Prior Research on Additive Manufacturing of Superconducting Radio frequency Cavity for Particle Accelerators

Prior Research on Additive Manufacturing of Superconducting Radio frequency Cavity for Particle Accelerators | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Prior Research on Additive Manufacturing of Superconducting Radio frequency Cavity for Particle Accelerators In Yong Moon, Seung Jun Han, Min Ji Ham, Won Rae Kim, Yeonghwan Song This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-5772268/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 09 May, 2025 Read the published version in The International Journal of Advanced Manufacturing Technology → Version 1 posted 5 You are reading this latest preprint version Abstract With the advent of the quantum technology era, there is a growing interest in the development of fundamental research equipment in related fields. Particle accelerators are crucial tools in the study of quantum mechanics and quantum field theory, playing a significant role in the advancement of quantum technology. The key component of particle accelerators, the superconducting radio frequency (SRF) cavity, is traditionally manufactured using conventional methods such as deep drawing and electron beam welding with pure niobium (Nb) sheets. However, this manufacturing process has drawbacks, including low material yield and electrical non-uniformity due to the presence of welded joints. To overcome these shortcomings, this study focused on the development of SRF cavity manufacturing technology using additive manufacturing (AM). Before producing the cavity with pure Nb, preliminary research was conducted using relatively inexpensive pure titanium powder to assess the feasibility of AM for the cavity's shape. Prior to performing the AM of the cavity, process analysis based on finite element method was conducted to verify the level of thermal deformation and stress distribution in the parts and optimal support design was suggested to ensure dimensional precision. After the completion of AM, a barrel finishing and turning process were performed to enhance the inner surface quality and dimensional accuracy of cavity cell. As a result, it was confirmed that the shape of cavity could be successfully manufactured through the AM method. Additive manufacturing Radio frequency cavity Particle accelerator Superconducting Design for additive manufacturing Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 9 Figure 10 1. Introduction Particle accelerators play a pivotal role in pushing the boundaries of scientific inquiry, enabling basic research across a variety of fields. Superconducting radio frequency (SRF) cavities are an essential component of these accelerators, providing the necessary energy boost to charged particles [ 1 – 4 ]. The constant pursuit of higher performance and efficiency in accelerator technology has led to continuous improvements in the SRF cavity manufacturing process [ 5 – 7 ]. SRF cavity manufacturing has traditionally involved creating a half-cell (or beam tube ring) through a deep drawing process and then completing the full cavity shape through electron beam welding (EBW) as shown in Fig. 1 . However, this approach is associated with problems such as low material yield and uneven electromagnetic properties due to crystal growth in the weld joints, leading to unstable particle accelerator performance. To overcome this drawback, hydroforming and spinning have been proposed, as these approaches can reduce the number of EBWs. However, hydroforming requires complex process design and can cause excessive local deformation, resulting in undesirable wall thickness reduction. Likewise, the spinning process, known to cause surface degradation resembling an orange peel texture, disrupts electrical conductivity, similar to the effects of crystal growth induced by electron beam welding. Therefore, there is a need to develop a new SRF cavity manufacturing process to overcome these shortcomings [ 8 ]. Additive manufacturing (AM) methods have received significant attention due to their ability to fabricate complex geometries from 3D models that are difficult to fabricate with traditional manufacturing methods. Applying AM to SRF cavity production has the potential to solve the aforementioned challenges, opening new avenues to achieve unprecedented efficiencies in particle accelerators. In addition, the layer-by-layer construction minimizes material waste, contributing to economic efficiency, making it suitable for large-scale accelerator projects. Recent attempts to fabricate SRF cavities using AM have been reported in the literature [ 9 – 12 ]. One study utilized pure niobium (Nb) powder and laser powder bed fusion (LPBF) to fabricate a 6 GHz cavity shape and analyze its resonance frequency and residual resistivity ratio (RRR). However, this study mainly focused on the material science aspects of AMed SRF cavities and neglected the in-depth details on design for additive manufacturing (DfAM) and post-processing techniques [ 13 , 14 ]. Therefore, it is believed that conducting research on AM for SRF cavities, particularly in the field of mechanical engineering, would greatly assist subsequent researchers in undertaking related studies. DfAM and post-process development requires numerous cavity cell manufacturing tests. However, the high cost of pure Nb powder for fabricating numerous cavity cells presents financial challenges, making extensive testing impossible. Therefore, as a preliminary study on the production of SRF cavity, it is thought that using pure titanium (Ti) powder, which is relatively cheaper than niobium, would be a good option. Also, pure Ti is known to share similar physical and chemical properties with pure Nb. Given these similarities, the tendencies in DfAM technology and surface processing characteristics are expected to be comparable when using pure Nb powder. Therefore, in this study, LPBF type AM was applied to fabricate 1.5 GHz SRF cavities using pure Ti powder. Process simulation based on finite element method (FEM) was performed to investigate thermal deformation during the AM process. Based on these results, the optimal support design for deformation control was proposed. Afterwards, heat treatment and support removal task were performed to remove residual stress and support. After that, barrel finishing (or turning process) was performed to improve the surface quality and dimensional accuracy of the cavity cell. Especially, experimental variations in barrel finishing conditions were investigated to determine the optimal polishing conditions for surface quality improvement. The results confirmed the additive manufacturability for the shape of SRF cavity cell with complex geometries. 2. Material and methods 2.1 Material and cavity cell model In order to evaluate the additive manufacturability for the shape of the SRF cavity, argon atomized grade 2 pure titanium powder (SLM Solutions Group AG, Germany) with a size range of 20-63 μm was used in this study. To emphasize once more, it is worth noting that the SRF cavity is originally made of pure Nb; however, due to the high cost of the material, this preliminary research was conducted using pure titanium powder, possessing mechanical and chemical properties similar to niobium to explore the feasibility of AM method. As shown in Fig. 1, 1.5 GHz SRF cavity model was applied for this study [15]. In the conventional manufacturing method consisting of deep drawing and EBW, half-cells are manufactured and assembled. However, since the AM process is used in this study, uni-cell and dumb-bell models, which combine two half-cells, are applied (Table 1). The characteristics of each model are as follows. For the uni-cell model, the turning process does not appear suitable for post-processing the inner surface due to the relatively small diameter of the iris. Therefore, surface quality must be ensured through barrel finishing. In the case of the uni-cell model, since it is impossible to secure dimensional accuracy through turning process, dimensional accuracy on the inner surface must be ensured through support optimization and deformation compensation design to minimize thermal deformation during AM. For the dumb-bell model, since the diameter of the equator is relatively large, turning processing on the inner surface is possible. Therefore, surface quality and dimensional accuracy can be secured through post-turning process. The characteristics of each model above cause differences in the work to produce a high quality SRF cavity. In the case of the uni-cell model, thermal deformation must be analyzed through process simulation at the DfAM stage and optimal support design to minimize thermal deformation must be performed. On the other hand, since the dumb-bell model can secure dimensional accuracy through post-processing, it can be seen that only design changes that add machining allowance will be required. 