A. Tsymbaliuk, D. Bortolato, F. Chiurlotto, E. Chyhyrynets, G. Keppel, E. Munaron, C. Pira, F. Stivanello
INFN/LNL, Legnaro (PD), Italy
E. Chyhyrynets
Università degli Studi di Padova, Padova, Italy
A. Tsymbaliuk
UNIFE, Ferrara, Italy
The SPES project is based at INFN LNL and covers basic research in nuclear physics, radionuclide production, materials science research, nuclear technology and medicine. The Radioactive Ion Beam (RIB) produced by SPES will be accelerated by ALPI, which is a linear accelerator, equipped with superconducting quarter wave resonators (QWRs) and operating at LNL since 1990. For RIB acceleration it is mandatory to perform an upgrade of ALPI which consists of the implementation of two additional cryostats, containing 4 accelerating cavities each, in the high-ß section. The QWRs production technology is well established. The production technology of Nb/Cu QWRs should be adjusted for high-ß cavities production. In the framework of the upgrade, several vacuum systems were refurbished, optimal parameters of the biased sputtering processes of copper QWR cavities and plates were defined. The process of mechanical and chemical preparation, sputtering and cryogenic measurement of the high-ß Nb/Cu QWR cavities were adjusted. Several QWR cavities were already produced and measured. Currently, the production of the Nb/Cu sputtered QWR cavities and plates is ongoing.
T. Conrad, M. Busch, H. Podlech, M. Schwarz
IAP, Frankfurt am Main, Germany
K. Aulenbacher, J. List
IKP, Mainz, Germany
K. Aulenbacher, W.A. Barth, M. Basten, F.D. Dziuba, V. Gettmann, T. Kürzeder, M. Miski-Oglu
HIM, Mainz, Germany
W.A. Barth, M. Heilmann, A. Rubin, A. Schnase, S. Yaramyshev
GSI, Darmstadt, Germany
S. Lauber
KPH, Mainz, Germany
Funding:BMBF In collaboration of GSI, HIM and IAP Frankfurt, the superconducting linear accelerator HELIAC is being built at GSI. The cw-mode operated linac with a final energy of 7.3 MeV/u at a mass-to-charge ratio of A/q=6 and a frequency of 216.816 MHz is intended for various experiments, especially with heavy ions at energies close to the Coulomb barrier for the research of SHE. The planned linac consists of 4 cryostats, 4 superconducting bunchers, 4 solenoids and 12 superconducting CH-cavities. After successful beam tests with CH0 and high frequency tests with CH1 and CH2, CH3 to CH11 will be designed. Based on previous experience and successful test results, individual optimizations of the cavity design will be performed. Attention has been paid to reducing production costs by designing as many components as possible, such as spokes or the tank caps with the same geometries. Despite this cost reduction, it was possible to improve the theoretical performance in the simulations. In addition, a test bench is being developed which will be used for the first-time investigation of the mechanical stability, possible material fatigue and the durability of the dynamic bellows tuners.
First N-Doping and Mid-T Baking of Medium-ß 644 MHz 5-Cell Elliptical Superconducting RF Cavities for Michigan State University’s Facility for Rare Isotope Beams
K.E. McGee, S.H. Kim, P.N. Ostroumov, A. Taylor
FRIB, East Lansing, Michigan, USA
G.V. Eremeev, M. Martinello, A.V. Netepenko
Fermilab, Batavia, Illinois, USA
M.P. Kelly, T. Reid
ANL, Lemont, Illinois, USA
Funding:Work supported by the 2020 US DoE, Office of Science Graduate Student Research award (SCGSR), and US DoE, Office of Science, High Energy Physics under Cooperative Agreement award number DE-SC0018362 Two hadron linacs currently under development in the US, the PIP-II linac at Fermi National Accelerator Laboratory (FNAL) and the upgrade for Michigan State University’s Facility For Rare Isotope Beams (FRIB), will employ 650 and 644 MHz ß-0.6 elliptical superconducting cavities respectively to meet their design energy requirements. The desired CW operation modes of these two linacs sets Q-factor requirements well above any previously achieved for cavities at this operating frequency and velocity, driving the need to explore new high-Q treatments. The N-doping technique developed at FNAL and employed at an industrial scale to the LCLS-II cryomodules is a strong candidate for high-Q treatments, but work is needed to refine the treatment to the lower operating frequency and velocity regime. We present the first results of the first N-doping tests and a "mid-T" bake test in the FRIB 644 MHz 5-cell elliptical cavities.
J.K. Tiskumara, J.R. Delayen
ODU, Norfolk, Virginia, USA
G.V. Eremeev
Fermilab, Batavia, Illinois, USA
U. Pudasaini, C.E. Reece
JLab, Newport News, Virginia, USA
The twin axis cavity with two identical accelerating beams has been proposed for energy recovery linac (ERL) applications. Nb3Sn is a superconducting material with a higher critical temperature and a higher critical field as compared to Nb, which promises a lower operating cost due to higher quality factors. Two niobium twin axis cavities were fabricated at JLab and were proposed to be coated with Nb3Sn. Due to their more complex geometry, the typical coating process used for basic elliptical cavi-ties needs to be improved to coat these cavities. This development advances the current coating system at JLab for coating complex cavities. Two twin axis cavities were coated recently for the first time. This contribution dis-cusses initial results from coating of twin axis cavities, RF testing and witness sample analysis with an overview of the current challenges towards high performance Nb3Sn coated twin axis cavities.
