Improved Space Charge Modeling of Photoinjectors

Photoinjectors have played a key role in advancing high-energy accelerators, reducing beam energy spreads, and enhancing undulator photon fluxes. However, photoinjector design is difficult and time consuming, due to the substantial differences in time and spatial scales that must be addressed. With the need to simultaneously resolve both electron bunches (with picosecond time scales and sub-millimeter spatial scales) and RF cavities (GHz time scales and spactial scales on the order of tens-of-centimeters), the required computational resources exceed the capabilities of the majority of accelerator design groups. This project will develop a high-accuracy photoinjector design tool capable of simultaneously simulating the electron bunch and the RF cavity. Starting with the well-tested OOPIC code, enhanced algorithms will be incorporated for the high accuracy treatment of space charge. Then, a multi-level, local subgrid capability will be implemented to provide localized high resolution for the electron bunch. Commercial Applications and other Benefits as described by the awardee: Advanced computational tools for the design of photoinjectors should help achieve further increases in the performance of accelerators, benefiting applications in biology, materials science, and defense/security. Other technical applications include the design and simulation of beam-based devices (e.g., microwave tubes, high power klystrons, and IOT's), as well as high precision applications such as electron microscopy, e-beam lithography, and ion milling.