton Scattering source. We show that using a high-power ultrashort pulse laser operating in burst mode and a Fabry-Pérot enhancement cavity, X-rays with flux values over 10¹³ ph/s and photon energies up to MeV are achievable. The resulting high-intensity and high-energy X-rays allow for various applications, including cancer therapy, tomography, and nuclear waste management. A preliminary conceptual design of such a compact ICS source is presented, together with simulations of the expected performance.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-MOPOJO09

About •

Received ※ 19 August 2022 — Revised ※ 30 August 2022 — Accepted ※ 01 September 2022 — Issue date ※ 06 September 2022

Cite •

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

MOPORI23

High-Power Testing Results of X-Band RF-Window and 45 Degrees Spiral Load

279

M. Boronat, H. Bursali, N. Catalán Lasheras, A. Grudiev, G. McMonagle, I. Syratchev
CERN, Meyrin, Switzerland

The X-Band test facilities at CERN have been running for some years now qualifying CLIC structure prototypes but also developing and testing high power general-purpose X-Band components, used in a wide range of applications. Driven by operational needs, several components have been redesigned and tested aiming to optimize the reliability and the compactness of the full system and therefore enhancing the accessibility of this technology inside and outside CERN. To this extent, a new high-power RF-window has been designed and tested aiming to avoid unnecessary venting of high-power sections already conditioned, easing the interventions, and protecting the klystrons. A new spiral load prototype has also been designed, built, and tested, optimizing the compactness, and improving the fabrication process. In these pages, the design and manufacturing for each component will be shortly described, along with the last results on the high-power testing.

Poster MOPORI23 [2.275 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-MOPORI23

About •

Received ※ 24 August 2022 — Revised ※ 29 August 2022 — Accepted ※ 29 August 2022 — Issue date ※ 31 August 2022

Cite •

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

TUPOPA06

Microscopy Investigation on Different Materials After Pulsed High Field Conditioning and Low Energy H-Irradiation

422

SUPCJO06

use link to see paper's listing under its alternate paper code

C.F. Da Palma Serafim, G. Bellodi, S. Calatroni, A. Grudiev, A.M. Lombardi, R.C. Peacock, A.T. Perez Fontenla, S. Ramberger, E. Sargsyan, S. Sgobba, W. Wuensch
CERN, Meyrin, Switzerland
F. Djurabekova
HIP, University of Helsinki, Finland

During operation the LINAC4 RFQ (Radio-Frequency-Quadrupole) is exposed to high electric fields which can lead to vacuum breakdown. It is also subject to beam loss that can cause surface modification, including blistering, which can result in reduced electric field handling and an increased breakdown rate. An experimental study has been made to identify materials with high electric field capability and robustness to low-energy irradiation. In this paper we briefly discuss the selection criteria and we analyze these materials investigating their metallurgical properties using advanced microscopic techniques such as Scanning Electron Microscope, Electron Back Scattered Diffraction, Energy-dispersive X-ray Spectroscopy and conventional optical microscopy. These allow to observe and characterize the different materials on aμand a nano-scale, allowing us to compare results before and after irradiation and breakdown testing.

Poster TUPOPA06 [2.771 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-TUPOPA06

About •

Received ※ 14 August 2022 — Revised ※ 23 August 2022 — Accepted ※ 29 August 2022 — Issue date ※ 31 August 2022

Cite •

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

TUPOPA09

RF Measurements and Tuning of the CERN 750 MHz ELISA-RFQ for Public Exhibition

426

M. Marchi, A. Grudiev, S.J. Mathot, H.W. Pommerenke
CERN, Meyrin, Switzerland

Over the last few years CERN has successfully designed, built and commissioned the smallest RFQ to date, the one meter long PIXE-RFQ operating at 750 MHz. Its compactness offers a unique opportunity for education and public presentation of the accelerator community: A duplicate machine called ELISA-RFQ (Experimental Linac for Surface Analysis) will be exhibited in the Science Gateway, CERN’s upcoming scientific education and outreach center. It will allow the public to approach within a few centimeters a live proton beam injected into air, which is visible to the naked eye. The construction of the ELISA-RFQ has been completed in 2022. In this paper, we present the results of low-power RF measurements as well as field and frequency tuning.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-TUPOPA09

About •

Received ※ 14 August 2022 — Revised ※ 18 August 2022 — Accepted ※ 30 August 2022 — Issue date ※ 01 September 2022

Cite •

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

TUPOPA10

Beam Dynamics and RF Design Studies for the New RFQ for CERN Linac4 Upgrade

430

H.W. Pommerenke, G. Bellodi, A. Grudiev, S. Kumar, A.M. Lombardi
CERN, Meyrin, Switzerland

The 352 MHz Linac4-RFQ is the first rf accelerating structure of the CERN accelerator complex, accelerating an H⁻ beam to 3 MeV. After successful commissioning in 2013, superficial vane damage has been observed in 2020. In view that the RFQ is a single point of failure, in parallel to the production of a near identical spare (RFQ2), design studies on a longer-term upgrade have been launched: Linac4-RFQ3. Main goals are to achieve a design with higher beam acceptance, reduced beam losses, and reduced RF breakdown rate. Two versions of RFQ are under study: a conventional RFQ built by brazing copper, as well as an RFQ with titanium vane tips (brazed on copper). High-gradient experiments suggest that titanium vane tips support higher surface fields compared to copper, up to 40 MV/m, and are more resistant against beam irradiation. In this paper, we present beam dynamics and rfdesign of both variants of RFQ3.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-TUPOPA10

About •

Received ※ 12 August 2022 — Revised ※ 19 August 2022 — Accepted ※ 29 August 2022 — Issue date ※ 02 September 2022

Cite •

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

TUPOPA13

Pulsed DC High Field Measurements of Irradiated and Non-Irradiated Electrodes of Different Materials

441

SUPCJO07

use link to see paper's listing under its alternate paper code

R.C. Peacock, G. Burt
Lancaster University, Lancaster, United Kingdom
G. Bellodi, S. Calatroni, C.F. Da Palma Serafim, A. Grudiev, A.M. Lombardi, A.T. Perez Fontenla, S. Ramberger, E. Sargsyan, S. Sgobba, W. Wuensch
CERN, Meyrin, Switzerland

Beam loss occurs in Radio Frequency Quadrupoles (RFQ), and has been observed in the H⁻ linear accelerator Linac4 (L4) at CERN. To determine if beam loss can induce breakdowns, and to compare the robustness of different materials, tests have been done using pulsed high-voltage DC systems. Electrical breakdown phenomena and conditioning processes have been studied using these systems. Cathodes of different materials were irradiated with 1.2x10¹⁹ H⁻ p/cm², the estimated beam loss of the L4 RFQ over 10 days. The irradiated electrodes were installed in a system to observe if the irradiated area coincided with the breakdown locations, with pulsing parameters similar to the RFQ. Tests of irradiated and non-irradiated electrodes of the same material were done for comparison. The main difference observed was an increase in the number of breakdowns during the initial conditioning that returned to non-irradiated sample values with further running. Visual observations after irradiation show the beam centre and a halo the same diameter of the beam pipe. Breakdown clusters occur in the centre and halo regions, suggesting irradiation is not the only factor determining the breakdown probability.

Poster TUPOPA13 [3.845 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-TUPOPA13

About •

Received ※ 23 August 2022 — Revised ※ 29 August 2022 — Accepted ※ 01 September 2022 — Issue date ※ 07 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

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)