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Basic Electropolishing Process Research And Development In Support Of Improved Reliable Performance Srf Cavities For The Future Accelerator
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Book Synopsis Basic Electropolishing Process Research and Development in Support of Improved Reliable Performance SRF Cavities for the Future Accelerator by :
Download or read book Basic Electropolishing Process Research and Development in Support of Improved Reliable Performance SRF Cavities for the Future Accelerator written by and published by . This book was released on 2009 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Future accelerators require unprecedented cavity performance, which is strongly influenced by interior surface nanosmoothness. Electropolishing is the technique of choice to be developed for high-field superconducting radiofrequency cavities. Electrochemical impedance spectroscopy (EIS) and related techniques point to the electropolishing mechanism of Nb in a sulfuric and hydrofluoric acid electrolyte of controlled by a compact surface salt film under F- diffusion-limited mass transport control. These and other findings are currently guiding a systematic characterization to form the basis for cavity process optimization, such as flowrate, electrolyte composition and temperature. This integrated analysis is expected to provide optimum EP parameter sets for a controlled, reproducible and uniform surface leveling for Nb SRF cavities.
Book Synopsis Research and Development for Electropolishing of Nb for ILC Accelerator Cavities by :
Download or read book Research and Development for Electropolishing of Nb for ILC Accelerator Cavities written by and published by . This book was released on 2009 with total page 7 pages. Available in PDF, EPUB and Kindle. Book excerpt: The objectives of this project are to 1, Expand the scientific and technological understanding of the effect of post-treatment (electropolish, buffered chemical polish, low-temperature baking) on the surface of niobium; 2, Relate the knowledge to the performance of niobium superconducting radiofrequency accelerator cavities; and, 3, Thereby design and demonstrate an electropolish process that can be applied to complete cavities.
Book Synopsis Improved Performance of JLab 7-Cell Cavities by Electropolishing by :
Download or read book Improved Performance of JLab 7-Cell Cavities by Electropolishing written by and published by . This book was released on 2009 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The great majority of experience in niobium SRF cavity processing at Jefferson Lab is with BCP etching. This has been used on CEBAF cavities and others totalling over 600 in number. With improved process quality control, field emission is now largely controlled and other factors limit performance. All of the prototype cavities developed for the 12 GeV upgrade, although meeting minimum requirements, have demonstrated a Q-drop in the 17?23 MV/m range that is not remedied by 120 C bake. Most of these cavities received>250 micron removal by BCP etch. Two of these cavities have been electropolished using the protocol under development within ILC R & D activities. The first such cavity was transformed from Q = 3×109 at 17 MV/m to quench from 1×1010 at 35 MV/m. The details of this and subsequent electropolished JLab 7-cell cavities will be reported.
Book Synopsis Buffered Electropolishing - A New Way for Achieving Extremely Smooth Surface Finish on Nb SRF Cavities to be Used in Particle Accelerators by :
Download or read book Buffered Electropolishing - A New Way for Achieving Extremely Smooth Surface Finish on Nb SRF Cavities to be Used in Particle Accelerators written by and published by . This book was released on 2009 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Future accelerators require unprecedented cavity performance, which is strongly influenced by interior surface nano-smoothness. Electropolishing (EP) is the technique of choice to be developed for high-field superconducting radio frequency (SRF) cavities. Electrochemical impedance spectroscopy (EIS) and related techniques point to the electropolishing mechanism of Nb in a sulphuric and hydrofluoric acid electrolyte controlled by a compact surface salt film under F- diffusion-limited mass transport control. These and other findings are guiding a systematic characterization to form the basis for cavities process optimization.
Book Synopsis Improvement of Cavity Performance by Electro-polishing in the 1.3GHz Nb Superconducting Cavities by : E. Kako
Download or read book Improvement of Cavity Performance by Electro-polishing in the 1.3GHz Nb Superconducting Cavities written by E. Kako and published by . This book was released on 1999 with total page 3 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Recent Developments in Electropolishing and Tumbling R & D at Fermilab by :
Download or read book Recent Developments in Electropolishing and Tumbling R & D at Fermilab written by and published by . This book was released on 2009 with total page 5 pages. Available in PDF, EPUB and Kindle. Book excerpt: Fermi National Accelerator Lab (Fermilab) is continuing to improve its infrastructure for research and development on the processing of superconducting radio frequency cavities. A single cell 3.9 GHz electropolishing tool built at Fermilab and operated at an industrial partner was recently commissioned. The EP tool was used to produce a single cell 3.9 GHz cavity that reached an accelerating gradient of 30 MV/m with a quality factor of 5 x 109. A single cell 1.3 GHz cavity was also electropolished at the same industrial vendor using the vendor's vertical full-immersion technique. On their first and only attempt the vendor produced a single cell 1.3 GHz cavity that reached 30 MV/m with a quality factor of 1 x 101°. These results will be detailed along with preliminary tumbling results.
