LINAC2022 - Table of Session: TUPOPA (Poster Session)

Paper	Title	Page
TUPOPA03	Status and RF Devopments of ESS Bilbao RFQ	410
	N. Garmendia, I. Bustinduy, A. Conde, P.J. González, A. Kaftoosian, J. Martin, S. Masa, J.L. Munozpresenter, Á. Rodríguez Páramo ESS Bilbao, Zamudio, Spain
	Within the framework of the plans for study of a light-ion linear accelerator, ESS Bilbao is manufacturing a radio frequency quadrupole (RFQ) aimed at accelerating up to 3 MeV the protons generated in the ion source. The progress made and the difficulties encountered with the RFQ are discussed in this paper. A power coupler proto-type for the RFQ has been developed while several me-chanical constraints were also studied in the final cou-pler. This prototype operates at a lower power, then it can work using PEEK window for the vacuum interface and it does not require neither brazing nor cooling system. Also, a complete RF test stand is being implemented to perform the high-power conditioning in traveling and standing wave mode, to verify the power handling capa-bility of the coupler and its thermal behaviour. The RF test stand, based on EPICS environment, can provide up to 2 MW peak power at 352.2 MHz in a pulse operation of 14 Hz and a duty cycle of 4.9%.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-TUPOPA03
About •	Received ※ 09 August 2022 — Revised ※ 28 August 2022 — Accepted ※ 30 August 2022 — Issue date ※ 02 September 2022
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TUPOPA04	First Beam Matching and Transmission Studies on the ESS RFQ	414
	D. Noll, R.A. Baron, C.S. Derrez, E.M. Donegani, M. Eshraqi, F. Grespan, H. Hassanzadegan, B. Jones, Y. Levinsen, N. Milas, R. Miyamoto, D.C. Plostinar, A.G. Sosa, R. Zeng ESS, Lund, Sweden A.C. Chauveau, O. Piquet CEA-IRFU, Gif-sur-Yvette, France
	The European Spallation Source will be driven by a 5 MW linear accelerator, producing 2.86 ms long proton beam pulses with a peak current of 62.5 mA at 14 Hz. Following the source commissioning in 2018 and 2019, the RFQ was successfully conditioned and subsequently commissioned with beam in 2021. In this paper, we will present results of studies on beam matching to the RFQ, both for low and high current beam modes, and will compare these results to model predictions.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-TUPOPA04
About •	Received ※ 26 August 2022 — Accepted ※ 05 September 2022 — Issue date ※ 05 September 2022
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TUPOPA05	RFQ Performance During RF Conditioning and Beam Commissioning at ESS	418
	R. Zeng, G.S. Fedel, B. Jones, R. Miyamoto, D.J.P. Nicosia, D. Noll, A.G. Sosa, A.M. Svensson, E. Trachanas ESS, Lund, Sweden M. Baudrier CEA-DRF-IRFU, France A.C. Chauveau, M.J. Desmons, P. Hamel, O. Piquet CEA-IRFU, Gif-sur-Yvette, France F. Grespan INFN/LNL, Legnaro (PD), Italy
	RFQ at ESS has been successfully gone through RF conditioning, RF re-conditioning and low duty cycle beam commissioning. RFQ fulfills required functions and overall performance is satisfactory. RF conditioning, three RF re-conditionings after LEBT intervention and beam commissioning will be reported and RFQ performance during these periods will be described. RFQ performance in a large extent is reflected by dynamics and interactions between RF, cavity and beam. Thanks to advanced hardware capabilities and intelligent software intelligence, observation of those dynamics and interactions are done in detailed level. Analysis of those dynamics and interaction will be introduced. Some techniques to deal with challenges resulted from those dynamics and interactions will also be discussed.
	Poster TUPOPA05 [25.281 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-TUPOPA05
About •	Received ※ 18 August 2022 — Revised ※ 25 August 2022 — Accepted ※ 31 August 2022 — Issue date ※ 05 September 2022
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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
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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. Pommerenkepresenter 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
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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
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TUPOPA11	Compact Proton Accelerator in UHF Band At KAHVELab	434
SUPCGE07	use link to see paper's listing under its alternate paper code
	S. Esen, A. Adiguzel, O. Kocer, S. Oz Istanbul University, Istanbul, Turkey A. Caglar YTU, Istanbul, Turkey E. Celebi, E.V. Ozcan Bogazici University, Bebek / Istanbul, Turkey E. Celebi IBU, Istanbul, Turkey A.K. Karatay, F. Yaman, Ö.H. Yilmaz IZTECH, Izmir, Turkey U. Kaya Istinye University, Institute of Sciences, Istanbul, Turkey A. Kilicgedik Marmara University, Istanbul, Turkey G. Türemen Turkish Atomic Energy Authority, Ankara, Turkey G. Unel UCI, Irvine, California, USA
