| Research Abstract |
We have studied the electrodynamics associated with space plasmas by performing computer experiments. Because of the restriction of memory and computational speed of computer, one or two-dimensional model has been conventionally used in computer experiments. However, to trace the time evolution of three-dimensional spatial variation of phenomena such as beam-plasma and vehicle-plasma interaction, a simulation code which can handle three-dimensional spatial variation is inevitable. As the first step to this research, therefore, we have developed a three dimensional electromagnetic particle code by applying the numerical method used in the two-dimensional code called KEMPO. Performing test simulations with thermal plasma, it is shown that the coding has been correctly done. We also introduced open boundary condition at the boundary surfaces surrounding the model region, which enables outgoing waves not to reflect at the boundary surfaces. The function of this boundary was also checked by
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performing test simulation with a wave radiator located at the center of the simulation region. It is successfully shown that the field reflection ratio is less than 5%. In the computer experiments, we focus on the situations in which three-dimensional effect is essentially dominant, such as beam propagation and vehicle-plasma interaction. To obtain and understand the basic physics associated with the electromagnetic environment in the vicinity of space vehicles such as satellite, tethered satellite system, and reentry vehicle, we have performed two-dimensional computer experiments. By analyzing the numerical data obtained in the computer experments, we studied the electrodynamic interaction of space vehicle with its surrounding plasma, such as enhancement of electromagnetic field, plasma heating, current-voltage characteristics, plasma distribution,and its dynamics. These results obtained by the two-dimensional computer experiments are definitely significant in carrying out the three-dimensional experiments. Less
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