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Ann. Geophys., 25, 755-767, 2007
www.ann-geophys.net/25/755/2007/
© European Geosciences Union 2007
Simulation study of solar wind push on a charged wire: basis of solar wind electric sail propulsion
P. Janhunen1,2 and A. Sandroos2
1University of Helsinki, Department of Physical Sciences, Finland
2Finnish Meteorological Institute, Space Research, Finland
Abstract. One possibility for propellantless propulsion in space is to use the
momentum flux of the solar wind. A way to set up a solar wind sail is
to have a set of thin long wires which are kept at high positive
potential by an onboard electron gun so that the wires repel and
deflect incident solar wind protons. The efficiency of this so-called
electric sail depends on how large force a given solar wind exerts on
a wire segment and how large electron current the wire segment draws
from the solar wind plasma when kept at a given potential. We use 1-D
and 2-D electrostatic plasma simulations to calculate the force and
present a semitheoretical formula which captures the simulation
results. We find that under average solar wind conditions at 1 AU the
force per unit length is (5±1×10−8 N/m for 15 kV
potential and that the electron current is accurately given by the
well-known orbital motion limited (OML) theory cylindrical Langmuir
probe formula. Although the force may appear small, an analysis shows
that because of the very low weight of a thin wire per unit length,
quite high final speeds (over 50 km/s) could be achieved by an electric
sailing spacecraft using today's flight-proved components. It is
possible that artificial electron heating of the plasma in the
interaction region could increase the propulsive effect even further.
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