	Funding: This project are supported by TUBITAK Project no: 118E838 Proton Test Beam at KahveLAB (Kandilli Detector, Accelerator and Instrumentation Laboratory) project aims to design and produce a radio frequency quadrupole (RFQ) operating at 800 MHz in Istanbul, Turkey using the local resources. The beamline consists of a proton source, a low energy beam transport (LEBT) line including the beam diagnostic section, and the RFQ cavity itself. This RFQ is a 4-vane, 1-meter-long cavity to accelerate the 20 keV beam extracted from the plasma ion source to 2 MeV. Its engineering prototype is already produced and subjected to mechanical, low-power RF, and vacuum tests. In this poster, the results of the first test production, especially the bead-pull test setup will be discussed.
	Poster TUPOPA11 [16.128 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-TUPOPA11
About •	Received ※ 21 August 2022 — Revised ※ 22 August 2022 — Accepted ※ 12 September 2022 — Issue date ※ 26 September 2022
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TUPOPA12	RF Measurements and Tuning of the Test Module of 800 MHz Radio-Frequency Quadrupole	438
SUPCGE02	use link to see paper's listing under its alternate paper code
	A. Kilicgedik Marmara University, Istanbul, Turkey A. Adiguzel, S. Esen Istanbul University, Istanbul, Turkey B. Baran Ankara University, Faculty of Sciences, Ankara, Turkey A. Caglar YTU, Istanbul, Turkey E. Celebi, E.V. Ozcan Bogazici University, Bebek / Istanbul, Turkey U. Kaya Istinye University, Institute of Sciences, Istanbul, Turkey G. Türemen TENMAK-NUKEN, Ankara, Turkey G. Unel UCI, Irvine, California, USA F. Yaman IZTECH, Izmir, Turkey
	Funding: This project are supported by The Scientific and Technological Research Council of Turkey (TUBITAK) Project no: 118E838 The 800 MHz RFQ (radio-frequency quadrupole), developed and built at KAHVElab (Kandilli Detector, Accelerator and Instrumentation Laboratory) at Bogazici University in Istanbul, Turkey, has been designed to provide protons that have an energy of 2 MeV within only 1 m length. The RFQ consists of two modules and the test module of RFQ was constructed. The algorithm developed by CERN, based on the measurements generated by the tuner settings estimated through the response matrix [1,2,3], has been optimized for a single module and 16 tuners. The desired field consistent with the simulation was obtained by bead pull measurements. In this study, we present low-power rf measurements and field tuning of the test module. [1] Koubek, B., et al., PHY. REV. ACC. AND BEAMS 20,08010(2017) [2] Koubek, B., et al., CERN-2017-0006,(2017) [3] Pommerenke, Hermann W., et al., Nuc. Inst. and Meth. in Phy. Res. Sec.A),165564(2021)
	Poster TUPOPA12 [1.699 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-TUPOPA12
About •	Received ※ 24 August 2022 — Revised ※ 27 August 2022 — Accepted ※ 31 August 2022 — Issue date ※ 02 September 2022
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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
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TUPOPA15	Multipactor Studies: Simulations and Measurements on the RF Coaxial Resonator Test Bench	445
	Y. Gómez Martínez, J. Angot, M.A. Baylac, T. Cabanel, M. Meyerpresenter LPSC, Grenoble Cedex, France D. Longuevergne, G. Sattonnay Université Paris-Saclay, CNRS/IN2P3, IJCLab, Orsay, France
	Multipactor is an undesired phenomenon triggered by electromagnetic fields in accelerator components and more specifically in RF structures, such as accelerating cavities and power couplers, and may lead to Electron Cloud build up in beam tubes. The accelerator group at LPSC has developed an experimental setup dedicated to multipactor studies. It consists in a coaxial resonator, tunable and operational between 100 MHz and 1 GHz. It allows to characterize under real conditions the efficiency of surface treatment mitigation processes (coatings, cleaning procedures) at room temperature. This paper presents the experimental measurements performed with this setup confronted to simulations.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-TUPOPA15
About •	Received ※ 12 August 2022 — Revised ※ 30 August 2022 — Accepted ※ 01 September 2022 — Issue date ※ 16 September 2022
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TUPOPA16	Complete Study of the Multipactor Phenomenon for the MYRRHA 80 kW CW RF Couplers	448
	Y. Gómez Martínez, P.-O. Dumont, M. Meyerpresenter LPSC, Grenoble Cedex, France P. Duchesne, C. Joly, W. Kaabi Université Paris-Saclay, CNRS/IN2P3, IJCLab, Orsay, France
	MYRRHA [1] (Multi Purpose Hybrid Reactor for High Tech Applications) is an Accelerator Driven System (ADS) project. Its superconducting linac will provide a 600 MeV - 4 mA proton beam. The first project phase based on a 100 MeV linac is launched. The Radio-Frequency (RF) couplers have been designed to handle 80 kW CW (Continuous Wave) at 352.2 MHz. This paper describes the multipacting studies on couplers.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-TUPOPA16
About •	Received ※ 12 August 2022 — Revised ※ 22 August 2022 — Accepted ※ 01 September 2022 — Issue date ※ 05 September 2022
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TUPOPA17	Solving the USB Communication Problem of the High-Voltage Modulator Control System in the European XFEL	451
	M. Bousonville, S. Choroba, T. Grevsmühl, S. Göller, A. Hauberg, T. Weinhausen DESY, Hamburg, Germany
