Particle Motion Algorithm for Arbitrary Gyro-Frequencies
Abstract
The transport of particles in a Particle-In-Cell (PIC) method is traditionally handled by a staggered algorithm, second-order accurate in time, originally developed by Boris [1-2]. The scheme is very efficient and although it is stable for time steps large compared to the cyclotron period ("gyro-period"), it ceases to be accurate in that case. In cases of strong applied magnetic field, this can impose an impractical time-step restriction. An alternative approach is to average over the orbital motion and consider only that of the guiding-center; this has led to so-called gyrokinetic simulations [3]. However, that approach can also lead to some inaccuracies, due to the loss of information regarding the phase of the orbital motion. Furthermore, it may also be desirable to have an algorithm that is not staggered in time, in order to guarantee exact conservation of total energy at all times. In this paper, we present an algorithm that solves the non-relativistic equation of motion exactly, and can yield exact conservation of energy for large time steps (compared to gyroperid). The algorithm accuracy is demonstrated and compared with the Boris scheme. These preliminary results are valid for the homogenous case only, and extension to spatially-varying fields should be considered next.
Document Details
- Document Type
- Technical Report
- Publication Date
- Sep 01, 2007
- Accession Number
- ADA474425
Entities
People
- Jean Luc Cambier
- Oleg Batishchev
Organizations
- Air Force Research Laboratory