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MOBA03 | Sensitivity of Niobium Superconducting RF Cavities to Magnetic Field | cavity, niobium, impedance, SRF | 34 |
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One important characteristic of nitrogen-doped cavities is their very high sensitivity to increased residual surface resistance from trapped ambient magnetic flux. We have performed a systematic study on the losses by trapped flux, and their dependence on the mean-free-path (MFP) of the niobium RF penetration layer. Cavities with a wide range of MFP values were tested in uniform ambient magnetic fields to measure trapped magnetic flux and resulting increase in RF surface resistance. MFP values were determined from surface impedance measurements. It was found that larger mean free paths lead to lower sensitivity to trapped magnetic flux. | |||
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Slides MOBA03 [1.817 MB] | ||
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MOPB001 | RF Performance of Ingot Niobium Cavities of Medium-Low Purity | cavity, SRF, operation, radio-frequency | 61 |
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Funding: This manuscript has been authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177. Superconducting radio-frequency cavities made of ingot niobium with residual resistivity ratio (RRR) greater than 250 have proven to have similar or better performance than fine-grain Nb cavities of the same purity, after standard processing. The high purity requirement contributes to the high cost of the material. As superconducting accelerators operating in continuous-wave typically require cavities to operate at moderate accelerating gradients, using lower purity material could be advantageous not only to reduce cost but also to achieve higher Q0-values, because of the well-known dependence of the BCS-surface resistance on mean free path. In this contribution we present the results from cryogenic RF tests of 1.3-1.5 GHz single-cell cavities made of ingot Nb of medium (RRR=100-150) and low (RRR=60) purity from different suppliers. Cavities made of medium-purity ingots routinely achieved peak surface magnetic field values greater than 70 mT with Q0-values above 1.5·1010 at 2 K. The performance of cavities made of low-purity ingots were affected by significant pitting of the surface after chemical etching. |
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MOPB004 | Understanding the Field Dependence of the Surface Resistance in Nitrogen-Doped Cavities | simulation, radio-frequency, cavity, impedance | 74 |
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Funding: NSF Grant PHYS-1416318 An important limiting factor in the performance of superconducting radio frequency (SRF) cavities in medium and high field gradients is the intrinsic quality factor and, thus, the surface resistance of the cavity. The exact dependence of the surface resistance on the magnitude of the RF field is not well understood. We present an analysis of experimental data of LT1-3 and LT1-4, 1.3 GHz single-cell nitrogen-doped cavities prepared and tested at Cornell. Most interestingly, the cavities display anti-Q slopes in the medium-field region (i.e. Rs decreases with increasing accelerating field). We extract the temperature dependent surface resistances of the cavities, analyze field dependencies, and compare with theoretical predictions. These comparisons and analyses provide new insights into the field dependence of the surface resistance and improve our understanding of the mechanisms behind the effect. |
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MOPB027 | Modifications of Superconducting Properties of Niobium Caused by Nitrogen Doping of Ultra-High Quality Factor Cavities | niobium, SRF, cavity, superconductivity | 144 |
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We have performed detailed studies using DC and AC magnetometry and electrical resistivity measurements of niobium samples prepared using different nitrogen doping recipes. We compare the results to the samples prepared by standard preparation techniques such as EP with and without additional 120C baking to get insight into driving factors of the lowered quench field in N-doped SRF cavities. | |||
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MOPB033 | LCLS-II SRF Cavity Processing Protocol Development and Baseline Cavity Performance Demonstration | cavity, cryomodule, SRF, linac | 159 |
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Funding: Work supported, in part, by the US DOE and the LCLS-II Project under U.S. DOE Contract No. DE-AC05-06OR23177 and DE-AC02-76SF00515. The ”Linac Coherent Light Source-II” Project will construct a 4 GeV CW superconducting RF linac in the first kilometer of the existing SLAC linac tunnel. The baseline design calls for 280 1.3 GHz nine-cell cavities with an average intrinsic quality factor Q0 of 2.7·1010 at 2K and 16 MV/m accelerating gradient. The LCLS-II high Q0 cavity treatment protocol utilizes the reduction in BCS surface resistance by nitrogen doping of the RF surface layer, which was discovered originally at FNAL. Cornell University, FNAL, and TJNAF conducted a joint high Q0 R&D program with the goal of (a) exploring the robustness of the N-doping technique and establishing the LCLS-II cavity high Q0 processing protocol suitable for production use, and (b) demonstrating that this process can reliably achieve LCLS-II cavity specification in a production acceptance testing setting. In this paper we describe the LCLS-II cavity protocol and analyze combined cavity performance data from both vertical and horizontal testing at the three partner labs, which clearly shows that LCLS-II specifications were met, and thus demonstrates readiness for LCLS-II cavity production. |
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MOPB035 | Nature and Implication of Found Actual Particulates on the Inner Surface of Cavities in a Full-Scale Cryomodule Previously Operated With Beams | cavity, cryomodule, ion, operation | 164 |
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Field emission in an SRF cavity is often the result of small foreign particulates lodging on the cavity inner surface. To avoid these particulate field emitters, careful cleaning and handling of individual cavities and clean room assembly of cavity strings are common practice. Despite these elaborate processes, some particulates persist to stay on the final surface of a beam-ready cavity. Moreover, as will be shown in this contribution, new particulates accumulate after a cryomodule is placed in the accelerator tunnel. The nature of these accumulated particulates on the inner surface of a beam-accelerating cavity is largely unknown for two reasons: (1) lack of access to such surfaces; (2) lack of a workable procedure for investigation without destroying the cavity. In this contribution, we report the first study on found actual particulates on the inner surface of 5-cell CEBAF cavities in a full-scale cryomodule previously operated with beam. The nature of the studied particulates is presented. The implication of the findings will be discussed in view of reliable and efficient operation of CEBAF and future large-scale SRF accelerators. | |||
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MOPB036 | TOF-SIMS Study of Nitrogen Doping Niobium Samples | niobium, experiment, cavity, ion | 169 |
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Nitrogen doping treatment with the subsequent electropolishing (EP) of the niobium superconducting cavity can significantly increase the cavity’s quality factor up to a factor of 3. The nitrogen doping experiment has been successfully repeated and demonstrated. But the mechanism of the nitrogen doping effect remains unclear. Nitrogen doping study on niobium samples was carried out in Peking University. The niobium samples were manual processed to avoid heat generation. The experiment condition is close to that of the Fermilab. After the nitrogen doping treatment, the samples were mildly electropolished with the thickness of 1.3μm, 1.9μm, 3.3μm, 4.2μm, 5.1μm, 5.9μm and 7.0μm. The time of flight secondary ion mass spectrometry (TOF-SIMS) measurements show that the samples directly after nitrogen doping have a much higher nitrogen concentration in the depth of about 90nm. When the EP removal is larger than 1.3μm, the samples’ impurity elements is remarkably reduced and their distribution is similar to each other. Also the measured results to some extent prove that EP removal can introduce H to the niobium surface. | |||
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MOPB042 | Fundamental Studies on Doped SRF Cavities | cavity, niobium, simulation, SRF | 187 |
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Funding: NSF Recently, doping with nitrogen has been demonstrated to help SRF cavities reach significantly higher intrinsic quality factors than with standard procedures. However, the quench fields of these cavities have also been shown to be frequently reduced. Here we report on fundamental studies of doped cavities, investigating the source of reduced quench field and exploring alternative dopants. We have focused on studying the quench of nitrogen-doped cavities with temperature mapping and measurements of the flux penetration field using pulsed power to investigate maximum fields in nitrogen doped cavities. We also report on studies of cavities doped with other gases such as helium. These studies have enabled us to shed light on the mechanisms behind the higher Q and lower quench fields that have been observed in cavities doped with impurities. |
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MOPB047 | Secondary Electron Yield of Electron Beam Welded Areas of SRF Cavities | electron, cavity, gun, niobium | 196 |
