Advanced 3D Photocathode Modeling and Simulations

76058-High brightness electron beams required by the proposed Next Linear Collider demand strong advances in photocathode electron gun performance. However, significant improvement in the production of such beams with radio frequency (rf) photocathode electron guns is hampered by the lack of high-fidelity simulations. The critical missing piece in existing gun codes is a detailed treatment of the very complex and highly nonlinear photoemission process. This project will implement advanced models for photocathode electron emission in a three-dimensional particle-in-cell (PIC) code to enable more realistic electron gun simulations. The simulation will include thermal effects, field-emission effects, direct response to spatial-temporal variations in the intensity of the drive laser pulse, and small regions of low quantum efficiency. Phase I will implement a recently developed photoemission model, including thermal and field-emission effects, into a three-dimensional particle-in-cell code. The implementation will be validated by comparison with published experimental data. More complex models, such as the detailed treatment of electron and lattice temperatures, will be studied numerically as well. Commercial Applications and Other Benefits as described by the awardee: The simulation code for advanced photocathode modeling should become an integral design tool for the development of high quality electron sources needed by the Next Linear Collider and many other applications.