	Since the commissioning of the modulators in the European XFEL in 2016, it happened from time to time that the modulator control system hung up. The reason for the problem was unknown at that time. Initially, the MTBF (Mean Time Between Failure) was 10⁴ days, which was so rare that other problems with the RF system clearly dominated and were addressed first. Over the next 2 years, the error became more frequent and occurred on average every 18 days. After the winter shutdown of the XFEL in 2020, the problem became absolutely dominant, with an MTBF of 2 days. Therefore, the fault was investigated with top priority and was finally identified. Two units of the control electronics communicate via USB 2.0 with the main server. Using special measurement technology, it was possible to prove that weak signal levels in the USB signal led to bit errors and thus to the crash of the control electronics. This article describes the troubleshooting process, how to measure the signal quality of USB signals and how the problem was solved in the end.
	Poster TUPOPA17 [6.650 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-TUPOPA17
About •	Received ※ 22 August 2022 — Revised ※ 19 August 2022 — Accepted ※ 29 August 2022 — Issue date ※ 15 September 2022
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TUPOPA18	Test and Commissioning of the HELIAC Power Coupler	454
	J. List, K. Aulenbacher, W.A. Barth, M. Basten, C. Burandt, F.D. Dziubapresenter, V. Gettmann, T. Kürzeder, S. Lauber, M. Miski-Oglu, S. Yaramyshev HIM, Mainz, Germany K. Aulenbacher, W.A. Barth, F.D. Dziubapresenter, S. Lauber, J. List KPH, Mainz, Germany K. Aulenbacher, W.A. Barth, M. Basten, C. Burandt, F.D. Dziubapresenter, V. Gettmann, T. Kürzeder, S. Lauber, J. List, M. Miski-Oglu, S. Yaramyshev GSI, Darmstadt, Germany T. Conrad, H. Podlech, M. Schwarz IAP, Frankfurt am Main, Germany
	The superconducting continuous wave (cw) heavy ion HElmholtz LInear ACcelerator (HELIAC) is intended to be built at GSI in Darmstadt. With its high average beam current and repetition rate, the HELIAC is designed to fulfill the requirements of the super heavy element (SHE) research user program and the material sciences community at GSI. The accelerating cavities are of the superconducting Crossbar H-mode (CH) type, developed by GUF. Within the Advanced Demonstrator project, the first cryomodule, consisting of four cavities is scheduled for commissioning with beam in 2023. The former RF power couplers introduced a high heat input into the cryostat. Therefore, the coupler is redesigned at HIM in order to not only reduce the heat input but to provide an overall improved power coupler for the HELIAC. It is designed for maximal power of 5 kW cw at the frequency of 216.816 MHz. A prototype has been tested and commissioned recently. This includes several RF-tests at room temperature and in cryogenic environments. The results of these tests will be presented in this paper.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-TUPOPA18
About •	Received ※ 20 August 2022 — Revised ※ 21 August 2022 — Accepted ※ 30 August 2022 — Issue date ※ 01 September 2022
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TUPOPA24	Design of an X-Band Bunching and Accelerating System for AWAKE Run 2	458
	J.M. Arnesano, S. Döbert CERN, Meyrin, Switzerland
	The AWAKE experiment at CERN demonstrated in its Run 1 that it is possible to accelerate electrons in plasma wakefields driven by a self-modulated proton bunch. In Run2, AWAKE aims to increase the accelerating gradient in the plasma even further and demonstrate beam quality in order to be ready for high-energy physics experiments. In this framework, a new electron injector, consisting of an S-band RF-gun and a subsequent X-band bunching and accelerating section, capable of producing very short bunches with a small emittance, has been designed. In this paper, two different configurations of the X-band section and their corresponding high-power distribution systems are presented. The first one consists of three identical cavities to bunch and accelerate the beam while the second one uses a separate short structure for velocity bunching followed by three long, pure accelerating structures. A discussion of the strengths and weaknesses of each configuration is carried out and beam dynamics aspects are analyzed. Finally the X-Band power distribution systems are described with particular attention to the choice of the klystron, the pulse compression system and the waveguide distribution.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-TUPOPA24
About •	Received ※ 12 August 2022 — Revised ※ 21 August 2022 — Accepted ※ 01 September 2022 — Issue date ※ 16 September 2022
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TUPOPA25	Design, Manufacturing, Assembly, Testing, and Lessons Learned of the Prototype 650 MHz Couplers	462
	J. Helsper, S.K. Chandrasekaran, F. Furuta, B.M. Hanna, S. Kazakov, J.P. Ozelis, K.S. Premo, N. Solyak, G. Wu Fermilab, Batavia, Illinois, USA
	Funding: Work supported, in part, by the U.S. Department of Energy, Office of Science, Office of High Energy Physics, under U.S. DOE Contract No. DE-AC02-07CH11359. Six 650 MHz high-power couplers will be integrated into the prototype High Beta 650 MHz (HB650) cryomodule for the PIP-II project at Fermilab. The design of the coupler is described, including design optimizations from the previous generation. This paper then describes the coupler life-cycle, including manufacturing, assembly, testing, conditioning and the lessons learned at each stage.
