An application of the dust grain charging model to determination of
secondary electron spectra |
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Authors: | I Richterová J Pavlu Z Něme?ek J ?afránková |
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Institution: | (1) Charles University, Faculty of Mathematics and Physics, V Holešovičkách 2, 180 00 Prague, Czech Republic |
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Abstract: | Dust grains – objects of different shapes with a size distribution from micro to nanometers – are generally considered as
a part of many space as well as laboratory plasmas. Among various dust charging processes, electron-induced secondary emission
plays an important role in plasmas containing a noteworthy portion of high-energy electrons. Since a part of secondary electrons
has not the energy high enough to overcome the surface potential barrier, the resulting
grain charge is determined not only by the secondary emission yield (related to the grain material and size) but also by the
secondary electron spectrum. We have developed a model of secondary electron emission from small dust grains. In the present
contribution, we discuss the profile of a secondary emission yield that can be received from the model and the measured equilibrium
grain charge, both as functions of an incident electron beam energy. A comparison of these quantities leads to an estimation
of secondary electron spectra. We have found that: (1) the energy spectrum of secondary electrons does not change with the
energy of primary electrons and (2) the energy spectrum depends on the target material being harder for gold and silver than
for glass grains. |
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Keywords: | PACS" target="_blank">PACS 79 20 Hx Electron impact: secondary emission 96 50 Dj Interplanetary dust and gas |
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