2.2 Process simulation based on finite element method Prior to perform AM process, a FEM-based process simulation was performed to predict the thermal deformation of the cavity cell. The simulation was performed using ANSYS Mechanical 2023 R2 software, specifically the AM LPBF Inherent Strain module. The layered tetrahedrons mesh with a size of 2 mm was applied to the part and support structures. The contact conditions between the part, support, and build plate were set to bond. 2.3 AM and post process The overall cavity cell fabrication process is shown in Fig. 2. AM process was conducted using SLM 280 equipment (SLM Solutions Group AG, Germany) under the following conditions: power 350 W, scan speed 1400 mm/s, layer thickness 0.03 mm, and hatch space 0.12 mm [16]. The cavity cell produced by AM process was heat treated at 590°C for 2 hours in a vacuum atmosphere of 10 -6 mbar to eliminate residual stresses generated during the AM process. Subsequently, the part was separated from the build plate using wire-electrical discharge machining (wire-EDM), followed by manual support removal. For the uni-cell model, a barrel finishing process was applied to refine the rough inner surface. The barrel finishing was divided into roughing and finishing and was carried out sequentially. In the roughing process, a coarse grinding stones were used with water, and in the finishing process, and fine grinding stones were used with chemical compound and water. In order to compare the degree of improvement in surface roughness according to barrel finishing condition, various roughing and finishing period were tested. On the other hands, for the dumb-bell model, turning process was applied to enhance not only surface quality but also dimensional accuracy. The surface quality of the inner surface of the post-processed cavity cell was measured using a 3D measuring laser microscope (OLS5000, Olympus Inc., Japan). After barrel finishing (or turning process), contour measurement on the cavity cells were conducted using a 3D laser scanning system (ZS-3040, Laser Design Inc., USA). For the uni-cell model, the inner contour was measured after cutting along the axis using wire-EDM. Subsequently, a comparison between the scan data and the blueprint model was made to calculate the error in the contour of the inner surface. 3. Results and discussion 3.1 Support optimization based on process simulation Figure 3 shows the support design used in the process simulation of the uni-cell and dumb-bell model. It is before support optimization, and basic block type supports were applied to the part surface with an overhang of 40 degrees or less; block type support is a commonly used support type and is characterized by high rigidity (Here, the overhang angle means the angle between the part and the build plate). The supports of the uni-cell model consist of an outer support, an inner support, and a bottom support (Fig. 3 (a)). As can be seen in the cross-sectional view of the build model, inner support is part-to-part support where the top and bottom points of the support are in contact with the part surface. In the case of the dumb-bell model, it consists of inner support and bottom support. Additionally, in order to not apply support between the upper and lower half cells, a design change was made by applying a self-supporting structure as shown in the Fig. 3 (b). Result of AM process simulation on the uni-cell and dumb-bell models are presented in Figure 4. In the case of total deformation of uni-cell model (Fig. 4(a)), the deformation occurs significantly at the lower region compared to the upper region. In particular, severe deformation occurs at the no support zone in the lower region (surface having overhang angle between 40 and 90 degrees as indicated using an arrow). Therefore, it is believed that the outer support having high-rigidity should be applied to entire lower surface to secure dimensional accuracy. With respect to inner support, since it is located inside the cylindrical cavity, it can be expected that support removal will be difficult. However, the simulation result shows that no significant deformation occurs in the upper region. Therefore, it is considered that a type of support with weak rigidity but easy to remove can be applied to that area. Figure. 4(b) shows the total deformation in the dumb-bell model. Relatively large deformation was predicted in the lower half-cell. However, since the turning process for the inside of the dumb-bell model will be performed after the AM is completed, no additional support optimization is required. On the other hand, relatively small deformation was calculated in the upper half-cell. This indicates that the self-supporting structure sufficiently suppresses deformation of the upper half-cell. Based on the analysis results, optimal support design for AM process was suggested as shown in Figure 5. For the uni-cell model (Fig. 5 (a)), three types of supports, including bottom, inner, and outer supports have been employed. The bottom support is applied between parts and build plate to mitigate excessive stress on the build plate during the AM process. The inner support is designed as a rod type with low rigidity and easy removal based on the analysis that deformations at the cell (top) are insignificant. The outer support is designed as a tree type with high rigidity and is applied to the entire area of the cell bottom to minimize deformation of the corresponding area. In the case of the dumb-bell model, two types of supports, including bottom and inner supports have been employed. For the inner support, the rod type support is chosen for convenience of removal. It is note here that machining allowance approximately 1 mm was applied to the inside surface of dumb-bell model for post turning process. 