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Author :
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ISBN 13 :
Total Pages : 3 pages
Book Rating : 4.:/5 (759 download)
Download or read book An Improved Surface Treatment for Superconducting Niobium Cavities written by and published by . This book was released on 1994 with total page 3 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book High Gradient Superconducting Niobium Cavities written by and published by . This book was released on 1998 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Superconducting niobium cavities used in particle accelerators are limited in their rf performance by two phenomena: quench field levels below the theoretical limit of the material caused by defects, and field emission loading resulting from artificial contamination of the superconducting surfaces during surface treatment and assembly procedures. In recent years, the community involved in SRF technology developments has successfully improved cavity performances by applying advanced surface treatment methods such as chemical polishing, electropolishing, tumbling, high temperature heat treatment, high pressure rinsing, ''in situ'' high peak power processing, and clean room assembly procedures. In addition, improvements in the material properties such as thermal conductivity by ''solid state'' gettering'' and very strict QA methods, both in material inspection and during cavity fabrication, have resulted in cavity performance levels of E{sub acc} up to 40 MV/m in monocells and gradients in the vicinity of 30 MV/m in multicell structures at Q-values of (almost equal to) 101° at a temperature of 2K. More recently the fabrication of ''seamless'' cavities by spinning is being pursued with encouraging results. This process eliminates electron beam welds, which sometimes are the causes of performance degradations.
Author : Christine Petit-jean-genaz
Publisher : World Scientific
ISBN 13 : 9814550272
Total Pages : 2968 pages
Book Rating : 4.8/5 (145 download)
Download or read book European Particle Accelerator Conference (Epac 94) (In 3 Volumes) written by Christine Petit-jean-genaz and published by World Scientific. This book was released on 1994-11-26 with total page 2968 pages. Available in PDF, EPUB and Kindle. Book excerpt: These proceedings aim to provide a comprehensive overview of research, technology and applications in the field of accelerators. Contributions from the entire field of accelerators are presented, including low and high energy machines, and medical and industrial accelerators.
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ISBN 13 :
Total Pages : 3 pages
Book Rating : 4.:/5 (727 download)
Download or read book Improvement and Protection of Niobium Surface Superconductivity by Atomic Layer Deposition and Heat Treatment written by and published by . This book was released on 2008 with total page 3 pages. Available in PDF, EPUB and Kindle. Book excerpt: A method to treat the surface of Nb is described, which potentially can improve the performance of superconducting rf cavities. We present tunneling and x-ray photoemission spectroscopy measurements at the surface of cavity-grade niobium samples coated with a 3 nm alumina overlayer deposited by atomic layer deposition. The coated samples baked in ultrahigh vacuum at low temperature degraded superconducting surface. However, at temperatures above 450 C, the tunneling conductance curves show significant improvements in the superconducting density of states compared with untreated surfaces.
Author : Hasan Padamsee
Publisher : John Wiley & Sons
ISBN 13 : 3527627189
Total Pages : 464 pages
Book Rating : 4.5/5 (276 download)
Download or read book RF Superconductivity written by Hasan Padamsee and published by John Wiley & Sons. This book was released on 2009-03-30 with total page 464 pages. Available in PDF, EPUB and Kindle. Book excerpt: This is the second book to RF Superconducting, written by one of the leading experts. The book provides fast and up-to-date access to the latest advances in the key technology for future accelerators. Experts as well as newcomers to the field will benefit from the discussion of progress in the basic science, technology as well as recent and forthcoming applications. Researchers in accelerator physics will also find much that is relevant to their discipline.
Author : Tyagi Puneet Veer
Publisher : LAP Lambert Academic Publishing
ISBN 13 : 9783659818165
Total Pages : 124 pages
Book Rating : 4.8/5 (181 download)
Download or read book Spectroscopic Studies of Surface Treatments for Nb SRF Cavities written by Tyagi Puneet Veer and published by LAP Lambert Academic Publishing. This book was released on 2015-12-31 with total page 124 pages. Available in PDF, EPUB and Kindle. Book excerpt: The superconducting radio frequency (SRF) cavities are being used worldwide in particle accelerators to achieve a high energy beam of charged particles. These cavities are made of high purity niobium (Nb) material and work at 2 K temperature. The inner surface of these cavities plays the most important role in order to obtain good performances in terms of the high field gradient. Therefore, the surface treatments associated with SRF cavities are the key issues toward the achievement of the high field gradient larger than 35 MV/m during vertical test of the nine-cell cavity for International Linear Collider (ILC). In the recent years, extensive research has been done to enhance the cavity performance by applying improved surface treatments such as mechanical grinding, buffered chemical polishing (BCP), electropolishing (EP), electrochemical buffing (ECB), mechanochemical polishing (MCP), tumbling, etc., followed by various post-treatment methods such as ultrasonic pure water rinse, alcoholic rinse, high pressure water rinse (HPR), hydrogen per oxide rinse and baking etc. to obtain smooth and contaminant free surface.
Author : David R. Smith
Publisher :
ISBN 13 :
Total Pages : 94 pages
Book Rating : 4.:/5 (572 download)
Download or read book Surface Studies of Acid-treated Niobium for Superconducting Radio Frequency Cavities written by David R. Smith and published by . This book was released on 2004 with total page 94 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Plasma Treatment of Bulk Niobium Surface for SRF Cavities written by and published by . This book was released on 2006 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Pulsed electric discharges were used to demonstrate the validity of plasma surface treatment of superconducting radio-frequency cavities. The experiments were performed on disc-shaped Nb samples and compared with identical samples treated with buffer chemical polishing techniques. The results of several standard surface analytical techniques indicate that plasma-treated samples have comparable or superior properties regarding the surface roughness and composition.
Author : Kristian Fossheim
Publisher : World Scientific
ISBN 13 : 9789810206284
Total Pages : 258 pages
Book Rating : 4.2/5 (62 download)
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.
Author : Liang Zhao (Ph. D.)
Publisher :
ISBN 13 :
Total Pages : 237 pages
Book Rating : 4.:/5 (971 download)
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:
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ISBN 13 :
Total Pages : 4 pages
Book Rating : 4.:/5 (16 download)
Download or read book Decrease of the Surface Resistance in Superconducting Niobium Resonator Cavities by the Microwave Field written by and published by . This book was released on 2014 with total page 4 pages. Available in PDF, EPUB and Kindle. Book excerpt: Measurements of the quality factor, Q, of Nb superconducting microwave resonators often show that Q increases by ≃ 10%-30% with increasing radio-frequency (rf) field, H, up to ≈ 15-20 mT. Recent high temperature heat treatments can amplify this rf field-induced increase of Q up to ≃ 50%-100% and extend it to much higher fields, but the mechanisms of the enhancement of Q(H) remain unclear. Here, we suggest a method to reveal these mechanisms by measuring temperature dependencies of Q at different rf field amplitudes. We show that the increase of Q(H) does not come from a field dependent quasi-particles activation energy or residual resistance, but rather results from the smearing of the density of state by the rf field.
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.
Author : Gianluigi Ciovati
Publisher :
ISBN 13 :
Total Pages : 398 pages
Book Rating : 4.:/5 (76 download)
Download or read book Investigation of the Superconducting Properties of Niobium Radio-frequency Cavities written by Gianluigi Ciovati and published by . This book was released on 2005 with total page 398 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Effect of Low Temperature Baking on the RF Properties of Niobium Superconducting Cavities for Particle Accelerators written by and published by . This book was released on 2004 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Radio-frequency superconducting (SRF) cavities are widely used to accelerate a charged particle beam in particle accelerators. The performance of SRF cavities made of bulk niobium has significantly improved over the last ten years and is approaching the theoretical limit for niobium. Nevertheless, RF tests of niobium cavities are still showing some ''anomalous'' losses that require a better understanding in order to reliably obtain better performance. These losses are characterized by a marked dependence of the surface resistance on the surface electromagnetic field and can be detected by measuring the quality factor of the resonator as a function of the peak surface field. A low temperature (100 C-150 C) ''in situ'' bake under ultra-high vacuum has been successfully applied as final preparation of niobium RF cavities by several laboratories over the last few years. The benefits reported consist mainly of an improvement of the cavity quality factor at low field and a recovery from ''anomalous'' losses (so-called ''Q-drop'') without field emission at higher field. A series of experiments with a CEBAF single-cell cavity have been carried out at Jefferson Lab to carefully investigate the effect of baking at progressively higher temperatures for a fixed time on all the relevant material parameters. Measurements of the cavity quality factor in the temperature range 1.37 K-280 K and resonant frequency shift between 6 K-9.3 K provide information about the surface resistance, energy gap, penetration depth and mean free path. The experimental data have been analyzed with the complete BCS theory of superconductivity. The hydrogen content of small niobium samples inserted in the cavity during its surface preparation was analyzed with Nuclear Reaction Analysis (NRA). The single-cell cavity has been tested at three different temperatures before and after baking to gain some insight on thermal conductivity and Kapitza resistance and the data are compared with different models. This paper describes the results of these experiments and comments on existing models to explain the effect of baking on the performance of niobium RF cavities.
Author : Gianluigi Ciovati
Publisher : LAP Lambert Academic Publishing
ISBN 13 : 9783843387439
Total Pages : 244 pages
Book Rating : 4.3/5 (874 download)
Download or read book Superconducting Properties of Niobium Radio-frequency Cavities written by Gianluigi Ciovati and published by LAP Lambert Academic Publishing. This book was released on 2012 with total page 244 pages. Available in PDF, EPUB and Kindle. Book excerpt: Superconducting radio-frequency (SRF) cavities are used to increase the energy of a charged particle beam in particle accelerators throughout the world. Bulk niobium is the material of choice to fabricate SRF cavities and their performance at cryogenic temperatures is characterized by a non-linearity of the surface resistance as a function of the RF field, in absence of field emission, which limits the operational accelerating gradient. This book presents the results on the investigation of such non-linearity in cavities which received different surface and bulk treatments as well as cavities made of single-crystal niobium. The experimental methods include measurements of the surface impedance as a function of temperature, of the quality factor as a function of the RF field below 4.2 K, and the excitation of different resonant modes. A thermometry system was used to better characterize the loss mechanisms. This book consists of the author's PhD dissertation at Old Dominion University (ODU) under the supervision of Prof. Colm T. Whelan of ODU and Dr. Peter Kneisel of Jefferson Lab. This book should be useful to students or young researchers in the field of SRF for accelerators.
Download or read book Development of Seamless Niobium Cavities for Accelerator Applications written by and published by . This book was released on 1999 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Superconducting niobium cavities for application in particle accelerators are usually fabricated by standard techniques such as forming of subcomponents by deep drawing and joining by electron beam welding. Even though these techniques are being used successfully in many larger-scale accelerator projects and improvements in accelerating gradients have been achieved over the last several years, there are often still problems with making defect-free electron beam welds. In addition, the manufacturing costs for such devices are significant and a drastic reduction in production costs is a necessary condition for future very large scale applications in, e.g., linear colliders. Seamless cavities made by spinning from a single sheet of material will dramatically reduce the fabrication costs and eliminate any problems associated with electron beam welding. The fabrication technique for seamless niobium cavities has been developed over the last few years at INFN LNL and several proto type single-cells of different material thickness and purity have been manufactured as well as a 5-cell cavity. Results from tests on these cavities after application of surface treatment techniques, such as buffered chemical polishing, ''barrel polishing'' and high temperature heat treatments, are discussed in this contribution. Q-values as high as 1011 and accelerating gradients up to E{_}acc (approximately) 30 MV/m have been measured.
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ISBN 13 :
Total Pages : 912 pages
Book Rating : 4.0/5 ( download)
Download or read book Nuclear Science Abstracts written by and published by . This book was released on 1976-04 with total page 912 pages. Available in PDF, EPUB and Kindle. Book excerpt:
