Obstacles in a plasma flow may act as sources or sinks for the plasma itself. A comet works in this way in the streaming solar wind (Interaction of the solar wind and comets). The outgased molecules from the comet are ionized by the solar UV photons and then integrated in the solar wind. Thus the solar wind flow is mass loaded. This mass loading is accompanied by momentum and energy loading. The microscopic integration process of the newborn particles is called pickup and it depends on the orientation of the interplanetary magnetic field and on the density of the injected particles.
https://www.tu-braunschweig.de/index.php?eID=dumpFile&t=f&f=31556&token=3317cceb8251379abc8f9139de84617ffa21621c
Pickup simulation (mpg, 730kB)
The animation got by a hybrid code simulationdemonstrates the pickup of ions injected at rest at x=100 into the plasma flow with perpendicular background magnetic field. The phase space trajectories of the pickup ions are cycloids. After few periods, however, their phase coherence decreases rather quickly.
References
Szegö, K., K. H. Glassmeier, R. Bingham, A. Bogdanov, C. Fischer, G. Haerendel, A. Brinca, T. Cravens, E. Dubinin, K. Sauer, L. Fisk, T. Gombosi, N. Schwadron, P. Isenberg, M. Lee, C. Mazelle, E. Möbius, U. Motschmann, V. Shapiro, B. Tsurutani, G. Zank, Physics of mass loaded plasmas, Space Science Rev., 94, 429-671, 2000.
Motschmann, U., Mass loading in submagnetosonic and supermagnetosonic flows: a hybrid simulation study, Proc. Sixth Int. School/Symposium Space Plasma Simulations (ISSS-6), München, 2001.