IPAC2022 - List of Keywords (cryogenics)

Paper	Title	Other Keywords	Page
TUOXSP1	Origin and Mitigation of the Beam-Induced Surface Modifications of the LHC Beam Screens	electron, radiation, ECR, MMI	780
	V. Petit, P. Chiggiato, M. Himmerlich, S. Marinoni, H. Neupert, M. Taborelli, L.J. Tavian CERN, Meyrin, Switzerland
	All over Run 2, the LHC beam-induced heat load on the cryogenic system exhibited a wide scattering along the ring. Studies ascribed the heat source to electron cloud build-up, indicating an unexpected high Secondary Electron Yield (SEY) of the beam screen surface in some LHC regions. The inner copper surface of high and low heat load beam screens, extracted during the Long Shutdown 2, was analysed. On the low heat load ones, the surface was covered with the native Cu2O oxide, while on the high heat load ones CuO dominated at surface, and it exhibited a very low carbon coverage. Such chemical modifications increase the SEY and inhibit a proper conditioning of the affected surfaces. Following this characterisation, the mechanisms for CuO build-up in the LHC beam pipe were investigated on a newly commissioned cryogenic system allowing electron irradiation, surface chemical characterisation by X-ray Photoelectron Spectroscopy and SEY measurements on samples held below 15 K. In parallel, curative solutions against the presence of CuO in the LHC beam screens were explored, which could be implemented in-situ to recover a proper conditioning and lower the beam-induced heat load.
	Slides TUOXSP1 [2.669 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-TUOXSP1
About •	Received ※ 17 May 2022 — Revised ※ 10 June 2022 — Accepted ※ 17 June 2022 — Issue date ※ 05 July 2022
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TUPOST014	Sirius Storage Ring RF System Status Update	cavity, LLRF, operation, storage-ring	872
	A.P.B. Lima, D. Daminelli, M. Hoffmann Wallner, F.K.G. Hoshino LNLS, Campinas, Brazil I. Carvalho de Almeida, R.H.A. Farias CNPEM, Campinas, SP, Brazil
	Sirius’s nominal operation phase consists of two 500 MHz CESR-B type superconducting cavities, each being driven by four 65 kW solid-state amplifiers, and a passive superconducting third harmonic cavity. Currently a normal conducting 7-cell PETRA cavity is being used along with two 65 kW RF amplifiers and was recently able to achieve 100 mA stored current. The performance of the storage ring RF system and the updated installation plans update are presented and discussed.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-TUPOST014
About •	Received ※ 08 June 2022 — Revised ※ 10 June 2022 — Accepted ※ 16 June 2022 — Issue date ※ 23 June 2022
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TUPOTK002	Results of the RF Power Tests of the ESS Cryomodules Tested at CEA	cryomodule, cavity, electron, detector	1186
	O. Piquet, S. Berry, A. Bouygues, E. Cenni, G. Devanz, C. Madec, C. Mayri, P. Sahuquet CEA-DRF-IRFU, France C. Arcambal, Q. Bertrand, P. Bosland, T. Hamelin CEA-IRFU, Gif-sur-Yvette, France M.J. Ellis STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom P. Pierini ESS, Lund, Sweden D. Sertore INFN/LASA, Segrate (MI), Italy
	Eight of the medium and high beta cryomodules deliv-ered to ESS by CEA are tested at CEA before delivery; the two medium and high beta prototypes and the three first of each type of the series. The goal of these tests is to validate the assembly and the performances on few cryomodules before the next cryomodules of the series are delivered to ESS. This paper summarizes the general results obtained during the tests at 2 K and at high RF power, Pmax = 1.1 MW. The cavities reach the ESS re-quirements, E_acc = 16.7 MV/m (Medium beta) and 19.9 MV/m (High beta) with an efficient compensation of the Lorentz detuning by the piezo tuner over the full RF pulse length of 3.6 ms at 14 Hz. After the successful tests at CEA, the first cryomodules have been shipped to ESS where the final acceptance test are performed.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-TUPOTK002
About •	Received ※ 03 June 2022 — Revised ※ 14 June 2022 — Accepted ※ 17 June 2022 — Issue date ※ 21 June 2022
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WEIYSP1	New Designs of Short-Period Undulators for Producing High-Brightness Radiation in Synchrotron Light Sources	undulator, vacuum, radiation, synchrotron	1624
	E.J. Wallén LBNL, Berkeley, California, USA
	We review modern state-of-the-art and new concepts of undulators planned for new generation light sources. Both superconducting and permanent-magnet-based insertion devices feature unique solutions to reach high precisely tunable fields in the period range of 10^-18 mm, 2-4 meters in length and with the ID gaps of less than 5 mm. The same quest for small gaps and shortest possible period length exists also for elliptically polarizing undulators. A review of new designs in Europe, Asia and Americas will be in the focus of this presentation.
	Slides WEIYSP1 [21.171 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEIYSP1
About •	Received ※ 15 June 2022 — Revised ※ 16 June 2022 — Accepted ※ 04 July 2022 — Issue date ※ 07 July 2022
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THPOST027	Fabrication of Robust Thermal Transition Modules and First Cryogenic Experiment with the Refurbished COLDDIAG	vacuum, operation, diagnostics, experiment	2505
	H.J. Cha, N. Glamann, A.W. Grau, A.-S. Müller, D. Saez de Jauregui KIT, Eggenstein-Leopoldshafen, Germany
	Funding: This work is supported by the BMBF project 05H18VKRB1 HIRING (Federal Ministry of Education and Research). Two sets of thermal transition modules as a key component for the COLDDIAG (cold vacuum chamber for beam heat load diagnostics) refurbishment were manufactured, based on the previous design study. The modules are installed in the existing COLDDIAG cryostat and tested with an operating temperature of approximately 50 K at both a cold bore and a thermal shield. This cool-down experiment is a preliminary investigation aiming at beam heat-load studies at the FCC-hh where the beam screens will be operated at almost the same temperature. In this contribution, we report the fabrication processes of the mechanically robust transition modules and the first thermal measurement results with the refurbished COLDDIAG in a cryogenic environment. The static heat load in the refurbished cryostat remains unchanged, compared to that in the former one (4-K cold bore and 50-K shield with thin transitions), despite the increase in the transition thickness. It originates from the identical temperature at the cold bore and the shield, which can theoretically allow the heat intakes by thermal conduction and radiation between them to vanish.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-THPOST027