Book Synopsis Effect of Surface Flow on Topography in Niobium Electropolishing by :
Download or read book Effect of Surface Flow on Topography in Niobium Electropolishing written by and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Electropolishing (EP) is reliably delivering improved performance of multi-celled niobium SRF accelerator cavities, attributed to the smoother surface obtained. This superior leveling is a consequence of an etchant concentration gradient layer that arises in the HF-H2SO4 electrolyte adjacent to the niobium surface during polishing. Electrolyte circulation raises the prospect that fluid flow adjacent to the surface might affect the diffusion layer and impair EP performance. In this study, preliminary bench-top experiments with a moving electrode apparatus were conducted. We find that flow conditions approximating cavity EP show no effects attributable to depletion layer disruption.
Book Synopsis Electropolishing on Small Samples at Fermilab by : P. Bauer
Download or read book Electropolishing on Small Samples at Fermilab written by P. Bauer and published by . This book was released on 2005 with total page 4 pages. Available in PDF, EPUB and Kindle. Book excerpt: The electropolishing process (EP) is considered an essential step in the processing of high gradient SRF cavities. Studies on EP of small samples has been started at Fermilab as part of the SRF materials R & D program. A simple bench top setup was developed to understand the basic variables affecting the EP. In addition a setup for vertical EP of half cells, based on the Cornell design, was used and another one for dumbbells was designed and tested. Results and findings are reported.
Book Synopsis High Gradient Performance by Electropolishing with 1300 MHz Single and Multi-cell Niobium Superconducting Cavities by : K. Saito
Download or read book High Gradient Performance by Electropolishing with 1300 MHz Single and Multi-cell Niobium Superconducting Cavities written by K. Saito and published by . This book was released on 2000 with total page 4 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Analysis of High Field Q-slope (hfqs) Causes and Development of New Chemical Polishing Acid for Niobium Srf Cavities by : Didi Luo
Download or read book Analysis of High Field Q-slope (hfqs) Causes and Development of New Chemical Polishing Acid for Niobium Srf Cavities written by Didi Luo and published by . This book was released on 2020 with total page 178 pages. Available in PDF, EPUB and Kindle. Book excerpt: Buffered Chemical Polishing (BCP) was the most conventional polishing method for superconducting radiofrequency (SRF) Niobium (Nb) cavity surface preparation before the discovery of Electropolishing (EP), which is superior to BCP in high gradient performance. The High Field Q-slope (HFQS) is entirely eliminated by taking the low-temperature bake (LTB) post EP, which guarantees high gradient performance in EP'ed cavities. The mechanism of the HFQS is well understood for EP'ed cavities. On the other hand, there is no common consensus on the HFQS with BCP, since even BCP with LTB does not always resolve the HFQS. BCP is much easier to apply and still a vital preparation technology for very complicated SRF structures like low beta cavities. Therefore, overcoming the issue of HFQS with BCP is highly beneficial to the SRF community. This thesis mines a large number of available data sets on BCP'ed cavity performance with fine grain, large grain, and even single-crystal niobium materials under different experimental settings. We found that all existing explanations for HFQS with BCP are inconsistent with some experimental results, and propounded nitrogen contamination as a new model to explain the result. Our conclusion is made based on previously unresolved phenomena which include (1) applying multiple BCP post EP; the maximum gradient does not always agree with roughness; (2) cavity treated with EP acid adding a drop of nitric acid started to have non-resolvable HFQS; (3) maximum field of BCP single-crystal cavities are lower than EP large grain cavities; (4) temperature map shows no high roughness area heating for a large-grain BCP cavity. We then checked that nitrogen contamination agrees with all existing data and nicely explains unresolved phenomena.According to this result, we have started developing a new nitrogen-free chemical polishing acid. Hydrogen peroxide with HF mixture was reported able to react with Nb, and there is no extra element contamination in it, so we replace the conventional BCP with this mixture to start our study.We discovered that this new acid could not provide sufficient smooth finishing surface, even after we adjusted all the parameters. However, adding a copper catalyst allows this acid to provide a smooth surface similar to or even better than conventional BCP. The copper remnant can be neglected according to an EDS study on the Nb surface. We studied the reaction mechanism and deduced that several other metals that can be promising as catalysts. One of those is iron, which was later shown to have the catalyst effect; this proved the mechanism we found is right. Further study can focus on other potential catalysts (such as Pb and Sn) and testing cavities treated by these acids. Pb is superconducting under operation temperature, may reduce potential harm to cavity performance, and Sn may react with Nb and generate Niobium Tin on its surface, which is another promising material for SRF cavities. These studies will offer more possibilities for SRF material.
