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Surface Characterization Of Niobium Samples Electro Polished Together With Real Cavities
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Book Synopsis Surface Characterization of Niobium Samples Electro-Polished Together with Real Cavities by :
Download or read book Surface Characterization of Niobium Samples Electro-Polished Together with Real Cavities written by and published by . This book was released on 2009 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: We report the results of surface characterizations of niobium samples electropolished together with single cell cavities. These witness samples were located in three regions of the cavity, namely at the equator, the iris and the beam-pipe. Auger electron spectroscopy (AES) was utilized to probe the chemical composition of the topmost four atomic layers. Scanning electron microscopy with energy dispersive x-ray for elemental analysis (SEM/EDX) was used to observe the surface topography and chemical composition at the micrometer scale. A few atomic layers of sulphur (S) were found covering the samples non-uniformly. Niobium oxide granules with a sharp geometry were observed on every sample. Some Nb-O granules appeared to also contain sulphur.
Book Synopsis Surface Characterization of Nb Samples Electro-polished Together With Real Superconducting Radio-frequency Accelerator Cavities by :
Download or read book Surface Characterization of Nb Samples Electro-polished Together With Real Superconducting Radio-frequency Accelerator Cavities written by and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: We report the results of surface characterizations of niobium (Nb) samples electropolished together with a single cell superconducting radio-frequency accelerator cavity. These witness samples were located in three regions of the cavity, namely at the equator, the iris and the beam-pipe. Auger electron spectroscopy (AES) was utilized to probe the chemical composition of the topmost four atomic layers. Scanning electron microscopy with energy dispersive X-ray for elemental analysis (SEM/EDX) was used to observe the surface topography and chemical composition at the micrometer scale. A few atomic layers of sulfur (S) were found covering the samples non-uniformly. Niobium oxide granules with a sharp geometry were observed on every sample. Some Nb-O granules appeared to also contain sulfur.
Book Synopsis Surface Characterization of Nb Samples Electropolished Together with Real Superconducting Rf Accelerator Cavities by :
Download or read book Surface Characterization of Nb Samples Electropolished Together with Real Superconducting Rf Accelerator Cavities written by and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Here, we report the results of surface characterizations of niobium (Nb) samples electropolished together with a single cell superconducting radio-frequency accelerator cavity. These witness samples were located in three regions of the cavity, namely at the equator, the iris and the beam-pipe. Auger electron spectroscopy (AES) was utilized to probe the chemical composition of the topmost four atomic layers. Scanning electron microscopy with energy dispersive X-ray for elemental analysis (SEM/EDX) was used to observe the surface topography and chemical composition at the micrometer scale. A few atomic layers of sulfur (S) were found covering the samples non-uniformly. Niobium oxide granules with a sharp geometry were observed on every sample. Some Nb-O granules appeared to also contain sulfur.
Book Synopsis Superconducting Radiofrequency Technology for Accelerators by : Hasan Padamsee
Download or read book Superconducting Radiofrequency Technology for Accelerators written by Hasan Padamsee and published by John Wiley & Sons. This book was released on 2023-05-15 with total page 405 pages. Available in PDF, EPUB and Kindle. Book excerpt: Superconducting Radiofrequency Technology for Accelerators Single source reference enabling readers to understand and master state-of-the-art accelerator technology Superconducting Radiofrequency Technology for Accelerators provides a quick yet thorough overview of the key technologies for current and future accelerators, including those projected to enable breakthrough developments in materials science, nuclear and astrophysics, high energy physics, neutrino research and quantum computing. The work is divided into three sections. The first part provides a review of RF superconductivity basics, the second covers new techniques such as nitrogen doping, nitrogen infusion, oxide-free niobium, new surface treatments, and magnetic flux expulsion, high field Q slope, complemented by discussions of the physics of the improvements stemming from diagnostic techniques and surface analysis as well as from theory. The third part reviews the on-going applications of RF superconductivity in already operational facilities and those under construction such as light sources, proton accelerators, neutron and neutrino sources, ion accelerators, and crab cavity facilities. The third part discusses planned accelerator projects such as the International Linear Collider, the Future Circular Collider, the Chinese Electron Positron Collider, and the Proton Improvement Plan-III facility at Fermilab as well as exciting new developments in quantum computing using superconducting niobium cavities. Written by the leading expert in the field of radiofrequency superconductivity, Superconducting Radiofrequency Technology for Accelerators covers other sample topics such as: Fabrication and processing on Nb-based SRF structures, covering cavity fabrication, preparation, and a decade of progress in the field SRF physics, covering zero DC resistance, the Meissner effect, surface resistance and surface impedance in RF fields, and non-local response of supercurrent N-doping and residual resistance, covering trapped DC flux losses, hydride losses, and tunneling measurements Theories for anti-Q-slope, covering the Xiao theory, the Gurevich theory, non-equilibrium superconductivity, and two fluid model based on weak defects Superconducting Radiofrequency Technology for Accelerators is an essential reference for high energy physicists, power engineers, and electrical engineers who want to understand the latest developments of accelerator technology and be able to harness it to further research interest and practical applications.
