An Inexpensive High Brightness Photoinjector using Solid Freeform Fabrication (SFF)

Development of very high duty cycle, high gradient photoinjectors is critical for the next generation of accelerator systems, such as X-ray free-electron lasers (FELs), inverse Compton scattering (ICS) sources, energy recovery linear accelerators (ERLs), injectors for linear colliders, as well as variety of industrial systems for homeland security applications. A key issue for high average power, normal conducting, and photoinjectors is efficient structure cooling. The fabrication of current state of the art high average power photoinjectors relies on conventional design and fabrication techniques, requiring a multitude of braze joints, and limited cooling channel geometries. An, inexpensive, high brightness photoinjector will be developed utilizing a novel fabrication technique allowing for enhanced thermal handling capability. Optimization of solid freeform fabrication (SFF) for copper RF components will be followed by the construction and testing of a prototype photoinjector with enhanced thermal handling features possible only through the use of SFF. In the SBIR Phase I we have demonstrated the feasibility of manufacturing pure copper parts using solid freeform fabrication. As well investigating the resultant material properties, and develop a conceptual design of a gun with optimized shaped conformal cooling channels based on thermal simulations. These steps position us to fabricate and test a high rep. rate prototype gun in Phase II, and eventually offer a high-power high-brightness photoinjector as a product in Phase III. In Phase II of the project, we will complete the engineering of the SFF high rep. rate gun, and build and test the prototype at LLNL. Commercial Applications and Other Benefits: The applications of very high duty cycle, high gradient photoinjectors include x-ray free-electron lasers (FELs), energy recovery linear accelerators (ERLs), and inverse Compton scattering (ICS) sources for medicine, as well associated imaging/analysis applications of interest to homeland security. The technical approach developed in this project may also be applied to a wide variety of rf structures, such as linacs and klystrons.