Modeling Tools and Techniques for Dielectric Laser Accelerators

Dielectric laser-driven accelerators have great potential for future high-energy colliders due to their ability to sustain high field gradients with low loss, using as sources near-infrared lasers which are powerful, efficient, and commercially available. Several designs exist which have been shown through simulation to meet several requirements of an accelerator, including an accelerating gradi- ent an order of magnitude greater than existing technology and high optical-to-beam efficiency; a method of stable transverse particle beam focusing has also been developed. Understanding of the beam-driven fields and their effects as well as nonlinearities are essential both for near-term proof- of-principle experiments, and for scaling the design from short accelerator segments to longer acceleration distances as needed for high-energy colliders and other applications. We propose to address these issues through high-performance simulation. We will use advanced features of the time-domain particle-in-cell code VORPAL to compute short-range wakefields and to simulate higher-order modes for computation of long-range wakefields. To assess the effects of these fields on beam quality, we will make improvements to an existing particle tracking code developed for simulation of beam dynamics in optical structures. We will validate our simulations against experimental data by computing the far-field patterns of beam-induced fields, comparing directly against experimental data expected to be taken at SLAC during the period of this project. In addition, we will implement models of the nonlinear material response to assess its effect on accelerating gradient and beam quality. Commercial applications and other benefits: The techniques described in this proposal will have commercial application in the large field of photonics research and development, both in academia and private industry. The addition of non- linear optical response to VORPAL will allow customers to model a wider variety of photonic de- vices. In addition, the modeling of the interaction of particle beams with complex electromagnetic structures will have application in the area of metamaterial-based RF devices. Optical accelerator structures such as the one developed in this project hold promise not only for high-energy colliders, but also as x-ray light sources and medical accelerators