About •	Received ※ 16 May 2022 — Accepted ※ 13 June 2022 — Issue date ※ 10 July 2022
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THPOST045	Temperature Dependent Effects on RF Surface Resistivity	cavity, electron, experiment, operation	2540
	G.E. Lawler, A. Fukasawa, N. Majernik, J.B. Rosenzweig UCLA, Los Angeles, California, USA
	Funding: This work was supported by DOE Contract DE-SC0020409 A promising future for linear accelerators such as compact free electron lasers and electron positron colliders is higher gradient RF cavities enabled by cryogenic temperature operation. Breakdown rates have been shown empirically to be significantly reduced at low temperatures allowing for higher gradient. The surface physics associated with this observation is complicated and there many remain questions as to the exact phenomena responsible. One major figure of merit that can better inform the theory of breakdown is the RF surface resistivity which can be used to compute for example the RF pulse heating during operation. We then use techniques developed for previous Xband and Sband low power surface resistivity measurement by way of temperature dependent quality factor measurements to study Cband cavities. We first present a review of low temperature effects that may be responsible for the change in surface resistivity at low temperature. We then explain some of the initial measurements of these low power RF quality factor tests and compare them to a review some of the physical phenomena that could determine the low temperature surface effects.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-THPOST045
About •	Received ※ 08 June 2022 — Revised ※ 16 June 2022 — Accepted ※ 17 June 2022 — Issue date ※ 20 June 2022
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THPOST046	CrYogenic Brightness-Optimized Radiofrequency Gun (CYBORG)	cathode, cavity, gun, brightness	2544
	G.E. Lawler, A. Fukasawa, N. Majernik, J.R. Parsons, J.B. Rosenzweig, Y. Sakai, A. Suraj UCLA, Los Angeles, California, USA
	Funding: This work was supported by the Center for Bright Beams, National Science Foundation Grant No. PHY-1549132 and DOE Contract DE-SC0020409 Producing higher brightness beams at the cathode is one of the main focuses for future electron beam applications. For photocathodes operating close to their emission threshold, the cathode lattice temperature begins to dominate the minimum achievable intrinsic emittance. At UCLA, we are designing a radiofrequency (RF) test bed for measuring the temperature dependence of the mean transverse energy (MTE) and quantum efficiency for a number of candidate cathode materials. We intend to quantify the attainable brightness improvements at the cathode from cryogenic operation and establish a proof-of-principle cryogenic RF gun for future studies of a 1.6-cell cryogenic photoinjector for the UCLA ultra compact XFEL concept (UC-XFEL). The test bed will use a C-band 0.5-cell RF gun designed to operate down to 45 K, producing an on-axis accelerating field of 120 MV/m. The cryogenic system uses conduction cooling and a load-lock system is being designed for transport and storage of air-sensitive high brightness cathodes.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-THPOST046
About •	Received ※ 08 June 2022 — Revised ※ 15 June 2022 — Accepted ※ 17 June 2022 — Issue date ※ 01 July 2022
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THPOPT002	Beam Power Deposition on the Cryogenic Permanent Magnet Undulator	simulation, SRF, undulator, impedance	2556
	L.R. Carver, C. Benabderrahmane, P. Brumund, N. Carmignani, J. Chavanne, G. Le Bec, R. Versteegen, S.M. White ESRF, Grenoble, France
	X-rays with high brilliance and low phase errors are generated in the Cryogenic Permanent Magnet Undulator (CPMU) currently in use at the ESRF. In the event of a failure of the cryogenic cooling the beam will continue to deposit power into the module, even when the undulator jaws are fully opened. This could lead to unacceptably high heating of the magnet blocks which could cause their demagnetisation. Impedance simulations were performed using IW2D and CST to compute the power deposited by the beam in both the closed and open jaw settings. This was followed by thermal simulations to compute the expected temperature rise. These results will help advise the operational procedure in the event of a cooling failure.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-THPOPT002
About •	Received ※ 07 June 2022 — Revised ※ 09 June 2022 — Accepted ※ 17 June 2022 — Issue date ※ 27 June 2022
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THPOPT033	Performance Characterisation at Daresbury Laboratory of Cs-Te Photocathodes Grown at CERN	cathode, electron, emittance, vacuum	2653
	L.A.J. Soomary, C.P. Welsch The University of Liverpool, Liverpool, United Kingdom C. Benjamin, H.M. Churn, L.B. Jones, T.C.Q. Noakes STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom C. Benjamin University of Warwick, Coventry, United Kingdom E. Chevallay, V.N. Fedosseev, E. Granados, M. Himmerlich, H. Panuganti CERN, Meyrin, Switzerland L.B. Jones, T.C.Q. Noakes, C.P. Welsch Cockcroft Institute, Warrington, Cheshire, United Kingdom
	Funding: STFC Doctoral Training Studentship The search for high-performance photocathodes is a priority in the field of particle accelerators. The surface characteristics of a photocathode affect many important factors of the photoemission process including the photoemission threshold, the intrinsic emittance and the quantum efficiency. These factors in turn define the electron beam quality, which is measurable using figures of merit like beam emittance, brightness and energy spread. We present characterisation measurements for four caesium telluride photocathodes synthesized at CERN. The photocathodes were transported under ultra-high vacuum (UHV) and analysed at STFC Daresbury Laboratory, using ASTeC’s Multiprobe (SAPI)* for surface characterisation via XPS and STM, and for Mean Transverse Energy (MTE) measurements using the Transverse Energy Spread Spectrometer (TESS)*. The MTE measurements were estimated at cryogenic and room temperatures based on the respective transverse energy distribution curves. We discuss correlations found between the synthesis parameters, and the measured surface characteristics and MTE values. B.L. Militsyn, 4-th EuCARD2 WP12.5 meeting, Warsaw, 14-15 March 2017 **L.B. Jones et al., Proc. FEL ’13, TUPPS033, 290-293; https://accelconf.web.cern.ch/FEL2013/papers/tupso33.pdf
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-THPOPT033
About •	Received ※ 07 June 2022 — Revised ※ 10 June 2022 — Accepted ※ 14 June 2022 — Issue date ※ 05 July 2022
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THPOPT050	Development and Construction of Cryogenic Permanent Magnet Undulators for ESRF-EBS	undulator, SRF, permanent-magnet, vacuum	2712
	C. Benabderrahmane, P. Brumund, J. Chavanne, D. Coulon, G. Le Bec, B. Ogier, R. Versteegen ESRF, Grenoble, France
	The ESRF Extremely Brilliant Source (ESRF-EBS) is on operation for Users since August 2020 after 20 months of shutdown. This first of a kind fourth generation high energy synchrotron is based on a Hybrid Multi-Bend Achromat lattice. The main goal of the ESRF-EBS is to reduce the horizontal emittance, which leads to a signifi-cant increase of the X-ray source brilliance. To cover the intensive demand of short period small gap undulators at ESRF-EBS, a new design for a 2 m Cryogenic Permanent Magnet Undulator (CPMU) has been developed. Six CPMUs will be installed in the next years; the first two CPMUs have been constructed and actually used on ID15 and ID16 beamline, the third one is under con-structing. An intensive refurbishment work has been done on the existing insertion devices to adapt them to the new accelerator which has shorter straight section and closer dipoles to the IDs than in the old one. This contribution will review the development, construc-tion and commissioning of the new CPMUs, and the refurbishment work done on the existing ones to adapt them to the new accelerator.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-THPOPT050
About •	Received ※ 02 June 2022 — Revised ※ 10 June 2022 — Accepted ※ 14 June 2022 — Issue date ※ 18 June 2022
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THPOTK013	Cold Test Results of the FAIR Super-FRS First-of-Series Multiplets and Dipole	quadrupole, dipole, sextupole, octupole	2796
	A. Chiuchiolo, A. Beaumont, E.J. Cho, F. Greiner, P. Kosek, M. Michels, H. Müller, C. Roux, H. Simon, K. Sugita, V. Velonas, F. Wamers, M. Winkler, Y. Xiang GSI, Darmstadt, Germany H. Allain, V. Kleymenov, A. Madur CEA-IRFU, Gif-sur-Yvette, France
	Within the collaboration between GSI and CERN, a dedicated cryogenic test facility has been built at CERN (Geneva, Switzerland) in order to perform the site acceptance tests of the 56 Superconducting FRagment Separator cryomodules before their installation at the the Facility for Antiproton and Ion Research (Darmstadt, Germany). Two of the three benches of the CERN test facility were successfully commissioned with the powering tests of the first-of-series multiplets and dipole. The long multiplet, with a warm bore radius of 192 mm, is composed of nine magnets of different type (quadrupole, sextupole, steering dipole and octupole) assembled with Nb-Ti racetrack and cosine-theta coils, mounted in a cold iron yoke and in a common cryostat. This work presents the first results of the cold powering tests at 4.5 K during which dedicated measurements have been implemented for the magnetic characterization of the single magnets up to nominal current (300 A for a long quadrupole) and the study of their crosstalk effects. The results of the acceptance tests will be presented together with the challenges and lessons learnt during the facility commissioning.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-THPOTK013
About •	Received ※ 08 June 2022 — Revised ※ 14 June 2022 — Accepted ※ 15 June 2022 — Issue date ※ 23 June 2022
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THPOTK022	Cryogenic Infrastructure for the Mainz Energy-Recovering Superconducting Accelerator (MESA)	experiment, target, cryomodule, SRF	2813
	T. Stengler, K. Aulenbacher, F. Hug, P.S. Plattner, D. Simon KPH, Mainz, Germany
	Funding: Work supported by the German Research Foundation (DFG) under the Cluster of Excellence "PRISMA+" EXC 2118/2019 The "Mainz Energy-Recovering Superconducting Accelerator" (MESA), currently under construction at the Institute of Nuclear Physics, Johannes Gutenberg University Mainz, Germany, requires a cryogenic infrastructure for its superconducting components. Prior to the start of the project, a helium liquefier was purchased that is capable of supplying the existing infrastructure of the Institute for Nuclear Physics, as well as the SRF test facility of the Helmholtz Institute. The liquefier has already been purchased in such a way that nitrogen pre-cooling can be integrated and can be upgraded for the operation of MESA. In addition to the superconducting accelerator modules, all components of the P2 experiment, i.e. solenoid, target and polarimeter (hydromoller), must also be supplied with liquid helium. Therefore, besides the upgrade of the liquefier, it is necessary to extend the system with a dedicated cryogenic supply for the P2 target. This paper presents the current status of the cryogenic supply of the MESA accelerator, the future modifications and additions.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-THPOTK022
About •	Received ※ 07 June 2022 — Revised ※ 13 June 2022 — Accepted ※ 16 June 2022 — Issue date ※ 06 July 2022
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THPOTK025	Heat Loads Measurement Methods for the ESS Elliptical Cryomodules SAT at Lund Test Stand	cavity, cryomodule, SRF, ECR	2819
	N. Elias, X.T. Su ESS, Lund, Sweden W. Gaj, P. Halczynski, M. Sienkiewicz, F.D. Skalka IFJ-PAN, Kraków, Poland
	The Site Acceptance Testing of all ESS elliptical cryomodules is done at Lund Test Stand. The cryogenic heat loads (static and dynamic) are an essential part of the acceptance criteria. We present complementary measurement methods for evaluating the cryogenic heat loads and discuss a qualitative comparison between them. We also present a summary of the results of these methods for one of the cryomodules.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-THPOTK025
About •	Received ※ 07 June 2022 — Revised ※ 13 June 2022 — Accepted ※ 16 June 2022 — Issue date ※ 10 July 2022
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THPOTK027	Temperature Dependent Effects on Quality Factor in C-band RF Cavities	cavity, vacuum, shielding, electron	2826
	J.R. Parsons, A. Fukasawa, G.E. Lawler, N. Majernik, J.B. Rosenzweig UCLA, Los Angeles, California, USA
	Funding: This work was supported by DOE Contract DE-SC0020409 Cryogenic operation and associated skin effects are encouraging fields of study for increasing RF gradients of beams within cavities and decreasing the required size for linear accelerators such as free electron lasers. Notably, a cavity’s RF quality factor Q, the ratio of the outgoing RF signal power to the input power, is theoretically multiplied by over 4 when subjected to cryogenic temperatures. Precise measurements of this Q factor require defining a cryostat unit, which consists of a high vacuum chamber, a coldhead, and MLI shielding. We optimized the cryostat by running several cool down tests at high vacuum, incorporating different geometries of MLI shielding to achieve the lowest possible temperatures. We then performed a low power C-band test after installing a cylindrical copper RF cavity to measure the Q factor. Finally, we improved stability and amplification within the chamber by installing edge welded bellows to the coldhead to reduce vibrations. These measurements provide a basis for the development of cryogenic infrastructure to sustain a cryogenic temperature environment for future RF applications.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-THPOTK027
About •	Received ※ 08 June 2022 — Revised ※ 13 June 2022 — Accepted ※ 14 June 2022 — Issue date ※ 27 June 2022
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THPOTK035	Thermo-Mechanical Modeling and Thermal Performance Analysis of Beam Vacuum Line Interconnections and Cold Warm Transitions in HL-LHC Long Straight Section Magnets	luminosity, radiation, vacuum, insertion	2839
	J. Harray, C. Garion, V. Petit CERN, Meyrin, Switzerland
	The HL-LHC upgrade, aiming at increasing the LHC levelled luminosity by factor of five, relies on new superconducting magnets requiring a new beam vacuum system. Along with the challenges related to magnet design, the beam optic configuration exposes this new equipment to stringent conditions for vacuum and cryogenic performance. Both cold-warm transitions and magnet interconnections appear to be delicate components that are crucial for the thermal heat transfer between diverse subsystems. The proposed study aims at assessing the heat loads to the cryogenic system and the temperature fields in the vacuum system. A nonlinear static thermal analysis is first performed. A thermo-mechanical approach is developed to capture additional thermal resistance arising from contact between components and their behaviour during cool-down. The system is then studied under dynamic operations when beams are circulating and colliding. A thorough analysis of beam-induced heat loads under ultimate conditions highlights the different relevant contributions. Finally, the transient response of the systems is computed to assess thermal time constants.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-THPOTK035
About •	Received ※ 08 June 2022 — Revised ※ 11 June 2022 — Accepted ※ 27 June 2022 — Issue date ※ 29 June 2022
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THPOMS052	Magnetic Field Shield for SC-Cavity with Thin Nb Sheet	cavity, niobium, shielding, experiment	3090
	Y. Iwashita, Y. Kuriyama Kyoto University, Research Reactor Institute, Osaka, Japan Y. Fuwa JAEA/J-PARC, Tokai-mura, Japan H. Tongu Kyoto ICR, Uji, Kyoto, Japan
	Funding: This work was partly supported by JSPS KAKENHI Grant Number 19K21877. Shielding the superconducting accelerating cavity made of niobium from the weak environmental magnetic field is an important subject. Niobium is a type-II superconductor, which traps the environmental magnetic flux in the material during the superconducting transition, resulting in increase of residual resistance and heating during operation during operation. Shielding from a weak magnetic field is essential for high performance operations. A magnetic shielding method that uses the diamagnetism of superconducting materials instead of magnetic flux absorption by high magnetic permeability materials is discussed.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-THPOMS052
About •	Received ※ 14 June 2022 — Revised ※ 15 June 2022 — Accepted ※ 16 June 2022 — Issue date ※ 18 June 2022
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FRPLYGD1	Towards Efficient Particle Accelerators - A Review	collider, cavity, radiation, luminosity	3141
	M. Seidel PSI, Villigen PSI, Switzerland
	Sustainability has become an important aspect of all human activities, and also for accelerator driven research infrastructures. For new facilities it is mandatory to optimize power consumption and overall sustainability. This presentation will give an overview of the power efficiency of accelerator concepts and relevant technologies. Conceptual aspects will be discussed for proton driver accelerators, light sources and particle colliders. Several accelerator technologies are particularly relevant for power efficiency. These are utilized across the various facility concepts and include superconducting RF and cryogenic systems, RF sources, energy efficient magnets, conventional cooling and heat recovery. Power efficiency has been a topic in the European programs EUCARD-2, ARIES and the ongoing I.FAST project and the documentation of these programs is a related source of information.
	Slides FRPLYGD1 [4.531 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-FRPLYGD1
About •	Received ※ 07 June 2022 — Revised ※ 12 June 2022 — Accepted ※ 13 June 2022 — Issue date ※ 29 June 2022
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Paper

Title

Other Keywords

Page

TUOXSP1

Origin and Mitigation of the Beam-Induced Surface Modifications of the LHC Beam Screens

electron, radiation, ECR, MMI

780

V. Petit, P. Chiggiato, M. Himmerlich, S. Marinoni, H. Neupert, M. Taborelli, L.J. Tavian
CERN, Meyrin, Switzerland

All over Run 2, the LHC beam-induced heat load on the cryogenic system exhibited a wide scattering along the ring. Studies ascribed the heat source to electron cloud build-up, indicating an unexpected high Secondary Electron Yield (SEY) of the beam screen surface in some LHC regions. The inner copper surface of high and low heat load beam screens, extracted during the Long Shutdown 2, was analysed. On the low heat load ones, the surface was covered with the native Cu2O oxide, while on the high heat load ones CuO dominated at surface, and it exhibited a very low carbon coverage. Such chemical modifications increase the SEY and inhibit a proper conditioning of the affected surfaces. Following this characterisation, the mechanisms for CuO build-up in the LHC beam pipe were investigated on a newly commissioned cryogenic system allowing electron irradiation, surface chemical characterisation by X-ray Photoelectron Spectroscopy and SEY measurements on samples held below 15 K. In parallel, curative solutions against the presence of CuO in the LHC beam screens were explored, which could be implemented in-situ to recover a proper conditioning and lower the beam-induced heat load.

Slides TUOXSP1 [2.669 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-TUOXSP1

About •

Received ※ 17 May 2022 — Revised ※ 10 June 2022 — Accepted ※ 17 June 2022 — Issue date ※ 05 July 2022

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TUPOST014

Sirius Storage Ring RF System Status Update

cavity, LLRF, operation, storage-ring

872

A.P.B. Lima, D. Daminelli, M. Hoffmann Wallner, F.K.G. Hoshino
LNLS, Campinas, Brazil
I. Carvalho de Almeida, R.H.A. Farias
CNPEM, Campinas, SP, Brazil

Sirius’s nominal operation phase consists of two 500 MHz CESR-B type superconducting cavities, each being driven by four 65 kW solid-state amplifiers, and a passive superconducting third harmonic cavity. Currently a normal conducting 7-cell PETRA cavity is being used along with two 65 kW RF amplifiers and was recently able to achieve 100 mA stored current. The performance of the storage ring RF system and the updated installation plans update are presented and discussed.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-TUPOST014

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Received ※ 08 June 2022 — Revised ※ 10 June 2022 — Accepted ※ 16 June 2022 — Issue date ※ 23 June 2022

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TUPOTK002

Results of the RF Power Tests of the ESS Cryomodules Tested at CEA

cryomodule, cavity, electron, detector

1186

O. Piquet, S. Berry, A. Bouygues, E. Cenni, G. Devanz, C. Madec, C. Mayri, P. Sahuquet
CEA-DRF-IRFU, France
C. Arcambal, Q. Bertrand, P. Bosland, T. Hamelin
CEA-IRFU, Gif-sur-Yvette, France
M.J. Ellis
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
P. Pierini
ESS, Lund, Sweden
D. Sertore
INFN/LASA, Segrate (MI), Italy

Eight of the medium and high beta cryomodules deliv-ered to ESS by CEA are tested at CEA before delivery; the two medium and high beta prototypes and the three first of each type of the series. The goal of these tests is to validate the assembly and the performances on few cryomodules before the next cryomodules of the series are delivered to ESS. This paper summarizes the general results obtained during the tests at 2 K and at high RF power, Pmax = 1.1 MW. The cavities reach the ESS re-quirements, E_acc = 16.7 MV/m (Medium beta) and 19.9 MV/m (High beta) with an efficient compensation of the Lorentz detuning by the piezo tuner over the full RF pulse length of 3.6 ms at 14 Hz. After the successful tests at CEA, the first cryomodules have been shipped to ESS where the final acceptance test are performed.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-TUPOTK002

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Received ※ 03 June 2022 — Revised ※ 14 June 2022 — Accepted ※ 17 June 2022 — Issue date ※ 21 June 2022

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WEIYSP1

New Designs of Short-Period Undulators for Producing High-Brightness Radiation in Synchrotron Light Sources

undulator, vacuum, radiation, synchrotron

1624

E.J. Wallén
LBNL, Berkeley, California, USA

We review modern state-of-the-art and new concepts of undulators planned for new generation light sources. Both superconducting and permanent-magnet-based insertion devices feature unique solutions to reach high precisely tunable fields in the period range of 10^-18 mm, 2-4 meters in length and with the ID gaps of less than 5 mm. The same quest for small gaps and shortest possible period length exists also for elliptically polarizing undulators. A review of new designs in Europe, Asia and Americas will be in the focus of this presentation.

Slides WEIYSP1 [21.171 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEIYSP1

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Received ※ 15 June 2022 — Revised ※ 16 June 2022 — Accepted ※ 04 July 2022 — Issue date ※ 07 July 2022

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THPOST027

Fabrication of Robust Thermal Transition Modules and First Cryogenic Experiment with the Refurbished COLDDIAG

vacuum, operation, diagnostics, experiment

2505

H.J. Cha, N. Glamann, A.W. Grau, A.-S. Müller, D. Saez de Jauregui
KIT, Eggenstein-Leopoldshafen, Germany

Funding: This work is supported by the BMBF project 05H18VKRB1 HIRING (Federal Ministry of Education and Research).
Two sets of thermal transition modules as a key component for the COLDDIAG (cold vacuum chamber for beam heat load diagnostics) refurbishment were manufactured, based on the previous design study. The modules are installed in the existing COLDDIAG cryostat and tested with an operating temperature of approximately 50 K at both a cold bore and a thermal shield. This cool-down experiment is a preliminary investigation aiming at beam heat-load studies at the FCC-hh where the beam screens will be operated at almost the same temperature. In this contribution, we report the fabrication processes of the mechanically robust transition modules and the first thermal measurement results with the refurbished COLDDIAG in a cryogenic environment. The static heat load in the refurbished cryostat remains unchanged, compared to that in the former one (4-K cold bore and 50-K shield with thin transitions), despite the increase in the transition thickness. It originates from the identical temperature at the cold bore and the shield, which can theoretically allow the heat intakes by thermal conduction and radiation between them to vanish.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-THPOST027

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Received ※ 16 May 2022 — Accepted ※ 13 June 2022 — Issue date ※ 10 July 2022

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THPOST045

Temperature Dependent Effects on RF Surface Resistivity

cavity, electron, experiment, operation

2540

G.E. Lawler, A. Fukasawa, N. Majernik, J.B. Rosenzweig
UCLA, Los Angeles, California, USA

Funding: This work was supported by DOE Contract DE-SC0020409
A promising future for linear accelerators such as compact free electron lasers and electron positron colliders is higher gradient RF cavities enabled by cryogenic temperature operation. Breakdown rates have been shown empirically to be significantly reduced at low temperatures allowing for higher gradient. The surface physics associated with this observation is complicated and there many remain questions as to the exact phenomena responsible. One major figure of merit that can better inform the theory of breakdown is the RF surface resistivity which can be used to compute for example the RF pulse heating during operation. We then use techniques developed for previous Xband and Sband low power surface resistivity measurement by way of temperature dependent quality factor measurements to study Cband cavities. We first present a review of low temperature effects that may be responsible for the change in surface resistivity at low temperature. We then explain some of the initial measurements of these low power RF quality factor tests and compare them to a review some of the physical phenomena that could determine the low temperature surface effects.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-THPOST045

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Received ※ 08 June 2022 — Revised ※ 16 June 2022 — Accepted ※ 17 June 2022 — Issue date ※ 20 June 2022

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THPOST046

CrYogenic Brightness-Optimized Radiofrequency Gun (CYBORG)

cathode, cavity, gun, brightness

2544

G.E. Lawler, A. Fukasawa, N. Majernik, J.R. Parsons, J.B. Rosenzweig, Y. Sakai, A. Suraj
UCLA, Los Angeles, California, USA

Funding: This work was supported by the Center for Bright Beams, National Science Foundation Grant No. PHY-1549132 and DOE Contract DE-SC0020409
Producing higher brightness beams at the cathode is one of the main focuses for future electron beam applications. For photocathodes operating close to their emission threshold, the cathode lattice temperature begins to dominate the minimum achievable intrinsic emittance. At UCLA, we are designing a radiofrequency (RF) test bed for measuring the temperature dependence of the mean transverse energy (MTE) and quantum efficiency for a number of candidate cathode materials. We intend to quantify the attainable brightness improvements at the cathode from cryogenic operation and establish a proof-of-principle cryogenic RF gun for future studies of a 1.6-cell cryogenic photoinjector for the UCLA ultra compact XFEL concept (UC-XFEL). The test bed will use a C-band 0.5-cell RF gun designed to operate down to 45 K, producing an on-axis accelerating field of 120 MV/m. The cryogenic system uses conduction cooling and a load-lock system is being designed for transport and storage of air-sensitive high brightness cathodes.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-THPOST046

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Received ※ 08 June 2022 — Revised ※ 15 June 2022 — Accepted ※ 17 June 2022 — Issue date ※ 01 July 2022

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THPOPT002

Beam Power Deposition on the Cryogenic Permanent Magnet Undulator

simulation, SRF, undulator, impedance

2556

L.R. Carver, C. Benabderrahmane, P. Brumund, N. Carmignani, J. Chavanne, G. Le Bec, R. Versteegen, S.M. White
ESRF, Grenoble, France

X-rays with high brilliance and low phase errors are generated in the Cryogenic Permanent Magnet Undulator (CPMU) currently in use at the ESRF. In the event of a failure of the cryogenic cooling the beam will continue to deposit power into the module, even when the undulator jaws are fully opened. This could lead to unacceptably high heating of the magnet blocks which could cause their demagnetisation. Impedance simulations were performed using IW2D and CST to compute the power deposited by the beam in both the closed and open jaw settings. This was followed by thermal simulations to compute the expected temperature rise. These results will help advise the operational procedure in the event of a cooling failure.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-THPOPT002

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Received ※ 07 June 2022 — Revised ※ 09 June 2022 — Accepted ※ 17 June 2022 — Issue date ※ 27 June 2022

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THPOPT033

Performance Characterisation at Daresbury Laboratory of Cs-Te Photocathodes Grown at CERN

cathode, electron, emittance, vacuum

2653

L.A.J. Soomary, C.P. Welsch
The University of Liverpool, Liverpool, United Kingdom
C. Benjamin, H.M. Churn, L.B. Jones, T.C.Q. Noakes
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
C. Benjamin
University of Warwick, Coventry, United Kingdom
E. Chevallay, V.N. Fedosseev, E. Granados, M. Himmerlich, H. Panuganti
CERN, Meyrin, Switzerland
L.B. Jones, T.C.Q. Noakes, C.P. Welsch
Cockcroft Institute, Warrington, Cheshire, United Kingdom

Funding: STFC Doctoral Training Studentship
The search for high-performance photocathodes is a priority in the field of particle accelerators. The surface characteristics of a photocathode affect many important factors of the photoemission process including the photoemission threshold, the intrinsic emittance and the quantum efficiency. These factors in turn define the electron beam quality, which is measurable using figures of merit like beam emittance, brightness and energy spread. We present characterisation measurements for four caesium telluride photocathodes synthesized at CERN. The photocathodes were transported under ultra-high vacuum (UHV) and analysed at STFC Daresbury Laboratory, using ASTeC’s Multiprobe (SAPI)* for surface characterisation via XPS and STM, and for Mean Transverse Energy (MTE) measurements using the Transverse Energy Spread Spectrometer (TESS)**. The MTE measurements were estimated at cryogenic and room temperatures based on the respective transverse energy distribution curves. We discuss correlations found between the synthesis parameters, and the measured surface characteristics and MTE values.
*B.L. Militsyn, 4-th EuCARD2 WP12.5 meeting, Warsaw, 14-15 March 2017
**L.B. Jones et al., Proc. FEL ’13, TUPPS033, 290-293; https://accelconf.web.cern.ch/FEL2013/papers/tupso33.pdf

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-THPOPT033

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Received ※ 07 June 2022 — Revised ※ 10 June 2022 — Accepted ※ 14 June 2022 — Issue date ※ 05 July 2022

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THPOPT050

Development and Construction of Cryogenic Permanent Magnet Undulators for ESRF-EBS

undulator, SRF, permanent-magnet, vacuum

2712

C. Benabderrahmane, P. Brumund, J. Chavanne, D. Coulon, G. Le Bec, B. Ogier, R. Versteegen
ESRF, Grenoble, France

The ESRF Extremely Brilliant Source (ESRF-EBS) is on operation for Users since August 2020 after 20 months of shutdown. This first of a kind fourth generation high energy synchrotron is based on a Hybrid Multi-Bend Achromat lattice. The main goal of the ESRF-EBS is to reduce the horizontal emittance, which leads to a signifi-cant increase of the X-ray source brilliance. To cover the intensive demand of short period small gap undulators at ESRF-EBS, a new design for a 2 m Cryogenic Permanent Magnet Undulator (CPMU) has been developed. Six CPMUs will be installed in the next years; the first two CPMUs have been constructed and actually used on ID15 and ID16 beamline, the third one is under con-structing. An intensive refurbishment work has been done on the existing insertion devices to adapt them to the new accelerator which has shorter straight section and closer dipoles to the IDs than in the old one. This contribution will review the development, construc-tion and commissioning of the new CPMUs, and the refurbishment work done on the existing ones to adapt them to the new accelerator.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-THPOPT050

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Received ※ 02 June 2022 — Revised ※ 10 June 2022 — Accepted ※ 14 June 2022 — Issue date ※ 18 June 2022

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THPOTK013

Cold Test Results of the FAIR Super-FRS First-of-Series Multiplets and Dipole

quadrupole, dipole, sextupole, octupole

2796

A. Chiuchiolo, A. Beaumont, E.J. Cho, F. Greiner, P. Kosek, M. Michels, H. Müller, C. Roux, H. Simon, K. Sugita, V. Velonas, F. Wamers, M. Winkler, Y. Xiang
GSI, Darmstadt, Germany
H. Allain, V. Kleymenov, A. Madur
CEA-IRFU, Gif-sur-Yvette, France

Within the collaboration between GSI and CERN, a dedicated cryogenic test facility has been built at CERN (Geneva, Switzerland) in order to perform the site acceptance tests of the 56 Superconducting FRagment Separator cryomodules before their installation at the the Facility for Antiproton and Ion Research (Darmstadt, Germany). Two of the three benches of the CERN test facility were successfully commissioned with the powering tests of the first-of-series multiplets and dipole. The long multiplet, with a warm bore radius of 192 mm, is composed of nine magnets of different type (quadrupole, sextupole, steering dipole and octupole) assembled with Nb-Ti racetrack and cosine-theta coils, mounted in a cold iron yoke and in a common cryostat. This work presents the first results of the cold powering tests at 4.5 K during which dedicated measurements have been implemented for the magnetic characterization of the single magnets up to nominal current (300 A for a long quadrupole) and the study of their crosstalk effects. The results of the acceptance tests will be presented together with the challenges and lessons learnt during the facility commissioning.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-THPOTK013

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Received ※ 08 June 2022 — Revised ※ 14 June 2022 — Accepted ※ 15 June 2022 — Issue date ※ 23 June 2022

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THPOTK022

Cryogenic Infrastructure for the Mainz Energy-Recovering Superconducting Accelerator (MESA)

experiment, target, cryomodule, SRF

2813

T. Stengler, K. Aulenbacher, F. Hug, P.S. Plattner, D. Simon
KPH, Mainz, Germany

Funding: Work supported by the German Research Foundation (DFG) under the Cluster of Excellence "PRISMA+" EXC 2118/2019
The "Mainz Energy-Recovering Superconducting Accelerator" (MESA), currently under construction at the Institute of Nuclear Physics, Johannes Gutenberg University Mainz, Germany, requires a cryogenic infrastructure for its superconducting components. Prior to the start of the project, a helium liquefier was purchased that is capable of supplying the existing infrastructure of the Institute for Nuclear Physics, as well as the SRF test facility of the Helmholtz Institute. The liquefier has already been purchased in such a way that nitrogen pre-cooling can be integrated and can be upgraded for the operation of MESA. In addition to the superconducting accelerator modules, all components of the P2 experiment, i.e. solenoid, target and polarimeter (hydromoller), must also be supplied with liquid helium. Therefore, besides the upgrade of the liquefier, it is necessary to extend the system with a dedicated cryogenic supply for the P2 target. This paper presents the current status of the cryogenic supply of the MESA accelerator, the future modifications and additions.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-THPOTK022

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Received ※ 07 June 2022 — Revised ※ 13 June 2022 — Accepted ※ 16 June 2022 — Issue date ※ 06 July 2022