3.2 Barrel finishing for surface quality enhancement Based on the optimized support design model, AM process was carried out for both of the uni-cell and dumb-bell models. The resulting specimens underwent stress-relief heat treatment and support removal processes. The surface quality inside the cavity cell is known to influence the stable maintenance of superconducting characteristics during the operation of a particle accelerator [17]. Therefore, as mentioned in Section 2.1, the barrel finishing was performed on the uni-cell model under various process conditions. Thereafter, the specimens were cut in half, and surface roughness measurement were conducted on the three measurement points: upper, middle, and lower (Figure 6). As can be seen in the figures, the upper and lower regions have rough surface due to the traces of rod type inner support. In particular, despite the application of barrel finishing, the bumpy shapes, consisting of peaks and valleys, remain noticeably intact on the upper surface. Figure 7 presents the results of surface roughness measurements according to barrel finishing condition. Overall, surface roughness increased in the order of middle, lower, and upper surfaces, and the combination of roughing 1 cycle + finishing 2 cycles (R1 + F2) was most effective in improving surface quality. In the case of the R2 + F1 combination, the effect of improving surface quality was negligible compared to the R1 + F1 combination. This is believed to be because the area to be polished in the roughing stage is sufficiently removed with a single roughing cycle. Figure 8 shows the 3D surface morphologies of the inner surface of the uni-cell model. For the upper surface, it was confirmed that the bumpy shape was still remained even after barrel finishing, and a lot of fine craters existed in the valley area. On the other hand, the middle surface was confirmed to be a relatively even surface without a bumpy shape. This characteristic is seems to be because the peak regions of the upper and lower surfaces play a role in hindering polishing of the valley area. Therefore, other processing techniques to remove the peak regions is necessary to further improve surface quality. In conclusion, despite the effective surface quality improvement of the R1 + F2 combination, the bumpy shapes of the upper surface still existed and the surface roughness also showed a high value of Ra 11.1 μm. Typically, in the SRF cavity manufacturing process, chemical polishing is performed at the final stage to maximize the internal surface quality [8]. However, even considering the post-chemical polishing process, it is judged that there are limitations in performing mechanical polishing only with the barrel finishing. Figure 9 shows the dumb-bell model after post-turning process. Unlike the uni-cell model after barrel finishing, a high-quality inner surface can be observed. The surface roughness of the machined surface was confirmed to be at the level of Ra 0.34 μm, which is sufficient for use in particle accelerators. Therefore, it can be seen that the method of manufacturing cavity cells in a dumb-bell type is reasonable in terms of securing surface quality. 3.3 Dimensional characterization of AMed cavity cell The resonant frequency, a critical factor in evaluating cavity performance, is significantly influenced by the dimensional accuracy of the inner surface of the cavity cells. To assess this, 3D scanning was conducted on the barrel-finished uni-cell model and the turning processed dumb-bell model, and the dimensional accuracy of the both model's internal surfaces was analyzed, as shown in Figure 10. In the case of the uni-cell model, as illustrated in Figure 10(a), dimensional errors were observed along the upper surface, decreasing toward the bottom (Fig. 10(b)). This issue was attributed to insufficient support provided by the rod type supports, resulting in sagging during the AM process. To address this dimensional inaccuracy, a compensation design incorporating the dimensional errors was applied, and the uni-cell cavity was remanufactured. As a result, a maximum dimensional error of -0.20 mm and an average dimensional error of 0.132 mm were achieved, as shown in Figure 10(c). For the dumb-bell model, as depicted in Figure 10(d), higher dimensional accuracy was achieved due to the post-processing performed through turning. The maximum dimensional error was -0.15 mm, and the average dimensional error was measured at 0.077 mm, as shown in Figure 9(e). As discussed, both the uni-cell and dumb-bell models demonstrated successful AM enabled by DfAM, including optimization of support structures. However, the geometric characteristics of the uni-cell model posed challenges in ensuring surface quality and dimensional accuracy. In conclusion, considering that surface quality and dimensional accuracy are critical factors closely tied to the stable operation of particle accelerators, the dumb-bell model is deemed more suitable for additive manufacturing. 4. Conclusions This study investigated the feasibility of AM for fabricating 1.5 GHz SRF cavities using pure titanium (Ti) powder, focusing on the DfAM, post-processing techniques, and dimensional characterization. The following conclusions were drawn: Support design optimization: The process simulation results emphasized the importance of optimized support structures in minimizing thermal deformation during the AM process. For the uni-cell model, a combination of high-rigidity outer supports and low-rigidity inner supports was designed to achieve a balance between deformation control and ease of removal. For the dumb-bell model, self-supporting structures and a machining allowance design enabled effective post-processing and minimized support dependency. Surface quality: Barrel finishing was applied to enhance the surface quality of the uni-cell model, revealing that the roughing 1 cycle + finishing 2 cycles combination was most effective in reducing surface roughness. However, the bumpy shapes on the upper surface remained a limitation, indicating the need for additional machining processes. In contrast, the turning process applied to the dumb-bell model demonstrated excellent surface quality, achieving a surface roughness of Ra 0.34 μm, which is sufficient for use in particle accelerators. Dimensional accuracy: Dimensional accuracy was significantly influenced by the geometric characteristics and post-processing methods of each model. The uni-cell model showed notable dimensional errors caused by insufficient support rigidity during the AM process. A compensation design reduced these errors to acceptable levels. The dumb-bell model exhibited better dimensional accuracy due to the turning process, achieving a maximum error of -0.15 mm and an average error of 0.077 mm. In conclusion, this study demonstrated that while both uni-cell and dumb-bell models can be successfully manufactured using AM, the dumb-bell model is more favorable for manufacturing the SRF cavities. This research provides valuable insights for AM processes as SRF cavity production, thereby contributing to advancements in accelerator technology. In the next study, we will develop an AM process using pure Nb powder based on the DfAM principles and the post-processing strategies implemented in this study. Declarations Competing Interests The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. Funding This work was supported by the Korea Institute of Industrial Technology's own research project, “Development of element technology for manufacturing non-welding integrated superconducting radio frequency cavity” (KITECH UR-24-0011). Author Contributions All authors contributed to the study conception and design. Part design, simulation and analysis were performed by [In Yong Moon] and [Min Ji Ham]. Additive manufacturing was performed by [Seung Jun Han] and [Won Rae Kim]. The first draft of the manuscript was written by [Yeonghwan Song] and all authors commented on previous versions of the manuscript. All authors read and approved the final manuscript References Hara H, Sennyu K, Miyamoto A, Yanagisawa T (2021) Manufacturing techniques of superconducting RF cavities for heavy ions. Mitsub Heavy Ind Tech Rev 58: 1. 