Book Synopsis Annealing to Mitigate Pitting in Electropolished Niobium Coupons and SRF Cavities by :
Download or read book Annealing to Mitigate Pitting in Electropolished Niobium Coupons and SRF Cavities written by and published by . This book was released on 2011 with total page 8 pages. Available in PDF, EPUB and Kindle. Book excerpt: Ongoing studies at Fermilab investigate whether dislocations and other factors instigate pitting during cavity electropolishing (EP), despite careful processing controls and the inherent leveling mechanism of EP itself. Here, cold-worked niobium coupons, which exhibited increased tendencies for pitting in our past study, were annealed in a high vacuum furnace and subsequently processed by EP. Laser confocal scanning microscopy and special defect counting algorithms were used to assess the population of pits formed. Hardness measurements indicated that annealing for 2 hours at 800 C produced recovery, whereas annealing for 12 hours at 600 C did not, as is consistent with known changes for cavities annealed in a similar way. The 800 C anneal was effective in some cases but not others, and we discuss reasons why tendencies for pitting remain. We discuss implications for cavities and continued work to understand pitting.
Book Synopsis Advance in Vertical Buffered Electropolishing on Niobium for Particle Accelerators* by :
Download or read book Advance in Vertical Buffered Electropolishing on Niobium for Particle Accelerators* written by and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Niobium (Nb) is the most popular material that has been employed for making superconducting radio frequency (SRF) cavities to be used in various particle accelerators over the last couple of decades. One of the most important steps in fabricating Nb SRF cavities is the final chemical removal of 150 [mu]m of Nb from the inner surfaces of the SRF cavities. This is usually done by either buffered chemical polishing (BCP) or electropolishing (EP). Recently a new Nb surface treatment technique called buffered electropolishing (BEP) has been developed at Jefferson Lab. It has been demonstrated that BEP can produce the smoothest surface finish on Nb ever reported in the literature while realizing a Nb removal rate as high as 10 [mu]m/min that is more than 25 and 5 times quicker than those of EP and BCP(112) respectively. In this contribution, recent advance in optimizing and understanding BEP treatment technique is reviewed. Latest results from RF measurements on BEP treated Nb single cell cavities by our unique vertical polishing system will be reported.
Book Synopsis Fundamental Study of Micro-Defects in Electropolished EB-Welded and Hydroformed SRF Accelerating Structures by :
Download or read book Fundamental Study of Micro-Defects in Electropolished EB-Welded and Hydroformed SRF Accelerating Structures written by and published by . This book was released on 2014 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: In the area of niobium elecropolishing fundamentals, we focused on understanding the influence of the surface topology, and geometry (with effects from gravity included. The formation of a viscous film is essential for the electropolishing process to take place. The exact nature and composition of the film formed on niobium is still unknown because of its solubility in the electrolyte. Extensive pitting may take place at surface where a stable film cannot form. This has to be taken into consideration while determining the speed with which the SRF cavities are rotated while EP. Hydrodynamic aspects must be taken into consideration while optimizing the polishing parameters. There is improvement in surface finish with polishing time. There is a huge change in surface quality when the EP time is increased from 2 hours to 4 hours but not much change takes place when the time is further increased to 6 hours. So keeping the economic points in view, about 100 um defect layer removal may be sufficient to get the desired performance. In the area of Electropolishing of untreated and treated niobium with Weld Joints we studied untreated and treated Nb, especially for the heat affected areas next to welded bumps, electropolished for different durations. The electropolishing of the untreated Nb caused the formation of pits on the surface at about 15 min but they disappeared when the electropolishing duration was more than 15 min. Electropolishing for 120 min smoothened the surface of untreated Nb by levelling the surface, but the severe formation of pits on the whole surface was found after 240 min. The treatment of Nb significantly changed the Nb surface morphology which was covered by grains of different size that looked light or dark in the optical microscope. The treated Nb was susceptible to pitting during the entire electropolishing starting from 15 min and the dark grains had more susceptibility to pitting than the light grains. In addition, electropolishing for 240 min again resulted in severe pit formation. In the area of Bulge test and microstructure studies, we worked to create a useful constitutive relationship for the complex stress state that accompanies SRF cavity formation. To do so, bulge tests were performed on Cu and Nb tube samples that exhibited the greatest degrees of uniaxial elongation after HT. The data from the bulge tests and an accompanying set of tensile tests provided input to a finite-element model that recreated the bulge tests numerically. As expected the model based on the bulge test results fit the experimental data well at least at low stress levels safely below the bursting pressure. Not so for that based on the tensile results. The results of the study emphasize the importance of for bulge testing rather than tensile testing when deriving the constitutional relationships eventually needed for modelling the hydroforming of Nb SRF cavities.