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Secondary Electron Emission (SEE) is a phenomenon that contributes to the total electron activity inside the Superconducting Radiofrequency (SRF) cavities during the accelerator operation. SEE is highly dependent on the state of the surface. During electron beam welding process, significant amount of heat is introduced into the material causing the microstructure change of Niobium (Nb). Currently, all simulation codes for field emission and multipacting are treating the inside of the cavity as a uniform, homogeneous surface. Due to its complex shape and fabricating procedure, and the sensitivity of the SEE on the surface state, it would be interesting to see if the Secondary Electron Yield (SEY) parameters vary in the surface area on and near the equator weld. For that purpose, we have developed experimental setup that can measure accurately the energy distribution of the SEY of coupon-like like samples. To test the influence of the weld area on the SEY of Nb, dedicated samples are made from a welded plate using electron beam welding parameters common for cavity fabrication. SEY data matrix of those samples will be presented. | |||
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MOPB050 | Characterization of SRF Materials at the TRIUMF muSR Facility | TRIUMF, SRF, positron, polarization | 205 |
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MuSR is a powerful tool to probe local magnetism and hence can be used to diagnose flux penetration in Type-II superconductors. Samples produced at TRIUMF and with collaborators in both coin shaped and ellipsoidal geometries have been characterized by applying either transverse or parallel fields between 0 and 300mT and measuring flux entry as a function of applied field. Samples include Nb treated in standard ways including forming, chemistry, and heat treatments. Further, Nb samples have been doped with Nitrogen and coated with a 2 micron layer of Nb3Sn by collaborators from FNAL and Cornell respectively and measured in three field/geometry configurations. Analysis of the method in particular the effects of geometry and the role of pinning will be presented. Results of the measurements will be presented. | |||
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MOPB058 | Field Emission From a Thermally Oxidized Nb Sample | site, collider, linear-collider, high-voltage | 233 |
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Funding: This work was funded by BMBF project 05H12PX6. Enhanced field emission (EFE) from particulates and surface defects is one of the main field limitations of superconducting Nb cavities required for XFEL and ILC. The activation field Eact of such emitters and the emitter number density N at a given Eact is strongly influenced by the thickness of the Nb oxide layer*. Combination of this effect with surface cleaning techniques, e.g. dry ice cleaning (DIC), potentially shifts the onset of EFE to even higher Eact. Therefore, we have started to investigate a single crystal Nb sample after thermal oxidation (TO) by a heat treatment (HT) in air (T = 360°C, t = 40 min). Field emission maps showed a first emitter at 100 MV/m, and N = 30/cm² at 225 MV/m. SEM analysis of the 10 strongest emitters revealed mainly surface defects and one particulate. Subsequent removal of the oxide by a HT (T = 400°C, t = 1 h) under UHV resulted in an EFE onset at 75 MV/m and increased N to 60/cm² at 225 MV/m. In a second step the TO as well as the measurement was repeated after DIC of the surface. The resulting field maps and the SEM analysis of selected emitters will be reported. *A.T. Wu et al., MOPC118, IPAC11. |
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MOPB059 | Field Emission Investigation of Centrifugal-Barrel-Polished Nb Samples | cavity, site, survey, electron | 237 |
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Funding: This work was funded by BMBF project 05H12PX6. Actual and future SRF-accelerators require high accelerating gradient Eacc and quality factor Q0, which are often limited by enhanced field emission (EFE)* caused by surface roughness or particulates**. Various expensive surface preparation techniques (e.g. BCP, EP, HPR etc.) have been developed to obtain the required surface quality and remove the emitters. Recently, centrifugal barrel polishing (CBP) has been reconsidered to obtain a comparable surface roughness as EP with less effort***. We have started to investigate Nb samples, which were prepared as coupons in a single cell 1.3 GHz cavity by an optimized five step CBP process with a final dry ice cleaning. EFE maps showed the first emitter (1 nA) at 60 MV/m, and 32 emitters at 110 MV/m. SEM/EDX analysis of the emitting sites revealed many Al2O3 inclusions with sharp edges. Therefore, subsequent BCP (~20 μm removal) was applied to the sample. Surface analysis as well as EFE characterization of CBP treated Nb coupons with/without BCP step will be presented. *D. Reschke et al., THPP021, LINAC14. **A. Navitski et al., PRSTAB 16, 112001 (2013). ***C.A. Cooper, L.D. Cooley, Supercond. Sci. Technol. 26, 015011 (2013). |
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MOPB077 | Vertical Tests of XFEL 3rd Harmonic Cavities | cavity, HOM, operation, instrumentation | 306 |
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The 10 cavities of the EXFEL 3rd Harmonic Cryomodule have been tested and qualified, before integration in the He-tank, in our upgraded Vertical Test stand. In this paper, we report the measured RF performance of these cavities together with the main features of the test facility. | |||
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MOPB079 | Analysis of the Test Rate for European XFEL Series Cavities | cavity, database, site, status | 316 |
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The main part of the superconducting European XFEL linear accelerator consists of 100 accelerator modules each containing eight RF-cavities. Before the installation to a module, all of these cavities will be tested at cryogenic temperatures in a vertical cryostat in the accelerator module test facility (AMTF) at DESY. This paper discusses the average vertical test rate at the present status. It should be 1 in the ideal case, but actually it’s observed to be approximately 1.5. Classification and analysis concerning the reasons for this deviation are given as well as suggestions for a reduction of the test rate for future production cycles. | |||
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Poster MOPB079 [0.632 MB] | ||
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MOPB087 | Integrated High-Power Tests of Dressed N-doped 1.3 GHz SRF Cavities for LCLS-II | cavity, HOM, cryomodule, resonance | 342 |
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New auxiliary components have been designed and fabricated for the 1.3 GHz SRF cavities comprising the LCLS-II linac. In particular, the LCLS-II cavity’s helium vessel, high-power input coupler, higher-order mode (HOM) feedthroughs, magnetic shielding, and cavity tuning system were all designed to meet LCLS-II specifications. Integrated tests of the cavity and these components were done at Fermilab’s Horizontal Test Stand (HTS) using several kilowatts of continuous-wave (CW) RF power. The results of the tests are summarized here. | |||
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MOPB089 | 1.3 GHz Cavity Test Program for ARIEL | cavity, cryomodule, induction, TRIUMF | 350 |
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The ARIEL eLINAC is a 50 MeV 10 mA electron LINAC. Once finished, five cavities will each provide 10MV of effective accelerating voltage. At the present time two cavities have been installed and successfully accelerated been above specifications of 10 MV/m at a Q0 of 1010. The next cavities are already in the pipeline and being processed. In addition, one additional cavity has been produced for our collaboration with VECC, India. This cavity has been tested and installed in a cryomodule identical to the eLINAC injector cryomodule. New developments for single cell testing at TRIUMF are a T-mapping system developed in collaboration with UoT and vertical EP for single cells. The progress of the performance after each treatment step has been measured and will be shown. measured and will be shown. | |||
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MOPB111 | Furnace N2 Doping Treatments at Fermilab | cavity, SRF, controls, PLC | 423 |
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Funding: Operated by Fermi Research Alliance, LLC under Contract No. De-AC02-07CH11359 with the United States Department of Energy. The Fermilab SRF group regularly performs Nitrogen (N2) doping heat treatments on superconducting cavities in order to improve their Radio Frequency (RF) performances. This paper describes the set up and operations of the Fermilab vacuum furnaces, with a major focus on the implementation and execution of the N2 doping recipe. The cavity preparation will be presented, N2 doping recipes will be analyzed and heat treatment data will be reported in the form of plot showing temperature, total pressure and partial pressures over time. Finally possible upgrades and improvements of the furnace and the N2 doping process are discussed. |
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MOPB112 | SRF Quality Assurance Studies and Their Application to Cryomodule Repairs at SNS | cryomodule, cavity, HOM, hardware | 428 |
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Funding: This work was supported by SNS through UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. DOE. Many of the SRF activities involve interactions to cavities which presents risk for particulate contamination to RF surfaces. In order to understand and reduce contamination in cavities during cleaning, vacuum pumping and purging, and in-situ cryomodule repairs, a Quality Assurance (QA) studies were initiated to evaluate these activities and improve them where possible. This paper covers the results of investigations on the effectiveness of the SNS ultrasonic cleaning systems, particulate control during pumping and purging, procedure development for in-situ cryomodule repairs, the application of these studies to the repair of a linac cryomodule, and discussion of further improvement in these areas. |
