Paper | Title | Page |
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TUP050 | A Multi-layered SRF Cavity for Conduction Cooling Applications | 538 |
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Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177. Some of the work was supported by the 2008 PECASE Award of G. Ciovati. I. Parajuli is supported by NSF Grant PHYS-100614-010 Industrial application of SRF technology would favor the use of cryocoolers to conductively cool SRF cavities for particle accelerators, operating at or above 4.3 K. In order to achieve a lower surface resistance than Nb at 4.3 K, a superconductor with higher critical temperature should be used, whereas a metal with higher thermal conductivity than Nb should be used to conduct the heat to the cryocoolers. A standard 1.5 GHz bulk Nb single-cell cavity has been coated with a ~2 µm thick layer of Nb3Sn on the inner surface and with a 5 mm thick Cu layer on the outer surface for conduction cooled applications. The cavity performance has been measured at 4.3 K and 2.0 K in liquid He. The cavity reached a peak surface magnetic field of ~40 mT with a quality factor of 6×109 and 3.5×109 at 4.3 K, before and after applying the thick Cu layer, respectively. |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-TUP050 | |
About • | paper received ※ 21 June 2019 paper accepted ※ 30 June 2019 issue date ※ 14 August 2019 | |
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TUP094 | Improvements to LCLS-II Cryomodule Transportation | 684 |
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The Linear Coherent Light Source (LCLS-II) is currently being constructed at the SLAC National Laboratory. A total of 35 cryomodules will be fabricated at Jefferson Lab (JLab) in Virginia and Fermi National Laboratory (FNAL) in Illinois and transported via road to SLAC. A shipping frame with an inner bed isolated by springs was designed to protect the CMs from shocks and vibrations during shipments. Successful road testing of the JLab prototype paved the way for production CM shipments. The initial production shipments lead to several catastrophic failures in beamline vacuum in the cryomodules. The failures were determined to be due to fatigue in Fundamental Power Coupler (FPC) bellows due to excessive motion during shipment. A series of instrumented CM shipping tests and component tests were undertaken to develop a solution. A modified spring layout was tested and implemented, which reduced shocks on the CMs. FPC coupler bellows restraints were tested on a shaker table and on a CM during shipping; they were able to reduce bellows motion by a factor of three. The updated shipping system is currently in use and has successfully delivered six cryomodules to SLAC from JLab and FNAL. | ||
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Poster TUP094 [0.958 MB] | |
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-TUP094 | |
About • | paper received ※ 23 June 2019 paper accepted ※ 01 July 2019 issue date ※ 14 August 2019 | |
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THP049 | Commissioning the JLab LERF Cryomodule Test Facility | 973 |
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The JLab Low Energy Recirculating Facility, LERF, has been modified to support concurrent testing of two LCLS-II cryomodules. The cryomodules are installed in a similar fashion as they would be in the L1 section of the LCLS-II linac, including the floor slope and using all of the LCLS-II hardware and controls for cryomodule cryogenics, vacuum, and RF (SSA and LLRF). From the start, it was intended to use LCLS-II electronics and EPICS software controls for cryomodule testing. In affect the LERF test facility becomes the first opportunity to commission and operate the LCLS-II LINAC hardware and software controls. Support for specific cryomodule high level test applications like Q0 and HOMs measurements, are being developed from the basic cryomodule control suite. To support the testing, 2 K He is supplied from the CEBAF south linac cryogenic system, where care must be taken when using the LERF test facility to not upset the CEBAF cryogenics plant. This paper discusses the commissioning of the hardware and software development for testing the first two LCLS-II cryomodules. | ||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-THP049 | |
About • | paper received ※ 22 June 2019 paper accepted ※ 02 July 2019 issue date ※ 14 August 2019 | |
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THP051 | Upgrades to Cryogenic Capabilities for Cryomodule Testing at JLab | 983 |
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The cryogenic facilities for cryomodule testing at Jefferson Lab (JLab) have been modified and to enable testing of Linear Coherent Light Source-II (LCLS-II) cryomodules. Temporary changes in u-tube connections at the Cryogenic Test Facility (CTF) has enabled rates of cavity cooling that are a factor of 10 higher than previously achieved. Cryogenic connections at JLab¿s Low Energy Recirculator Facility (LERF) have been repurposed to enable two LCLS-II cryomodules to be tested in series. This testing shares the helium space with the Central Helium Liquefier (CHL) that is also used by the Continuous Electron Beam Accelerator Facility (CEBAF). Cryomodule testing can occur while beam operation is ongoing at CEBAF. Improvements to these facilities have allowed the testing of the JLab¿s highest ever performing cryomodules. | ||
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Poster THP051 [0.722 MB] | |
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-THP051 | |
About • | paper received ※ 20 June 2019 paper accepted ※ 29 June 2019 issue date ※ 14 August 2019 | |
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THP056 | Current Results From Acceptance Testing of LCLS-II Cryomodules at Jefferson Lab | 1007 |
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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 Department of Energy (DOE) national laboratories, in the Linac Co-herent Light Source II project (LCLS-II). The SRF Insti-tute at Jefferson Lab is currently building 21 cryomod-ules for this project. The cryomodules are based on the XFEL design and have been modified for continuous wave (CW) operation and to comply with other LCLS-II specifications. Each cryomodule contains eight 9-cell cavities with coaxial power couplers operating at 1.3 GHz. The cryomodule also contain a magnet package that consists of a quadrupole and two correctors. Most of these cryomodules will be tested in the Cryomodule Test Facility (CMTF) at Jefferson Lab before shipment to SLAC. Up to three of these cryomodules will be tested in a test stand set up in the Low Energy Recovery Facility (LERF) at Jefferson Lab. Acceptance testing of the LCLS-II cryomodules began in December 2016. Twelve cryomodules have currently completed Acceptance Test-ing. This paper will summarize the results of those tests. |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-THP056 | |
About • | paper received ※ 22 June 2019 paper accepted ※ 30 June 2019 issue date ※ 14 August 2019 | |
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FRCAA3 | Industrial Cavity Production: Lessons Learned to Push the Boundaries of Nitrogen-Doping | 1199 |
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Funding: Work supported by US DOE Contract DE-AC02-76SF00515. Nitrogen doping has been proven now in several labs to enhance Q0 values of 1.3 GHz cavities in the gradient domain favored by CW operation. The choice of doping for the LCLS-II project has given the community a wealth of statistics and experience on the challenge of transferring the doping technology to industry. Overall, industry-produced nitrogen-doped cavities have shown excellent performance, however some technical issues have arisen. This talk focuses on lessons learned from the production of over 300 nitrogen-doped cavities for LCLS-II and how issues were mitigated to further improve performance. Finally, I will discuss pushing the boundaries of nitrogen-doping further by exploring different doping regimes in order to maintain excellent Q0 performance, while reaching higher quench fields. |
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Slides FRCAA3 [16.880 MB] | |
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-FRCAA3 | |
About • | paper received ※ 02 July 2019 paper accepted ※ 03 July 2019 issue date ※ 14 August 2019 | |
Export • | reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml) | |