Advanced Strained-Superlattice Photocathodes for Polarized Electron Sources

65702 A continuous wave cryogenic photocathode electron gun operating in the L-band is the preferred approach for a wide variety of next generation and advanced electron accelerators and light sources. The high average current required for these applications results in average power densities that are much higher than in previous electron guns due to the continuous wave operation. In addition, these advanced applications require improvements in cathode lifetime to meet operational availability goals. This project will address both of these issues by developing a cryogenically cooled continuous wave gun that will utilize the high heat transfer characteristics of two-phase, forced flow cooling in a subcooled cryogen. In Phase I, a three-dimensional thermal and structural finite element analysis, backed up with radio frequency analysis and beam dynamics, will be used to determine the heat flux required to be absorbed by the cryogen. The high-power of this electron gun will be removed using subcooled two-phase cryogenic flow. A complete preliminary design of the electron gun with its cooling passages and associated coolant distribution system, and the required inlet thermodynamic properties of the cryogen will be developed. Commercial Applications And Other Benefits as described by awardee: Continuous wave electron guns should provide the high-brightness, high average current requirements necessary for the Photo Injected Energy Recovery Linac (PERL) and other applications requiring high power electron beams, e.g., electron cooling of ions, an electron ion collider, and a PERL based light source.