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MOPB115 | Surface Studies of Plasma Processed Nb Samples | plasma, cavity, SRF, ion | 438 |
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Funding: This work is supported by SNS through UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. DOE. Contaminants present at top surface of superconducting radio frequency (SRF) cavities can act as field emitters and restrict the cavity accelerating gradient. A room temperature in-situ plasma processing technology for SRF cavities aiming to clean hydrocarbons from inner surface of cavities has been recently developed at the Spallation Neutron Source (SNS). Surface studies of the plasma processed Nb samples by Secondary ion mass spectrometry (SIMS) and Scanning Kelvin Probe (SKP) showed that the NeO2 plasma processing is very effective to remove carbonaceous contaminants from top surface and improves the surface work function by 0.5 to 1.0 eV. *M. Doleans et al., Proc. 2013 SRF, Paris, France. **P. V. Tyagi, et al., Proc. Linac14, Geneva, Switzerland. ***M. Doleans et al., These proceedings. |
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Poster MOPB115 [0.524 MB] | ||
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MOPB116 | Developments of Horizontal High Pressure Rinsing for SuperKEKB SRF Cavities | cavity, factory, operation, SRF | 443 |
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The Q factors of the eight superconducting accelerating cavities gradually degraded during the long-term operation of the KEKB accelerator. Since we will re-use those SRF cavities for the SuperKEKB, the performance degradation will be a serious problem. Several cavities degraded their performance significantly at high accelerating fields. The Q degradation is still acceptable for the 1.5 MV operations at SuperKEKB. However, further degradation will make the operation difficult. In order to recover the cavity performance, we developed horizontal high pressure water rinsing (HHPR). This method uses a horizontal high pressure water nozzle and inserts it directly into the cavity module. We applied this method to two degraded cavities and their degraded Q factors recovered above 109 at around 2 MV. In this paper we will present the HHPR method, high power test results after the HHPR and the residual gas analysis. | |||
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MOPB118 | Cleanliness and Vacuum Acceptance Tests for the UHV Cavity String of the XFEL Linac | cavity, operation, controls, cryomodule | 452 |
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The main linac of the European XFEL will consist of 100 accelerator modules, i.e. 800 superconducting accelerator cavities operated at a design gradient of 23.6MV/m. In this context CEA-Saclay built an assembly facility designed to produce one module per week, ready to be tested at DESY. The facility overcame the foreseen production rate. We would like to highlight and discuss the critical fields: cleanliness and vacuum. A new assembly method to protect final assembly against particulates contamination has been implemented on the production line. Impact on cryomodule RF test is presented. Particle transport measurements on components used for the European XFEL accelerator module are presented. The results indicate that the nominal operation of the automated pumping and venting units will not lead to particle transport. Vacuum acceptance tests are of major interest: leak tests and residual gas analysis (RGA) are used to control the absence of air leak and contamination. The RGA specifications have been slightly relaxed to ensure the production rate. | |||
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TUBA01 | Status of the SRF Systems at HIE-ISOLDE | cavity, cryomodule, cryogenics, solenoid | 481 |
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The HIE-ISOLDE project has been approved by CERN in 2009 and gained momentum after 2011. The final energy goal of the upgrade is to boost the radioactive beams of REX-ISOLDE from the present 3 MeV/u up to 10 MeV/u for A/q up to 4.5. This is to be achieved by means of a new superconducting linac, operating at 101.28 MHz and 4.5 K with independently phased quarter wave resonators (QWR). The QWRs are based on the Nb sputtering on copper technology, pioneered at CERN and developed at INFN-LNL for this cavity shape. Transverse focusing is provided by Nb-Ti superconducting solenoids. The cryomodules hosting the active elements are of the common vacuum type. In this contribution we will report on the recent advancements of the HIE-ISOLDE linac technical systems involving SRF technology. The paper is focused on the cavity production, on the experience with the assembly of the first cryomodule (CM1), and on the results of the first hardware commissioning campaign. | |||
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Slides TUBA01 [27.129 MB] | ||
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TUBA05 | Progress With Multi-Cell Nb3Sn Cavity Development Linked With Sample Materials Characterization | cavity, niobium, SRF, factory | 505 |
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Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177. Exploiting both the new Nb3Sn coating system and the materials characterization tools nearby, we report our progress in low-loss Nb3Sn films development. Nb3Sn films a few micrometers thick were grown on Nb coupons as well as single- and multi-cell cavities by the Sn-diffusion technique. Films structure and composition were investigated on coated samples and cavity cutouts with characterization tools including SEM/EDS/EBSD, AFM, XPS, SIMS towards correlating film growth and RF loss to material properties and deposition parameters. Cavity coating efforts focused on establishing techniques for coating progressively more complicated RF structures, and understanding limiting mechanisms in coated cavities. Nb3Sn coated 1.5 GHz 1-cell and 1.3 GHz 2-cell cavities have shown quality factors of 1010 at 4.3 K, with several cavities reaching above Eacc = 10 MV/m. The dominant limiting mechanisms were low field quenches and quality factor degradation above 8 MV/m. The surface data indicates a near-stoichiometric Nb3Sn consistent with the transition temperature and gap measurements. The Nb3Sn layer is covered with Nb2O5 and SnO2 native oxides and has little memory of the pre-coating surface. |
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Slides TUBA05 [2.418 MB] | ||
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TUPB007 | Progress in the Elliptical Cavities and Cryomodule Demonstrators for the ESS LINAC | cryomodule, cavity, cryogenics, linac | 544 |
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The European Spallation Source (ESS) accelerator is a large superconducting linac under construction in Lund, Sweden. A collaboration between CEA Saclay, IPN Orsay and ESS-AB is established to design the elliptical cavities cryomodule of the linac. It is foreseen to build and test two cryomodule demonstrators within the next two years. We present the design evolution and the fabrication status of the cryomodule components housing four cavities. The latest test results of two prototype cavities are shown. The cryomodule assembly process and the on-going testing infrastructures at CEA Saclay are also described. | |||
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TUPB010 | Plug Transfer System for GaAs Photocathodes | gun, SRF, cathode, operation | 553 |
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The transport and exchange technology of Cs2Te photocathode for the ELBE superconducting rf photoinjector (SRF gun) has been successfully developed and tested at HZDR. The next goal is to realize the transport of GaAs photocathode into SRF gun, which will need a new transfer system with XHV 10-11 mbar. The key component of the system is the transfer chamber and the load-lock system that will be connected to the SRF-gun. In the carrier four small plugs will be transported, and one of them will be plug on the cathode-body and inserted into the cavity. The new transport chamber allows the transfer and exchange of plugs between HZDR, HZB and other cooperating institutes. In HZDR this transfer system will also provide a direct connection between the SRFGUN and the GaAs preparation chamber in the Elbe-accelerator hall. | |||
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TUPB017 | 1.3 GHz SRF Technology R&D Progress of IHEP | cavity, cryomodule, cryogenics, HOM | 581 |
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IHEP started the 1.3GHz SRF technology R&D in 2006 and recently enters the stage of integration and industrialization. After successfully making several single cell and 9-cell cavities of different shape and material, we designed and assembled a short cryomodule containing one large grain low loss shape 9-cell cavity with an input coupler and a tuner etc. This module will perform horizontal test in 2016 with the newly commissioned 1.3GHz 5MW klystron and the 2K cryogenic system. Beam test with a DC photocathode gun is also foreseen in the near future. We report here the problems, key findings and improvements in cavity dressing, clean room assembly, cryomodule assembly and the liquid nitrogen cool down test. A fine grain TESLA 9-cell cavity is also under fabrication in a company as the industrialization study. | |||
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TUPB018 | Preparation of the 3.9 GHz System for the European XFEL Injector Commissioning | cavity, HOM, operation, alignment | 584 |