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Int J Adv Manuf Technol 84:1115–1126. https://doi.org/10.1007/s00170-015-7767-x Motschmann F, Gerard R, Gilles F (2019) Purification of selective laser melting additive manufactured niobium for superconducting RF applications. IEEE Transactions on Applied Superconductivity 29:1–5. https://doi.org/10.1109/TASC.2019.2900521 Liu M, Zhang J, Chen C, Geng Z, Wu Y, Li D, Guo Y (2023) Additive manufacturing of pure niobium by laser powder bed fusion: Microstructure, mechanical behavior, and oxygen-assisted embrittlement. Mater Sci Eng A 866:144691. https://doi.org/10.1016/j.msea.2023.144691 Frigola P, Agustsson RB, Faillace L, Murokh AY, Ciovati G, Clemens WA, Wicker RB (2015, September) Advance additive manufacturing method for SRF cavities of various geometries. In Proceedings of the 17th International Conference on RF Superconductivity (SRF’15) , Whistler, BC, Canada (pp. 13–18). Griemsmann T, Abel A, Hoff C, Hermsdorf J, Weinmann M, Kaierle S (2021) Laser-based powder bed fusion of niobium with different build-up rates. Int J Adv Manuf Technol 114:305–317. https://doi.org/10.1007/s00170-021-06645-y Candela S, Bonesso M, Candela V, Dima R, Favero G, Pepato A, Pira C (2023) Laser powder bed fusion of pure niobium for particle accelerator applications. In Proceedings of the 14th International Particle Accelerator Conference (IPAC-2023), Venice, Italy. https://doi.org/10.18429/JACoW-IPAC2023-THPM021 Ciovati G (2022) Superconducting radiofrequency cavities. In Handbook of Superconductivity (pp. 583–594). CRC Press. Kim HG, Kim WR, Kwon O, Bang GB, Ham MJ, Park HK, Kim GH (2019) Laser beam melting process based on complete-melting energy density for commercially pure titanium. 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Supplementary Files Table1.docx Cite Share Download PDF Status: Published Journal Publication published 09 May, 2025 Read the published version in The International Journal of Advanced Manufacturing Technology → Version 1 posted Editorial decision: Major Revisions Needed 22 Feb, 2025 Reviewers agreed at journal 15 Jan, 2025 Reviewers invited by journal 08 Jan, 2025 Editor assigned by journal 07 Jan, 2025 First submitted to journal 05 Jan, 2025 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-5772268","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":399602271,"identity":"1832a100-0fe7-459d-8a81-78ae9ea28e24","order_by":0,"name":"In Yong 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03:47:50","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":700886,"visible":true,"origin":"","legend":"\u003cp\u003eOverall process sequence for cavity cell production through AM.\u003c/p\u003e","description":"","filename":"floatimage3.png","url":"https://assets-eu.researchsquare.com/files/rs-5772268/v1/402664e6ef74c83631febd1d.png"},{"id":73442986,"identity":"6e688f06-f7ee-4a7b-8cd4-8baf20f3601f","added_by":"auto","created_at":"2025-01-10 04:11:50","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":411025,"visible":true,"origin":"","legend":"\u003cp\u003eSupport structure configuration in AM process simulation for (a) uni-cell, and (b) dumb-bell models\u003c/p\u003e","description":"","filename":"floatimage4.png","url":"https://assets-eu.researchsquare.com/files/rs-5772268/v1/d069cd04578539ed1fa596cc.png"},{"id":73441318,"identity":"34c94409-6758-49d5-ab99-7d4809c11ab5","added_by":"auto","created_at":"2025-01-10 03:39:50","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":283334,"visible":true,"origin":"","legend":"\u003cp\u003eResults of process simulation showing the total deformation of (a) uni-cell, and (b) dumb-bell model.\u003c/p\u003e","description":"","filename":"floatimage5.png","url":"https://assets-eu.researchsquare.com/files/rs-5772268/v1/813d36230d2de447aff3fa11.png"},{"id":73441349,"identity":"eac30241-a6a6-42e6-ac4d-38edb64ba5c1","added_by":"auto","created_at":"2025-01-10 03:39:51","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":260413,"visible":true,"origin":"","legend":"\u003cp\u003eResults of support optimization for (a) uni-cell, and (b) dumb-bell model.\u003c/p\u003e","description":"","filename":"floatimage6.png","url":"https://assets-eu.researchsquare.com/files/rs-5772268/v1/d572c8af70e618f09388caae.png"},{"id":73442257,"identity":"0a452e37-3daf-4961-b866-d1e12267771f","added_by":"auto","created_at":"2025-01-10 03:55:50","extension":"png","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":146237,"visible":true,"origin":"","legend":"\u003cp\u003eThree regions for surface roughness measurement.\u003c/p\u003e","description":"","filename":"floatimage7.png","url":"https://assets-eu.researchsquare.com/files/rs-5772268/v1/4b7874e770abefacfb3a121b.png"},{"id":73441345,"identity":"25dd80dc-87ea-403d-96e1-bb8fde936f7e","added_by":"auto","created_at":"2025-01-10 03:39:51","extension":"png","order_by":7,"title":"Figure 7","display":"","copyAsset":false,"role":"figure","size":56789,"visible":true,"origin":"","legend":"\u003cp\u003eResult of surface roughness measurement after barrel finishing for the uni-cell model\u003c/p\u003e","description":"","filename":"floatimage8.png","url":"https://assets-eu.researchsquare.com/files/rs-5772268/v1/8377b355cfaf274e714b0343.png"},{"id":73441596,"identity":"242bcb18-0aa3-406f-9f3e-205f81b0621b","added_by":"auto","created_at":"2025-01-10 03:47:50","extension":"png","order_by":8,"title":"Figure 8","display":"","copyAsset":false,"role":"figure","size":366933,"visible":true,"origin":"","legend":"\u003cp\u003eResult of 3D surface profiler measurement in the case of the roughing 1 cycle + finishing 2 cycles\u003c/p\u003e","description":"","filename":"floatimage9.png","url":"https://assets-eu.researchsquare.com/files/rs-5772268/v1/8e8d42709c36a5f1cd2654de.png"},{"id":73441320,"identity":"7c6d73e4-7f66-46ec-b3df-f6757ef6b792","added_by":"auto","created_at":"2025-01-10 03:39:50","extension":"jpeg","order_by":9,"title":"Figure 9","display":"","copyAsset":false,"role":"figure","size":138754,"visible":true,"origin":"","legend":"\u003cp\u003eInner surface of the AMed dumb-bell model after post-turning process\u003c/p\u003e","description":"","filename":"floatimage10.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-5772268/v1/b5c106ad22f9e576ea778680.jpeg"},{"id":73441600,"identity":"7769187f-4c05-410c-abab-c71bb4f51fa7","added_by":"auto","created_at":"2025-01-10 03:47:50","extension":"png","order_by":10,"title":"Figure 10","display":"","copyAsset":false,"role":"figure","size":239291,"visible":true,"origin":"","legend":"\u003cp\u003eResult of 3D laser scanning measurement depicting (a) comparison between AMed unicell and blueprint model, (b) cross-section contour of the uni-cell, (c) cross-section contour of thermal distortion compensated uni-cell model, (d) comparison between AMed dumb-bell and blueprint model, and (e) cross-section contour of the dumb-bell model.\u003c/p\u003e","description":"","filename":"floatimage11.png","url":"https://assets-eu.researchsquare.com/files/rs-5772268/v1/54b59ade3f5b9ae56466d461.png"},{"id":82537979,"identity":"f0b95f29-0e03-4742-8733-9c80ff8ead3f","added_by":"auto","created_at":"2025-05-12 16:10:26","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":3444113,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-5772268/v1/296139d3-04ca-424a-8f57-4e7456eb9c55.pdf"},{"id":73441313,"identity":"c5f3ed7b-8ae1-488e-b082-bef611be64c2","added_by":"auto","created_at":"2025-01-10 03:39:50","extension":"docx","order_by":1,"title":"","display":"","copyAsset":false,"role":"supplement","size":115602,"visible":true,"origin":"","legend":"","description":"","filename":"Table1.docx","url":"https://assets-eu.researchsquare.com/files/rs-5772268/v1/0a25a7903256f34761c86b47.docx"}],"financialInterests":"","formattedTitle":"Prior Research on Additive Manufacturing of Superconducting Radio frequency Cavity for Particle Accelerators","fulltext":[{"header":"1. Introduction","content":"\u003cp\u003eParticle accelerators play a pivotal role in pushing the boundaries of scientific inquiry, enabling basic research across a variety of fields. Superconducting radio frequency (SRF) cavities are an essential component of these accelerators, providing the necessary energy boost to charged particles [\u003cspan additionalcitationids=\"CR2 CR3\" citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e]. The constant pursuit of higher performance and efficiency in accelerator technology has led to continuous improvements in the SRF cavity manufacturing