C. Contreras-Martinez
FRIB, East Lansing, Michigan, USA
S.K. Chandrasekaran, S. Cheban, G.V. Eremeev, F. Furuta, T.N. Khabiboulline, Y.M. Pischalnikov, O.V. Prokofiev, A.I. Sukhanov, J.C. Yun
Fermilab, Batavia, Illinois, USA
The PIP-II linac will include thirty-six β=0.61 and twenty-four β=0.92 650 MHz 5 cell elliptical SRF cavities. Each cavity will be equipped with a tuning system consisting of a double lever slow tuner for coarse frequency tuning and a piezoelectric actuator for fine frequency tuning. One dressed cavity equipped with an SRF tuner has been tested in the horizontal test stand at Fermilab. Results of testing the cavity-tuner system will be presented.
C. Contreras-Martinez
FRIB, East Lansing, Michigan, USA
Y.M. Pischalnikov, J.C. Yun
Fermilab, Batavia, Illinois, USA
The new generation of low beam intensity superconducting linacs will require high accelerating gradients for new scientific discoveries. The high accelerating gradient cavities in pulsed SRF linacs will experience large (~1000’s of Hz) detuning caused by Lorentz force detuning (LFD). The piezo actuators that will be used to compensate large LFD must operate at a nominal voltage of 120V to 150V to deliver the required stroke to the cavity. In this high voltage range, the piezo is expected to warm up drastically due to its location in an insulating vacuum environment. Overheating of the piezo will significantly decrease the longevity of the actuator. A collaboration between FNAL and Physik Instrumente (PI) developed a novel piezo actuator design that mitigates piezo overheating. The design consists of using a metal foam in contact with the piezoelectric ceramic stack for heat removal. The second solution used lithium niobite as an alternative material. A comparison of the temperature stability will be presented and discussed. This study characterizes the dielectric properties for both materials. The results obtained are in the temperature range of 10 K to 300 K.
K. Yamada, T. Dantsuka, M. Fujimaki, E. Ikezawa, H. Imao, O. Kamigaito, M. Komiyama, K. Kumagai, T. Nagatomo, T. Nishi, H. Okuno, K. Ozeki, N. Sakamoto, K. Suda, A. Uchiyama, T. Watanabe, Y. Watanabe
RIKEN Nishina Center, Wako, Japan
H. Hara, A. Miyamoto, K. Sennyu, T. Yanagisawa
MHI-MS, Kobe, Japan
E. Kako, H. Nakai, H. Sakai, K. Umemori
KEK, Ibaraki, Japan
A new superconducting booster linac, so-called SRILAC, has been constructed at the RIKEN Nishina Center to upgrade the acceleration voltage of the existing linac in order to enable further investigation of new super-heavy elements and the production of useful RIs. The SRILAC consists of 10 TEM quarter-wavelength resonators made from pure niobium sheets which operate at 4.5 K. We succeeded to develop high performance SC-cavities which satisfies the required Q0 of 1E+9 with a wide margin. Installation of the cryomodule and He refrigerator system was completed by the end of FY2018, and the first cooling test was performed in September 2019. After various tests of the RF system, the beam acceleration was successfully commissioned in January 2020. In June 2020, the beam supply to the experiment was started. In this talk, I will report on the beam commissioning of SRILAC as well as the status of the frequency tuner and the differential pump system.
Y.U. Sohn, T.Y. Ki, Y. Kim, M. Lee, K.T. Seol
IBS, Daejeon, Republic of Korea
Funding:Ministry of Science and ICT (MSIT) RAON, being constructed as the Rare Isotope Science Project (RISP) by the Institute for Basic Science (IBS) since 2011 is a flagship heavy ion accelerator facility in Korea to promote fundamental science and application of isotope nuclei and related science. The installation of the heavy ion accelerator systems including injector, rare isotope (RI) production systems, and experimental systems are currently being progressed toward to commissioning of RAON, while the civil construction of the RAON site in Shindong, Daejeon of Korea, is going to finish in 2021. The superconducting LINAC with low energy, so-call SCL3 as the 1st phase will be commissioned on the December of 2021. The overview RAON accelerator facility and status of RISP are reported in this paper.
A.L. Klebaner, C. Boffo, S.K. Chandrasekaran, D. Passarelli, G. Wu
Fermilab, Batavia, Illinois, USA
Funding:US Department of Energy The Proton Improvement Plan II (PIP-II) project is an essential upgrade to Fermilab’s particle accelerator complex to enable the world’s most intense neutrino beam for LBNF/DUNE and a broad particle physics program for many decades to come. PIP-II will deliver 1.2 MW of proton beam power from the Main Injector, upgradeable to multi-MW capability. The central element of PIP-II is an 800 MeV linac, which comprises a room temperature front end followed by an SRF accelerator. The front end has been constructed and operated with (pulsed & CW) beam in the PIP-II Injector Test facility (PIP2IT). The SRF accelerator consists of five different types of cavities/cryomodules, including Half Wave Resonators (HWR), Single Spoke and elliptical resonators operating at state-of-the-art parameters. The first two PIP-II cryomodules, HWR and Single Spoke Resonator 1 (SSR1) are installed in PIP2IT and have accelerated beam to 17 MeV. PIP-II is the first U.S. accelerator project that will be constructed with significant contributions from international partners, including India, Italy, France, United Kingdom and Poland. The project was recently baselined, and site construction is underway
J. Branlard, S. Choroba, M.K. Grecki, S. Köpke, D. Kostin, D. Nölle, V. Vogel, N. Walker, S. Wiesenberg
DESY, Hamburg, Germany
The European X-Ray Free-Electron Laser (EuXFEL) has been successfully operating for almost 4 years, and routinely delivering 6- to 14-KeV X-rays to users (30 KeV photon energy was demonstrated). At the heart of the machine is the 1.3 km long 1.3 GHz SCRF linac which can reach a maximum electron energy of 17.6 GeV, and is capable of accelerating up to 2700 bunches per RF pulse at a repetition rate of 10 Hz, delivering beam to 6 experiments via 3 SASE undulator sections. In this contribution, we relate on the linac operational experience and highlight some recent developments towards monitoring and improving operations and linac availability.