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The 3.9 GHz cryomodule and RF system for the XFEL Injector is being assembled and delivered to the underground building in summer 2015, for the injector commissioning in Fall 2015. This contribution outlines the status of the activity and reports the preparation stages of the technical commissioning of the system. | |||
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TUPB022 | Low-Beta SRF Cavity Processing and Testing Facility for the Facility for Rare Isotope Beams at Michigan State University | cavity, SRF, controls, cryomodule | 597 |
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Funding: This material is based upon work supported by the U.S. Department of Energy Office of Science under Cooperative Agreement DE SC0000661, the State of Michigan and Michigan State University Major work centers of the new SRF Highbay are fully installed and in use for FRIB pre-production SRF quarter-wave and half-wave resonators, including inspection area, high temperature vacuum furnace for cavity degassing, chemical etching facility and processing and assembly cleanrooms. Pre-production activities focus on optimizing workflow by reducing process time, tracking part status and related data, and identifying bottlenecks. Topics discussed may include; buffered chemical polish (BCP) etching for cavity frequency control, degassing time reduction, automated high pressure rinse, particle control against field emission, pre-production cavity test results and implementation of workflow status programs |
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TUPB026 | Cryogenic Performance of the HNOSS Test Facility at Uppsala University | cavity, cryogenics, operation, controls | 612 |
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Funding: Knut and Alice Wallenbergs foundation The FREIA Laboratory at Uppsala University, Sweden, is developing part of the RF system and testing the superconducting double spoke cavitites for ESS. During 2014 it was equipped with HNOSS, a versatile horizontal cryostat system for testing superconducting cavities. HNOSS is designed for high power RF testing of up to two superconducting accelerating cavities equipped with helium tank, fundamental power coupler and tuning system. In particular it will be used to characterise the performance of spoke cavities like used in the accelerator for the ESS project. HNOSS is connected to a cryogenic plant providing liquid helium and a sub-atmospheric pumping system enabling operation in the range 1.8 to 4.5~K. We present a brief description of the major components, installation and results from the recent operation and tests. |
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TUPB040 | High Power Impulse Magnetron Sputtering of Thin Films for Superconducting RF Cavities | power-supply, target, radio-frequency, scattering | 647 |
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The production of superconducting coatings for radio frequency cavities is a rapidly developing field that should ultimately lead to acceleration gradients greater than those obtained by bulk Nb RF cavities. Optimizing superconducting properties of Nb and Nb compound thin-films is therefore essential. Nb films were deposited by magnetron sputtering in pulsed DC mode onto Si (100) and MgO (100) substrates and also by high impulse magnetron sputtering (HiPIMS) onto Si (100), MgO (100) and polycrystalline Cu. HiPIMS was then used to deposit NbN and NbTiN thin films onto Si(100) and polycrystalline Cu. The films were characterised using scanning electron microscopy, x-ray diffraction, DC SQUID magnetometry and Q factor for a flat thin film sample. | |||
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TUPB050 | Secondary Electron Yield of SRF Materials | electron, niobium, SRF, cavity | 686 |
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The secondary electron yield (SEY) describes the number of electrons emitted to the vacuum per arriving electron at the surface. For a given geometry, the SEY is the defining factor for multipacting activity. In the quest of superconducting RF materials beyond bulk niobium, we studied the SEY of the currently most important candidates for future SRF applications: Nb3Sn, NbTiN and MgB2. All studies were done on clean but technical surfaces, i.e. on clean surfaces exposed to air and with their native oxides as it would be the case for SRF cavities. | |||
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TUPB051 | Development of Nb3Sn Coatings by Magnetron Sputtering for SRF Cavities | radio-frequency, SRF, target, quadrupole | 691 |
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Funding: The work is part of EuCARD-2, partly funded by the European Commission, GA 312453 Cost and energy savings are an integral requirement in the design of future particle accelerators. Very low losses SRF accelerating systems, together with high-efficiency cryogenics systems, have the potential of low running costs. The association to the capital cost reduction allowed by thin films coated copper cavities may represent the best overall cost-performance compromise. This strategy has been applied for instance in LEP, the LHC and HIE-ISOLDE with the niobium thin films technology. New materials must be considered to improve the quality factor of the cavities, such as Nb3Sn, which could also ideally operate at higher temperature thus allowing further energy savings. The study considers the possibility to coat a copper resonator with an Nb3Sn layer by means of magnetron sputtering using an alloyed target. We present the impact of the process parameters on the as-deposited layer stoichiometry. The latter is in good agreement with previous results reported in the literature and can be tuned by acting on the coating pressure. The effect of post-coating annealing temperature on the morphology, crystallinity and superconducting properties of the film was also investigated. |
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TUPB053 | Research on MgB2 at LANL for the Application to SRF Structures | SRF, superconductivity, status, electron | 700 |
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Funding: U.S. Department of Energy (DOE) Office of Science Office of Nuclear Physics Early Career Research Program This paper is focused on the development of MgB2 coating technique at LANL. Using boron film samples obtained at a large furnace system, we succeeded in obtaining superconducting MgB2 films (Tc of up to 37 K so far) by reacting them with Mg vapor. The major improvements were 1) confinement of the Mg vapor in a hot zone to mitigate the insufficient Mg pressure due to condensation on low temperature surfaces of the connected vacuum pipes and 2) reduction of cooldown time, i.e., ~13 minutes instead of ~1 day with the large system to prevent MgB2 from decomposing. |
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TUPB060 | Measurements of RF Properties of Thin Film Nb3Sn Superconducting Multilayers Using a Calorimetric Technique | SRF, cavity, impedance, radio-frequency | 720 |
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Funding: DOE Contract No. DE-AC05-06OR23177 DOE Grant No. DE-SC0010081 Results of RF tests of Nb3Sn thin film samples related to the superconducting multilayer coating development are presented. We have investigated thin film samples of Nb3Sn/Al2O3/Nb with Nb3Sn layer thicknesses of 50 nm and 100 nm using a Surface Impedance Characterization system. These samples were measured in the temperature range 4 K-19 K, where significant screening by Nb3Sn layers was observed below 16-17 K, consistent with the bulk critical temperature of Nb3Sn. |
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TUPB062 | Evaluation of Sc Property Coated on a Surface | ion, gun, neutron, cavity | 723 |
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Funding: This work was supported by JSPS KAKENHI Grant Number 26600142. We are trying to deposit thin superconducting material on a substrate for higher accelerating field gradients. In order to evaluate the deposit method, surface properties are under measurement. Some results on measurements at DC and a preparation status toward RF measurement will be reported. |
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TUPB064 | Superconducting Thin Film Test Cavity Commissioning | cavity, niobium, cryogenics, resonance | 731 |
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A radiofrequency (RF) cavity and cryostat dedicated to the measurement of superconducting coatings at GHz frequencies was designed to evaluate surface resistive losses on a flat sample. The test cavity consists of two parts: a cylindrical half-cell made of bulk niobium (Nb) and a flat Nb disc. The two parts can be thermally and electrically isolated via a vacuum gap, whereas the electromagnetic fields are constrained through the use of RF chokes. Both parts are conduction cooled hence the cavity halves are suspended in vacuum during operation. The flat disc can be replaced with a sample, such as a Cu disc coated with a film of niobium or any other superconducting material. The RF test provides simple cavity Q-factor measurements as well as calorimetric measurements of the losses on the sample. The advantage of this method is the combination of a compact cavity with a simple planar sample. The paper describes the RF, mechanical and cryogenic design, and initial commissioning of the system with notes on how any issues arising are to be addressed. | |||
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TUPB071 | Development and Testing of a 325 MHz beta0 = 0.82 Single-Spoke Cavity | cavity, linac, impedance, cryogenics | 744 |
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A single-spoke cavity operating at 325 MHz with geometric beta of 0.82 has been developed and tested. Initial results* showed high levels of field emission which limited the achievable gradient. Several rounds of helium processing significantly improved the cavity performance. Here we discuss the development process and report on the improved results.
*C.S. Hopper, HyeKyoung Park, and J.R. Delayen, “Cryogenic Testing of High-Velocity Spoke Cavities,” Proc. of the 27th Linear Accelerator Conference, Geneva, Switzerland, TUPP109, (2014). |
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TUPB072 | Report of Vertical Test of the β=0.12 Half-Wave Resonator at RISP | cavity, ion, TRIUMF, simulation | 747 |
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β=0.12, f=162.5 MHz half-wave resonator for Rare Isotope Science Project (RISP) was recently tested at TRIUMF. We briefly report the vertical test result: At 2K, the cavity achieved Q0=2·109 at Eacc=6.4 MV/m and the performance was limited at Eacc=7.8 MV/m by intense field emission. The surface processing was standard: 120 micron buffered chemical polishing followed by high pressure rinsing. After first cold test, 120C baking was done and the corresponding result was also obtained. | |||
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Poster TUPB072 [0.414 MB] | ||
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TUPB074 | High-Vacuum Simulations and Measurements on the SSR1 Cryomodule Beam-Line | cavity, cryomodule, simulation, niobium | 754 |
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Funding: Work supported by Fermi Research Alliance, LLC under Contract No. DEAC02- 07CH11359 with the United States Department of Energy In order to guarantee an effective cool-down process for the SSR1 cryomodule, a high-vacuum level must be achieved at room temperature in the beam-line before introducing gaseous and liquid helium. The SSR1 cavities in the beamline have a small beam aperture compared to the size of their internal volume. To avoid unnecessary complications for the vacuum piping of the cryomodule cold-mass, a pilot study was conducted on the string prior to processing and qualification of the components to investigate the vacuum level achievable by pumping only through the beam-line. To estimate the pressure distribution inside the cavity string we used a mathematical model implemented in a test-particle Monte-Carlo simulator for ultra-high-vacuum systems. |
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TUPB100 | CEA Experience and Effort to Limit Magnetic Flux Trapping in Superconducting Cavities | cryomodule, cavity, solenoid, SRF | 847 |
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Protecting superconducting cavities from the surrounding static magnetic field is considered as a key point to reach very good cavity performances. This can be achieved by both limiting the causes of magnetic flux around the cavity in the cryomodule, and enclosing cavities and/or cryomodules into magnetic shields. We will present the effort made at CEA into this direction: shield design, shield material characterization, at room and cryogenic temperature, and search and attenuation of the magnetic background present in the cryomodule during the cavities superconducting transition. This last point will be especially studied for the IFMIF project where the cryomodule houses the focusing magnets. Aspects of the cold magnetic shields for ESS will also be discussed. | |||
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TUPB103 | Cryomodule Protection for ARIEL e-Linac | cavity, cryomodule, beam-loading, linac | 861 |
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The e-Linac cryomodules require high RF power, cryogenics, ultra-high vacuum, and precise mechanical adjustment. They require protection against of failures, like quench in the cavity, bad vacuum or multipacting in power couplers, low liquid helium level or high temperatures. The protection unit should stop RF power in the cryomodule in case of the listed failures. A Interlock Box is developed to implement protection function for the cryomodule. The paper will describe the design of Interlock Box for e-Linac cryomodule protection. As quench protection required, quench evolution analysis with RF transient analysis is investigated. The details of quench detection for e-Linac will also be reported. | |||
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TUPB104 | Series Production of BQU at DESY for the EU-XFEL Module Assembly at CEA Saclay | acceleration, quadrupole, cavity, diagnostics | 865 |
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Each of the 103 XFEL modules foreseen for the EU-XFEL as well as the 3,9 GHZ injector module is equipped with a combination of beam position monitors, superconducting quadrupole and a gate valve connected to the beam position monitor. The subunits are prequalified by the different work package of the EU-XFEL collaboration and handover to the DESY cleanroom. These subunits are assembled in the DESY ISO 4 cleanroom to unit named BQU, quality controlled in respect of cleanliness and handover in status “ready for assembly in ISO 4 cleanroom” for string assembly to the ISO 4 cleanroom located at CEA France. Series production started with production sequences of one unit per week and needed to be accelerated up to five or six units per month (>=1.25 units per week) in beginning of 2015. Analysis of data taken during production and the optimization of work flow for higher production rates are presented. | |||
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TUPB105 | String Assembly for the EU-XFEL 3.9 GHz Module at DESY | cavity, alignment, quadrupole, linac | 869 |
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For the injector of the EU- XFEL one so-called 3.9 GHz module is required. This special module houses eight 3.9 GHz s.c. cavities, a beam position monitor and a quadrupole package. The cavities were fabricated and vertically tested as an in-kind contribution to the EU-XFEL by INFN Milano collaborators. The power couplers have been fabricated and conditioned by FNAL. The string assembly took place inside the ISO 4 cleanroom at DESY. A seven meter long alignment and assembly girder for this special string assembly has been designed and fabricated at DESY. The girder facilitates the assembly of the 3.9 GHz resonators with alternating power coupler orientation in ISO 4 cleanrooms. For redundancy and fast action on problems during string assembly, the DESY high pressure rinsing system (HPR) has been modified on the basis of the INFN Milano design for this 3.9 GHz application. The HPR has been qualified by four 3.9 GHz resonators, tested at INFN Milano. The integration of the cavities into Helium vessels, power coupler coupling factor and the power coupler assembly at DESY is qualified by one cavity that has been equipped with Helium tank and a power coupler and tested horizontally. | |||
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TUPB106 | First HIE-ISOLDE Cryo-module Assembly at CERN | cavity, pick-up, insertion, instrumentation | 874 |
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The first phase of the HIE-ISOLDE project aims to increase the energy of the existing REX ISOLDE facilities from 3MeV/m to 5MeV/m. It involves the assembly of two superconducting cryo-modules based on quarter wave resonators made by niobium sputtered on copper. The first cryo-module was installed in the linac in May 2015 followed by the commissioning. The first beam is expected for September 2015. In parallel the second cryo-module assembly started. In this paper, we present the different aspects of these two cryo-modules including the assembly facilities and procedures, the quality assurance and the RF parameters (cavity performances, cavity tuning and coupling). | |||
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TUPB108 | Connection of EU-XFEL Cryomodules, Caps, Boxes in EU-XFEL Main Linac and Injector: Welding of Cryo-Pipes and Assembly of Beam-Line Absorbers Under Requirements of PED Regulation | linac, cryomodule, cryogenics, operation | 883 |
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The European X-ray Free Electron Laser (EU-XFEL) cold linac consists of 100 assembled cryomodules, 6 feed-/end-boxes and 6 string connection boxes fixed to the ceiling of the accelerator tunnel; the injector consists of a radio frequency gun, one 1.3 GHz and one 3.9 GHz cryomodule, one feed- and one end-cap lying on ground supports. The components are connected together in the tunnel, after cold testing, transport, final positioning and alignment. The cold linac is a pressure equipment and is therefore subjected to the requirements of the Pressure Equipment Directive (PED). This paper describes the welding and subsequent non-destructive testing of the cryo-pipes (with a deeper look at the technical solutions adopted to satisfy the PED requirements), the assembly of the beam line absorbers and the final steps before closing the connection with a DN1000 bellows. A special paragraph will be dedicated to the connection of the injector components, where the lack of space makes this installation a particularly challenging task. | |||
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TUPB109 | Assembly and Cool-Down Tests of STF2 Cryomodule at KEK | cavity, HOM, cryomodule, network | 888 |
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As the next step of the quantum beam project, the STF2 project is in progress at KEK. Eight 9-cell SC cavities and one superconducting quardrapole magnet were assembled into the cryomodule called CM1. Four 9-cell SC cavities were assembled into the cryomodule called CM2a. These two cryomodules were connected as one unit, and the examination of completion by a prefectural government was carried out. The target value of beam energy in the STF2 accelerator is 400 MeV with a beam current of 6 mA. The first cool down test for low power level RF measurements was performed in autumn of 2014. In this paper, the assembly procedure of the STF2 cryomodules and the results of the low-power measurement are reported. | |||
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TUPB110 | LCLS-II 1.3 GHz Design Integration for Assembly and Cryomodule Assembly Facility Readiness at Fermilab | cryomodule, cavity, instrumentation, alignment | 893 |
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Funding: DOE LCLS-II is a planned upgrade project for the linear coherent light source (LCLS) at Stanford Linear Accelerator Center (SLAC). The LCLS-II linac will consist of thirty-five 1.3 GHz and two 3.9 GHz superconducting RF continuous wave (CW) cryomodules that Fermilab and Jefferson Lab will assemble in collaboration with SLAC. The LCLS-II 1.3 GHz cryomodule design is based on the European XFEL pulsed-mode cryomodule design with modifications needed for CW operation. Both Fermilab and Jefferson Lab will each assemble and test a prototype 1.3 GHz cryomodule to assess the results of the CW modifications. After prototype cryomodule tests, both laboratories will increase cryomodule production rate to meet the challenging LCLS-II project installation schedule requirements of approximately one cryomodule per month per laboratory. This paper presents the 1.3 GHz CW cryomodule design integration for assembly at Fermilab, Fermilab Cryomodule Assembly Facility (CAF) infrastructure modifications for the LCLS-II cryomodules, and readiness for the required assembly throughput. |
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TUPB113 | JLab Cryomodule Assembly Infrastructure Modifications for LCLS-II | cavity, cryomodule, cryogenics, controls | 898 |
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Funding: This work was supported by the LCLS-II Project and the U.S. Department of Energy, Contract DE-AC02-76SF00515. The Thomas Jefferson National Accelerator Facility is currently engaged, along with several other DOE national laboratories, in the Linac Coherent Light Source II project (LCLS II). The SRF Institute at Jefferson Lab will be building 1 prototype and 17 production cryomodules based on the TESLA / ILC / XFEL design. Each cryomodule will contain eight nine cell cavities with coaxial power couplers operating at 1.3 GHz. New and modified infrastructure and assembly tooling is required to construct cryomodules in accordance with LCLS-II requirements. The approach for modifying assembly infrastructure included evaluating the existing assembly infrastructure implemented at laboratories world-wide in support of ILC and XFEL production activities and considered compatibility with existing infrastructure at JLab employed for previous cryomodule production projects. These modifications include capabilities to test cavities, construct cavity strings in a class 10 cleanroom environment, assemble cavity strings into cryostats, and prepare cryomodules for cryogenic performance testing. This paper will give a detailed description of these modifications. |
