Hostname: page-component-7c8c6479df-p566r Total loading time: 0 Render date: 2024-03-29T04:50:48.228Z Has data issue: false hasContentIssue false

Floating surface potential of spherical dust grains in magnetized plasmas

Published online by Cambridge University Press:  07 January 2016

Dennie Lange*
Affiliation:
Theoretische Physik I, Ruhr-Universität Bochum, Universitätsstr. 150, D-44780 Bochum, Germany
*
Email address for correspondence: dennie.lange@rub.de

Abstract

A particle-in-cell (PIC) simulation study of the charging processes of spherical dust grains in a magnetized plasma environment is presented. Different magnetic field strengths with corresponding electron/ion gyration radii of smaller, the same or larger size than the grain radius and the plasma Debye length are examined. The magnetized plasma is created by overlapping the simulation box with a homogeneous, constant magnetic field. The charging currents are significantly reduced in the presence of a magnetic field, resulting in a more negative grain floating potential. Indeed, the most probable electron gyration radius is always smaller than that of ions in a Maxwellian plasma: however, it is demonstrated that the situation of simultaneous magnetized electron but an unmagnetized ion charging current never exists. The simulation results do not fit with a modified orbital motion limited (OML) theory approach for this situation, since the ion current is significantly reduced due to the increase of the gyration radius in the potential field of the dust grain. For very small gyration radii, the simulation results are in good agreement with a modified OML approach for both magnetized electron and ion charging currents.

Type
Research Article
Copyright
© Cambridge University Press 2016 

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

Birdsall, C.K. & Langdon, A. B. 1991 Plasma Physics via Computer Simulation. Adam Hilger.Google Scholar
Chang, J.-S. & Spariosu, K. 1993 Dust particle charging characteristics under a collisionless magneto-plasma. J. Phys. Soc. Japan 62, 97104.Google Scholar
Fortov, V. E., Ivlev, A. V., Khrapak, S. A., Khrapak, A. G. & Morfill, G. E. 2005 Complex (dusty) plasmas: Current status, open issues, perspectives. Phys. Rep. 421, 1103.Google Scholar
Fortov, V. E., Nefedov, A. P., Molotkov, V. I., Poustylnik, M. Y. & Torchinsky, V. M. 2001 Dependence of the dust-particle charge on its size in a glow-discharge plasma. Phys. Rev. Lett. 87 (20), 205002.CrossRefGoogle Scholar
Kennedy, R. V. & Allen, J. E. 2003 The floating potential of spherical probes and dust grains. II: Orbital motion theory. J. Plasma Phys. 69, 485506.Google Scholar
Kersten, H., Thieme, G., Froehlich, M., Bojic, D., Tung, D. H., Quaas, M., Wulff, H., Hippler & Rainer 2005 Complex (dusty) plasmas: Examples for applications and observation of magnetron-induced phenomena. Pure Appl. Chem. 77 (2), 415.CrossRefGoogle Scholar
Lampe, M. 2001 Limits of validity for orbital-motion-limited theory for a small floating collector. J. Plasma Phys. 65, 171180.Google Scholar
Mott-Smith, H. M. & Langmuir, I. 1926 The theory of collectors in gaseous discharges. Phys. Rev. 28, 727763.Google Scholar
Patacchini, L., Hutchinson, I. H. & Lapenta, G. 2007 Electron collection by a negatively charged sphere in a collisionless magnetoplasma. Phys. Plasmas 14 (6), 062111.Google Scholar
Shukla, P. K. & Mamun, A. A. 2002 Introduction to Dusty Plasma Physics, Series in Plasma Physics. Institute of Physics Publishing, c2002.Google Scholar
Thomas, H., Morfill, G. E., Demmel, V., Goree, J., Feuerbacher, B. & Möhlmann, D. 1994 Plasma crystal: Coulomb crystallization in a dusty plasma. Phys. Rev. Lett. 73, 652655.Google Scholar
Thomas, H. M., Morfill, G. E., Hagl, T., Ivlev, A., Konopka, U., Rothermel, H., Zuzic, M., Nefedov, A. P., Fortov, V. E., Molotkov, V. I. et al. 2001 Dusty plasmas experiments on the space station and related theory/simulations – overview. In Space Plasma Simulation (ed. Büchner, J., Dum, C. T. & Scholer, M.), p. 181.Google Scholar
Tsytovich, V. N., Sato, N. & Morfill, G. E. 2003 Note on the charging and spinning of dust particles in complex plasmas in a strong magnetic field. New J. Phys. 5, 43.Google Scholar
Walch, B., Horányi, M. & Robertson, S. 1995 Charging of dust grains in plasma with energetic electrons. Phys. Rev. Lett. 75, 838841.Google Scholar