T. Xu, Y. Al-Mahmoud, H. Ao, J. Asciutto, B. Bird, J. Bonofiglio, B. Bullock, N.K. Bultman, F. Casagrande, W. Chang, Y. Choi, C. Compton, J.C. Curtin, K.D. Davidson, K. Elliott, A. Facco, V. Ganni, A. Ganshyn, J. Gao, P.E. Gibson, Y. Hao, W. Hartung, N.M. Hasan, L. Hodges, K. Holland, J.D. Hulbert, M. Ikegami, T. Kanemura, S.H. Kim, P. Knudsen, Z. Li, S.M. Lidia, G. Machicoane, C. Magsig, P.E. Manwiller, F. Marti, T. Maruta, K.E. McGee, E.S. Metzgar, S.J. Miller, D.G. Morris, H. Nguyen, P.N. Ostroumov, A.S. Plastun, J.T. Popielarski, L. Popielarski, X. Rao, M.A. Reaume, H.T. Ren, K. Saito, M. Shuptar, A. Stolz, A. Taylor, B.P. Tousignant, A.D.F. Victory, D.R. Victory, J. Wei, E.M. Wellman, J.D. Wenstrom, Y. Yamazaki, C. Zhang, Q. Zhao, S. Zhao
FRIB, East Lansing, Michigan, USA
K. Hosoyama
KEK, Ibaraki, Japan
M.P. Kelly
ANL, Lemont, Illinois, USA
R.E. Laxdal
TRIUMF, Vancouver, Canada
M. Wiseman
JLab, Newport News, Virginia, USA
Funding:This work is supported by the U.S. Department of Energy Office of Science under Cooperative Agreement DE-SC0000661. The Facility for Rare Isotope Beams (FRIB) is an ac-celerator-based facility funded by the US Department of Energy for nuclear physics research. FRIB is nearing the end of technical construction, with first user beams ex-pected in Summer 2022. Key features are the delivery of a variety of rare isotopes with a beam energy of ’ 200 MeV/u and a beam power of up to 400 kW. The facility is upgradable to 400 MeV/u and multi-user capability. The FRIB driver linac consists of 324 superconducting resonators and 69 superconducting solenoids in 46 cry-omodules. FRIB is the first linac to deploy a large number of HWRs (220) and the first heavy ion linac to operate at 2 K. We report on the completion of production and in-stallation of the FRIB cryomodules and phased beam commissioning results.
Y.M. Pischalnikov, T.T. Arkan, C.J. Grimm, B.D. Hartsell, J.A. Kaluzny, T.N. Khabiboulline, Y.M. Orlov, J.C. Yun
Fermilab, Batavia, Illinois, USA
C. Contreras-Martinez
FRIB, East Lansing, Michigan, USA
Funding:This manuscript has been authorized by Fermi Research Alliance LLC under Contract N. DE-AC02-07CH11359 with U.S. Department of Energy. The off-frequency detune method is being considered to be applied in the LCLS-II-HE superconducting linac to produce multi-energy electron beams for supporting multiple undulator lines simultaneously. To deliver off-frequency operation (OFO) requirements for SRF cavity tuner must be changed. Tuner design modifications and results of the testing eight cavity/tuner system, deployed in verification cryomodule (vCM), will be presented.
S. Zhao, W. Chang, E. Daykin, E. Gutierrez, S.H. Kim, S.R. Kunjir, T.L. Larter, D.G. Morris, J.T. Popielarski
FRIB, East Lansing, Michigan, USA
Funding:Work supported by the U.S. Department of Energy Office of Science under Cooperative Agreement DE-SC0000661. The installation and commissioning of the FRIB superconducting linac adopts a phased strategy. In SRF’19 we reported the progress on the commissioning of the linear segment 1 (LS1) which contains mainly the quarter wave resonators (QWRs). In this paper, we will report the recent progress on the commissioning of the remainder of the linac, including linear segment 2 (LS2), folding segment 2 (FS2) and linear segment 3 (LS3), focusing on the RF system experience for the half wave resonators (HWRs). Compared to the QWRs, the HWRs have a different type of tuner, run at higher power levels and have additional components (for example, high voltage bias tee for multipacting suppression and spark detector). Topics such as nonlinear tuner control for the pneumatic tuners; auto turn on/off implementation; and early issues and failures will be discussed in more detail.
N. Gandolfo, S. Blivet, P. Duchesne, D. Le Dréan
Université Paris-Saclay, CNRS/IN2P3, IJCLab, Orsay, France
In the framework of the MINERVA construction (MYRRHA Isotopes productioN coupling the linEar acceleRator to the Versatile proton target fAcility), a fully equipped prototype cryomodule is being developed. In order to control the resonance frequency of the cavities during operation, a deformation tuner has been studied. The kinematic model is based on a double lever system coupled with a screw nut linear actuator. The motion is generated by a stepper motor and two piezoelectric actuators working at low temperatures within the thermal insulation vacuum of the cryomodule. Key parameter of this work is the high tuning speed which is required to fulfill the fault tolerance strategy. This paper reports the design study and first tests of the built tuners at room temperature and in vertical cryostat configuration.