	Poster TUPOPA25 [2.695 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-TUPOPA25
About •	Received ※ 24 August 2022 — Revised ※ 25 August 2022 — Accepted ※ 29 August 2022 — Issue date ※ 02 September 2022
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TUPOPA27	Conceptual Analysis of a Compact High Efficiency Klystron	466
	J.P. Edelen, S.D. Webb RadiaSoft LLC, Boulder, Colorado, USA K.E. Nichols LANL, Los Alamos, New Mexico, USA
	Traditional klystron efficiencies are limited by the output electron beam harmonic current and energy spread. Increasing the amount of harmonic current produced in the klystron requires increasing the velocity bunching in the input cavity. Additional cavities may be used to improve the bunching, however they do so at additional cost and space requirements for the klystron. Moreover, at higher currents space charge counteracts this velocity bunching reducing the amount of harmonic current that can be produced. Our concept resolves these challenges by employing a new type of high-efficiency, multi-beam klystron. Our design consists of a single two-frequency input cavity, a wiggler, and an output cavity. The two-frequency input cavity approximates a linear function in time thereby increasing the harmonic content of the beam, while the wiggler provides strong longitudinal focusing to mitigate the effects of space charge. In this paper we provide the theoretical foundation for our design and present initial numerical calculations showing improved bunching from the harmonic mode and the wiggler.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-TUPOPA27
About •	Received ※ 14 August 2022 — Revised ※ 24 August 2022 — Accepted ※ 30 August 2022 — Issue date ※ 31 August 2022
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TUPOPA29	Design Enhancements for the SNS RFQ Coaxial Coupler	469
	G.D. Toby, C.N. Barbier, Y.W. Kang, S.W. Lee, J.S. Moss ORNL, Oak Ridge, Tennessee, USA A.H. Narayan ORNL RAD, Oak Ridge, Tennessee, USA
	Funding: ORNL is managed by UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. Department of Energy. This research was supported by the DOE Office of Science, Basic Energy Science. The H⁻ ion linear accelerator at the Spallation Neutron Source (SNS) at Oak Ridge National Laboratory operates with reliability that routinely surpasses 90% during scheduled beam operation. With the ambitious goal of eventually achieving at least 95% availability, several upgrade and improvement projects are ongoing. One such project is the modification of the coaxial couplers that transfer radio frequency (RF) power to the accelerator’s Radio Frequency Quadrupole (RFQ). The proposed modification utilizes stub sections and capacitive coupling to construct a physically separable assembly with DC isolation. With a separated coupler assembly, the section that includes the magnetic coupling loop can be permanently mounted to the RFQ which would eliminate the need to re-adjust the couplers after maintenance activities, upgrades, and repairs. Additionally, the modified design would provide increased multipaction suppression with DC biasing and potentially lower thermal gradients across the device. This paper presents the design and simulation results of the project.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-TUPOPA29
About •	Received ※ 23 August 2022 — Revised ※ 29 August 2022 — Accepted ※ 30 August 2022 — Issue date ※ 01 September 2022
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TUPOPA30	Innovative Magnetron Power Sources for SRF Linacs	473
TUOPA05	use link to see paper's listing under its alternate paper code
	M. Popovic, M.A. Cummings, A. Dudas, R.P. Johnson, R.R. Lentz, M.L. Neubauer, T. Wynn Muons, Inc, Illinois, USA T. Blassick, J.K. Wessel Richardson Electronics Ltd, Lafox, Illinois, USA K. Jordan, R.A. Rimmer, H. Wang JLab, Newport News, Virginia, USA
	Funding: Supported in part by US Department of Energy Nuclear Physics SBIR Grant DE-SC0022484 Magnetron RF power sources for single cavities can cost much less and operate at much higher efficiency than klystrons, but they do not have the phase and amplitude control, or the lifetime, needed to drive SRF cavities for superconducting particle accelerators. Existing magnetrons that are typically used to study methods of control or lifetime improvements for SRF accelerators are built for much different applications such as kitchen microwave ovens (1kW, 2.45 GHz) or industrial heating (100 kW, 915 MHz). Muons, Inc. is working with Richardson Electronics LLC to develop fast and flexible manufacturing techniques to allow many ideas to be tested for construction variations that enable new phase and amplitude injection locking control methods, longer lifetime, and inexpensive refurbishing resulting in the lowest possible life-cycle costs. A magnetron suitable for 1497 MHz klystron replacements at Jefferson Lab has been designed, constructed, and tested.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-TUPOPA30
About •	Received ※ 16 August 2022 — Revised ※ 26 August 2022 — Accepted ※ 29 August 2022 — Issue date ※ 01 September 2022
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Paper

