Download or read book Optimization of the SRF Cavity Design for the Cebaf 12 GeV Upgrade written by and published by . This book was released on 2008 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Based on initial testing of the "HG" and "LL" 7-cell cavities in the prototype cryomodule Renascence, several opportunities for improved optimization were identified. The HOM damping configuration was refined so as to meet the requirements for damping key dipole modes while simultaneously dramatically reducing risk of HOM pickup probe heating and also creating beamline clearance for mounting the tuner to stainless steel helium vessel endplates (rather than NbTi/Ti transitions to a titanium helium vessel). Code modeling and bench measurements were performed. The new design maintains the 7-cell LL cells and incorporates a brazed transition between Nb and the SS helium vessel. The resulting configuration is now called the "C100" design. Cavity design details as well as vertical dewar and horizontal test bed performance are presented.
Download or read book SRF CAVITY PERFORMANCE OVERVIEW FOR THE 12 GeV UPGRADE written by and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The CEBAF accelerator, a recirculating CW electron accelerator that is currently operating at Jefferson Laboratory, is in the process of having 10 new cryomodules installed to allow for the maximum beam energy to be increased from 6 GeV to 12 GeV. This upgrade required the fabrication, processing and RF qualification of 80, seven cell elliptical SRF cavities, a process that was completed in February 2012. The RF performance achieve in the vertical testing dewars has exceeded the design specification by ≈25% and is a testament to the cavity design and processing cycle that has been implemented. This paper will provide a summary of the cavity RF performance in the vertical tests, as well as review the overall cavity processing cycle and duration for the project.
Download or read book Preparation and Testing of the SRF Cavities for the CEBAF 12 GeV Upgrade written by and published by . This book was released on 2011 with total page 7 pages. Available in PDF, EPUB and Kindle. Book excerpt: Eighty new 7-cell, low-loss cell-shaped cavities are required for the CEBAF 12 GeV Upgrade project. In addition to ten pre-production units fabricated at JLab, the full set of commercially-produced cavities have been delivered. An efficient processing routine, which includes a controlled 30 micron electropolish, has been established to transform these cavities into qualified 8-cavity strings. This work began in 2010 and will run through the end of 2011. The realized cavity performance consistently exceeds project requirements and also the maximum useful gradient in CEBAF: 25 MV/m. We will describe the cavity processing and preparation protocols and summarize test results obtained to date.
Download or read book Production and Testing Experience with the SRF Cavities for the CEBAF 12 GeV Upgrade written by and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The CEBAF recirculating CW electron linear accelerator at Jefferson Lab is presently undergoing a major upgrade to 12 GeV. This project includes the fabrication, preparation, and testing of 80 new 7-cell SRF cavities, followed by their incorporation into ten new cryomodules for subsequent testing and installation. In order to maximize the cavity Q over the full operable dynamic range in CEBAF (as high as 25 MV/m), the decision was taken to apply a streamlined preparation process that includes a final light temperature-controlled electropolish of the rf surface over the vendor-provided bulk BCP etch. Cavity processing work began at JLab in September 2010 and will continue through December 2011. The excellent performance results are exceeding project requirements and indicate a fabrication and preparation process that is stable and well controlled. The cavity production and performance experience to date will be summarized and lessons learned reported to the community.
Download or read book Testing of the New Tuner Design for the CEBAF 12 GeV Upgrade SRF Cavities written by and published by . This book was released on 2005 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The new tuner design for the 12 GeV Upgrade SRF cavities consists of a coarse mechanical tuner and a fine piezoelectric tuner. The mechanism provides a 30:1 mechanical advantage, is pre-loaded at room temperature and tunes the cavities in tension only. All of the components are located in the insulating vacuum space and attached to the helium vessel, including the motor, harmonic drive and piezoelectric actuators. The requirements and detailed design are presented. Measurements of range and resolution of the coarse tuner are presented and discussed.
Download or read book Fabrication and Testing of the SRF Cavities for the CEBAF 12 GeV Upgrade Prototype Cryomodule Renascence written by and published by . This book was released on 2005 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Twelve seven-cell niobium cavities for the CEBAF 12 GeV upgrade prototype cryomodule Renascence have been fabricated at JLab and tested individually. This set includes four of the ''Low Loss'' (LL) design and eight of the ''High Gradient'' (HG) design. The fabrication strategy was an efficient mix of batch job-shop component machining and in-house EBW, chemistry, and final-step machining to meet mechanical tolerances. Process highlights will be presented. The cavities have been tested at 2.07 K, the intended CEBAF operating temperature. Performance exceeded the tentative design requirement of 19.2 MV/m CW with less than 29 W dynamic heat dissipation. These results, as well as the HOM damping performance are presented.
