# Advanced Modeling for Particle Accelerators

**Key Challenges**: Work in this area consists of both application development and production computing. Because of the complexity, precision, and beam intensity requirements of next generation accelerators, application development includes changing from single machine, single-component simulations to end-to-end, multi-physics simulations. There are efforts devoted to assessment of wakefields on beam dynamics and multiphysics, multi-bunch modeling of injectors, boosters, and debunchers for performance optimization. These applications include large-scale electromagnetic modeling of superconducting radio-frequency devices with realistic shapes and misalignments cavities. Production runs include design optimization of accelerator components with complicated geometries such as the LHC crab cavity and beam-beam and electron-cloud simulations to help understand and optimize LHC machine performance. Applications must include the interaction of beam dynamics with electromagnetics effects. Other challenges include development of advanced accelerator concepts and providing real-time or near-real-time feedback between simulation and advanced accelerator experiments.

**Why it matters**: Particle accelerators are invaluable tools for making fundamental scientific discoveries and DOE has clearly identified them as critical facilities for advancing research. Development and optimization of accelerators is essential for advancing our understanding of the fundamental properties of matter, energy, space, and time. This includes full support of the Large Hadron Collider (LHC) at CERN and the establishment of leadership in the R&D effort to design and build the proposed International Linear Collider (ILC) on U.S. soil.

**Accomplishments**: In the area of beam dynamics, activity focused on electron cloud applications for Project-X; multi-bunch, multi-physics (beam-beam and impedance) simulations for the Tevatron; design studies of the Fermilab debuncher extraction scheme for Mu2e; and space-charge simulations of the Fermilab Main Injector for Project-X era beam parameters. In the area of electromagnetics, activity focused on design optimization studies for the LARP crab cavity program, including optimization of the 800-MHz SLAC design for the LHC upgrade. This optimization achieved the elimination of coupling between fundamental power modes to the LOM/SOM couples. The design was incorporated into the FNAL cryostat system design.

At NERSC simulations commonly use 2,000 cores and can use as many as 32,000 effectively. In three to five years it is expected that the range will be 10,000 - 100,000 cores per simulation.

**Principal Investigator**: Panagiotis Spentzouris (Fermilab National Laboratory)

**More Information**: See, for example, *Phys. Rev. ST Accel. Beams* **13**, 024401 (2010) and the COMPASS web site.