Book Synopsis Roughness Analysis of Variously Polished Niobium Surfaces by :
Download or read book Roughness Analysis of Variously Polished Niobium Surfaces written by and published by . This book was released on 2008 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Niobium superconducting radio frequency (SRF) cavities have gained widespread use in accelerator systems. It has been shown that surface roughness is a determining factor in the cavities' effi ciency and maximum accelerating potential achievable through this technology. Irregularities in the surface can lead to spot heating, undesirable local electrical fi eld enhancement and electron multipacting. Surface quality is typically ensured through the use of acid etching in a Buffered Chemical Polish (BCP) bath and electropolishing (EP). In this study, the effects of these techniques on surface morphology have been investigated in depth. The surface of niobium samples polished using different combinations of these techniques has been characterized through atomic force microscopy (AFM) and stylus profi lometry across a range of length scales. The surface morphology was analyzed using spectral techniques to determine roughness and characteristic dimensions. Experimentation has shown that this method is a valuable tool that provides quantitative information about surface roughness at different length scales. It has demonstrated that light BCP pretreatment and lower electrolyte temperature favors a smoother electropolish. These results will allow for the design of a superior polishing process for niobium SRF cavities and therefore increased accelerator operating effi ciency and power.
Book Synopsis Surface Characterization of Niobium for Superconducting RF Cavities by : Cao Chaoyue
Download or read book Surface Characterization of Niobium for Superconducting RF Cavities written by Cao Chaoyue and published by . This book was released on 2014 with total page 210 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis NOVEL CHARACTERIZATION OF THE ELECTROPOLISHING OF NIOBIUM WITH SULFURIC AND HYDROFLUORIC ACID MIXTURES. by :
Download or read book NOVEL CHARACTERIZATION OF THE ELECTROPOLISHING OF NIOBIUM WITH SULFURIC AND HYDROFLUORIC ACID MIXTURES. written by and published by . This book was released on 2008 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Niobium surfaces are commonly electropolished in an effort to obtain optimally smooth surfaces for high-field SRF cavity applications. We report the first use of controlled electrochemical analysis techniques to characterize electropolishing of Nb in a sulfuric and hydrofluoric acid electrolyte. Through the use of a reference electrode we are able to clearly distinguish the anode, cathode polarization potentials as well as the electrolyte voltage drop that sum to the applied power supply voltage. We then separate the temperature and HF concentration dependence of each. We also report the first use of Electrochemical Impedance Spectroscopy (EIS) on this system. EIS results are consistent with a presence of a compact salt film at the Nb/electrolyte interface that is responsible for the limiting current. Microscopic understanding of the basic Nb EP mechanism is expected to provide an appropriate foundation with which to optimize the preparation of high-field niobium cavity surfaces. The implication of EIS for monitoring Nb surface during electropolishing shows this technology could be potentially used as a source of on-line feedback.
Book Synopsis Surface Polishing of Niobium for Superconducting Radio Frequency (SRF) Cavity Applications by :
Download or read book Surface Polishing of Niobium for Superconducting Radio Frequency (SRF) Cavity Applications written by and published by . This book was released on 2014 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Niobium cavities are important components in modern particle accelerators based on superconducting radio frequency (SRF) technology. The interior of SRF cavities are cleaned and polished in order to produce high accelerating field and low power dissipation on the cavity wall. Current polishing methods, buffered chemical polishing (BCP) and electro-polishing (EP), have their advantages and limitations. We seek to improve current methods and explore laser polishing (LP) as a greener alternative of chemical methods. The topography and removal rate of BCP at different conditions (duration, temperature, sample orientation, flow rate) was studied with optical microscopy, scanning electron microscopy (SEM), and electron backscatter diffraction (EBSD). Differential etching on different crystal orientations is the main contributor to fine grain niobium BCP topography, with gas evolution playing a secondary role. The surface of single crystal and bi-crystal niobium is smooth even after heavy BCP. The topography of fine grain niobium depends on total removal. The removal rate increases with temperature and surface acid flow rate within the rage of 0~20 °C, with chemical reaction being the possible dominate rate control mechanism. Surface flow helps to regulate temperature and avoid gas accumulation on the surface. The effect of surface flow rate on niobium EP was studied with optical microscopy, atomic force microscopy (AFM), and power spectral density (PSD) analysis. Within the range of 0~3.7 cm/s, no significant difference was found on the removal rate and the macro roughness. Possible improvement on the micro roughness with increased surface flow rate was observed. The effect of fluence and pulse accumulation on niobium topography during LP was studied with optical microscopy, SEM, AFM, and PSD analysis. Polishing on micro scale was achieved within fluence range of 0.57~0.90 J/cm2, with pulse accumulation adjusted accordingly. Larger area treatment was proved possible by overlapping laser tracks at proper ratio. Comparison of topography and PSD indicates that LP smooths the surface in a way similar to EP. The optimized LP parameters were applied to different types of niobium surfaces representing different stages in cavity fabrication. LP reduces the sharpness on rough surfaces effectively, while doing no harm to smooth surfaces. Secondary ion mass spectrometer (SIMS) analysis showed that LP reduces the oxide layer slightly and no contamination occurred from LP. EBSD showed no significant change on crystal structure after LP.