process [\u003cspan additionalcitationids=\"CR6\" citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eSRF cavity manufacturing has traditionally involved creating a half-cell (or beam tube ring) through a deep drawing process and then completing the full cavity shape through electron beam welding (EBW) as shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e. However, this approach is associated with problems such as low material yield and uneven electromagnetic properties due to crystal growth in the weld joints, leading to unstable particle accelerator performance. To overcome this drawback, hydroforming and spinning have been proposed, as these approaches can reduce the number of EBWs. However, hydroforming requires complex process design and can cause excessive local deformation, resulting in undesirable wall thickness reduction. Likewise, the spinning process, known to cause surface degradation resembling an orange peel texture, disrupts electrical conductivity, similar to the effects of crystal growth induced by electron beam welding. Therefore, there is a need to develop a new SRF cavity manufacturing process to overcome these shortcomings [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e].\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eAdditive manufacturing (AM) methods have received significant attention due to their ability to fabricate complex geometries from 3D models that are difficult to fabricate with traditional manufacturing methods. Applying AM to SRF cavity production has the potential to solve the aforementioned challenges, opening new avenues to achieve unprecedented efficiencies in particle accelerators. In addition, the layer-by-layer construction minimizes material waste, contributing to economic efficiency, making it suitable for large-scale accelerator projects.\u003c/p\u003e \u003cp\u003eRecent attempts to fabricate SRF cavities using AM have been reported in the literature [\u003cspan additionalcitationids=\"CR10 CR11\" citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e]. One study utilized pure niobium (Nb) powder and laser powder bed fusion (LPBF) to fabricate a 6 GHz cavity shape and analyze its resonance frequency and residual resistivity ratio (RRR). However, this study mainly focused on the material science aspects of AMed SRF cavities and neglected the in-depth details on design for additive manufacturing (DfAM) and post-processing techniques [\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e, \u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e]. Therefore, it is believed that conducting research on AM for SRF cavities, particularly in the field of mechanical engineering, would greatly assist subsequent researchers in undertaking related studies.\u003c/p\u003e \u003cp\u003eDfAM and post-process development requires numerous cavity cell manufacturing tests. However, the high cost of pure Nb powder for fabricating numerous cavity cells presents financial challenges, making extensive testing impossible. Therefore, as a preliminary study on the production of SRF cavity, it is thought that using pure titanium (Ti) powder, which is relatively cheaper than niobium, would be a good option. Also, pure Ti is known to share similar physical and chemical properties with pure Nb. Given these similarities, the tendencies in DfAM technology and surface processing characteristics are expected to be comparable when using pure Nb powder.\u003c/p\u003e \u003cp\u003eTherefore, in this study, LPBF type AM was applied to fabricate 1.5 GHz SRF cavities using pure Ti powder. Process simulation based on finite element method (FEM) was performed to investigate thermal deformation during the AM process. Based on these results, the optimal support design for deformation control was proposed. Afterwards, heat treatment and support removal task were performed to remove residual stress and support. After that, barrel finishing (or turning process) was performed to improve the surface quality and dimensional accuracy of the cavity cell. Especially, experimental variations in barrel finishing conditions were investigated to determine the optimal polishing conditions for surface quality improvement. The results confirmed the additive manufacturability for the shape of SRF cavity cell with complex geometries.\u003c/p\u003e"},{"header":"2. Material and methods","content":"\u003ch2\u003e2.1 Material and cavity cell model\u003c/h2\u003e\n\u003cp\u003eIn order to evaluate the additive manufacturability for the shape of the SRF cavity, argon atomized grade 2 pure titanium powder (SLM Solutions Group AG, Germany) with a size range of 20-63 \u0026mu;m was used in this study. To emphasize once more, it is worth noting that the SRF cavity is originally made of pure Nb; however, due to the high cost of the material, this preliminary research was conducted using pure titanium powder, possessing mechanical and chemical properties similar to niobium to explore the feasibility of AM method.\u003c/p\u003e\n\u003cp\u003eAs shown in Fig. 1, 1.5 GHz SRF cavity model was applied for this study [15]. In the conventional manufacturing method consisting of deep drawing and EBW, half-cells are manufactured and assembled. However, since the AM process is used in this study, uni-cell and dumb-bell models, which combine two half-cells, are applied (Table 1). The characteristics of each model are as follows.\u003c/p\u003e\n\u003cul\u003e\n \u003cli\u003eFor the uni-cell model, the turning process does not appear suitable for post-processing the inner surface due to the relatively small diameter of the iris. Therefore, surface quality must be ensured through barrel finishing.\u003c/li\u003e\n \u003cli\u003eIn the case of the uni-cell model, since it is impossible to secure dimensional accuracy through turning process, dimensional accuracy on the inner surface must be ensured through support optimization and deformation compensation design to minimize thermal deformation during AM.\u003c/li\u003e\n \u003cli\u003eFor the dumb-bell model, since the diameter of the equator is relatively large, turning processing on the inner surface is possible. Therefore, surface quality and dimensional accuracy can be secured through post-turning process.\u003c/li\u003e\n\u003c/ul\u003e\n\u003cp\u003eThe characteristics of each model above cause differences in the work to produce a high quality SRF cavity. In the case of the uni-cell model, thermal deformation must be analyzed through process simulation at the DfAM stage and optimal support design to minimize thermal deformation must be performed. On the other hand, since the dumb-bell model can secure dimensional accuracy through post-processing, it can be seen that only design changes that add machining allowance will be required.\u003c/p\u003e\n\u003ch2\u003e2.2 Process simulation based on finite element method\u003c/h2\u003e\n\u003cp\u003ePrior to perform AM process, a FEM-based process simulation was performed to predict the thermal deformation of the cavity cell. The simulation was performed using ANSYS Mechanical 2023 R2 software, specifically the AM LPBF Inherent Strain module. The layered tetrahedrons mesh with a size of 2 mm was applied to the part and support structures. The contact conditions between the part, support, and build plate were set to bond.\u0026nbsp;\u003c/p\u003e\n\u003ch2\u003e2.3 AM and post process\u003c/h2\u003e\n\u003cp\u003eThe overall cavity cell fabrication process is shown in Fig. 2. AM process was conducted using SLM 280 equipment (SLM Solutions Group AG, Germany) under the following conditions: power 350 W, scan speed 1400 mm/s, layer thickness 0.03 mm, and hatch space 0.12 mm [16].