M. Xu, H. Guo, Y. He, S.C. Huang, Y.L. Huang, T.C. Jiang, C.L. Li, L.B. Liu, S.H. Liu, T. Liu, S.M. Shanab, T. Tan, Y. Tao, Y.Q. Wan, F.F. Wang, R.X. Wang, Z.J. Wang, P.R. Xiong, J.C. Yang, Z.Q. Yang, S.H. Zhang, S.X. Zhang
IMP/CAS, Lanzhou, People’s Republic of China
E.Z. Zaplatin
FZJ, Jülich, Germany
Funding:Work supported by Large Research Infrastructures "China initiative Accelerator Driven System’(Grant No.2017-000052-75-01-000590 ) Two accelerators facilities, China initiative Accelerator Driven Sub-critical System (CiADS) and High Intensity heavy-ion Accelerator Facility (HIAF), co-funded by the China central and local government, is being designed and constructed at Huizhou city, Guangdong Province. The Institute of Modern Physics(IMP), Chinese Academy of Science is responded for constructing and operating the facility. CiADS’s mission is to demonstrate the principle and technical of employing high power protons to transit fission nuclear plant wastes. HIAF is defined as a nuclear structure research facility. The two linacs contains six types , totally 233 superconducting cavities, will be constructed in recent three years. Stable production rate and reliable surface processing will be the main challenges. This paper reports the cavity design, prototype status and massive production plan and status.
T.C. Jiang, F. Bai, Y. He, Z.Q. Lin, Y.Q. Wan, R.X. Wang, Z.J. Wang, M. Xu, S.H. Zhang
IMP/CAS, Lanzhou, People’s Republic of China
More than 100 Half-wave resonators (HWR) will be adopted for China Initiative Accelerator Driven Sys-tem (CiADS) and High Intensity heavy-ion Accelerator Facility (HIAF) at IMP. Each HWR cavity equips with one variable coupling, dual-warm-ceramic fundamen-tal power coupler (FPC). The FPC should be able to transmit up to 30 kW in CW mode. This paper will give an overview of the RF design of the 162.5 MHz CW power coupler. The coupler employs two warm ceram-ics in a 50 Ω coaxial line to ensure operation relia-bility. The results of thermal and thermomechanical will also be reported. Two prototype couplers have been fabricated and the RF measurements with low RF power were carried out.
Y. Kondo, H. Kabumoto, M. Matsuda
JAEA, Ibaraki-ken, Japan
T. Dohmae, E. Kako, H. Sakai, K. Umemori
KEK, Ibaraki, Japan
H. Harada, J. Kamiya, K. Moriya, J. Tamura
JAEA/J-PARC, Tokai-mura, Japan
The Japan Atomic Energy Agency (JAEA) tandem booster is one of the pioneering superconducting heavy ion linac in the world. It consists of 40 QWRs with an operation frequency of 130 MHz and βopt=0.1, and has potential to accelerate various ions up to Au to 10 MeV/u. The user operation was started in 1994, however, it has been suspended since the Great East Japan Earthquake in 2011. Recently, we started activities to investigate and improve the performance of the QWR cavities towards the restart of the tandem booster. In addition, design work of new lower beta cavities to improve the acceleration efficiency of heavier ions such as Uranium has been launched. Now we are surveying some operation frequencies and types of cavities including multi-gap QWR with use of electro-magnetic simulation of the cavities. In this work, the current status of the R&D program for the JAEA tandem facility is presented.
N. Sakamoto, H. Imao, O. Kamigaito, T. Nagatomo, T. Nishi, K. Ozeki, K. Suda, A. Uchiyama, K. Yamada
RIKEN Nishina Center, Wako, Japan
After commissioning of the RIKEN superconducting linac (SRILAC) in the end of FY2019, heavy ion beams were provided to the nuclear physics experiments. In this paper operation history and evolution of field emission levels through the year will be presented.
B. Yee-Rendón, Y. Kondo, F. Maekawa, S.I. Meigo, J. Tamura
JAEA/J-PARC, Tokai-mura, Japan
To overcome the nuclear waste problem, the Japan Atomic Energy Agency (JAEA) has been developing an accelerator-driven subcritical system (ADS) since the late 1980s. In the JAEA-ADS proposal, an 800 MWth subcritical reactor is driven by a 30 MW cw proton linear accelerator (linac). The biggest challenges for the ADS machines are the high reliability and availability required for their operations. To this end, the present JAEA-ADS linac was redesigned by adopting the current developments in Superconducting Radio-Frequency (SRF) technology. Additionally, we developed a robust lattice to control the beam loss and implemented a fault-tolerance scheme for the fast recovery of SRF cavity failures. This work presents the latest results of the R&D of the JAEA-ADS superconducting linac.
