Download or read book Single Crystal Large Grain Niobium Technology written by Ganapati Rao Myneni and published by AIP Conference Proceedings / H. This book was released on 2007-08-30 with total page 222 pages. Available in PDF, EPUB and Kindle. Book excerpt: SRF Technology based accelerators, FEL’s, and ERL’s, are becoming common worldwide. Several new frontier technologies and applications are expected to be evolving in coming years as the cost of SRF technology comes. Terra Hertz (THz) Science could benefit from these advances, and many applications are likely to be developed in the fields of medical imaging, material science, pharmaceuticals, communications etc.

Download or read book Single Crystal large Grain Niobium Technology written by and published by . This book was released on 2007 with total page 202 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Development of Large Grain Single Crystal Niobium Cavity Technology at Jefferson Lab written by Peter Kneisel and published by . This book was released on 2006 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Approximately two years ago we started to develop high performance niobium accelerating cavities based on large grain or single crystal high purity niobium. We have fabricated and tested 15 single cell cavities of various shapes and frequencies between 1300 MHz and 2300 MHz using material from a total of 9 different very large grain niobium ingots from four niobium suppliers. The materials differed not only in grain sizes, but also in RRR? value and in the amount of Ta contained in the material. In one ingot supplied by CBMM the central grain exceeded 7 inches in diameter and this was used to fabricate two 2.2 GHz cavities. A single crystal 1300 MHz mono-cell cavity was also produced at DESY by rolling out a single crystal to the size required for this cavity. It was sent to Jlab for surface treatment and testing. In addition, we have fabricated three 7-cell cavities: two of the Jlab high gradient (HG) shape and one of the ILC Low Loss shape. Two 9-cell TESLA shape cavities are presently in fabrication at Jlab and are close to completion.

Download or read book Single Crystal and Large Grain Niobium Research at Michigan State University written by and published by . This book was released on 2007 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: As Superconducting Radio Frequency (SRF) technology is used in more accelerator designs, research has focused on increasing the efficiency of these accelerators by pushing gradients and investigating cast reduction options. Today, most SRF structures are fabricated from high purity niobium. Over years of research, a material specification has been derived that defines a uniaxial, fine gain structure for SRF cavity fabrication. Most recently a push has been made to investigate the merits of using single or large grain niobium as a possible alternative to fine grain niobium. Michigan State University (MSU), in collaboration with Fermi National Accelerator Laboratory (FNAL) and Thomas Jefferson National Accelerator Facility (JLAB), is researching large grain niobium via cavity fabrication processes end testing, as well as exploring materials science issues associated with recrystallization and heat transfer. Single-cell 1.3 GHz (Beta=0.081) cavities made from both fine end large grain niobium were compared both in terms of fabrication procedures and performance. Two 7-cell cavities are currently being fabricated.

Download or read book RF Superconductivity written by Hasan Padamsee and published by John Wiley & Sons. This book was released on 2009-04-20 with total page 465 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.

Download or read book Reviews of Accelerator Science and Technology written by Alexander W. Chao and published by World Scientific. This book was released on 2013-01-28 with total page 369 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book is dedicated to superconducting technology and its applications, including superconducting magnets (SC magnets) and superconducting radio-frequency (SRF) cavities.

Download or read book Performance of Large Grain and Single Crystal Niobium Cavities written by and published by . This book was released on 2006 with total page 114013 pages. Available in PDF, EPUB and Kindle. Book excerpt: We have fabricated and tested several single and one multi-cell cavity made from large grain niobium of four different ingots. Two cavities at a frequency of ~ 2.2 GHz were made from single crystal sheets. Large grain material was used for four single cell cavities of the HG â and OC shapes, a 7-cell cavity of the HG â shape â all resonating at 1500 MHz â and an ILC_LL single cell cavity at 1300 MHz. We began to explore also different chemical polishing baths such as a 1:1:1 and a 1:1:2 buffered solution and explored the change of cavity performance as a function of material removal. The results from these preliminary investigations are reported in this contribution.