\u003c/p\u003e\n\u003cp\u003eThe cavity cell produced by AM process was heat treated at 590\u0026deg;C for 2 hours in a vacuum atmosphere of 10\u003csup\u003e-6\u003c/sup\u003e mbar to eliminate residual stresses generated during the AM process. Subsequently, the part was separated from the build plate using wire-electrical discharge machining (wire-EDM), followed by manual support removal.\u003c/p\u003e\n\u003cp\u003eFor the uni-cell model, a barrel finishing process was applied to refine the rough inner surface. The barrel finishing was divided into roughing and finishing and was carried out sequentially. In the roughing process, a coarse grinding stones were used with water, and in the finishing process, and fine grinding stones were used with chemical compound and water. In order to compare the degree of improvement in surface roughness according to barrel finishing condition, various roughing and finishing period were tested. On the other hands, for the dumb-bell model, turning process was applied to enhance not only surface quality but also dimensional accuracy. The surface quality of the inner surface of the post-processed cavity cell was measured using a 3D measuring laser microscope (OLS5000, Olympus Inc., Japan).\u003c/p\u003e\n\u003cp\u003eAfter barrel finishing (or turning process), contour measurement on the cavity cells were conducted using a 3D laser scanning system (ZS-3040, Laser Design Inc., USA). For the uni-cell model, the inner contour was measured after cutting along the axis using wire-EDM. Subsequently, a comparison between the scan data and the blueprint model was made to calculate the error in the contour of the inner surface.\u003c/p\u003e"},{"header":"3. Results and discussion","content":"\u003ch2\u003e3.1 Support optimization based on process simulation\u003c/h2\u003e\n\u003cp\u003eFigure 3 shows the support design used in the process simulation of the uni-cell and dumb-bell model. It is before support optimization, and basic block type supports were applied to the part surface with an overhang of 40 degrees or less; block type support is a commonly used support type and is characterized by high rigidity (Here, the overhang angle means the angle between the part and the build plate). The supports of the uni-cell model consist of an outer support, an inner support, and a bottom support (Fig. 3 (a)). As can be seen in the cross-sectional view of the build model, inner support is part-to-part support where the top and bottom points of the support are in contact with the part surface. In the case of the dumb-bell model, it consists of inner support and bottom support. Additionally, in order to not apply support between the upper and lower half cells, a design change was made by applying a self-supporting structure as shown in the Fig. 3 (b).\u003c/p\u003e\n\u003cp\u003eResult of AM process simulation on the uni-cell and dumb-bell models are presented in Figure 4. In the case of total deformation of uni-cell model (Fig. 4(a)), the deformation occurs significantly at the lower region compared to the upper region. In particular, severe deformation occurs at the no support zone in the lower region (surface having overhang angle between 40 and 90 degrees as indicated using an arrow). Therefore, it is believed that the outer support having high-rigidity should be applied to entire lower surface to secure dimensional accuracy. With respect to inner support, since it is located inside the cylindrical cavity, it can be expected that support removal will be difficult. However, the simulation result shows that no significant deformation occurs in the upper region. Therefore, it is considered that a type of support with weak rigidity but easy to remove can be applied to that area.\u003c/p\u003e\n\u003cp\u003eFigure. 4(b) shows the total deformation in the dumb-bell model. Relatively large deformation was predicted in the lower half-cell. However, since the turning process for the inside of the dumb-bell model will be performed after the AM is completed, no additional support optimization is required. On the other hand, relatively small deformation was calculated in the upper half-cell. This indicates that the self-supporting structure sufficiently suppresses deformation of the upper half-cell.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eBased on the analysis results, optimal support design for AM process was suggested as shown in Figure 5. For the uni-cell model (Fig. 5 (a)), three types of supports, including bottom, inner, and outer supports have been employed. The bottom support is applied between parts and build plate to mitigate excessive stress on the build plate during the AM process. The inner support is designed as a rod type with low rigidity and easy removal based on the analysis that deformations at the cell (top) are insignificant. The outer support is designed as a tree type with high rigidity and is applied to the entire area of the cell bottom to minimize deformation of the corresponding area.\u003c/p\u003e\n\u003cp\u003eIn the case of the dumb-bell model, two types of supports, including bottom and inner supports have been employed. For the inner support, the rod type support is chosen for convenience of removal. It is note here that machining allowance approximately 1 mm was applied to the inside surface of dumb-bell model for post turning process.\u003c/p\u003e\n\u003ch2\u003e3.2 Barrel finishing for surface quality enhancement\u003c/h2\u003e\n\u003cp\u003eBased on the optimized support design model, AM process was carried out for both of the uni-cell and dumb-bell models. The resulting specimens underwent stress-relief heat treatment and support removal processes. The surface quality inside the cavity cell is known to influence the stable maintenance of superconducting characteristics during the operation of a particle accelerator [17]. Therefore, as mentioned in Section 2.1, the barrel finishing was performed on the uni-cell model under various process conditions. Thereafter, the specimens were cut in half, and surface roughness measurement were conducted on the three measurement points: upper, middle, and lower (Figure 6). As can be seen in the figures, the upper and lower regions have rough surface due to the traces of rod type inner support. In particular, despite the application of barrel finishing, the bumpy shapes, consisting of peaks and valleys, remain noticeably intact on the upper surface.\u003c/p\u003e\n\u003cp\u003eFigure 7 presents the results of surface roughness measurements according to barrel finishing condition. Overall, surface roughness increased in the order of middle, lower, and upper surfaces, and the combination of roughing 1 cycle + finishing 2 cycles (R1 + F2) was most effective in improving surface quality. In the case of the R2 + F1 combination, the effect of improving surface quality was negligible compared to the R1 + F1 combination. This is believed to be because the area to be polished in the roughing stage is sufficiently removed with a single roughing cycle.\u003c/p\u003e\n\u003cp\u003eFigure 8 shows the 3D surface morphologies of the inner surface of the uni-cell model. For the upper surface, it was confirmed that the bumpy shape was still remained even after barrel finishing, and a lot of fine craters existed in the valley area. On the other hand, the middle surface was confirmed to be a relatively even surface without a bumpy shape. This characteristic is seems to be because the peak regions of the upper and lower surfaces play a role in hindering polishing of the valley area. Therefore, other processing techniques to remove the peak regions is necessary to further improve surface quality. In conclusion, despite the effective surface quality improvement of the R1 + F2 combination, the bumpy shapes of the upper surface still existed and the surface roughness also showed a high value of Ra 11.1 \u0026mu;m. Typically, in the SRF cavity manufacturing process, chemical polishing is performed at the final stage to maximize the internal surface quality [8]. However, even considering the post-chemical polishing process, it is judged that there are limitations in performing mechanical polishing only with the barrel finishing.