Self-consistent calculation of ion-drag force in a gas discharge plasma

Summary form only given. The ion-drag force acting on a negatively charged dust particle in a positive ion flux was calculated self-consistently. The particle size, range of gas pressure, strength of electrical field in calculations referred to the experimental conditions of a radio frequency gas discharge bulk plasma. The Monte-Carlo simulation technique was employed to follow the ion trajectories in an electrical field which was found solving the Poisson equation. As a result we have calculated the 3D ion and electrical field distributions around the negatively charged dust particle and forces acting on the particle in ion flux. We observed a new regime in which the ion drag force is negative. Essential is that the ion collisions with the gas atoms and ion-ion interaction are taken into account. A phase diagram was constructed indicating the sign of the ion drag force, depending on the gas pressure and the strength of external electrical field.