Book Synopsis Methodology for the Characterization of Surface Treated High Purity Niobium by : Santosh Chetri
Download or read book Methodology for the Characterization of Surface Treated High Purity Niobium written by Santosh Chetri and published by . This book was released on 2023 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: High-purity niobium is the material of choice for making superconducting radio-frequency cavities for the modern particle accelerator. While making the cavities from the Nb sheet, it goes through a series of processes including chemical and thermal treatments. These treatments affect the microstructural as well as magnetic properties of niobium. In order to optimize the efficiency of Nb cavities, various treatments have been explored. During the last decade, surface modification through impurity diffusion has been extensively explored and found that the quality factor of Nb cavities can be enhanced by impurity diffusion to the niobium surface. The surface treatments that are found to enhance the quality factor include high-temperature nitrogen doping, low-temperature nitrogen infusion, and most recently mid-temperature furnace baking. Even though these treatments have been shown to improve cavity performance, the fundamental understanding of the phenomenon is very limited, and each treatment has its own drawbacks. During the operation of Nb cavities, the oscillating electromagnetic field penetrates the Nb surface only to the 40-200 nm depth. Hence, the cavity performance is dependent largely on the condition of this layer. Thus, a detailed understanding of the effect of different treatments on the Nb surface is essential.Cutting a Nb cavity for the characterization of its surface after different treatments is economically not viable and the characterizing tools are also limited for the cut-out samples. Based on the characterization techniques, the requirements for sample shape and size vary, for example, microscopy, x-ray photoelectron spectroscopy, ellipsometry et cetera require flat samples whereas magnetization measurements are best made using cylindrical samples. Hence, using a coupon sample characterization turns out to be a cost-effective way of probing the effect of different processing steps. In this thesis, I have used surface-characterizing tools such as scanning electron microscopy (SEM), x-ray photoelectron spectroscopy (XPS), and magnetization to explore the effect of some of the recent cavity treatments on the microstructure, chemistry, and magnetic properties of high purity Nb surface. The goal is to construct a coupon-based methodology to explore the effect of different processing treatments.
Book Synopsis Surface Roughness Characterization of Niobium Subjected to Incremental BCP and EP Processing Steps by :
Download or read book Surface Roughness Characterization of Niobium Subjected to Incremental BCP and EP Processing Steps written by and published by . This book was released on 2008 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The surface of niobium samples polished under incremental Buffered Chemical Polish (BCP) and Electro-Polishing (EP) have been characterized through Atomic Force Microscopy (AFM) and stylus profilometry across a range of length of scales. The results were analyzed using Power Density Spectral (PSD) technique to determine roughness and characteristic dimensions. This study has shown that the PSD method is a valuable tool that provides quantitative information about surface roughness at different length scales.
Book Synopsis Surface Characterization of Impurities in Superconducting Niobium for Radio Frequency (RF) Cavities Used in Particle Accelerators by : Prateek Maheshwari
Download or read book Surface Characterization of Impurities in Superconducting Niobium for Radio Frequency (RF) Cavities Used in Particle Accelerators written by Prateek Maheshwari and published by . This book was released on 2012 with total page 236 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Surface Polishing of Niobium for Superconducting Radio Frequency (SRF) Cavity Application by : Liang Zhao (Ph. D.)
