Molecular dynamics simulations of wake structures behind a microparticle in a magnetized ion flow. I. Collisionless limit with cold ion beam

Abstract

Molecular dynamics simulations of wake structures behind a microparticle in a magnetized ion flow. II. Effects of velocity spread and ion collisions

Numerical simulations of a dust grain in a flowing magnetized plasma

“…In the recent works, we have demonstrated that the kinetic effects are important in magnetized plasma flows, where the novel process of a dynamic shadow of ions can lead to a topological change in the wake potential in strongly magnetized supersonic plasma flows. [38][39][40] Strong magnetization of plasma influences the charging and can result in a chain of ion depletions in the wake, a process that is not captured by the LR calculations. 39 In the present work, we investigate in detail the wake formation in a magnetized, collisionless plasma for a range of magnetic fields and flow velocities.…”

Experiments on wake structures behind a microparticle in a magnetized plasma flow

“…This vertical alignment remains unchanged at weak magnetic inductions B 0.6 T. Simulations 36 show that for low magnetizations, there is no significant difference from the unmagnetized case, which has been broadly studied in previous investigations 7,9,16,50 and hence is well known: The particle arrangement with respect to the flow is stable against changes in the interparticle distance (a decrease in the particle distance can be induced by an increase in the rf power or by means of plasma inherent etching processes in combination with particles of different materials 9 ). The particle distance is mainly given by the undisturbed equilibrium position of the single particles in the plasma sheath.…”

“…Note that the ratio of the particle radius and the electron gyro radius a/r ge just becomes unity at about 0.6 T, i.e., the electron fluxes on the particle become anisotropic and particle charging is still affected by an increasing magnetic field. 36 The levitation height in our experiment corresponds to the position, where v i % v B is reached, as it has been determined in Sec. II C. Hence, it is reasonable to compare our results with simulations for streaming ions at M ¼ 1.…”

“…For details on the code and its results, see Refs. 16, 36, and 37. In the collisionless limit 36 [ Fig. 10(a)], ion accumulation in the focus region immediately behind the particle is found.…”

“…25, 073703-1 damping of the wake potential. Self-consistent particle-incell (PIC) simulations 34,35 and molecular dynamics (MD) simulations 36,37 have shown the appearance of ion shadows (regions of ion depletion) and the vanishing of the attractive interaction forces at strong magnetic fields.…”