Title

Page

Status and RF Devopments of ESS Bilbao RFQ

410

N. Garmendia, I. Bustinduy, A. Conde, P.J. González, A. Kaftoosian, J. Martin, S. Masa, J.L. Munozpresenter, Á. Rodríguez Páramo
ESS Bilbao, Zamudio, Spain

Within the framework of the plans for study of a light-ion linear accelerator, ESS Bilbao is manufacturing a radio frequency quadrupole (RFQ) aimed at accelerating up to 3 MeV the protons generated in the ion source. The progress made and the difficulties encountered with the RFQ are discussed in this paper. A power coupler proto-type for the RFQ has been developed while several me-chanical constraints were also studied in the final cou-pler. This prototype operates at a lower power, then it can work using PEEK window for the vacuum interface and it does not require neither brazing nor cooling system. Also, a complete RF test stand is being implemented to perform the high-power conditioning in traveling and standing wave mode, to verify the power handling capa-bility of the coupler and its thermal behaviour. The RF test stand, based on EPICS environment, can provide up to 2 MW peak power at 352.2 MHz in a pulse operation of 14 Hz and a duty cycle of 4.9%.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-TUPOPA03

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Received ※ 09 August 2022 — Revised ※ 28 August 2022 — Accepted ※ 30 August 2022 — Issue date ※ 02 September 2022

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TUPOPA04

First Beam Matching and Transmission Studies on the ESS RFQ

414

D. Noll, R.A. Baron, C.S. Derrez, E.M. Donegani, M. Eshraqi, F. Grespan, H. Hassanzadegan, B. Jones, Y. Levinsen, N. Milas, R. Miyamoto, D.C. Plostinar, A.G. Sosa, R. Zeng
ESS, Lund, Sweden
A.C. Chauveau, O. Piquet
CEA-IRFU, Gif-sur-Yvette, France

The European Spallation Source will be driven by a 5 MW linear accelerator, producing 2.86 ms long proton beam pulses with a peak current of 62.5 mA at 14 Hz. Following the source commissioning in 2018 and 2019, the RFQ was successfully conditioned and subsequently commissioned with beam in 2021. In this paper, we will present results of studies on beam matching to the RFQ, both for low and high current beam modes, and will compare these results to model predictions.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-TUPOPA04

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Received ※ 26 August 2022 — Accepted ※ 05 September 2022 — Issue date ※ 05 September 2022

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TUPOPA05

RFQ Performance During RF Conditioning and Beam Commissioning at ESS

418

R. Zeng, G.S. Fedel, B. Jones, R. Miyamoto, D.J.P. Nicosia, D. Noll, A.G. Sosa, A.M. Svensson, E. Trachanas
ESS, Lund, Sweden
M. Baudrier
CEA-DRF-IRFU, France
A.C. Chauveau, M.J. Desmons, P. Hamel, O. Piquet
CEA-IRFU, Gif-sur-Yvette, France
F. Grespan
INFN/LNL, Legnaro (PD), Italy

RFQ at ESS has been successfully gone through RF conditioning, RF re-conditioning and low duty cycle beam commissioning. RFQ fulfills required functions and overall performance is satisfactory. RF conditioning, three RF re-conditionings after LEBT intervention and beam commissioning will be reported and RFQ performance during these periods will be described. RFQ performance in a large extent is reflected by dynamics and interactions between RF, cavity and beam. Thanks to advanced hardware capabilities and intelligent software intelligence, observation of those dynamics and interactions are done in detailed level. Analysis of those dynamics and interaction will be introduced. Some techniques to deal with challenges resulted from those dynamics and interactions will also be discussed.

Poster TUPOPA05 [25.281 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-TUPOPA05

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Received ※ 18 August 2022 — Revised ※ 25 August 2022 — Accepted ※ 31 August 2022 — Issue date ※ 05 September 2022

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TUPOPA06

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

422

SUPCJO06

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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]

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

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

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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. Pommerenkepresenter
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

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

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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

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

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TUPOPA11

Compact Proton Accelerator in UHF Band At KAHVELab

434

SUPCGE07

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

S. Esen, A. Adiguzel, O. Kocer, S. Oz
Istanbul University, Istanbul, Turkey
A. Caglar
YTU, Istanbul, Turkey
E. Celebi, E.V. Ozcan
Bogazici University, Bebek / Istanbul, Turkey
E. Celebi
IBU, Istanbul, Turkey
A.K. Karatay, F. Yaman, Ö.H. Yilmaz
IZTECH, Izmir, Turkey
U. Kaya
Istinye University, Institute of Sciences, Istanbul, Turkey
A. Kilicgedik
Marmara University, Istanbul, Turkey
G. Türemen
Turkish Atomic Energy Authority, Ankara, Turkey
G. Unel
UCI, Irvine, California, USA

Funding: This project are supported by TUBITAK Project no: 118E838
Proton Test Beam at KahveLAB (Kandilli Detector, Accelerator and Instrumentation Laboratory) project aims to design and produce a radio frequency quadrupole (RFQ) operating at 800 MHz in Istanbul, Turkey using the local resources. The beamline consists of a proton source, a low energy beam transport (LEBT) line including the beam diagnostic section, and the RFQ cavity itself. This RFQ is a 4-vane, 1-meter-long cavity to accelerate the 20 keV beam extracted from the plasma ion source to 2 MeV. Its engineering prototype is already produced and subjected to mechanical, low-power RF, and vacuum tests. In this poster, the results of the first test production, especially the bead-pull test setup will be discussed.