Download or read book Cryostat Design written by J.G. Weisend II and published by Springer. This book was released on 2016-08-12 with total page 293 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book enables the reader to learn the fundamental and applied aspects of practical cryostat design by examining previous design choices and resulting cryostat performance. Through a series of extended case studies the book presents an overview of existing cryostat design covering a wide range of cryostat types and applications, including the magnet cryostats that comprise the majority of the Large Hadron Collider at CERN, space-borne cryostats containing sensors operating below 1 K, and large cryogenic liquid storage vessels. It starts with an introductory section on the principles of cryostat design including practical data and equations. This section is followed by a series of case studies on existing cryostats, describing the specific requirements of the cryostat, the challenges involved and the design choices made along with the resulting performance of the cryostat. The cryostat examples used in the studies are chosen to cover a broad range of cryostat applications and the authors of each case are leading experts in the field, most of whom participated in the design of the cryostats being described. The concluding chapter offers an overview of lessons learned and summarises some key hints and tips for practical cryostat design. The book will help the reader to expand their knowledge of many disciplines required for good cryostat design, including the cryogenic properties of materials, heat transfer and thermal insulation, instrumentation, safety, structures and seals.
Download or read book Cebaf SRF Performance During Initial 12 GeV Commissioning written by and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The Continuous Electron Beam Accelerator Facility (CEBAF) energy upgrade from 6 GeV to 12 GeV includes the installation of eleven new 100 MV cryomodules (88 cavities). The superconducting RF cavities are designed to operate CW at an accelerating gradient of 19.3 MV/m with a QL of 3×107. Not all the cavities were operated at the minimum gradient of 19.3 MV/m with the beam. Though the initial 12 GeV milestones were achieved during the initial commissioning of CEBAF, there are still some issues to be addressed for long term reliable operation of these modules. This paper reports the operational experiences during the initial commissioning and the path forward to improve the performance of C100 (100 MV) modules.
Download or read book Overview of CEBAF Operations and SRF related Activities at Jefferson Lab written by and published by . This book was released on 1999 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The Jefferson Lab nuclear physics accelerator, CEBAF, continues to reliably deliver polarized CW electron beams with energy in the range of 1--5.5 GeV. The 330 installed 1,500 MHz SRF cavity systems perform solidly, contributing a small fraction of the machine downtime. The 5-pass energy capability has been pushed to near 6 GeV by application of in situ helium processing to almost all of the cavities. New operational tools have been developed and deployed which allow the operators to quickly reconfigure the linacs for optimal performance under various energy and beamloading conditions. Plans are being developed for upgrading CEBAF to 12 GeV. This requires a new cryomodule design and use of 5.5 recirculations for the top energy. Subsystem development is underway on a 7-cell cavity, new zero-backlash tuner, improved magnetic shielding, and an arc-free waveguide rf feed, as well as a new cryomodule mechanical system. Significant facility changes have been made in preparation for this work. A new rf control system will also be required. In addition to the successful nuclear physics program, the JLab FEL produced a world-record 1.7 kW CW in the infrared. An upgrade program is ready to begin. Significant efforts have also been directed in support of APT and RIA, as well as collaborations related to cavity fabrication and processing techniques.
Download or read book HOM Survey of the First CEBAF Upgrade Style Cavity Pair written by and published by . This book was released on 2009 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The planned upgrade of the Continuous Electron Beam Accelerator Facility (CEBAF) at the Thomas Jefferson National Accelerator Laboratory (JLab) requires ten new superconducting rf (SRF) cavity cryomodules to double the beam energy to the envisaged 12 GeV. Adequate cavity Higher Order Mode (HOM) suppression is essential to avoid multipass, multibunch beam break-up (BBU) instabilities of the recirculating beam. We report on detailed HOM surveys performed for the first two upgrade style cavities tested in a dedicated cavity pair cryomodule at 2K. The safety margin to the BBU threshold budget at 12 GeV has been assessed.
