Swarm parameter measurement in hydrogen, considering secondary photonic electron emission
Abstract
Discharges in hydrogen at pressures above kPa and a reduced electric field of Td show a characteristic current oscillation in Pulsed Townsend experiments. This is explained by secondary emission of electrons from the photo-cathode: some hundreds of nano-seconds after the laser-pulse that released the initial primary electrons, secondary electrons are emitted from the cathode. Mechanisms discussed in literature are UV-emission from neutral molecules, emission by positive ions reaching the cathode, and back-scattering of excited neutrals. For a measurement up to Td and pressures up to kPa we model different sources, and agree with previous findings that the observed secondary emission is purely due to ultra-violet light below Td: the simulation fits with the complicated form of the oscillating waveform. Obtained swarm parameters agree well with the literature. Our findings suggest a very high efficiency of the photo-cathode for UV light of energies above eV.
Keywords
Cite
@article{arxiv.1802.02916,
title = {Swarm parameter measurement in hydrogen, considering secondary photonic electron emission},
author = {Andreas Hösl and Christian Michael Franck},
journal= {arXiv preprint arXiv:1802.02916},
year = {2018}
}