Poster TUPOPA11 [16.128 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-TUPOPA11

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Received ※ 21 August 2022 — Revised ※ 22 August 2022 — Accepted ※ 12 September 2022 — Issue date ※ 26 September 2022

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TUPOPA12

RF Measurements and Tuning of the Test Module of 800 MHz Radio-Frequency Quadrupole

438

SUPCGE02

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A. Kilicgedik
Marmara University, Istanbul, Turkey
A. Adiguzel, S. Esen
Istanbul University, Istanbul, Turkey
B. Baran
Ankara University, Faculty of Sciences, Ankara, Turkey
A. Caglar
YTU, Istanbul, Turkey
E. Celebi, E.V. Ozcan
Bogazici University, Bebek / Istanbul, Turkey
U. Kaya
Istinye University, Institute of Sciences, Istanbul, Turkey
G. Türemen
TENMAK-NUKEN, Ankara, Turkey
G. Unel
UCI, Irvine, California, USA
F. Yaman
IZTECH, Izmir, Turkey

Funding: This project are supported by The Scientific and Technological Research Council of Turkey (TUBITAK) Project no: 118E838
The 800 MHz RFQ (radio-frequency quadrupole), developed and built at KAHVElab (Kandilli Detector, Accelerator and Instrumentation Laboratory) at Bogazici University in Istanbul, Turkey, has been designed to provide protons that have an energy of 2 MeV within only 1 m length. The RFQ consists of two modules and the test module of RFQ was constructed. The algorithm developed by CERN, based on the measurements generated by the tuner settings estimated through the response matrix [1,2,3], has been optimized for a single module and 16 tuners. The desired field consistent with the simulation was obtained by bead pull measurements. In this study, we present low-power rf measurements and field tuning of the test module.
[1] Koubek, B., et al., PHY. REV. ACC. AND BEAMS 20,08010(2017)
[2] Koubek, B., et al., CERN-2017-0006,(2017)
[3] Pommerenke, Hermann W., et al., Nuc. Inst. and Meth. in Phy. Res. Sec.A),165564(2021)

Poster TUPOPA12 [1.699 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-TUPOPA12

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Received ※ 24 August 2022 — Revised ※ 27 August 2022 — Accepted ※ 31 August 2022 — Issue date ※ 02 September 2022

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TUPOPA13

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

441

SUPCJO07

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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]

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

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

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TUPOPA15

Multipactor Studies: Simulations and Measurements on the RF Coaxial Resonator Test Bench

445

Y. Gómez Martínez, J. Angot, M.A. Baylac, T. Cabanel, M. Meyerpresenter
LPSC, Grenoble Cedex, France
D. Longuevergne, G. Sattonnay
Université Paris-Saclay, CNRS/IN2P3, IJCLab, Orsay, France

Multipactor is an undesired phenomenon triggered by electromagnetic fields in accelerator components and more specifically in RF structures, such as accelerating cavities and power couplers, and may lead to Electron Cloud build up in beam tubes. The accelerator group at LPSC has developed an experimental setup dedicated to multipactor studies. It consists in a coaxial resonator, tunable and operational between 100 MHz and 1 GHz. It allows to characterize under real conditions the efficiency of surface treatment mitigation processes (coatings, cleaning procedures) at room temperature. This paper presents the experimental measurements performed with this setup confronted to simulations.

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-TUPOPA15

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Received ※ 12 August 2022 — Revised ※ 30 August 2022 — Accepted ※ 01 September 2022 — Issue date ※ 16 September 2022

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TUPOPA16

Complete Study of the Multipactor Phenomenon for the MYRRHA 80 kW CW RF Couplers

448

Y. Gómez Martínez, P.-O. Dumont, M. Meyerpresenter
LPSC, Grenoble Cedex, France
P. Duchesne, C. Joly, W. Kaabi
Université Paris-Saclay, CNRS/IN2P3, IJCLab, Orsay, France

MYRRHA [1] (Multi Purpose Hybrid Reactor for High Tech Applications) is an Accelerator Driven System (ADS) project. Its superconducting linac will provide a 600 MeV - 4 mA proton beam. The first project phase based on a 100 MeV linac is launched. The Radio-Frequency (RF) couplers have been designed to handle 80 kW CW (Continuous Wave) at 352.2 MHz. This paper describes the multipacting studies on couplers.

