Dynamic Friction in Magnetized Electron Coolers for Relativistic Beams

Proposed electron-ion collider (EIC) designs require hadron beam cooling at collision energies. One choice is magnetized electron cooling with high-charge relativistic electron bunches. Dynamic friction is the key physics underlying electron cooling. Present design efforts are based on parametric and approximate models for magnetized dynamic friction, which were developed for low-energy cooling systems and do not properly include the finite time effects at relativistic energies. Higher-fidelity simulations of magnetized friction are required to reduce risk and cost. We are developing a browser-based GUI for electron cooling and IBS simulations in hadron rings, building on the JSPEC code and our cloud-computing framework. We will support multiple dynamic friction and IBS models, including our new friction algorithm, which will include finite time effects, space charge forces and non-ideal magnetic fields. The enhanced JSPEC will be benchmarked with other community codes and with experimental data and will be used to assist in EIC design studies. We developed a new semi-analytic approach to calculating magnetized dynamic friction, applicable to high-energy EIC parameter regimes, which can be extended in the future to capture additional physical effects. This enables rapid calculation of dynamic friction for arbitrary electron beam distributions, and we have shown that the functional form is suitable for parametric approximations. We improved the treatment of impact ionization in the open source particle-in-cell code Warp, demonstrating that a uniform neutralizing background of ions is difficult to generate in a magnetized electron cooling system. We will complete the development, implementation, testing and benchmarking of our new semi-analytic calculation of magnetized dynamic friction. We will develop parameterized approximations. We will implement the full algorithm and the fast approximations in the JSPEC code. We will repeat the above process, including both space charge forces and non-ideal magnetic fields, which can reduce the friction force and, hence, increase the cooling time. We will continue to develop the browser-based GUI for JSPEC, with improved connectivity to tracking codes and improved physics models. The new Warp capabilities will be supported, as needed by the nuclear physics community. We will automate the containerization and archiving of EIC design simulations, for archival and for scientific reproducibility. Commercial Applications and Other Benefits: The proposed work will help to improve performance and reduce technical risk for the proposed electron ion collider. Our commercialization strategy is to develop a subscription-based website for the publication of computational scientific results, enabling other scientists to immediately reproduce and easily extend previous work.