Speaker
Tomaz Gyergyek
Description
See the full Abstract at http://ocs.ciemat.es/EPS2018ABS/pdf/P5.1016.pdf
Potential formation in front of a floating, planar, electron emitting
electrode studied by particle in cell simulations
T. Gyergyek1,2, J. Kovačič2, J. P. Gunn3, I. Gomez2, M. Mozetič2
1
University of Ljubljana, Faculty of electrical engineering, Ljubljana, Slovenia
2
Jožef Stefan Institute, Ljubljana, Slovenia
3
CEA, IRM, F-13108 Saint-Paul-Lez-Durance, France
The study of electron emitting surfaces is of great importance for plasma physics.
Understanding the potential formation in front of an electron emitting solid surface in contact
with a plasma is important for various applications – from emissive probes to implications in
the field of fusion. For instance the divertor in ITER is expected to reach such high
temperatures that it could become strongly emissive [1].
In this work potential formation in front of a planar, floating, electron emitting
electrode is investigated using a 1d3v particle in cell code BIT1 [2]. Plasma is created by
volume ionization in the entire space between two planar electrodes. The right electrode is at
zero (reference) potential, while the left electrode is floating and emits electrons. It is
assumed that the flux of emitted electrons is a given quantity. This corresponds to Richardson
emission from a hot metal electrode. The distribution function of the emitted electrons is
assumed to be a drifting Maxwellian. Effects of drift velocity, temperature and flux of
emitted electrons on the potential profile are studied. As those three parameters are varied
transitions between monotonic, space charge limited and inverted sheath [3] are observed.
The drift velocity of emitted electrons turns out to be a rather important parameter.
References
1) J. P. Gunn et al, Nucl. Fusion, 57, 046025 (2017).
2) D. Tskhakaya and R. Schneider, J. Comp. Phys. 225, 829 (2007).
3) M. D. Campanell, Phys. Rev E, 88, 033103 (2013).
Acknowledgements
This work has been partially supported by the grant P2-0073 of the Slovenian research
agency and partially by the grant BI-FR/CEA/17-19-002.
