CDS&E:Noise Reduction Methods for Particle Simulations of Intense Beams in Cyclotrons

New York University, New York NY

Investigators

Abstract

A growing number of technologies rely on the production of energetic beams of charged particles in accelerators for their operation. Proton therapy for cancer treatment and food irradiation to eliminate pathogens are among the most remarkable applications. These successes are paving the way for new applications for particle accelerators, such as materials science experiments and nuclear waste transmutation, which would require much more intense beams than are currently available. A difficulty is that at such high beam intensities, beam induced damages on the accelerator structures cannot be tolerated. Achieving a high beam quality throughout the acceleration process thus becomes a critical issue. The dynamics of beams in accelerators is described by equations which can only be accurately solved with long and expensive simulations run on supercomputers. Accelerator design studies therefore involve time consuming, computer intensive simulations, limiting the range of design options which can be investigated. This project addresses this limitation by developing a numerical method that will significantly reduce the run times of existing numerical codes while maintaining a high level of accuracy. By accelerating beam dynamics simulations in accelerators, the new solver will help improve design optimization for the next generation of high intensity accelerators. The purpose of this project is to develop new methods to predict the dynamics of high intensity beams in cyclotrons. The beam dynamics is described by the Vlasov equation, a six-dimensional nonlinear partial differential equation, and quantitative results can only be obtained through numerical simulation. Particle codes based on the Particle-In-Cell (PIC) algorithm have been successfully used for this purpose. Still, a limitation of these codes is that a large number of particles need to be followed to limit statistical error, which leads to long run times. To reduce run times, the PI and graduate students will develop a novel noise reduction technique for the standard PIC algorithm, based on the use of sparse grids. In order to maximize the leverage from this new technique, they will implement high performance algorithms in their sparse-PIC solver, and optimize the sparse grids using model reduction techniques tailored for cyclotron simulations. At every stage of the development of the solver, they will compare the performance of the new code with the state-of-the-art code OPAL. The code will be available to collaborators at major cyclotron facilities to answer unresolved questions regarding the stability of high intensity beams in cyclotrons and to design new machines. 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.