F. Éozénou, M. Baudrier, E. Cenni, E. Fayette, L. Maurice, C. Servouin
CEA-DRF-IRFU, France
V. Chouhan, Y.I. Ida, K. Nii, T.Y. Yamaguchi
MGH, Hyogo-ken, Japan
H. Hayano, H. Ito, S. Kato, T. Kubo, H. Monjushiro, T. Saeki
KEK, Ibaraki, Japan
G. Jullien
CEA-IRFU, Gif-sur-Yvette, France
Vertical Electro-Polishing (VEP) of elliptical cavities using rotating Ninja cathodes (Marui Company patented technology) has continually been improved since 2012 and successfully applied for 1300MHz multicell ILC-type resonators. The goal of the presented study is to apply this technology to 704 MHz ESS-type resonators with both better Q0 and accelerating gradients in mind. We intend to demonstrate the superiority of VEP compared to standard Buffer Chemical Polishing (BCP), for possible applications such as MYRRHA accelerator. We describe here the promising results achieved on β=0.86 single-cell cavity after 200 µm uniform removal. The cavity quenched at 27 MV/m without any heat treatment. The surface resistance achieved was less than 5nΩ at 1.8K. Substantial performance improvement is expected after heat treatment of the cavity and additional 20 µm VEP sequence. A cathode for 5-Cell ESS cavity is concomitantly under design stage.
Y.L. Huang, Y. He, H. Jia, Y.S. Qin, Z.J. Wang, Z.L. Zhang
IMP/CAS, Lanzhou, People’s Republic of China
Funding:Large Research Infrastructures "China initiative Accelerator Driven System’(Grant No.2017-000052-75-01-000590 ) and National Natural Science Foundation of China (Grant NO. 11805249) Chinese initiative Accelerator Driven Subcritical System (CiADS) is supposed to accelerate continuous 162.5 MHz, 10 mA (or higher) proton beam to 500 MeV (or higher energy) with a superconducting driver linac. More application scenarios based on this high power intensity proton linac are now under considerations. Beam spreader system based on deflecting cavities for multiple users simultaneous operation are discussed in this paper, as well as the RF structure options for the equal eight- and nigh- beam-line split schemes. #huangyulu@impcas.ac.cn
D. Kostin, J. Eschke, K. Jensch, N. Krupka, L. Lilje, A. Muhs, D. Reschke, S. Saegebarth, J. Schaffran, M. Schalwat, P. Schilling, M. Schmökel, S. Sievers, N. Steinhau-Kühl, E. Vogel, H. Weise, M. Wiencek, B. van der Horst
DESY, Hamburg, Germany
Eight SRF cavities assembled in an accelerating module represent a building block of the particle linear accelerator based on TESLA SRF technology. DESY has two machines, European XFEL and FLASH. Both use almost same module and cavity types. During the module assembly many factors can deteriorate the cavity performance and cause a need for a repair action. Currently two European XFEL modules and two FLASH ones underwent reassembly procedures. The repair was not immediately successful on every of these modules and re-iterations did follow. The degradation causes were investigated. SRF modules were tested on both test-stands at DESY: AMTF and CMTB. The results of the described actions are presented and discussed.
For several years, CEA has been involved in the development of superconducting linac for fusion related project, with the goal to develop an high flux neutrons source to test and qualify specific materials to be used in fusion power plants. In the framework of the ITER Broder Approch, a prototype cryomodule is under construction in Japan for the IFMIF/EVEDA phase(Engineering Validation and Engineering Design Activities) and the construction of the Accelerator Prototype (LIPAc) at Rokkasho, fully representative of the IFMIF low energy (9 MeV) accelerator (125 mA of D+beam in continuous wave). Meanwhile, the design studies of a plant called DONES (Demo Oriented NEutron Source, derived from IFMIF) started, with a superconducting linac made of 5 cryomodules. These one are based on the same principles as the one developed for IFMIF/EVEDA, but taking into account the lessons learnt from the prototype. This paper will present the similarities but also the differences between the cryomodules for IFMIF/EVEDA and DONES.
We consider ILC upgrade paths beyond 1 TeV: (1) to 2 TeV and (2) to 3 TeV depending on the needs of high energy physics. Parameters for four scenarios will be presented and challenges discussed. 1. From 1 TeV to 2 TeV based on: a. Gradient advances of Nb cavities to 55 MV/m anticipated from on-going SRF R&D on Nb structures discussed in Section 4.3.x. b. Radically new travelling wave (TW) superconducting structures [1,2] optimized for effective gradients of 70+ MV/m, along with 100% increase in R/Q (discussed in more detail in Section 4.3.x). The large gain in R/Q has a major beneficial impact on the refrigerator heat load, the RF power, and the AC operating power. OR 2. From 1 TeV to 3 TeV based on a. Radically new travelling wave (TW) superconducting structures [1,2] optimized for effective gradients of 70+ MV/m, along with 100% increase in R/Q. The large gain in R/Q has a major beneficial impact on heat load, RF power, and the AC operating power. b. 80 MV/m gradient potential for Nb3Sn [3] with Q of 1x1010, based on extrapolations from high power pulsed measurements on single cell Nb3Sn cavities. Further, the operating temperature is 4.2 K instead of 2K.
M. Major, L. Alff, M. Arnold, J. Conrad, S. Flege, R. Grewe, N. Pietralla
TU Darmstadt, Darmstadt, Germany
Funding:Work supported by the German Federal Ministry for Education and Research (BMBF) through grant 05H18RDRB2 and the German Research Foundation (DFG) via the AccelencE Research Training Group (GRK 2128). Niobium is the standard material for superconducting RF (SRF) cavities for particle acceleration. Superconducting materials with higher critical temperature or higher critical magnetic field allow cavities to work at higher operating temperatures or higher accelerating fields, respectively. One direction of search for new materials with better properties is the modification of bulk niobium by nitrogen doping. In the Nb-N phase diagram, the cubic delta-phase of NbN has the highest critical temperature. Niobium samples were annealed and doped with nitrogen in the high-temperature furnace at TU Darmstadt and investigated at its Materials Research Department with respect to structural modifications. X-ray diffraction (XRD) confirmed the appearance of Nb4N3 and Nb2N phases on the surface of the samples. A single cell cavity was annealed under optimized doping conditions. The test samples treated together with the cavity showed almost single Nb4N3 phase. XRD pole figures also showed grain growth during sample annealing.
