Continuation of Three-Dimensional Numerical Experiments on High-Intensity Particle and Laser Beam-Matter Interactions

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This project will use computer modeling to investigate and understand a possible new technology for developing compact particle accelerators. Particle accelerators are some of the most complex and expensive tools used for scientific discovery. They are used to discover the most fundamental particles in nature, to understand fundamental processes in biology, to probe and develop materials, and to treat cancer. A plasma, or ionized gas, is sometimes called the fourth state of matter. When a short pulse of very bright light or a short pulse of a high current of electrons are sent through a plasma a wake is created. The crests and troughs in this wake move near the speed of light. Charged particles such as electrons and positrons can then surf this wake, and if they surf for a long time their energy keeps increasing. In a plasma wake it takes a shorter distance to achieve high energies than in existing accelerators. Complex computer models using the nation's most advanced supercomputers can model what would happen in a laboratory experiment. This helps to determine if it makes sense to build a large and expensive experimental facility to further study this new technology. This research also leads to new discoveries and better understanding of fundamental processes that occur in plasmas. This can generate new concepts for new technologies and applications. A particle-in-cell (PIC) method will be used to simulate how intense and short-pulse particle beams interact with a plasma. The PIC method follows the individual trajectories of individual electrons and ions in the plasma as they interact through their self-consistently generated electric and magnetic fields and any externally applied fields. The project will study how the intense laser and particle beam creates a nonlinear plasma wave wakefield as well as how it self-modulates from the wakefield. The project will also explore how charged particle beams are injected into the plasma wave and how the six-dimensional phase space of the beam evolves as it is accelerated. These highly accurate simulations provide a testbed for theoretical ideas and new concepts, as well as a method for guiding ongoing and near term experiments. High-fidelity full-scale modeling also provides a means to extrapolate parameters into regimes that will not be accessible to experiments for years to come. The PIC software will continue to be developed so that it can continue to effectively utilize the largest and fastest computers in the world.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.