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TUPB115 | Improvements of the Mechanical, Vacuum and Cryogenic Procedures for European XFEL Cryomodule Testing | cryomodule, operation, cryogenics, detector | 906 |
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The European X-ray Free Electron Laser is under construction at DESY, Hamburg. The linear accelerator part of the laser consists of 100 SRF cryomodules. Before installation in the tunnel the cryomodules undergo a series of performance tests at the AMTF Hall. Testing procedures have been implemented based on TTF (Tesla Test Facility) experience. However, the rate of testing and number of test benches is greater than in the TTF infrastructure. To maintain the goal testing rate of one module per week, improvement to the existing procedures were implemented at AMTF. Around 50% of the testing time is taken by connection of the cryomodule to the test bench, performing all necessary checks and cool down. Most of the preparation procedures have been optimized to decrease mounting time. This paper describes improvements made to the mechanical connections, vacuum checks and cryogenics operation. | |||
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TUPB117 | Cavities and Cryomodules Managing System at AMTF | cavity, cryomodule, cryogenics, status | 910 |
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800 SRF cavities and 100 SRF cryomodules are under test in the AMTF Hall at DESY, Hamburg. Testing of such a large volume of components requires a management system which can store the measurement data. In addition the system should simplify tasks which are recurrent. In the case of the system developed at AMTF, communication with external databases has also been developed. An added complication is that not all the test procedures are identical for each component, and therefore the management system keeps track of all work done for each of the individual components. In the case of the vertical acceptance tests for the 800 SRF cavities, the management system provides an interface for specifying a decision of the next step each cavity (e.g. send for module assembly or retreatment). This paper describes the most important parts of this system. | |||
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WEBA03 | Production Status of SRF Cavities for the Facility for Rare Isotope Beams (FRIB) Project | cavity, niobium, linac, controls | 961 |
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As the Facility for Rare Isotope Beams (FRIB) project ramps into production, vendor relations, cavity quality, and schedule become critical to success. The driver linac will be constructed of 332 cavities housed in 48 cryomodules and designed with two cavity classes (quarter-wave and half-wave) and four different betas (0.041, 0.085, 0.29, and 0.53). The cavities will be supplied to FRIB from awarded industrial vendors. FRIB’s experience with SRF cavity fabrication will be presented including acceptance inspections, test results, technical issues, and mitigation strategies. | |||
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Slides WEBA03 [1.672 MB] | ||
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WEBA05 | Achieving High Peak Fields and Low Residual Resistance in Half-Wave Cavities | cavity, niobium, accelerating-gradient, cryomodule | 973 |
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Funding: Work supported by the U.S. Department of Energy Office of Science, Office of Nuclear Physics contract number DE-AC02-06CH11357, and the Office of High Energy Physics contract number DE-AC02-76CH03000. We have designed, fabricated and tested two new half-wave resonators following the successful development of a series of niobium superconducting quarter-wave cavities. The half-wave resonators are optimized for β = 0.11 ions, operate at 162.5 MHz and are intended to provide up to 2 MV effective voltage for particles with the optimal velocity. Testing of the first two half-wave resonators is complete with both reaching accelerating voltages greater than 3.5 MV with low-field residual resistances of 1.7 and 2.3 nΩ respectively. The intention of this paper is to provide insight into how Argonne achieves low-residual resistances and high surface fields in low-beta cavities by describing the cavity design, fabrication, processing and testing. |
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Slides WEBA05 [2.927 MB] | ||
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THAA04 | Comparison of Cavity Fabrication and Performances Between Fine Grains, Large Grains and Seamless Cavities | cavity, electron, SRF, niobium | 1006 |
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In KEK-CFF, L-band SRF cavity fabrication studies have been actively proceeded. Main target of the R&D is investigation of cavity fabrication methods using different Nb materials. In this talk, we report mainly focus on the experiences obtained from single cell cavity fabrications. First, different Nb materials are compared, between fine grain Nb and large grain(LG) Nb from different vendors including low RRR LG Nb, in which, cavities were fabricated by electron beam welding method. Difficulty on LG cavity fabrication come from deformation due to stressed grain boundaries. In addition to nominal electron beam welded cavities, hydro-formed seamless cavities have been fabricated. Relatively large difference of equator and iris ratio cause difficulty on expansion of Nb pipes. Good qualified Nb pipe is essential and control of hydro-forming steps including annealing of materials is also important. In order to evaluate these cavity performances, vertical tests were carried out. Generally, they showed good performances. In this presentation, fabrication processes, technical difficulties, mitigation strategies and vertical test results are presented. | |||
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Slides THAA04 [2.810 MB] | ||
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THPB010 | INFN Milano - LASA Activities for ESS | cavity, niobium, linac, cryomodule | 1081 |
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INFN Milano – LASA is involved in the development and industrialization for the production of 704.4 MHz medium beta (β = 0.67) cavities for the ESS project. In this framework, we are designing a medium beta prototype cavity exploring both Large Grain and Fine Grain Niobium for its production as well as a high beta (β = 0.86) Large Grain cavity. In the meanwhile, an activity is ongoing for upgrading the LASA test facility to be able to test these kind of resonators. | |||
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THPB027 | Welding a Helium Vessel to a 1.3 GHz 9-Cell Nitrogen Doped Cavity at Fermilab for LCLS-II | cavity, alignment, operation, pick-up | 1132 |
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Fermilab has developed a TIG welding procedure that is used attach a nitrogen doped 1.3 GHz 9-cell niobium (Nb) cavity to a titanium (Ti) helium vessel. These cavities will be used in the two prototype cryomodules for the Linac Coherent Light Source (LCLS-II) upgrade at SLAC National Accelerator Laboratory. Discussion in further detail will include setting up TIG welding parameters and tooling requirements for assembly and alignment of the cavity to the helium vessel. The weld designs and glovebox environment produce the best quality TIG welds that meet ASME Boiler and Pressure Vessel Code. The cavity temperature was monitored to assure the nitrogen doping is preserved, and RF measurements are taken throughout the process to monitor the cavity for excessive cell deformation due to heat loads from welding. | |||
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THPB040 | Hydroforming of Large Grain Niobium Tube | niobium, cavity, experiment, electron | 1171 |
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Funding: This work was supported by the U.S. Department of Energy, Office of High Energy Physics, through Grant No. DE-FG02-09ER41638. Currently most of Niobium (Nb) cavities are manufactured from fine grain Nb sheets. As-cast ingots go through a series of steps including forging, milling, rolling, and intermediate annealing, before they are deep-drawn into a half-cell shape and subsequently electron beam welded to make a full cavity. Tube hydroforming, a manufacturing technique where a tube is deformed using a pressurized fluid, is an alternative to the current costly manufacturing process. A whole cavity can be made from a tube using tube hydroforming. This study focuses on deformation of large grain Nb tubes during hydroforming. The crystal orientation of the grains is recorded. The tube is marked with a square-circle-grid which is used to measure the strain after deformation. The deformation of the tube is going to be modeled with crystal plasticity finite element and compared with experiments. This paper only covers the characterization of the tube and the hydroforming process. |
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THPB042 | Advance Additive Manufacturing Method for SRF Cavities of Various Geometries | niobium, cavity, SRF, electron | 1181 |
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An alternative fabrication method for superconducting radio frequency (SRF) cavities is presented. The novel fabrication method, based on 3D printing (or additive manufacturing, AM) technology capable of producing net-shape functional metallic parts of virtually any geometry, promises to greatly expand possibilities for advance cavity and end-group component designs. A description of the AM method and conceptual cavity designs are presented along with material analysis and RF measurement results of additively manufactured niobium samples. | |||
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THPB045 | Progress in IFMIF Half Wave Resonators Manufacturing and Test Preparation | cavity, simulation, cryomodule, controls | 1191 |
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The IFMIF accelerator aims to provide an accelerator-based D-Li neutron source to produce high intensity high energy neutron flux to test samples as possible candidate materials to a full lifetime of fusion energy reactors. The first phase of the project aims at validating the technical options for the construction of an accelerator prototype, called LIPAc (Linear IFMIF Prototype Accelerator). A cryomodule hosting 8 Half Wave Resonators (HWR) at 175 MHz will provide the acceleration from 5 to 9 MeV. We report on the progress of the HWR manufacturing. A pre-series cavity will be used to assess and optimize the tuning procedure of the HWR, as well as the processing steps and related tooling. A new horizontal test cryostat (SATHORI) is also being set up at Saclay in the existing SRF test area. The SATHORI is dedicated to the IFMIF HWR performance check, fully equipped with its power coupler and cold tuning system. A 30kW-RF power will be available for these tests. | |||
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THPB051 | Lorentz Detuning for a Double-Quarter Wave Cavity | cavity, simulation, radiation, electromagnetic-fields | 1215 |
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Funding: Work supported by US DOE via BSA LLC contract No.DE-AC02-98CH10886 and US LARP program and by EU FP7 HiLumi LHC grant No.284404. Used NERSC resources by US DOE contract No.DE-AC02-05CH11231. The Lorentz detuning is the resonant frequency change in an RF cavity due to the radiation pressure on the cavity walls. We present benchmarking studies of Lorentz detuning calculations for a Double-Quarter Wave Crab Cavity (DQWCC) using the codes ACE3P. The results are compared with the Lorentz detuning measurements performed during the cold tests of the Proof-of-Principle DQWCC at BNL. |
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THPB060 | Development of SRF Cavity Tuners for CERN | cavity, cryomodule, operation, SRF | 1247 |
