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Experimental determinations of electron energy distributions for Townsend discharges in helium gas

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Title Experimental determinations of electron energy distributions for Townsend discharges in helium gas
Names Roberts, Thomas David (creator)
Burch, David S. (advisor)
Date Issued 1965-04-07 (iso8601)
Note Graduation date: 1965
Abstract The energy distribution of electrons in Townsend discharges in
helium has been experimentally investigated in a direct fashion.
A discharge is initiated between parallel plates of a small cell
mounted at the center of a spherical retarding field energy analyzer.
The anode of the cell is perforated and some electrons from the discharge
enter the retarding field region. Pressures in the discharge
cell are of the order of 1 torr and the pressure in the analyzer region
is about 10⁻⁷ torr, so no significant alteration of the electron
energy spectrum due to collisions takes place after electrons have left
the discharge cell. The electron current reaching the collecting surface
of the analyzer is measured as a function of retarding field
strength. The usual perturbations due to probe measurements in the
discharge itself are thus minimized.
The interaction of electrons with the surfaces of the analyzer
is considered, and the experimental data are corrected for the resulting electron reflection and secondary emission. A gold black
analyzer surface exhibiting low total electron secondary emission coefficient
is utilized.
Experimental electron energy distributions are compared with
the theoretical calculations of Heylen and Lewis, and qualitative agreement
is found for helium. The correction due to electron reflection
and secondary emission is shown to be minor.
Genre Thesis/Dissertation
Topic Electric discharges through gases
Identifier http://hdl.handle.net/1957/48098

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