Finite time step and spatial grid effects in δf simulation of warm plasmas

JOURNAL OF COMPUTATIONAL PHYSICS

卷:305

Article

Sturdevant, Benjamin J.^1,2  Parker, Scott E.¹ 

[1] Univ Colorado, Dept Phys, Boulder, CO 80309 USA

[2] Univ Colorado, Dept Appl Math, Boulder, CO 80309 USA

关键词: delta f method;    Plasma simulation;    Particle-in-cell;    Numerical dispersion;    Numerical stability;    Time integration;    Implicit methods;   

DOI  :  10.1016/j.jcp.2015.10.055

来源: Elsevier

【 摘 要 】

This paper introduces a technique for analyzing time integration methods used with the particle weight equations in delta f method particle-in-cell (PIC) schemes. The analysis applies to the simulation of warm, uniform, periodic or infinite plasmas in the linear regime and considers the collective behavior similar to the analysis performed by Langdon for full-f PIC schemes [1,2]. We perform both a time integration analysis and spatial grid analysis for a kinetic ion, adiabatic electron model of ion acoustic waves. An implicit time integration scheme is studied in detail for delta f simulations using our weight equation analysis and for full-f simulations using the method of Langdon. It is found that the delta f method exhibits a CFL-like stability condition for low temperature ions, which is independent of the parameter characterizing the implicitness of the scheme. The accuracy of the real frequency and damping rate due to the discrete time and spatial schemes is also derived using a perturbative method. The theoretical analysis of numerical error presented here may be useful for the verification of simulations and for providing intuition for the design of new implicit time integration schemes for the delta f method, as well as understanding differences between delta f and full-f approaches to plasma simulation. (C) 2015 Elsevier Inc. All rights reserved.

【 授权许可】

Free