An Injector Test Facility for the LCLS

Abstract

EXECUTIVE SUMMARYSurvey advanced gun concepts and their potential impact on LCLS performance. The short time horizon (5 years) for prototyping then producing the first upgrade gun for LCLS necessarily means efforts must be directed at the most mature, compatible technology: rf guns. Longer term, different gun working frequencies, the inclusion of 3 rd harmonic field shaping, and long guns ("integrated photoinjectors") should be tested. In the next decade, technologies such as plasma-based or DC pseudospark sources will mature sufficiently that their value can be assessed, and pursued if warranted.List the requirements that the test facility must satisfy to fulfill its goals. The test facility must provide beam acceleration, manipulation, and measurement capabilities for demonstrating fully equilibrated electron beams-that is, to demonstrate beam properties under circumstances identical to those required of the LCLS injector. The facility must also provide world-leading facilities for material science, with analytical tools specifically honed for photoemission studies, and a dedicated laser R&D laboratory not constrained by the requirement to support a running accelerator.Describe a facility that can meet these requirements. A 150 MeV test injector, with cleanroom facilities for laser and cathode development, is required to provide the foundation for a test facility capable of addressing these goals. Significantly enhanced material science laboratories at SLAC SMS will be needed to provide expanded analytical capabilities for cathode development. Collaboration with LBNL, UCLA, and ANL will provide access to world-class talent and facilities and result in coordination and synergy of source development efforts directed at the LCLS, ERLs, and Sparc.List potential sites for the facility, including an evaluation of pros/cons. Nine SLAC sites were considered. Two stood out based on the availability and quality of existing infrastructure. The committee recommends End Station B as the best location for the ITF, given the very extensive infrastructure and potential for growth. The Klystron Test Lab ranks a close second, requiring more extensive alteration to accommodate the ITF, but offering close coupling to the unique skills and facilities of the Klystron Department. The SLD pit and End Station A rank third and fourth, with each offering open space and some infrastructure, but significantly less hospitable conditions than ESB or KTL.Describe relevant facilities and programs at other labs. There is just one dedicated injector lab-Sparc at INFN/Rome-that is matched in accelerator capabilities to the ITF requirements. Numerous other gun test facilities exist which can test some aspects of the gun, but none is dedicated to short-pulse gun optimization and accelerates to high enough energy to provide a direct demonstration of the full injector performance. The ERL injector effort at LBNL shares many goals with LCLS, and collaborating on cathodes, simulations, instruments, and rf design techniques provides great synergy. The ...