| Paper | Title | Page |
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| WEPIK100 | The Applicability of NEG Coated Undulator Vessels for the CLARA FEL Test Facility | 3181 |
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| CLARA is a FEL test facility at Daresbury Laboratory (DL), UK. The undulator vacuum chamber is 20 m long with inner diameter 6 mm and its vacuum performance can benefit from a NEG coating. The thickness of the coating layer must be carefully optimised. A layer ~ 1 um would help the vacuum but a thinner layer would be partially transparent for the EM field reducing the resistive wall wakefields due to the NEG. A very thin layer, however, may not yield the necessary vacuum performance. Two types of NEG coatings produced at DL - dense and columnar - were considered. Their bulk conductivities were measured in a separate study. The resistive wall wakefield impedance was calculated following the standard approach for multilayer vessels. A 250 fs rms electron bunch was generated in ASTRA and its wakefield was obtained from the vessel impedance. The FEL performance was then studied through GENESIS simulations and the result compared to the case with no wakefields. It was found that NEG layers thicker than 100 nm give an unacceptable reduction of the FEL power and the vacuum performance of such thin coatings is unknown. Possible solutions to this problem are discussed. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPIK100 | |
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| MOPVA100 | Atomic Layer Deposition of Niobium Nitride from Different Precursors | 1094 |
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| Advancements in technology have taken bulk niobium cavities close to their theoretical operational limits of 45 MV/m, pushing the research to explore novel materials, such as niobium based alloys . Theoretical studies suggest that a composite material composed of alternative superconductor / insulator multilayers would surpass the bulk niobium limits. Chemical vapour deposition (CVD) can deposit mi-crons thick Nb films in less than an hour, at the expense of precise thickness control. Atomic layer deposition (ALD), instead, even if considerably slower than CVD can be used in applications where the thickness of the deposited layers needs to be controlled with a resolution down to the nanometer. This article presents the preliminary results obtained by using plasma assisted ALD techniques to deposit NbN based compounds starting from chlorinated precursors and organic ones, and the design for a new deposition system currently being built at the Daresbury Laboratories. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPVA100 | |
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| MOPVA104 | Physical Vapour Deposition of NbTiN Thin Films for Superconducting RF Cavities | 1102 |
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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. The use of thin films made from superconductors with thermodynamic critical field, HC>HCNb, allows the possibility of multilayer superconductor ' insulator ' superconductor (SIS) films and accelerators that could operate at temperatures above the 2 K typically used. SIS films theoretically allow increased acceleration gradient due to magnetic shielding of underlying superconducting layers [1] and higher operating temperature can reduce cost [2]. High impulse magnetron sputtering (HiPIMS) and pulsed DC magnetron sputtering processes were used to deposit NbTiN thin films onto Si(100) substrate. The films were characterised using scanning electron microscopy (SEM), x-ray diffraction (XRD), Rutherford back-scattering spectroscopy (RBS) and a four-point probe. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPVA104 | |
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| TUPVA154 | Project-Based Cooperative Learning in Accelerator Science and Technology Education | 2458 |
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Funding: The work is funded by STFC via the Cockcroft Institute core grant. The next generation of particle accelerators will require the training of greater numbers of specialist accelerator physicists and engineers . These physicists and engineers should have a broad understanding of accelerator physics as well as the technology used in particle accelerators as well as a specialist in some area of accelerator science and technology . Such specialists can be trained by combining a University based PhD, in collaboration with national laboratory training with a broad taught accelerator lecture program. In order to have a faster start we decided to run an intensive two week school to replace the basic course at the Cockcroft Institute. At the same time we decided to investigate the use of problem based learning to simulate the way accelerator science tends to work in practice. In this exercise he students worked in groups of 5 to design a 3rd generation light source from scratch based on photon light specifications. In comparison to similar design exercises we stipulate that all students must do all parts and students are not allowed to specialise. A comparison with a standard lecture based education programme is discussed in this paper. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPVA154 | |
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