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Superconducting RF cavity developments are currently on-going for new accelerator projects at CERN such as HIE ISOLDE and HL-LHC. Mechanical RF tuning systems are required to compensate cavity frequency shifts of the cavities due to temperature, mechanical, pressure and RF effects on the cavity geometry. A rich history and experience is available for such mechanical tuners developed for existing RF cavities. Design constraints in the context of HIE ISOLDE and HL-LHC such as required resolution, space limitation, reliability and maintainability have led to new concepts in the tuning mechanisms. This paper will discuss such new approaches, their performances and planned developments. | |||
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THPB065 | Reliability of the LCLS II SRF Cavity Tuner | radiation, SRF, operation, cavity | 1267 |
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The SRF cavity tuner for LCLS II must work reliably for more than 20 years in a cryomodule environment. Tuner’s active components- electromechanical actuator and piezo-actuators must work reliably in an insulating vacuum environment at low temperature for the lifetime of the machine. Summary of the accelerated lifetime tests (ALT) of the electromechanical and piezo actuators inside cold/ insulated vacuum environment and irradiation hardness test (dose level up to 5*108 Rad) of tuner components are presented. Methodology to design and build reliable SRF cavity tuner, based on “lessons learned” approach, are discussed. | |||
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THPB076 | Quality Control of Welding, Brazing Joints and Cu Deposition on EU-XFEL Coupler Parts | controls, interface, electron, Windows | 1301 |
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In frames of EU-XFEL Project the quality control of fundamental 1.3GHz power couplers is very important task. The power coupler consists of a several number of parts including itself the different types of welding and brazing joints between ceramic, copper and stainless steel components. The quality of these joints is subject to be investigated and controlled according to EU-XFEL Coupler specification taking into account the different coupler manufacturers involved. The quality of Cu deposition on some EU-XFEL coupler parts is also the issue to be qualified according to specs. The number of microscope images of different types of joints and Cu deposition on some EU-XFEL 1.3GHz coupler parts are presented. | |||
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THPB077 | Modified TTF3 Couplers for LCLS-II | operation, simulation, cavity, linac | 1306 |
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The LCLS-II 4 GeV SC electron linac will use 280 TESLA cavities and TTF3 couplers, modified for CW operation with input power up to about 7 kW. The coupler modifications include shortening the antenna to achieve higher Qext and thickening the copper plating on the warm section inner conductor to lower the peak temperature. Another change is the use a waveguide transition box that is machined out of a solid piece of aluminum, significantly reducing its cost and improving its fit to the warm coupler window section. This paper describes the changes, simulations of the coupler operation (heat loads and temperatures), rf processing results and CW tests with LCLS-II dressed cavities. | |||
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THPB078 | Status of the Power Couplers for the ESS Elliptical Cavity Prototypes | cavity, cryomodule, status, simulation | 1309 |
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In the frame of the European Spallation Source (ESS) project, a linear accelerator composed of a superconducting section is being developed. This accelerator owns two kinds of cavities called “medium beta cavity” (β=0.67) and “high beta cavity” (β= 0.86). These cavities are equipped with RF power couplers whose main characteristics are: fundamental frequency: 704.42MHz, peak RF power: 1.1MW, repetition rate: 14Hz, RF pulse width>3.1ms. These couplers are common to the two cavities. The CEA Saclay is responsible for the design, the manufacture, the preparation and the conditioning of the couplers used for the Elliptical Cavities Cryomodule Technological Demonstrators (ECCTD). This work is performed in collaboration with ESS and the IPNO. This paper describes the coupler architecture, its different components, the main characteristics and the specific features of its elements (RF performance, dissipated power, cooling, coupler box test for the conditioning). The status of the manufacture of each coupler part is also presented. | |||
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THPB080 | Next Generation Cavity and Coupler Interlock for the European XFEL | FPGA, operation, interface, timing | 1316 |
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The safe operation of cavities and couplers in the European XFEL accelerator environment is secured by a new technical interlock (TIL) design, which is based on the XFEL crate standard (MTCA(TM).4). The new interlock is located inside the accelerator tunnel. Several remote test capabilities ensure the correct operation of sensors for light, temperature and free electrons. Due to the space costs and the very high number of channels, the electronic concept was moved from a conservative, mostly analog electronic approach, with real comparators and thresholds, to a concept, where the digitizing of the signals is done at a very early stage. Filters, thresholds and comparators are moved into the digital part. The usage of an FPGA and an additional watchdog increase the flexibility dramatically, with respect to be as reliable as possible. An overview of the system is shown.
MTCA (Micro Telecommunications Computing Architecture) is a standard defined by the PCI Industrial Computer Manufacturers Group (PICMG, www.picmg.org). |
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Poster THPB080 [1.123 MB] | ||
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THPB086 | LCLS-II Fundamental Power Coupler Mechanical Integration | interface, cryomodule, pick-up, operation | 1340 |
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Funding: DOE LCLSII is a planned upgrade project for the linear coherent light source (LCLS) at SLAC. The LCLSII linac will consist of thirtyfive 1.3 GHz and two 3.9 GHz superconducting RF continuous wave (CW) cryomodules that Fermilab and Jefferson Lab will assemble in collaboration with SLAC. The LCLSII 1.3 GHz cryomodule design is based on the European XFEL pulsed mode cryomodule design with modifications needed for CW operation. The 1.3 GHz cryomodules for LCLSII will utilize a modified TTF3 syle fundamental power coupler design. Due to CW operation heat removal from the power coupler is critical. This paper presents the details of the mechanical integration of the power coupler into the cryomodule. Details of thermal braids, connections, and other interfaces are discussed. |
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Poster THPB086 [1.031 MB] | ||
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THPB091 | Mechanical Design of a High Power Coupler for the PIP-II 325 MHz SSR1 RF Cavity | cavity, status, cryomodule, instrumentation | 1354 |
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The Project X Injector Experiment (PXIE) at Fermilab will include one cryomodule with eight 325 MHz single spoke superconductive cavities (SSR1). Each cavity requires approximately 2 kW CW RF power for 1 mA beam current operation. A future upgrade will require up to 8 kW RF power per cavity. Fermilab has designed and procured ten production couplers for the SSR1 type cavities. Status of the 325 MHz main coupler development for PXIE SSR1 cryomodule is reported. | |||
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Poster THPB091 [1.821 MB] | ||
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THPB092 | Mechanical Design of a High Power Coupler for the PIP-II 162.5 MHz RF Quadrupole | rfq, ion, cavity, ion-source | 1357 |
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PXIE is a prototype front end system for the proposed PIP-II accelerator upgrade at Fermilab. An integral component of the front end is a 162.5 MHz, normal conducting, continuous wave (CW), radiofrequency quadrupole (RFQ) cavity. Two identical couplers will deliver approximately 100 kW total CW RF power to the RFQ. Fermilab has designed and procured main couplers for the CW RFQ accelerating cavity. The mechanical design of the coupler, along with production status, is presented below. | |||
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Poster THPB092 [0.476 MB] | ||
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THPB094 | Status of the Fundamental Power Coupler Production for the European XFEL Accelerator | status, Windows, cryomodule, factory | 1364 |
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For the XFEL accelerator, Thales, RI Research Instrument and LAL are working on the manufacturing, assembly and conditioning of fundamental power couplers. 670 couplers have to be manufactured according to strict specifications. The paper describes the full production activity from the program starting to the currentphase with main measurements for the coupler characteristic: copper and TiN coating characteristics. The status of the production is given with an output rate of 8 couplers per week. The status for more than 500 couplers manufactured and conditionned is presented. | |||
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THPB095 | Automatic RF Conditioning Test Bench of Fundamental Power Couplers for the European XFEL Accelerator | controls, SRF, interface, data-acquisition | 1367 |
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In order to perform the RF conditioning of the fundamental coupler for the XFEL accelerator, Thales and LAL developed together a test bench being able to make the automatic RF conditioning. The capability of this test bench is of 4 pairs of coupler at the same time with automatic sequences of increasing the RF power. The test bench is composed of the overall RF station providing up to 5 MW peak power at 1.3 GHz. The waveguide distribution allows 4 individual RF lines for conditionning,and the automatic sequence applied to the couplers in respect with all signals monitored and controlled during the RF process. The paper will also provide some examples of such process. | |||
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THPB101 | High Power Input Couplers for C-ADS | cavity, cryomodule, linac, proton | 1383 |
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High power input couplers are key components of the superconducting system for China Accelerator Driven sub-critical System (C-ADS) project. For the first phase, C-ADS includes four types of superconducting cavities (SCCs) of two frequencies, 162.5 MHz HWR SCC and 325 MHz Spoke SCC up to the energy of 25 MeV. All input couplers for the SCCs are developed in IHEP. This paper will describe the development status of the high power input couplers for C-ADS. | |||
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Poster THPB101 [0.430 MB] | ||
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THPB102 | RF Conditioning of the XFEL Power Couplers at the Industrial Scale | pick-up, electron, monitoring, controls | 1387 |
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LAL has in charge the production monitoring and the RF conditioning of 800 power couplers to equip 100 XFEL cryomodules. The conditioning process and all the preceding preparation steps are performed in a 70m2 clean room. This infrastructure, its equipment and the RF station are designed to allow the treatment of 8 couplers in the same time, after a ramp-up phase. Clean room process and conditioning results are presented and discussed. | |||
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THPB103 | High Power Coupler Test for ARIEL SC Cavities | TRIUMF, cavity, linac, cryomodule | 1390 |
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TRIUMF ARIEL[1](The Advanced Rare Isotope Laboratory) project employs five 1.3 GHz 9-cell superconducting elliptical cavities[2] for acceleration of 10 mA electron beam up to energy of 50 MeV. 100 kW CW RF power will be delivered into each cavity by means of pair of Power Couplers: 50 kW per each coupler. Before installing the power couplers with the cavities, they have to be assembled on Power Coupler Test Stand(PCTS) and conditioned with a 30 kW IOT. Six couplers have been conditioned at room temperature and four of them have been installed to the cavities and tested during beam commissioning. Test results of the power couplers will be described and discussed in this paper.