Book Synopsis Superconducting Technology by : Kristian Fossheim
Download or read book Superconducting Technology written by Kristian Fossheim and published by World Scientific. This book was released on 1991 with total page 258 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book contains an interdisciplinary selection of timely articles which cover a wide range of superconducting technologies ranging from high tech medicine (10-12 Gauss) to multipurpose sensors, microwaves, radio engineering, magnet technology for accelerators, magnetic energy storage, and power transmission on the 109 watt scale. It is aimed primarily at the non-specialist and will be suitable as an introductory course book for those in the relevant fields and related industries. As shown in the title several examples of high-c applications are included. While low-Tc is still the leading technology, for instance, in cables and SQUIDS, case studies in these areas are presented.
Book Synopsis Impact of Forming, Welding, and Electropolishing on Pitting and the Surface Finish of SRF Cavity Niobium by :
Download or read book Impact of Forming, Welding, and Electropolishing on Pitting and the Surface Finish of SRF Cavity Niobium written by and published by . This book was released on 2010 with total page 6 pages. Available in PDF, EPUB and Kindle. Book excerpt: A broad range of coupon electropolishing experiments are described to ascertain the mechanism(s) by which large defects are formed near superconducting radiofrequency (SRF) cavity welds. Cold-worked vs. annealed metal, the presence of a weld, and several variations of electropolishing (EP) parameters were considered. Pitting is strongly promoted by cold work and agitation of the EP solution. Welding also promotes pitting, but less so compared with the other factors above. Temperature increase during EP did not strongly affect glossiness or pitting, but the reduced viscosity made the electrolyte more susceptible to agitation. The experiments suggest that several factors that are rather benign alone are combined by the cavity forming, welding, and processing sequence to promote the formation of defects such as pits. Process changes to mitigate these risks are discussed.
Book Synopsis RF Superconductivity for Accelerators by : Hasan Padamsee
Download or read book RF Superconductivity for Accelerators written by Hasan Padamsee and published by John Wiley & Sons. This book was released on 2008-02-26 with total page 548 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book introduces some of the key ideas of this exciting field, using a pedagogic approach, and presents a comprehensive overview of the field. It is divided into four parts. The first part introduces the basic concepts of microwave cavities for particle acceleration. The second part is devoted to the observed behavior of superconducting cavities. In the third part,general issues connected with beam-cavity interaction and the related issues for the critical components are covered. The final part discusses applications of superconducting cavities to frontier accelerators of the future, drawing heavily on the examples that are in their most advanced stage. Each part of the book ends in a Problems section to illustrate and amplify text material as well as draw on example applications of superconducting cavities to existing and future accelerators.
Book Synopsis Status of Accelerator Driven Systems Research and Technology Development by : International Atomic Energy Agency
Download or read book Status of Accelerator Driven Systems Research and Technology Development written by International Atomic Energy Agency and published by IAEA Tecdoc. This book was released on 2015 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: One of the greatest challenges for nuclear energy is how to properly manage the highly radioactive waste generated during irradiation in nuclear reactors. Accelerator Driven Systems (ADSs) may offer new prospects and advantages for the transmutation of such high level nuclear waste. ADS or accelerator driven transmutation of waste (ATW) consists of a high power proton accelerator, a heavy metal spallation target that produces neutrons when bombarded by the high power beam, and a sub-critical core that is neutronically coupled to the spallation target. This publication provides a comprehensive state of the art of the ADS technology by representing the different ADS concepts proposed worldwide in the last 15 years, as well as the related R&D activities and demonstration initiatives carried out at national international level.
