Jefferson Lab is preparing to upgrade its 6 GeV Continuous Electron Beam Accelerator Facility (CEBAF) to 12 GeV. The doubled energy will significantly extend research reach of the three existing experimental Halls A, B and C, and the upgrade will add scientific capability, with a newly constructed hall, Hall D. Areas of special initial interest are reactions at high xBjorken, GPD's and exotic hybrid mesons. The present linacs will have their acceleration roughly doubled through the addition of 10 new cryomodules which will perform at {approx}5 times the original specification for CEBAF. The cryogenics plant will be roughly doubled and new rf systems will be installed for the new cryomodules. The beam transport system will strongly leverage existing hardware but must be enhanced with new power supplies, one new recirculation arc, and a beamline to the new Hall D.A brief description of the scope for the various accelerator subsystems will be given as well as the status of the project as a whole.
This Conceptual Design Report (CDR) presents the compelling scientific case for upgrading the Continuous Electron Beam Accelerator Facility (CEBAF) at Jefferson Lab to 12 GeV. Such a facility will make profound contributions to the study of hadronic matter.
The Thomas Jefferson National Accelerator Facility, Jefferson Lab, is planning an upgrade of the CEBAF accelerator from a maximum energy of 6 GeV to 12 GeV and from 3 to 4 experimental halls. This paper will discuss the plans for upgrading the energy of the machine which requires improvements of the existing Super Conducting Radio Frequency (SRF) cryomodules and the additions of ten newly designed high performance SRF cryomodules.
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.
Jefferson Lab is planning a major upgrade of CEBAF accelerator from 6 to 12 GeV. The injection energy needs to be increased accordingly from 67 MeV to 123 MeV. While the present 100 keV electron gun and beam formation up to 5 MeV would remain unchanged, the accelerating SRF modules in the current injector cannot provide the desired energy increase. Two options for attaining the energy increase have been considered: (1) replacing the present injector SRF modules with new, higher gradient modules, or (2) re-circulating the electron beam through the existing cryomodules to achieve the necessary energy gain in two passes. In this paper we present computer simulation studies for these two options of the injector upgrade and list their advantages and disadvantages.
In recent years, the technology of cryogenic comminution has been widely applied in the field of chemical engineering, food making, medicine production, and particularly in recycling of waste materials. Because of the increasing pollution of waste tires and the shortage of raw rubber resource, the recycling process for waste rubber products has become important and commercially viable. This technology has shown a great number of advantages such as causing no environmental pollution, requiring low energy consumption and producing high quality products. Hence, the normal crusher which was used to reclaim materials, such as waste tires, nylon, plastic and many polymer materials at atmospheric 12 temperature is being replaced by a cryogenic crusher. • In the cryogenic crusher, the property of the milled material is usually very sensitive to temperature change. When a crusher is in operation, it will generate a great deal of heat that causes the material temperature increased. Once the temperature increases over the vitrification temperature, the material property will change and lose the brittle behavior causing the energy consumption to rise sharply. Consequently, the comminution process cannot be continued. Therefore, it is believed that the cryogenic crusher is the most critical component in the cryogenic comminution system. The research on the temperature increase and energy consumption in the cryogenic crusher is not only to reduce the energy consumption of the crasher, but also to reduce the energy consumption of the cryogenic system.
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.
Long-term plans for CEBAF at Jefferson Lab call for achieving 12 GeV in the middle of the next decade and 24 GeV after 2010. Such energies can be achieved within the existing footprint by fully populating the accelerator with cryomodules capable of providing 3 to 4 times as much voltage as the design value of the existing ones within the same length. In particular, this requires the development of superconducting cavities capable of operating at gradients above 12 MV/m and Q close to 101°.