\u003c/p\u003e\n\u003cp\u003eFigure 9 shows the dumb-bell model after post-turning process. Unlike the uni-cell model after barrel finishing, a high-quality inner surface can be observed. The surface roughness of the machined surface was confirmed to be at the level of Ra 0.34 \u0026mu;m, which is sufficient for use in particle accelerators. Therefore, it can be seen that the method of manufacturing cavity cells in a dumb-bell type is reasonable in terms of securing surface quality.\u003c/p\u003e\n\u003ch2\u003e3.3 Dimensional characterization of AMed cavity cell\u003c/h2\u003e\n\u003cp\u003eThe resonant frequency, a critical factor in evaluating cavity performance, is significantly influenced by the dimensional accuracy of the inner surface of the cavity cells. To assess this, 3D scanning was conducted on the barrel-finished uni-cell model and the turning processed dumb-bell model, and the dimensional accuracy of the both model\u0026apos;s internal surfaces was analyzed, as shown in Figure 10.\u003c/p\u003e\n\u003cp\u003eIn the case of the uni-cell model, as illustrated in Figure 10(a), dimensional errors were observed along the upper surface, decreasing toward the bottom (Fig. 10(b)). This issue was attributed to insufficient support provided by the rod type supports, resulting in sagging during the AM process. To address this dimensional inaccuracy, a compensation design incorporating the dimensional errors was applied, and the uni-cell cavity was remanufactured. As a result, a maximum dimensional error of -0.20 mm and an average dimensional error of 0.132 mm were achieved, as shown in Figure 10(c).\u003c/p\u003e\n\u003cp\u003eFor the dumb-bell model, as depicted in Figure 10(d), higher dimensional accuracy was achieved due to the post-processing performed through turning. The maximum dimensional error was -0.15 mm, and the average dimensional error was measured at 0.077 mm, as shown in Figure 9(e).\u003c/p\u003e\n\u003cp\u003eAs discussed, both the uni-cell and dumb-bell models demonstrated successful AM enabled by DfAM, including optimization of support structures. However, the geometric characteristics of the uni-cell model posed challenges in ensuring surface quality and dimensional accuracy. In conclusion, considering that surface quality and dimensional accuracy are critical factors closely tied to the stable operation of particle accelerators, the dumb-bell model is deemed more suitable for additive manufacturing.\u003c/p\u003e"},{"header":"4. Conclusions","content":"\u003cp\u003eThis study investigated the feasibility of AM for fabricating 1.5 GHz SRF cavities using pure titanium (Ti) powder, focusing on the DfAM, post-processing techniques, and dimensional characterization. The following conclusions were drawn:\u003c/p\u003e\n\u003cul\u003e\n \u003cli\u003e\n \u003ch2\u003eSupport design optimization:\u003c/h2\u003e\n \u003c/li\u003e\n\u003c/ul\u003e\n\u003cp\u003eThe process simulation results emphasized the importance of optimized support structures in minimizing thermal deformation during the AM process. For the uni-cell model, a combination of high-rigidity outer supports and low-rigidity inner supports was designed to achieve a balance between deformation control and ease of removal. For the dumb-bell model, self-supporting structures and a machining allowance design enabled effective post-processing and minimized support dependency.\u003c/p\u003e\n\u003cul\u003e\n \u003cli\u003e\n \u003ch2\u003eSurface quality:\u003c/h2\u003e\n \u003c/li\u003e\n\u003c/ul\u003e\n\u003cp\u003eBarrel finishing was applied to enhance the surface quality of the uni-cell model, revealing that the roughing 1 cycle + finishing 2 cycles combination was most effective in reducing surface roughness. However, the bumpy shapes on the upper surface remained a limitation, indicating the need for additional machining processes. In contrast, the turning process applied to the dumb-bell model demonstrated excellent surface quality, achieving a surface roughness of Ra 0.34 \u0026mu;m, which is sufficient for use in particle accelerators.\u003c/p\u003e\n\u003cul\u003e\n \u003cli\u003e\n \u003ch2\u003eDimensional accuracy:\u003c/h2\u003e\n \u003c/li\u003e\n\u003c/ul\u003e\n\u003cp\u003eDimensional accuracy was significantly influenced by the geometric characteristics and post-processing methods of each model. The uni-cell model showed notable dimensional errors caused by insufficient support rigidity during the AM process. A compensation design reduced these errors to acceptable levels. The dumb-bell model exhibited better dimensional accuracy due to the turning process, achieving a maximum error of -0.15 mm and an average error of 0.077 mm.\u003c/p\u003e\n\u003cp\u003eIn conclusion, this study demonstrated that while both uni-cell and dumb-bell models can be successfully manufactured using AM, the dumb-bell model is more favorable for manufacturing the SRF cavities. This research provides valuable insights for AM processes as SRF cavity production, thereby contributing to advancements in accelerator technology. In the next study, we will develop an AM process using pure Nb powder based on the DfAM principles and the post-processing strategies implemented in this study.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e \u003ch2\u003eCompeting Interests\u003c/h2\u003e \u003cp\u003eThe authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.\u003c/p\u003e \u003c/p\u003e\u003ch2\u003eFunding\u003c/h2\u003e \u003cp\u003eThis work was supported by the Korea Institute of Industrial Technology's own research project, \u0026ldquo;Development of element technology for manufacturing non-welding integrated superconducting radio frequency cavity\u0026rdquo; (KITECH UR-24-0011).\u003c/p\u003e\u003ch2\u003eAuthor Contributions\u003c/h2\u003e \u003cp\u003eAll authors contributed to the study conception and design. Part design, simulation and analysis were performed by [In Yong Moon] and [Min Ji Ham]. Additive manufacturing was performed by [Seung Jun Han] and [Won Rae Kim]. The first draft of the manuscript was written by [Yeonghwan Song] and all authors commented on previous versions of the manuscript. All authors read and approved the final manuscript\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eHara H, Sennyu K, Miyamoto A, Yanagisawa T (2021) Manufacturing techniques of superconducting RF cavities for heavy ions. Mitsub Heavy Ind Tech Rev\u003cem\u003e 58:\u003c/em\u003e1. \u003c/li\u003e\n\u003cli\u003eAwasthi PD, Agrawal P, Haridas RS, Mishra RS, Stawovy MT, Ohm S, Imandoust A (2022) Mechanical properties and microstructural characteristics of additively manufactured C103 niobium alloy. Mater Sci Eng A 831:142183. https://doi.org/10.1016/j.msea.2021.142183\u003c/li\u003e\n\u003cli\u003eFietek C, Brizes E, Milner J (2024) Evaluation of high-vacuum annealing and hot isostatic pressing on the microstructure and properties of an additively manufactured niobium alloy. JOM 76: 1223\u0026ndash;1234. https://doi.org/10.1007/s11837-023-06320-5\u003c/li\u003e\n\u003cli\u003ePark SM, Oh YS, Kim SJ, Kim HR, Lee H, Moon IY, Kang SH (2019) Effect of ECAP on change in microstructure and critical current density of low-temperature superconducting monowire. Int J Precis Eng Manuf 20:1563\u0026ndash;1572. https://doi.org/10.1007/s12541-019-00164-3\u003c/li\u003e\n\u003cli\u003eSafa H, Moffat D, Bonin B, Koechlin F (1996) Advances in the purification of niobium by solid state gettering with titanium. J Alloys Compd 232:281\u0026ndash;288. https://doi.org/10.1016/0925-8388(95)01997-9\u003c/li\u003e\n\u003cli\u003ePosen S, Hall DL (2017) Nb3Sn superconducting radiofrequency cavities: Fabrication, results, properties, and prospects. Supercond Sci Technol 30:033004. https://doi.org/10.1088/1361-6668/30/3/033004\u003c/li\u003e\n\u003cli\u003eVogel E, Arnold S, Bazyl D, Buettner T, van der Horst B, Klinke D, Umemori K (2023) Surface treatment experience of the all superconducting gun cavities\u003cem\u003e. Proceedings of IPAC2023, Venice, Italy.