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-TUPOPA16

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Received ※ 12 August 2022 — Revised ※ 22 August 2022 — Accepted ※ 01 September 2022 — Issue date ※ 05 September 2022

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TUPOPA17

Solving the USB Communication Problem of the High-Voltage Modulator Control System in the European XFEL

451

M. Bousonville, S. Choroba, T. Grevsmühl, S. Göller, A. Hauberg, T. Weinhausen
DESY, Hamburg, Germany

Since the commissioning of the modulators in the European XFEL in 2016, it happened from time to time that the modulator control system hung up. The reason for the problem was unknown at that time. Initially, the MTBF (Mean Time Between Failure) was 10⁴ days, which was so rare that other problems with the RF system clearly dominated and were addressed first. Over the next 2 years, the error became more frequent and occurred on average every 18 days. After the winter shutdown of the XFEL in 2020, the problem became absolutely dominant, with an MTBF of 2 days. Therefore, the fault was investigated with top priority and was finally identified. Two units of the control electronics communicate via USB 2.0 with the main server. Using special measurement technology, it was possible to prove that weak signal levels in the USB signal led to bit errors and thus to the crash of the control electronics. This article describes the troubleshooting process, how to measure the signal quality of USB signals and how the problem was solved in the end.

Poster TUPOPA17 [6.650 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-TUPOPA17

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Received ※ 22 August 2022 — Revised ※ 19 August 2022 — Accepted ※ 29 August 2022 — Issue date ※ 15 September 2022

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TUPOPA18

Test and Commissioning of the HELIAC Power Coupler

454

J. List, K. Aulenbacher, W.A. Barth, M. Basten, C. Burandt, F.D. Dziubapresenter, V. Gettmann, T. Kürzeder, S. Lauber, M. Miski-Oglu, S. Yaramyshev
HIM, Mainz, Germany
K. Aulenbacher, W.A. Barth, F.D. Dziubapresenter, S. Lauber, J. List
KPH, Mainz, Germany
K. Aulenbacher, W.A. Barth, M. Basten, C. Burandt, F.D. Dziubapresenter, V. Gettmann, T. Kürzeder, S. Lauber, J. List, M. Miski-Oglu, S. Yaramyshev
GSI, Darmstadt, Germany
T. Conrad, H. Podlech, M. Schwarz
IAP, Frankfurt am Main, Germany

The superconducting continuous wave (cw) heavy ion HElmholtz LInear ACcelerator (HELIAC) is intended to be built at GSI in Darmstadt. With its high average beam current and repetition rate, the HELIAC is designed to fulfill the requirements of the super heavy element (SHE) research user program and the material sciences community at GSI. The accelerating cavities are of the superconducting Crossbar H-mode (CH) type, developed by GUF. Within the Advanced Demonstrator project, the first cryomodule, consisting of four cavities is scheduled for commissioning with beam in 2023. The former RF power couplers introduced a high heat input into the cryostat. Therefore, the coupler is redesigned at HIM in order to not only reduce the heat input but to provide an overall improved power coupler for the HELIAC. It is designed for maximal power of 5 kW cw at the frequency of 216.816 MHz. A prototype has been tested and commissioned recently. This includes several RF-tests at room temperature and in cryogenic environments. The results of these tests will be presented in this paper.

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-TUPOPA18

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Received ※ 20 August 2022 — Revised ※ 21 August 2022 — Accepted ※ 30 August 2022 — Issue date ※ 01 September 2022

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TUPOPA24

Design of an X-Band Bunching and Accelerating System for AWAKE Run 2

458

J.M. Arnesano, S. Döbert
CERN, Meyrin, Switzerland

The AWAKE experiment at CERN demonstrated in its Run 1 that it is possible to accelerate electrons in plasma wakefields driven by a self-modulated proton bunch. In Run2, AWAKE aims to increase the accelerating gradient in the plasma even further and demonstrate beam quality in order to be ready for high-energy physics experiments. In this framework, a new electron injector, consisting of an S-band RF-gun and a subsequent X-band bunching and accelerating section, capable of producing very short bunches with a small emittance, has been designed. In this paper, two different configurations of the X-band section and their corresponding high-power distribution systems are presented. The first one consists of three identical cavities to bunch and accelerate the beam while the second one uses a separate short structure for velocity bunching followed by three long, pure accelerating structures. A discussion of the strengths and weaknesses of each configuration is carried out and beam dynamics aspects are analyzed. Finally the X-Band power distribution systems are described with particular attention to the choice of the klystron, the pulse compression system and the waveguide distribution.

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-TUPOPA24

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Received ※ 12 August 2022 — Revised ※ 21 August 2022 — Accepted ※ 01 September 2022 — Issue date ※ 16 September 2022

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TUPOPA25

Design, Manufacturing, Assembly, Testing, and Lessons Learned of the Prototype 650 MHz Couplers

462

J. Helsper, S.K. Chandrasekaran, F. Furuta, B.M. Hanna, S. Kazakov, J.P. Ozelis, K.S. Premo, N. Solyak, G. Wu
Fermilab, Batavia, Illinois, USA

Funding: Work supported, in part, by the U.S. Department of Energy, Office of Science, Office of High Energy Physics, under U.S. DOE Contract No. DE-AC02-07CH11359.
Six 650 MHz high-power couplers will be integrated into the prototype High Beta 650 MHz (HB650) cryomodule for the PIP-II project at Fermilab. The design of the coupler is described, including design optimizations from the previous generation. This paper then describes the coupler life-cycle, including manufacturing, assembly, testing, conditioning and the lessons learned at each stage.

