Issue |
A&A
Volume 438, Number 1, July IV 2005
|
|
---|---|---|
Page(s) | 1 - 9 | |
Section | Astrophysical processes | |
DOI | https://doi.org/10.1051/0004-6361:20042327 | |
Published online | 06 July 2005 |
Further experiments on collisional tribocharging of cosmic grains
Institut für Geophysik und extraterrestrische Physik, Technische Universität Braunschweig, Mendelssohnstraße 3, 38106 Braunschweig, Germany e-mail: t.poppe@tu-bs.de
Received:
8
November
2004
Accepted:
8
March
2005
We experimentally investigated
tribocharging in bouncing dust grain collisions
under conditions
which are relevant for the early solar nebula.
We used silica, diamond, graphite,
and silicon carbide grains and
cm-sized targets of aluminum, iron, and graphite.
We varied particle size around 1 , collision velocity
between 38 to 106
,
and target temperature between 240 K and 360 K.
Generally, the grains acquire
something in the order of hundreds or thousands of negative elementary charges,
which is at the upper end of the range previously
discussed in astrophysical research.
Mainly, a temperature difference caused by the dissipation of collisional energy
or by initial temperatures determines
the amount of charge transfer.
It suggests a thermally diffusive charge transfer process
of negative charge carriers.
Nevertheless, also other processes
of secondary importance were effective.
Material-dependent contact charging is ruled out as the dominant charge
transfer process in our experiments.
For most particle-target combinations,
the charge transfer can be described
by an empirical function of collision energy
which we propose for future astrophysical applications, especially for applications on the sticking efficiency
in the preplanetary dust aggregation process, on the particle motion in the solar nebula,
and on the possibility of nebular lightning.
Key words: solar system: formation / methods: laboratory / dust, extinction
© ESO, 2005
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