Download or read book Frequency Tuning of the CEBAF Upgrade Cavities written by and published by . This book was released on 1999 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Long-term plans for CEBAF at Jefferson Lab calls for achieving 12 GeV in the middle of the next decade and 24 GeV after 2010. In support of these plans, an Upgrade Cryomodule capable of providing more than twice the voltage of the existing ones is under development. One requirement is to operate the superconducting cavities, which are 40% longer than existing ones, at 2.5 times the original design gradient with the same amount of rf power. This puts stringent requirements on the accuracy of the frequency tuner: range of 400 kHz and resolution of 1 Hz. A new tuner design to meet these requirements is under development. This system avoids problem areas of previous designs by holding to the principles of not placing moving parts in the vacuum and/or low temperature space, and of having all drive components readily accessible for maintenance and replacement without cryomodule warm-up.
Download or read book Exploiting New Electrochemical Understanding of Niobium Electropolishing for Improved Performance of SRF Cavities for CEBAF written by and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Recent incorporation of analytic electrochemistry into the development of protocols for electropolishing niobium SRF cavities has yielded new insights for optimizing this process for consistent, high-performance results. Use of reference electrodes in the electrolyte, electrochemical impedance spectroscopy (EIS), rotating disk electrodes (RDE), and controlled sample temperatures has greatly clarified the process dynamics over the empirical understanding developed via years of practice. Minimizing RF losses at high operational gradients is very valuable for CW linacs. Jefferson Lab is applying these new insights to the low-loss 7-cell cavity design developed for the CEBAF 12 GeV Upgrade. Together with controlled cleaning and assembly techniques to guard against field-emission-causing particulates, the resulting process is yielding consistent cavity performance that exceeds project requirements. Cavity tests show BCS-limited Q well above 30 MV/m. Detailed process data, interpretation, and resulting rf performance data will be presented.
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.
Download or read book STANDARDIZATION OF CEBAF 12 GEV UPGRADE CAVITY TESTING written by and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: CEBAF 12GeV upgrade project includes 80 new 7-cell cavities to form 10 cryomodules. Each cavity underwent RF qualification at 2.07K using a high power accelerating gradient test and an HOM survey in Jefferson Lab's Vertical Testing Area (VTA) before cavity string assembly. In order to ensure consistently high quality data, updated cavity testing procedures and analysis were implemented and used by a group of VTA operators. For high power tests, a cavity testing procedure was developed and used in conjunction with a LabVIEW program to collect the test data. Additionally while the cavity was at 2.07K, an HOM survey was performed using a network analyzer and a combination of Excel and Mathematica programs. Data analysis was standardized and an online logbook, Pansophy, was used for data storage and mining. The Pansophy system allowed test results to be easily summarized and searchable across all cavity tests. In this presentation, the CEBAF 12GeV upgrade cavity testing procedure, method for data analysis, and results reporting results will be discussed.
Download or read book High Current SRF Cavity Design for SPL and ERHIC written by and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: A high current five-cell Nb superconducting cavity, called BNL3 cavity, was optimized and designed for the SPL and eRHIC. For the fundamental mode, the optimization process aimed at maximizing the R/Q of the fundamental mode and the geometry factor G under an acceptable RF field ratio level of B{sub peak}/E{sub acc} and E{sub peak}/E{sub acc}. For higher order modes, the optimization is to lower (R/Q)Q{sub ext} for dipole and quadrupole modes to suppress the beam-break-up (BBU). To extract the HOM power out of the cavity, the BNL3 cavity employs a larger beam pipe, allowing the propagation of HOMs, but not the fundamental mode. Six HOM couplers (three at each end) are used to extract large HOM power. To avoid the cross-talk between cavities, tapers are employed between the cavities. This paper presents the design of the BNL3 cavity, end groups and BBU simulation results.
Download or read book Applied Superconductivity written by Paul Seidel and published by John Wiley & Sons. This book was released on 2015-01-29 with total page 1334 pages. Available in PDF, EPUB and Kindle. Book excerpt: This wide-ranging presentation of applied superconductivity, from fundamentals and materials right up to the details of many applications, is an essential reference for physicists and engineers in academic research as well as in industry. Readers looking for a comprehensive overview on basic effects related to superconductivity and superconducting materials will expand their knowledge and understanding of both low and high Tc superconductors with respect to their application. Technology, preparation and characterization are covered for bulk, single crystals, thins fi lms as well as electronic devices, wires and tapes. The main benefit of this work lies in its broad coverage of significant applications in magnets, power engineering, electronics, sensors and quantum metrology. The reader will find information on superconducting magnets for diverse applications like particle physics, fusion research, medicine, and biomagnetism as well as materials processing. SQUIDs and their usage in medicine or geophysics are thoroughly covered, as are superconducting radiation and particle detectors, aspects on superconductor digital electronics, leading readers to quantum computing and new devices.