Download or read book Reviews Of Accelerator Science And Technology Volume 5 Applications Of Superconducting Technology To Accelerators written by Alexander Wu Chao and published by World Scientific. This book was released on 2013-01-28 with total page 369 pages. Available in PDF, EPUB and Kindle. Book excerpt: Over the past several decades major advances in accelerators have resulted from breakthroughs in accelerator science and accelerator technology. After the introduction of a new accelerator physics concept or the implementation of a new technology, a leap in accelerator performance followed. A well-known representation of these advances is the Livingston chart, which shows an exponential growth of accelerator performance over the last seven or eight decades. One of the breakthrough accelerator technologies that support this exponential growth is superconducting technology. Recognizing this major technological advance, we dedicate Volume 5 of Reviews of Accelerator Science and Technology (RAST) to superconducting technology and its applications.Two major applications are superconducting magnets (SC magnets) and superconducting radio-frequency (SRF) cavities. SC magnets provide much higher magnetic field than their room-temperature counterparts, thus allowing accelerators to reach higher energies with comparable size as well as much reduced power consumption. SRF technology allows field energy storage for continuous wave applications and energy recovery, in addition to the advantage of tremendous power savings and better particle beam quality. In this volume, we describe both technologies and their applications. We also include discussion of the associated R&D in superconducting materials and the future prospects for these technologies.

Download or read book PROGRESS ON LARGE GRAIN AND SINGLE GRAIN NIOBIUM written by and published by . This book was released on 2008 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Large grain and single crystal niobium has been proposed several years ago as an alternative material to poly-crystalline niobium for superconducting cavities, exhibiting potential advantages such as ¿stream-lined¿ procedures, reduced costs and better reproducibility in performance. Several major laboratories have investigated the use of large grain and single crystal material in the past years and the niobium producing industry has responded in providing ingot material with enlarged grain sizes. Besides a large number of single cell and multi-cell cavities from large grain niobium, several single crystal cavities have been fabricated and tested with good performances. This contribution will review the progress since the SRF workshop in 2005 in material processing and handling and in cavity performances.

Download or read book Preliminary Results from Single Crystal and Very Large Crystal Niobium Cavities written by and published by . This book was released on 2005 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: We have fabricated and tested several single cell cavities using material from very large grain niobium ingots. In one case the central grain exceeded 7 inches in diameter and this was used to fabricate two 2.2 GHz cavities. This activity had a dual purpose: to investigate the influence of grain boundaries on the often observed Q-drop at gradients E[sub acc]> 20 MV/m in the absence of field emission, and to study the possibility of using ingot material for cavity fabrication without going through the expensive rolling process. The sheets for these cavities were cut from the ingot by wire electro-discharge machining (EDM) and subsequently formed into half-cells by deep drawing. The following fabrication steps were standard: machining of weld recesses, electron beam welding of beam pipes onto the half cells and final equator weld to join both half cell/beam pipe subunits. The cavities showed heavy Q-disease caused by the EDM. After hydrogen degassing at 800 C for 3 hrs in UHV and about 200 [micro]m total removals from the inner surface by BCP 1:1:1, the cavities showed promising results, however, the Q-drop was still present. In the two cavities made from large grain material accelerating gradients of 30 MV/m have been reached. After ''in-situ'' baking the Q-drop disappeared. The smaller cavities made from single crystal material showed very low residual resistances and accelerating gradients up to E[sub acc] = 45 MV/m were reached (one of the highest ever achieved), corresponding to a peak surface magnetic fields (B[sub p]) of 160 mT. In one rf test at 2 K, a B[sub p] = 185 mT was reached for few hundred milliseconds, close to the theoretical critical field of this material.

Download or read book Recent Progress in Large Grain written by and published by . This book was released on 2005 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: High RRR bulk niobium Superconducting Radio Frequency (SRF) cavity technology is chosen for the International Linear Collider (ILC). The SRF community was convinced until now that fine grain polycrystalline RRR niobium sheets obtained via forging and cross rolling are essential for forming the SRF Cavities. However, it was recently discovered under a joint Reference Metals Company, Inc., - JLAB CRADA that large grain/single crystal RRR niobium sliced directly from ingots is highly ductile reaching 100 percent elongation. This discovery led to the successful fabrication of several SRF single and/or multi cell structures, formed with sliced RRR discs from the ingots, operating at 2.3, 1.5 and 1.3 GHz. This new exciting development is expected to offer high performance accelerator structures not only at reduced costs but also with simpler fabrication and processing conditions. As a result there is a renewed interest in the evaluation and understanding of the large grain and single crystal niobium with respect to their mechanical & physical properties as well as the oxidation behavior and the influence of impurities such as hydrogen and Ta. In this paper the results of many collaborative studies on large grain and single crystal high RRR niobium between JLAB, Universities and Industry are presented.