Y.L. Huang, H. Guo, Y. He, C.L. Li, T. Liu, R.X. Wang, Z.J. Wang, M. Xu, Z.Q. Yang, S.X. Zhang
IMP/CAS, Lanzhou, People’s Republic of China
Funding:Large Research Infrastructures "China initiative Accelerator Driven System"(Grant No.2017-000052-75-01-000590 ) and National Natural Science Foundation of China (Grant NO. 11805249) 650MHz multi-cell superconducting elliptical cavities with optimum beta equal to 0.62 and 0.82 were adopted in the driver linac of Chinese initiative Accelerator Driven Subcritical System (CiADS) to accelerate the 10 mA proton beam from 175 MeV up to 500 MeV, with the possibility to upgrade the energy to 1 GeV and higher. Mechanical design and optimization of the niobium cavity-titanium helium vessel assembly will be summarized in this paper. Vertical test results of three single cell prototype cavities will also be discussed, with comparisons with the simulation values. *Work supported by Large Research Infrastructures "China initiative Accelerator Driven System’(Grant No.2017-000052-75-01-000590 ) and National Natural Science Foundation of China (Grant NO. 11805249)
S. Weih, M. Arnold, M. Dutine, J. Enders, R. Grewe, L.E. Jürgensen, N. Pietralla, F. Schließmann, M. Steinhorst
TU Darmstadt, Darmstadt, Germany
Funding:work supported by German research council (DFG) through GRK 2128 ’AccelencE’ and the state of Hesse through the LOEWE research project Nuclear Photonics and the Collaborative Research Cluster ELEMENTS The superconducting part of the injector section of the superconducting Darmstadt electron linear accelerator (S-DALINAC) [1] consisted of one five-cell capture cavity and two 20-cell cavities at 3 GHz resonance frequency. All of them were geometrically adapted to electron velocities with a beta of 1, while the thermionic gun provides electrons with a beta of 0.74. This mismatch resulted in an insufficient capture process for optimum beam quality. For this reason, a new six-cell capture cavity with a beta of 0.86 has been designed and built. Field flatness tuning, a test in the vertical bath cryostat, and a UHV furnace treatment have been carried out in-house to finalize the cavity processing. The cryostat module was adapted to house the new cavity, which has been recently installed. Following the module assembly, a first RF test run was conducted at the S-DALINAC. We report on these latest advancements towards the implementation of the injector upgrade. * N. Pietralla, Nuclear Physics News, Vol. 28, No. 2, 4 (2018).
Funding:TRIUMF receives funding via a contribution through the National Research Council Canada. The balloon variant of the spoke resonator was proposed to eliminate the intensive multipacting (MP) barriers around the operating field level by modifying the local electro-magnetic (EM) fields. TRIUMF has previously reported the prototyping of a 325MHz β=0.3 single spoke resonator (SSR) that demonstrated the principle of the balloon concept. To extend the benefits of the balloon variant to multi-spoke resonators, this paper will report a conceptual design of a 325MHz β=0.5 balloon double spoke resonator (DSR). The consequences from the balloon SSR design, such as the relations between EM field distributions and the field levels of the MP barriers, were applied to the DSR design. Other particular geometry features were also added due to the characters of DSRs. The simulated MP barriers were significantly squeezed to the lower field level compared to a conventional DSR design. Simulation results and conceptual design will be reported.
J. Tamura, Y. Kondo, F. Maekawa, S.I. Meigo, B. Yee-Rendón
JAEA/J-PARC, Tokai-mura, Japan
T. Dohmae, E. Kako, H. Sakai, K. Umemori
KEK, Ibaraki, Japan
The Japan Atomic Energy Agency (JAEA) is proposing an accelerator-driven subcritical system (ADS) for efficient reduction of high-level radioactive waste generated in nuclear power plants. One of the challenging R¥&Ds for ADS is the reliability of the accelerator. In preparation for the full-scale design of the proton linac for the JAEA-ADS, we are now prototyping a single-spoke cavity for low-beta (around 0.2) beam acceleration. As there is no experience of manufacturing a superconducting spoke cavity in Japan, the cavity prototyping and performance testing are essential to ensure the feasibility of the JAEA-ADS linac. To proceed to an actual cavity fabrication, we have carefully reviewed the fabrication process. And then, we examined the electron-beam welding using niobium test pieces and investigated the welding condition for realizing the smooth underbead. We have finally started the press forming of niobium sheets and the machine work to shape the cavity parts. Now, we are parparing for the electron-beam welding of the shaped niobium parts.