#mayanyun@triumf.ca |
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THPB109 | ESS Spoke Cryomodule and Test Valve Box | cryomodule, cryogenics, linac, operation | 1400 |
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ESS project aims being the world’s most powerful neutron source feeding multidisplinary researches. The superconducting part of the ESS linear accelerator includes 28 b=0.5 352.2 MHz SRF niobium double Spoke cavities. Paired in 13 cryomodules and held at 2K in a saturated helium bath those cavities will generate of an accelerating field of 9MV/m. The prototype Spoke cryomodule holds two cavities and their RF power couplers and integrates all the interfaces necessary to be operational within the linac machine. It is now being fabricated and its assembly will be performed with dedicated tooling and procedures in and out of the clean room. This prototype will be tested by the end of 2015 at IPNO site and then at full power at FREIA (Uppsala university) test stand. A valve box has thus been designed to take into account the specific features of this prototype cryomodule and of the cryogenic environments of both test sites. This valve box is also considered as a prototype of the cryogenic distribution of the linac Spoke section. This element will then be used for the tests of the series cryomodules. We propose to present this prototype Spoke cryomodule for ESS and the test valve box. | |||
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Poster THPB109 [2.852 MB] | ||
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THPB110 | Procurements for LCLS-II Cryomodules at JLab | cavity, HOM, cryomodule, operation | 1405 |
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Funding: This work was supported by the LCLS-II Project and the U.S. Department of Energy, Contract DE-AC02-76SF00515. The Thomas Jefferson National Accelerator Facility is currently engaged, along with several other DOE national laboratories, in the Linac Coherent Light Source II project (LCLS II). The SRF Institute at Jefferson Lab will be building 1 prototype and 17 production cryomodules based on the TESLA / ILC / XFEL design. Each cryomodule will contain eight nine cell cavities with coaxial power couplers operating at 1.3 GHz. Procurement of components for cryomodule construction has been divided amongst partner laboratories in a collaborative manner. JLab has primary responsibility for six procurements include the dressed cavities, cold gate valves, higher-order-mode (HOM) and field probe feedthroughs, beamline bellows cartridges, cavity tuner assemblies and HOM absorbers. For procurements led by partner laboratories, JLab collaborates and provides technical input on specifications, requirements and assembly considerations. This paper will give a detailed description of plans and status for JLab procurements. |
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THPB119 | LCLS-II 1.3 GHz Cryomodule Design – Modified TESLA-Style Cryomodule for CW Operation | cryomodule, cryogenics, cavity, operation | 1417 |
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Funding: Work supported, in part, by the US DOE and the LCLS-II Project. We will present the design of the 1.3 GHz cryomodule for the Linear Coherent Light Source upgrade (LCLS-II) at SLAC. Fermilab is responsible for the design of this cryomodule, a modified TESLA-style cryomodule to accommodate continuous wave (CW) mode operation and LCLS-II beam parameters, consisting of eight 1.3 GHz superconducting RF cavities, a corrector magnet package, and instrumentation. Thirty-five of these cryomodules, approximately half built at Fermilab and half at Jefferson Lab, will become the main accelerating elements of the 4 GeV linac. The modifications and special features of the cryomodule include: thermal and cryogenic design to handle high heat loads in CW operation, magnetic shielding and cool-down configurations to enable high quality factor (Q0) performance of the cavities, liquid helium management to address the different liquid levels in the 2-phase pipe with 0.5% SLAC tunnel longitudinal slope, support structure design to meet California seismic design requirements, and with the overall design consistent with space constrains in the existing SLAC tunnel. The prototype cryomodule assembly will begin in August 2015 and is to be completed in early 2016. |
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FRAA03 | High Gradient Performance in Fermilab ILC Cryomodule | cavity, cryomodule, operation, detector | 1432 |
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Funding: Operated by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the United States Department of Energy. Fermilab has assembled an ILC like cryomodule using U.S. processed high gradient cavities and achieved an average gradient of 31.5 MV/m for the entire cryomodule. Test results and challenges along the way will be discussed. |
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Slides FRAA03 [5.878 MB] | ||
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FRAA06 | Construction and Performance of FRIB Quarter Wave Prototype Cryomodule | cryomodule, alignment, cryogenics, solenoid | 1446 |
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Funding: Work supported by the U.S. Department of Energy Office of Science under Cooperative Agreement DE-SC0000661 The driver linac for the Facility for Rare Isotope Beams (FRIB) will require the production of 48 cryomodules. FRIB has completed the fabrication and testing of a β=0.085 quarter-wave cryomodule as a pre-production prototype. This cryomodule qualified the performance of the resonators, fundamental power couplers, tuners, and cryogenic systems of the β=0.085 quarter-wave design. In addition to the successful systems qualification; the ReA6 cryomodule build also verified the FRIB bottom up assembly and alignment method. The lessons learned from the ReA6 cryomodule build, as well as valuable fabrication, sourcing, and assembly experience are applied to the design and fabrication of FRIB production cryomodules. This paper will report the results of the β=0.085 quarter-wave cryomodule testing, fabrication, and assembly; production implications to future cryomodules will also be presented. Authors: |
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Slides FRAA06 [10.892 MB] | ||
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FRBA01 | Technical and Logistical Challenges for IFMIF-LIPAC Cryomodule Construction | cryomodule, cavity, cryogenics, solenoid | 1453 |
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This paper provides an overview of the final design and fabrication status of the IFMIF cryomodule, including the design issues, and deals with the strategies implemented in order to mitigate the main technical and logistical risks identified. The seismic constraints as well as licensing requirements, transportation issue and assembly process are also addressed. The IFMIF cryomodule presented here will be part of the LIPAc project (Linear IFMIF Prototype Accelerator). It is a full scale prototype of one of the IFMIF accelerators, from the injector to the first cryomodule, aiming at validating the technical options for the future accelerator-based D-Li neutron source to produce high intensity high energy neutron flux for testing of candidate materials for use in fusion energy reactors. The cryomodule contains all the equipment to transport and accelerate a 125 mA deuteron beam from an input energy of 5 MeV up to 9 MeV. It consists of a horizontal cryostat of about 6 m long, 3 m high and 2 m wide, which includes 8 superconducting HWRs for beam acceleration working at 175 MHz and at 4.5 K, 8 power couplers to provide RF power to cavities, and 8 Solenoid Packages as focusing elements. | |||
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Slides FRBA01 [9.263 MB] | ||
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