Development of an SRF Crab Crossing Cavity for an Electron Ion Collider

The highest priority in the Nuclear Physics program is, at present, the Facility for Rare Isotope Beams. In the longer term it is likely that a high priority will be an Electron Ion Collider, and several concepts are under development. In order to achieve the high luminosities that would be required to make such a machine attractive, some kind of bunch crabbing system will be required. For example, the Electron Ion Collider under study at Jefferson Lab would require a crabbing voltage between 20 and 50 MV at either 499 or 1497 MHz. RF crabbing systems are important components in linear colliders where the beams meet at an angle. A crabbing system rotates the bunches at the collision point so they meet head-on, instead of crossing at an angle, thus restoring and increasing the luminosity. The requirements for a crabbing system for an Electron Ion Collider, as envisaged at Jefferson Lab, are quite stringent, exceeding what has been accomplished so far. A crabbing system could, in principle, be built using room temperature cavities. However, in order to produce the needed voltage a large number of cavities and their associated rf power system would be required. An attractive alternative solution would be based on a superconducting cavity of a new design that has been introduced recently. This new design, if optimized for this application, could provide the required deflecting voltage in a footprint that would be compatible with the design of the interaction regions. Commercial Applications and Other Benefits: This STTR research would continue ODU, JLab, and Niowaves collaboration by developing multi-spoke structures for future facilities. Phase I would develop the accelerating structure and cryomodule design and its requirements based on systems efficiency, beam dynamics simulations, and higher order mode (HOM) analysis. Phase II would finalize the cryomodule design and prototype critical aspects of the system such as the SRF cavities, power coupler, HOM spectrum and frequency tuners. Phase III would be funded by an R & amp;D program to complete the full module and test in realistic accelerator conditions. At this point, the system would be marketed internationally to existing and planned facilities.