K. Suda, O. Kamigaito, K. Ozeki, N. Sakamoto, K. Yamada
RIKEN Nishina Center, Wako, Japan
H. Hara, A. Miyamoto, K. Sennyu, T. Yanagisawa
MHI-MS, Kobe, Japan
E. Kako, H. Nakai, H. Sakai, K. Umemori
KEK, Ibaraki, Japan
The superconducting booster linac at RIKEN (SRILAC) has ten 73-MHz quarter-wavelength resonators (QWRs) that are contained in three cryomodules. The beam commissioning of SRILAC was successfully performed in January 2020. Frequency tuning during cold operation is performed by compressing the beam port of the cavity with stainless wires and decreasing the length of each beam gap, similar to the method adopted at ANL and FRIB. However, each tuner is driven by a motor connected to gears, instead of using gas pressure. Since the intervals of the QWRs are small due to the beam dynamics, a compact design for the tuner was adopted. Each cavity was tuned to the design frequency, which required frequency changes of 3 kHz to 7 kHz depending on the cavity. Although no piezoelectric actuator is mounted on the tuning system, phase noise caused by microphonics can be sufficiently reduced by a phase-locked loop using a newly developed digital LLRF. The details of the tuning system as well as the digital LLRF will be presented.
G. Ferrand, G. Jullien, S. Ladegaillerie, N. Misiara, N. Pichoff, C. Servouin
CEA-IRFU, Gif-sur-Yvette, France
M. Baudrier, E. Fayette, L. Maurice
CEA-DRF-IRFU, France
A. Navitski, L. Zweibäumer
RI Research Instruments GmbH, Bergisch Gladbach, Germany
CEA is committed to delivering a Medium Energy Beam Transfer line and a superconducting linac (SCL) for SARAF accelerator in order to accelerate 5 mA beam of either protons from 1.3 MeV to 35 MeV or deuterons from 2.6 MeV to 40 MeV. The SCL consists in four cryomodules. The first two identical cryomodules host 6 half-wave resonator (HWR) low beta cavities (β= 0.09) at 176 MHz. The last two identical cryomodules will host 7 HWR high-beta cavities (β = 0.18) at 176 MHz. The low-beta prototypes was qualified in 2019. Low-beta series manufacturing is on-going. The high-beta prototype was first tested in 2019 but failed. A new prototype was tested in the end of 2020. This contribution will present the results of the tests for low- and high-beta SARAF cavities, series and prototypes.
H. Sakai, M. Adachi, D.A. Arakawa, S. Eguchi, M.K. Fukuda, K. Haga, M. Hagiwara, K. Hara, K. Harada, N. Higashi, T. Honda, Y. Honda, T. Honma, M. Hosumi, E. Kako, Y. Kamiya, R. Kato, H. Kawata, Y. Kobayashi, Y. Kojima, T. Konomi, H. Matsumura, S. Michizono, C. Mitsuda, T. Miura, T. Miura, T. Miyajima, Y. Morikawa, S. Nagahashi, H. Nakai, N. Nakamura, K. Nakanishi, K.N. Nigorikawa, T. Nogami, T. Obina, F. Qiu, H. Sagehashi, M. Shimada, H. Shimizu, T. Shioya, M. Tadano, T. Takahashi, R. Takai, H. Takaki, O.A. Tanaka, Y. Tanimoto, A. Toyoda, K. Tsuchiya, T. Uchiyama, A. Ueda, K. Umemori, M. Yamamoto
KEK, Ibaraki, Japan
R. Hajima, K. Kawase
QST, Tokai, Japan
N.P. Norvell
SLAC, Menlo Park, California, USA
F. Sakamoto
Akita National College of Technology, Akita, Japan
M. Shimada
HSRC, Higashi-Hiroshima, Japan
Funding:Supported by Accelerator Inc. and a New Energy and Industrial Technology Development Organization (NEDO) project and JSPS Grant-in-Aid for Scientific Research (KAKENHI) Grant Number JP18H03473. A superconducting Compact Energy Recovery Linac (cERL) for electrons was constructed in 2013 at KEK to demonstrate energy recovery concept with low emittance, high-current CW beams of more than 10 mA for future multi-GeV ERL. Recently this cERL was operated not only to demonstrate energy recovery linac high current beam operation but also to promote and conduct a variety of industrial applications such as FEL, THz operation and Rare Isotope Production and irradiation for some materials. In this talk, I will present the status of the studies to realize the stable high-current low emittance CW beam and some applications with this beam.
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Funding:Department of Atomic Energy, India This talk is a summary talk of the recent progress of SRF activities in India including RRCAT, BARC, VECC, IUAC. The latest SRF activities for several national accelerator projects and international projects like PIP-II in FNAL are presented. RRCAT in Indore has been pursuing a complete chain of fabrication, RF tests and characterization at various stages including the SCRF infrastructure facilities, processing, HPR, vertical test stand and Horizontal Test Stand. Several cavities have been successfully tested in the vertical test stand and the Horizontal Test Stand has been commissioned and ready to test the cavities. BARC in Mumbai has developed low beta single spoke cavities for PIP-II R & D in collaboration with IUAC. VECC is pursuing development of single cell and five cell low beta SCRF cavities for PIP-II R &D. IUAC in New Delhi have developed SRF cavities in their infrastructure facilities and has supported institutes in India towards 1.3 GHz cavities, single cell LB and HB cavities and development of SSR1 cavities. Status of the SRF cavity development and the latest results of cavity performance qualification should be presented in this talk
R. Paparella, M. Bertucci, M. Bonezzi, A. Bosotti, D. Cardelli, A. D’Ambros, A.T. Grimaldi, P. Michelato, L. Monaco, D. Sertore
INFN/LASA, Segrate (MI), Italy
C. Pagani
Università degli Studi di Milano & INFN, Segrate, Italy
The international effort for the PIP-II project at Fermilab has been joined by INFN with its planned contribution to the PIP-II proton linac in the low-beta section. INFN-LASA is finalizing its commitment to deliver in kind the full set of the LB650 cavities, 36 plus spares resonators with 5-cell cavities at 650 MHz and geometrical beta 0.61. All cavities, designed by INFN-LASA, will be produced and surface treated in industry to reach the unprecedented performances required by PIP-II, qualified through vertical cold test at state-of-the art infrastructures and delivered as ready for the linac at the string assembly site. The status of INFN contribution to PIP-II, the development of infrastructures and prototypes as well as the ongoing activities toward the start of series production are summarized in this paper.