Download or read book Surface Polishing of Niobium for Superconducting Radio Frequency (SRF) Cavity Application written by Liang Zhao (Ph. D.) and published by . This book was released on 2015 with total page 237 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Nanostructural Features Degrading the Performance of Superconducting Radio Frequency Niobium Cavities Revealed by Transmission Electron Microscopy and Electron Energy Loss Spectroscopy by :
Download or read book Nanostructural Features Degrading the Performance of Superconducting Radio Frequency Niobium Cavities Revealed by Transmission Electron Microscopy and Electron Energy Loss Spectroscopy written by and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Nanoscale defect structure within the magnetic penetration depth of ~100 nm is key to the performance limitations of niobium superconducting radio frequency cavities. Using a unique combination of advanced thermometry during cavity RF measurements, and TEM structural and compositional characterization of the samples extracted from cavity walls, we discover the existence of nanoscale hydrides in electropolished cavities limited by the high field Q slope, and show the decreased hydride formation in the electropolished cavity after 120°C baking. Furthermore, we demonstrate that adding 800°C hydrogen degassing followed by light buffered chemical polishing restores the hydride formation to the pre-120°C bake level. We also show absence of niobium oxides along the grain boundaries and the modifications of the surface oxide upon 120°C bake.
Book Synopsis Study on Electro-Polishing Process by Niobium-Plate Sample With Artificial Pits by :
Download or read book Study on Electro-Polishing Process by Niobium-Plate Sample With Artificial Pits written by and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The Electro-polishing (EP) process is the best candidate of final surface-treatment for the production of ILC cavities. Nevertheless, the development of defects on the inner-surface of the Superconducting RF cavity during EP process has not been studied by experimental method. We made artificial pits on the surface of a Nb-plate sample and observed the development of the pit-shapes after each step of 30um-EP process where 120um was removed by EP in total. This article describes the results of this EP-test of Nb-sample with artificial pits.
Book Synopsis Plasma Treatment of Bulk Niobium Surfaces for SRF Cavities by : L. Phillips
Download or read book Plasma Treatment of Bulk Niobium Surfaces for SRF Cavities written by L. Phillips and published by . This book was released on 2006 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Two types of electric discharges were used to demonstrate the validity of plasma surface treatment for superconducting radio-frequency (SRF) cavities. The experiments were performed on disc-shaped Nb samples and compared with identical samples treated with buffer chemical polishing (BCP) techniques. Surface analysis indicates comparable or superior properties of plasma-treated samples. These promising results are still preliminary and additional work is in progress.
Book Synopsis Modifications of Superconducting Properties of Niobium Caused by Nitrogen Doping Recipes for High Q Cavities by :
Download or read book Modifications of Superconducting Properties of Niobium Caused by Nitrogen Doping Recipes for High Q Cavities written by and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: A study is presented on the superconducting properties of niobium used for the fabrication of the SRF cavities after treating by recently discovered nitrogen doping methods. Cylindrical niobium samples have been subjected to the standard surface treatments applied to the cavities (electro-polishing, l 20°C bake) and compared with samples treated by additional nitrogen doping recipes routinely used to reach ultra-high quality factor values (>3· 1010 at 2 K, 16 MV/m). The DC magnetization curves and the complex magnetic AC susceptibility have been measured. Evidence for the lowered field of first flux penetration after nitrogen doping is found suggesting a correlation with the lowered quench fields. Superconducting critical temperatures Tc = 9.25 K are found to be in agreement with previous measurements, and no strong effect on the critical surface field (Bd) from nitrogen doping was found.
Book Synopsis Buffered Electrochemical Polishing of Niobium by :
Download or read book Buffered Electrochemical Polishing of Niobium written by and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The standard preparation of superconducting radio-frequency (SRF) cavities made of pure niobium include the removal of a 'damaged' surface layer, by buffered chemical polishing (BCP) or electropolishing (EP), after the cavities are formed. The performance of the cavities is characterized by a sharp degradation of the quality factor when the surface magnetic field exceeds about 90 mT, a phenomenon referred to as 'Q-drop'. In cavities made of polycrystalline fine grain (ASTM 5) niobium, the Q-drop can be significantly reduced by a low-temperature (≈ 120 C) 'in-situ' baking of the cavity if the chemical treatment was EP rather than BCP. As part of the effort to understand this phenomenon, we investigated the effect of introducing a polarization potential during buffered chemical polishing, creating a process which is between the standard BCP and EP. While preliminary results on the application of this process to Nb cavities have been previously reported, in this contribution we focus on the characterization of this novel electrochemical process by measuring polarization curves, etching rates, surface finish, electrochemical impedance and the effects of temperature and electrolyte composition. In particular, it is shown that the anodic potential of Nb during BCP reduces the etching rate and improves the surface finish.
