Parametric study of electron flat-top distribution formation

Electron flat-top distributions have been observed in various regions in space, such as Earth's bow shock, Earth's magnetotail, and solar wind. It has been suggested that wave-particle interactions are the responsible mechanism for the formation of the electron flat-top distributions. In the present study we report the formation of electron flat-top distributions by ion beam driven instabilities using 1D PIC simulations. Simulation results show that in the early phase of the development electrostatic solitary waves are quasi-periodically formed, and later they are fully dissipated resulting in heated, flat-top distributions. Occasionally new electron beam components are also formed. We parametrically investigate the development of electron phase space distributions for various drift speeds of ion beams and temperature ratios between ions and electrons. These results will be compared with the observations of the flat-top distributions in space. Also, we will discuss the physical implication of the formation of the flat-top distributions for the equilibrium of a plasma system.