J.D. Mammosser, B.E. Robertson
ORNL RAD, Oak Ridge, Tennessee, USA
R. Afanador, M.S. Champion, M.N. Greenwood, M.P. Howell, S.-H. Kim, S.E. Stewart, D.J. Vandygriff
ORNL, Oak Ridge, Tennessee, USA
A. Bitter, K.B. Bolz, A. Navitski, L. Zweibäumer
RI Research Instruments GmbH, Bergisch Gladbach, Germany
E. Daly, G.K. Davis, P. Dhakal, D. Forehand, K. Macha, C.E. Reece, K.M. Wilson
JLab, Newport News, Virginia, USA
Funding:UT-Battelle, LLC, under contract DE-AC05-00OR22725 with the US Department of Energy (DOE) The Proton Power Upgrade (PPU) Project at Oak Ridge National Lab’s Spallation Neutron Source (SNS) is currently under construction. The project will double the beam power from 1.4 to 2.8 MW. This is accomplished by increasing the beam current and adding seven new Superconducting Radio Frequency (SRF) cryomodules. Each new cryomodule will contain four six-cell, beta 0.81, PPU style cavities. A quality assurance plan was developed and implemented for the procurement of 32 PPU cavities. As part of this plan, reference cavities were qualified and sent to Research Instruments Co. for the development and verification of process steps. Here we present the results from this plan to date.
A. Pandey, R. Ahuja, G.K. Chaudhari, B.B. Chaudhary, R.N. Dutt, S. Ghosh, B. Karmakar, J. Karmakar, R. Kumar, D.S. Mathuria, P. Patra, P.N. Potukuchi, A. Rai, B.K. Sahu, S.K. Saini, A. Sharma, S.K. Sonti, S.K. Suman
IUAC, New Delhi, India
The phase locking of the QWRs by dynamic phase control method in the superconducting linac at IUAC is done in a faster time scale. The slow frequency drifts (few hundreds of ms) are corrected using a niobium bellows tuner attached at the open end of the cavity. Initially, the tuners in the cavities were operated using helium gas. This system had the limitation of non-linearity, hysteresis and slow response due to which the cavities could not be phase locked at higher fields. To address this, piezo based tuning system was implemented in the cavities of the 2nd and 3rd linac modules. But due to space constraints, the same could not be used in the 1st linac module and the buncher modules. For them, the helium gas based system was continued, albeit with suitable modifications. The old flow control valves which operated with DC voltages were replaced with valves operating in pulsed mode and controlled by varying the duty cycle of the input pulses. The above mentioned limitations were overcome by using this PWM based technique and this enabled phase locking at higher gradients. This paper presents our operational experience with all the different tuning systems and their comparison.
D. Sertore, M. Bertucci, M. Bonezzi, A. Bosotti, D. Cardelli, A. D’Ambros, A.T. Grimaldi, L. Monaco, R. Paparella, G.M. Zaggia
INFN/LASA, Segrate (MI), Italy
C. Pagani
Università degli Studi di Milano & INFN, Segrate, Italy
INFN Milano - LASA contributes in-kind to the ESS ERIC Superconducting Linac supplying 36 cavities for the Medium Beta section of the proton accelerator. All the cavities have been mechanical fabricated, BCP treated and, for most of them, also qualified with vertical test at cold at DESY. We present the result of the cavities already qualified and delivered to CEA, discussing the lessons learnt so far. For remaining cavities, we discuss the actions taken and the plans foreseen to recover them to full specifications.
K. Ozeki, O. Kamigaito, N. Sakamoto, K. Suda, K. Yamada
RIKEN Nishina Center, Wako, Japan
In RIKEN, three cryomodules which contain ten SC-QWRs in total (4 + 4 + 2) were constructed, and beam supply has been started since last year. The FPCs for RIKEN QWR have a disk-type single vacuum window at room-temperature region. A vacuum leakage occurred at one FPC, after 4th cool-down test. In addition, second vacuum leakage occurred at another FPC, after starting beam supply. A dew condensation at air side of vacuum window may degrade the brazing of vacuum window. In order to prevent a dew condensation and to restore damaged FPCs, an additional outer vacuum window using machinable ceramics was designed and attached to the FPCs. In this contribution, a structure of the FPC, troubles, provision for those troubles, and plan for reconstruction are reported.
H. Jenhani, P. Carbonnier
CEA-IRFU, Gif-sur-Yvette, France
The Proton Improvement Plan - II (PIP-II) project is underway at Fermilab with an international collaboration involving CEA in the development and testing of 650 MHz cryomodules. The risk analysis related to cryomodule operation proposed to add a vacuum gauge on the power coupler to prevent the untimely rupture of its ceramic. Due to the advanced design of the cryomodules, the gauge needs to be integrated inside the insulation vacuum to reduce the impact of this new modification. The lack of experience feedback on a similar operating condition requires an experimental validation before the implementation. This article details the experimental tests carried out before the approval of this solution.