Poster TUPOPA25 [2.695 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-TUPOPA25

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Received ※ 24 August 2022 — Revised ※ 25 August 2022 — Accepted ※ 29 August 2022 — Issue date ※ 02 September 2022

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TUPOPA27

Conceptual Analysis of a Compact High Efficiency Klystron

466

J.P. Edelen, S.D. Webb
RadiaSoft LLC, Boulder, Colorado, USA
K.E. Nichols
LANL, Los Alamos, New Mexico, USA

Traditional klystron efficiencies are limited by the output electron beam harmonic current and energy spread. Increasing the amount of harmonic current produced in the klystron requires increasing the velocity bunching in the input cavity. Additional cavities may be used to improve the bunching, however they do so at additional cost and space requirements for the klystron. Moreover, at higher currents space charge counteracts this velocity bunching reducing the amount of harmonic current that can be produced. Our concept resolves these challenges by employing a new type of high-efficiency, multi-beam klystron. Our design consists of a single two-frequency input cavity, a wiggler, and an output cavity. The two-frequency input cavity approximates a linear function in time thereby increasing the harmonic content of the beam, while the wiggler provides strong longitudinal focusing to mitigate the effects of space charge. In this paper we provide the theoretical foundation for our design and present initial numerical calculations showing improved bunching from the harmonic mode and the wiggler.

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-TUPOPA27

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Received ※ 14 August 2022 — Revised ※ 24 August 2022 — Accepted ※ 30 August 2022 — Issue date ※ 31 August 2022

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TUPOPA29

Design Enhancements for the SNS RFQ Coaxial Coupler

469

G.D. Toby, C.N. Barbier, Y.W. Kang, S.W. Lee, J.S. Moss
ORNL, Oak Ridge, Tennessee, USA
A.H. Narayan
ORNL RAD, Oak Ridge, Tennessee, USA

Funding: ORNL is managed by UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. Department of Energy. This research was supported by the DOE Office of Science, Basic Energy Science.
The H⁻ ion linear accelerator at the Spallation Neutron Source (SNS) at Oak Ridge National Laboratory operates with reliability that routinely surpasses 90% during scheduled beam operation. With the ambitious goal of eventually achieving at least 95% availability, several upgrade and improvement projects are ongoing. One such project is the modification of the coaxial couplers that transfer radio frequency (RF) power to the accelerator’s Radio Frequency Quadrupole (RFQ). The proposed modification utilizes stub sections and capacitive coupling to construct a physically separable assembly with DC isolation. With a separated coupler assembly, the section that includes the magnetic coupling loop can be permanently mounted to the RFQ which would eliminate the need to re-adjust the couplers after maintenance activities, upgrades, and repairs. Additionally, the modified design would provide increased multipaction suppression with DC biasing and potentially lower thermal gradients across the device. This paper presents the design and simulation results of the project.

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-TUPOPA29

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Received ※ 23 August 2022 — Revised ※ 29 August 2022 — Accepted ※ 30 August 2022 — Issue date ※ 01 September 2022

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TUPOPA30

Innovative Magnetron Power Sources for SRF Linacs

473

TUOPA05

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M. Popovic, M.A. Cummings, A. Dudas, R.P. Johnson, R.R. Lentz, M.L. Neubauer, T. Wynn
Muons, Inc, Illinois, USA
T. Blassick, J.K. Wessel
Richardson Electronics Ltd, Lafox, Illinois, USA
K. Jordan, R.A. Rimmer, H. Wang
JLab, Newport News, Virginia, USA

Funding: Supported in part by US Department of Energy Nuclear Physics SBIR Grant DE-SC0022484
Magnetron RF power sources for single cavities can cost much less and operate at much higher efficiency than klystrons, but they do not have the phase and amplitude control, or the lifetime, needed to drive SRF cavities for superconducting particle accelerators. Existing magnetrons that are typically used to study methods of control or lifetime improvements for SRF accelerators are built for much different applications such as kitchen microwave ovens (1kW, 2.45 GHz) or industrial heating (100 kW, 915 MHz). Muons, Inc. is working with Richardson Electronics LLC to develop fast and flexible manufacturing techniques to allow many ideas to be tested for construction variations that enable new phase and amplitude injection locking control methods, longer lifetime, and inexpensive refurbishing resulting in the lowest possible life-cycle costs. A magnetron suitable for 1497 MHz klystron replacements at Jefferson Lab has been designed, constructed, and tested.

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-TUPOPA30

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Received ※ 16 August 2022 — Revised ※ 26 August 2022 — Accepted ※ 29 August 2022 — Issue date ※ 01 September 2022

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