https://doi.org/10.1140/epjd/e2016-60601-4
Regular Article
Sampling of ions at atmospheric pressure: ion transmission and ion energy studied by simulation and experiment
Research Group Reactive Plasmas, Institute for
Experimental Physics II, Ruhr-Universität Bochum, 44780
Bochum,
Germany
a e-mail: simon.grosse-kreul@rub.de
Received:
22
October
2015
Received in final form:
26
February
2016
Published online:
3
May
2016
Mass spectrometry of ions from atmospheric pressure plasmas is a challenging diagnostic method that has been applied to a large variety of cold plasma sources in the past. However, absolute densities can usually not be obtained, moreover, the process of sampling of ions and neutrals from such a plasma inherently influences the measured composition. These issues are studied in this contribution by a combination of experimental and numerical methods. Different numerical domains are sequentially coupled to calculate the ion transmission from the source to the mass analyzer. It is found that the energy of the sampled ions created by a radio-frequency microplasma operated in a He-N2 mixture at atmospheric pressure is of the order of 0.1 eV and that it depends linearly on the ion mass in good agreement with the expectation for seeded particles accelerated in a supersonic expansion. Moreover, the measured ion energy distribution from an afterglow of an atmospheric pressure plasma can be reproduced on basis of the particle trajectories in the sampling system. Eventually, an estimation of the absolute flux of ions to the detector is deduced.
Key words: Plasma Physics
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag 2016