\u003c/em\u003e Advance online publication. https://doi.org/10.18429/JACoW-IPAC2023-TUPAB001\u003c/li\u003e\n\u003cli\u003eSinger W (2015) SRF cavity fabrication and materials. arXiv preprint arXiv:1501.07142.\u003c/li\u003e\n\u003cli\u003eTerrazas CA, Mireles J, Gaytan SM, Morton PA, Hinojos A, Frigola P, Wicker RB (2016) Fabrication and characterization of high-purity niobium using electron beam melting additive manufacturing technology. Int J Adv Manuf Technol 84:1115\u0026ndash;1126. https://doi.org/10.1007/s00170-015-7767-x\u003c/li\u003e\n\u003cli\u003eMotschmann F, Gerard R, Gilles F (2019) Purification of selective laser melting additive manufactured niobium for superconducting RF applications. IEEE Transactions on Applied Superconductivity 29:1\u0026ndash;5. https://doi.org/10.1109/TASC.2019.2900521\u003c/li\u003e\n\u003cli\u003eLiu M, Zhang J, Chen C, Geng Z, Wu Y, Li D, Guo Y (2023) Additive manufacturing of pure niobium by laser powder bed fusion: Microstructure, mechanical behavior, and oxygen-assisted embrittlement. Mater Sci Eng A 866:144691. https://doi.org/10.1016/j.msea.2023.144691\u003c/li\u003e\n\u003cli\u003eFrigola P, Agustsson RB, Faillace L, Murokh AY, Ciovati G, Clemens WA, Wicker RB (2015, September) Advance additive manufacturing method for SRF cavities of various geometries. \u003cem\u003eIn Proceedings of the 17th International Conference on RF Superconductivity (SRF\u0026rsquo;15)\u003c/em\u003e, Whistler, BC, Canada (pp. 13\u0026ndash;18).\u003c/li\u003e\n\u003cli\u003eGriemsmann T, Abel A, Hoff C, Hermsdorf J, Weinmann M, Kaierle S (2021) Laser-based powder bed fusion of niobium with different build-up rates. Int J Adv Manuf Technol 114:305\u0026ndash;317. https://doi.org/10.1007/s00170-021-06645-y\u003c/li\u003e\n\u003cli\u003eCandela S, Bonesso M, Candela V, Dima R, Favero G, Pepato A, Pira C (2023) Laser powder bed fusion of pure niobium for particle accelerator applications. In Proceedings of the 14th International Particle Accelerator Conference (IPAC-2023), Venice, Italy. https://doi.org/10.18429/JACoW-IPAC2023-THPM021\u003c/li\u003e\n\u003cli\u003eCiovati G (2022) Superconducting radiofrequency cavities. \u003cem\u003eIn Handbook of Superconductivity\u003c/em\u003e (pp. 583\u0026ndash;594). CRC Press.\u003c/li\u003e\n\u003cli\u003eKim HG, Kim WR, Kwon O, Bang GB, Ham MJ, Park HK, Kim GH (2019) Laser beam melting process based on complete-melting energy density for commercially pure titanium. J Manuf Process 45:455\u0026ndash;459. https://doi.org/10.1016/j.jmapro.2019.07.031\u003c/li\u003e\n\u003cli\u003eRomanenko A, Harnik R, Grassellino A, Pilipenko R, Pischalnikov Y, Liu Z, Hook A (2023) Search for dark photons with superconducting radiofrequency cavities. Phys Rev Lett 130:261801. https://doi.org/10.1103/PhysRevLett.130.261801\u003c/li\u003e\n\u003c/ol\u003e"},{"header":"Table","content":"\u003cp\u003eTable 1 is available in the Supplementary Files section.\u003c/p\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":true,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"the-international-journal-of-advanced-manufacturing-technology","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"jamt","sideBox":"Learn more about [The International Journal of Advanced Manufacturing Technology](https://www.springer.com/journal/170)","snPcode":"170","submissionUrl":"https://submission.nature.com/new-submission/170/3","title":"The International Journal of Advanced Manufacturing Technology","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"Additive manufacturing, Radio frequency cavity, Particle accelerator, Superconducting, Design for additive manufacturing","lastPublishedDoi":"10.21203/rs.3.rs-5772268/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-5772268/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eWith the advent of the quantum technology era, there is a growing interest in the development of fundamental research equipment in related fields. Particle accelerators are crucial tools in the study of quantum mechanics and quantum field theory, playing a significant role in the advancement of quantum technology. The key component of particle accelerators, the superconducting radio frequency (SRF) cavity, is traditionally manufactured using conventional methods such as deep drawing and electron beam welding with pure niobium (Nb) sheets. However, this manufacturing process has drawbacks, including low material yield and electrical non-uniformity due to the presence of welded joints. To overcome these shortcomings, this study focused on the development of SRF cavity manufacturing technology using additive manufacturing (AM). Before producing the cavity with pure Nb, preliminary research was conducted using relatively inexpensive pure titanium powder to assess the feasibility of AM for the cavity's shape. Prior to performing the AM of the cavity, process analysis based on finite element method was conducted to verify the level of thermal deformation and stress distribution in the parts and optimal support design was suggested to ensure dimensional precision. After the completion of AM, a barrel finishing and turning process were performed to enhance the inner surface quality and dimensional accuracy of cavity cell. As a result, it was confirmed that the shape of cavity could be successfully manufactured through the AM method.\u003c/p\u003e","manuscriptTitle":"Prior Research on Additive Manufacturing of Superconducting Radio frequency Cavity for Particle Accelerators","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-01-10 03:39:45","doi":"10.21203/rs.3.rs-5772268/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Major Revisions Needed","date":"2025-02-23T03:55:47+00:00","index":"","fulltext":""},{"type":"reviewerAgreed","content":"","date":"2025-01-15T11:36:28+00:00","index":0,"fulltext":""},{"type":"reviewersInvited","content":"","date":"2025-01-08T19:57:42+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2025-01-08T02:20:05+00:00","index":"","fulltext":""},{"type":"submitted","content":"The International Journal of Advanced Manufacturing Technology","date":"2025-01-06T03:59:11+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"the-international-journal-of-advanced-manufacturing-technology","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"jamt","sideBox":"Learn more about [The International Journal of Advanced Manufacturing Technology](https://www.springer.com/journal/170)","snPcode":"170","submissionUrl":"https://submission.nature.com/new-submission/170/3","title":"The International Journal of Advanced Manufacturing Technology","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"6bbcbafb-4dfa-438b-a93e-85e0a2bfb3a5","owner":[],"postedDate":"January 10th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[],"tags":[],"updatedAt":"2025-05-12T16:08:25+00:00","versionOfRecord":{"articleIdentity":"rs-5772268","link":"https://doi.org/10.1007/s00170-025-15625-5","journal":{"identity":"the-international-journal-of-advanced-manufacturing-technology","isVorOnly":false,"title":"The International Journal of Advanced Manufacturing Technology"},"publishedOn":"2025-05-09 15:57:46","publishedOnDateReadable":"May 9th, 2025"},"versionCreatedAt":"2025-01-10 03:39:45","video":"","vorDoi":"10.1007/s00170-025-15625-5","vorDoiUrl":"https://doi.org/10.1007/s00170-025-15625-5","workflowStages":[]},"version":"v1","identity":"rs-5772268","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-5772268","identity":"rs-5772268","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}