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THPOTK025

Heat Loads Measurement Methods for the ESS Elliptical Cryomodules SAT at Lund Test Stand

cavity, cryomodule, SRF, ECR

2819

N. Elias, X.T. Su
ESS, Lund, Sweden
W. Gaj, P. Halczynski, M. Sienkiewicz, F.D. Skalka
IFJ-PAN, Kraków, Poland

The Site Acceptance Testing of all ESS elliptical cryomodules is done at Lund Test Stand. The cryogenic heat loads (static and dynamic) are an essential part of the acceptance criteria. We present complementary measurement methods for evaluating the cryogenic heat loads and discuss a qualitative comparison between them. We also present a summary of the results of these methods for one of the cryomodules.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-THPOTK025

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Received ※ 07 June 2022 — Revised ※ 13 June 2022 — Accepted ※ 16 June 2022 — Issue date ※ 10 July 2022

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THPOTK027

Temperature Dependent Effects on Quality Factor in C-band RF Cavities

cavity, vacuum, shielding, electron

2826

J.R. Parsons, A. Fukasawa, G.E. Lawler, N. Majernik, J.B. Rosenzweig
UCLA, Los Angeles, California, USA

Funding: This work was supported by DOE Contract DE-SC0020409
Cryogenic operation and associated skin effects are encouraging fields of study for increasing RF gradients of beams within cavities and decreasing the required size for linear accelerators such as free electron lasers. Notably, a cavity’s RF quality factor Q, the ratio of the outgoing RF signal power to the input power, is theoretically multiplied by over 4 when subjected to cryogenic temperatures. Precise measurements of this Q factor require defining a cryostat unit, which consists of a high vacuum chamber, a coldhead, and MLI shielding. We optimized the cryostat by running several cool down tests at high vacuum, incorporating different geometries of MLI shielding to achieve the lowest possible temperatures. We then performed a low power C-band test after installing a cylindrical copper RF cavity to measure the Q factor. Finally, we improved stability and amplification within the chamber by installing edge welded bellows to the coldhead to reduce vibrations. These measurements provide a basis for the development of cryogenic infrastructure to sustain a cryogenic temperature environment for future RF applications.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-THPOTK027

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Received ※ 08 June 2022 — Revised ※ 13 June 2022 — Accepted ※ 14 June 2022 — Issue date ※ 27 June 2022

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THPOTK035

Thermo-Mechanical Modeling and Thermal Performance Analysis of Beam Vacuum Line Interconnections and Cold Warm Transitions in HL-LHC Long Straight Section Magnets

luminosity, radiation, vacuum, insertion

2839

J. Harray, C. Garion, V. Petit
CERN, Meyrin, Switzerland

The HL-LHC upgrade, aiming at increasing the LHC levelled luminosity by factor of five, relies on new superconducting magnets requiring a new beam vacuum system. Along with the challenges related to magnet design, the beam optic configuration exposes this new equipment to stringent conditions for vacuum and cryogenic performance. Both cold-warm transitions and magnet interconnections appear to be delicate components that are crucial for the thermal heat transfer between diverse subsystems. The proposed study aims at assessing the heat loads to the cryogenic system and the temperature fields in the vacuum system. A nonlinear static thermal analysis is first performed. A thermo-mechanical approach is developed to capture additional thermal resistance arising from contact between components and their behaviour during cool-down. The system is then studied under dynamic operations when beams are circulating and colliding. A thorough analysis of beam-induced heat loads under ultimate conditions highlights the different relevant contributions. Finally, the transient response of the systems is computed to assess thermal time constants.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-THPOTK035

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Received ※ 08 June 2022 — Revised ※ 11 June 2022 — Accepted ※ 27 June 2022 — Issue date ※ 29 June 2022

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THPOMS052

Magnetic Field Shield for SC-Cavity with Thin Nb Sheet

cavity, niobium, shielding, experiment

3090

Y. Iwashita, Y. Kuriyama
Kyoto University, Research Reactor Institute, Osaka, Japan
Y. Fuwa
JAEA/J-PARC, Tokai-mura, Japan
H. Tongu
Kyoto ICR, Uji, Kyoto, Japan

Funding: This work was partly supported by JSPS KAKENHI Grant Number 19K21877.
Shielding the superconducting accelerating cavity made of niobium from the weak environmental magnetic field is an important subject. Niobium is a type-II superconductor, which traps the environmental magnetic flux in the material during the superconducting transition, resulting in increase of residual resistance and heating during operation during operation. Shielding from a weak magnetic field is essential for high performance operations. A magnetic shielding method that uses the diamagnetism of superconducting materials instead of magnetic flux absorption by high magnetic permeability materials is discussed.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-THPOMS052

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Received ※ 14 June 2022 — Revised ※ 15 June 2022 — Accepted ※ 16 June 2022 — Issue date ※ 18 June 2022

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FRPLYGD1

Towards Efficient Particle Accelerators - A Review

collider, cavity, radiation, luminosity

3141

M. Seidel
PSI, Villigen PSI, Switzerland

Sustainability has become an important aspect of all human activities, and also for accelerator driven research infrastructures. For new facilities it is mandatory to optimize power consumption and overall sustainability. This presentation will give an overview of the power efficiency of accelerator concepts and relevant technologies. Conceptual aspects will be discussed for proton driver accelerators, light sources and particle colliders. Several accelerator technologies are particularly relevant for power efficiency. These are utilized across the various facility concepts and include superconducting RF and cryogenic systems, RF sources, energy efficient magnets, conventional cooling and heat recovery. Power efficiency has been a topic in the European programs EUCARD-2, ARIES and the ongoing I.FAST project and the documentation of these programs is a related source of information.

Slides FRPLYGD1 [4.531 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-FRPLYGD1

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Received ※ 07 June 2022 — Revised ※ 12 June 2022 — Accepted ※ 13 June 2022 — Issue date ※ 29 June 2022

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