### Abstract

The radialmotion of isolated filamentary structures inmagnetized plasmas strongly
depends on both the level of collisional dissipation and the parallel dynamics. In
weakly ionized plasmas, such as the ionosphere and basic laboratory experiments,
the motion of localized plasma blobs or depletions is influenced by the collisional
friction with the neutral gas fluid.
In magnetically confined plasmas, the motion of filamentary structures in the edge
region can be influenced by parallel dynamics in a manner that resembles an effective
friction. In the presence of strong ballooning, such a frictional response
may take place in both the electrostatic and the electromagnetic regimes.
Results are presented from two-dimensional numerical simulations of an isolated
blob structure in a non-uniform magnetic field [1,2]. The effect of a linear damping
term in the vorticity equation, which describes an effective friction, is investigated.
In the inertial regime the radial filament velocity scales as the square root
of its size. In the limit of strong friction regime the velocity scales as the inverse
of the structure size.
A discussion of these results will be given in the context of irregularities in the
equatorial ionosphere, field-aligned structures in simply magnetized torus configurations,
and filamentary structures in magnetically confined plasmas.

Original language | English |
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Publication date | 2008 |

Publication status | Published - 2008 |

Event | 13. EU-US TTF workshop 2008 and 1. EFDA Transport Topical Group meeting - Copenhagen (DK), 1-4 Sep Duration: 1 Jan 2008 → … |

### Conference

Conference | 13. EU-US TTF workshop 2008 and 1. EFDA Transport Topical Group meeting |
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City | Copenhagen (DK), 1-4 Sep |

Period | 01/01/2008 → … |

## Cite this

Garcia, O. E., Madsen, J., Naulin, V., Nielsen, A. H., & Juul Rasmussen, J. (2008).

*Effect of friction on the motion of plasma filaments*. Paper presented at 13. EU-US TTF workshop 2008 and 1. EFDA Transport Topical Group meeting, Copenhagen (DK), 1-4 Sep, .