Investigation of plasma density disturbances caused by spacecraft-plasma interactions at 4 Rs

The proposed Small Solar Probe mission features a close approach to the sun with a perihelion of 4 R_S. Carbon molecules emitted from the spacecraft\u27s heat shield will become ionized by electron impact and photoionization. The newly created ions and electrons may generate electromagnetic and electrostatic plasma waves which are possible sources of interference with in-situ plasma measurements. To understand this possible interference, we have performed computer simulations to model the plasma particle distributions caused by the pick-up process of C^+_2 ions and related electrons as the spacecraft flies across the external solar coronal magnetic field. In order to study the wave-particle interactions, which includes inhomogeneities (of the C^+_2 plasma) and kinetic effects, we use the electromagnetic particle code called Kyoto University Electromagnetic Particle Code (KEMPO). We find that there are no substantial density disturbances such as neither shock nor instabilities. The electric field disturbance in the vicinity of the spacecraft is also small enough to detect the solar wind plasma