Download or read book Investigations of Residual Stresses and Mechanical Properties of Single Crystal Niobium for SRF Cavities written by and published by . This book was released on 2007 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This work investigates properties of large grained, high purity niobium with respect to the forming of superconducting radio frequency (SRF) cavities from such large grained sheets. The yield stresses were examined using tensile specimens that were essentially single crystals in orientations evenly distributed in the standard projection triangle. No distinct yield anisotropy was found, however, vacuum annealing increased the yield strength by a factor 2.3. The deep drawing forming operation of the half cells raises the issues of elastic shape changes after the release of the forming tool (springback) and residual stresses, both of which are indicated to be negligible. This is a consequence of the low yield stress (

Download or read book Superconductivity in Niobium Single Crystals written by Craig Seward Tedmon and published by . This book was released on 1962 with total page 78 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Energy Gap Anisotropy in Superconducting Single Crystal Niobium by Electron Tunneling written by Margaret Love Agnes MacVicar and published by . This book was released on 1967 with total page 320 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Single Crystal Niobium Tubes for Particle Colliders Accelerator Cavities written by and published by . This book was released on 2013 with total page 6 pages. Available in PDF, EPUB and Kindle. Book excerpt: The objective of this research project is to produce single crystal niobium (Nb) tubes for use as particle accelerator cavities for the Fermi laboratory’s International Linear Collider project. Single crystal Nb tubes may have superior performance compared to a polycrystalline tubes because the absence of grain boundaries may permit the use of higher accelerating voltages. In addition, Nb tubes that are subjected to the high temperature, high vacuum crystallization process are very pure and well annealed. Any impurity with a significantly higher vapor pressure than Nb should be decreased by the relatively long exposure at high temperature to the high vacuum environment. After application of the single crystal process, the surfaces of the Nb tubes are bright and shiny, and the tube resembles an electro polished Nb tube. For these reasons, there is interest in single crystal Nb tubes and in a process that will produce single crystal tubes. To convert a polycrystalline niobium tube into a single crystal, the tube is heated to within a few hundred °C of the melting temperature of niobium, which is 2477 °C. RF heating is used to rapidly heat the tube in a narrow zone and after reaching the operating temperature, the hot zone is slowly passed along the length of the tube. For crystallization tests with Nb tubes, the traverse rate was in the range of 1-10 cm per hour. All the crystallization tests in this study were performed in a water-cooled, stainless steel chamber under a vacuum of 5 x10-6 torr or better. In earliest tests of the single crystal growth process, the Nb tubes had an OD of 1.9 cm and a wall thickness of 0.15 mm. With these relatively small Nb tubes, the single crystal process was always successful in producing single crystal tubes. In these early tests, the operating temperature was normally maintained at 2200 °C, and the traverse rate was 5 cm per hour. In the next test series, the Nb tube size was increased to 3.8 cm OD and the wall thickness was increased 0.18 mm and eventually to 0.21 mm. Again, with these larger tubes, single crystal tubes were usually produced by the crystallization process. The power supply was generally operated at full output during these tests, and the traverse rate was 5 cm per hour. In a few tests, the traverse rate was increased to 10 cm per hour, and at the faster traverse rate, single crystal growth was not achieved. In these tests with a faster traverse rate, it was thought that the tube was not heated to a high enough temperature to achieve single crystal growth. In the next series of tests, the tube OD was unchanged at 3.8 cm and the wall thickness was increased to 0.30 mm. The increased wall thickness made it difficult to reach an operating temperature above 2,000 °C, and although the single crystal process caused a large increase in the crystal grains, no single crystal tubes were produced. It was assumed that the operating temperature in these tests was not high enough to achieve single crystal growth. In FY 2012, a larger power supply was purchased and installed. With the new power supply, temperatures above the melting point of Nb were easily obtained regardless of the tube thickness. A series of crystallization tests was initiated to determine if indeed the operating temperature of the previous tests was too low to achieve single crystal growth. For these tests, the Nb tube OD remained at 3.8 cm and the wall thickness was 0.30 mm. The first test had an operating temperature of 2,000 °C. and the operating temperature was increased by 50 °C increments for each successive test. The final test was very near the Nb melting temperature, and indeed, the Nb tube eventually melted in the center of the tube. These tests showed that higher temperatures did yield larger grain sizes if the traverse rate was held constant at 5 cm per hour, but no single crystal tubes were produced even at the highest operating temperature. In addition, slowing the traverse rate to as low as 1 cm per hour...

Download or read book Physical and Mechanical Properties of Niobium for SRF Science and Technology written by Ganapati Rao Myneni and published by . This book was released on 2006 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Optimized mechanical and physical properties of high purity niobium are crucial for obtaining high performance SRF particle beam accelerator structures consistently. This paper summarizes these important material properties for both high purity polycrystalline and single crystal niobium.

Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1991 with total page 268 pages. Available in PDF, EPUB and Kindle. Book excerpt: