Particle-In-Cell Codes for Plasma-based Particle Acceleration

Abstract

In this report we discuss the basic principles of Particle-In-Cell (PIC) codes and their application to plasma-based acceleration. The ab initio full electromagnetic relativistic PIC codes provide the most reliable description of plasmas, and their properties are described in detail. However, while they represent the most fundamental model, full PIC codes are  computationally expensive. Plasma-based acceleration is a multi-scale problem with very disparate scales. The smallest scale is the laser or plasma wavelength (on the order of one to a hundred microns), and the largest scale is the acceleration distance (which ranges from a few centimetres to metres or even kilometres). The Lorentz boost technique allows the scale disparity to be reduced, at the cost of complicating the simulations and causing unphysical numerical instabilities in the code. Another possibility is to use the quasi-static  approximation, whereby the different scales are separated analytically.