Formation of trapped-ion population in the process of charging of an absorbing sphere in a collisionless plasma
1 Space Research Institute, Russian Academy of Sciences - Profsoyuznaya 84/32, Moscow 117997, Russia
2 Moscow Institute of Physics and Technology - 9 Institutskiy per., Dolgoprudny, Moscow Region, 141700, Russia
Received: 29 April 2015
Accepted: 8 July 2015
Dynamics of charging of an absorbing spherical body is studied by means of a numerical simulation. Upon saturation of the charge of the body and relaxation of transient oscillatory phenomena accompanying the charging, the disturbed plasma passes into a stable steady state. Along with the determination of space-time dependences of electrostatic quantities, the numerical experiment allows to observe the time evolution of electron and ion distributions in phase space. A dense cloud of trapped ions is formed near the spherical body, provided that the ion Debye length is of the order of the radius of the body, and the electron Debye length exceeds appreciably the radius. The trapped ions contribute substantially to the screening of the charged sphere, thereby affecting the structure of the disturbed plasma in the asymptotic steady state at long times.
PACS: 52.25.Dg – Plasma kinetic equations / 52.20.Dq – Particle orbits / 52.65.Rr – Particle-in-cell method
© EPLA, 2015