Simulating the Injection of Magnetized Plasma without Electromagnetic Precursor Wave

摘要

Injecting magnetized plasma with changes in magnetization or injection ratenecessitate a time variable magnetic field at the boundary of the simulationbox. Naive implementation will lead to electromagnetic precursor waves that canaffect the simulation results. The problem is well-known and is described e.g.in Lemebege and Dawson 1987. Since then few papers have attempted to deal withthis problem and no standard solution exists. In this research note we suggest that the ad-hoc pulse shape that was used inthe paper by Lemebege and Dawson 1987 can be replaces by a standard digital lowpass filter. The cut off frequency of this filter should coincide with the gyrofrequency in the magnetized plasma, to make use of (Doppler-broadend) resonantabsorption caused by gyrating electrons. We illustrate this idea with a codeexample and demonstrate the efficency of this method throug sample simulationswith our electromagnetic particle-in-cell code.