Azimuthal and axial structures in 3D Particle-in-Cell simulations of Penning discharge
ORAL
Abstract
We report the results of 3D particle-in-cell simulations of cylindrical Penning dis-
charge in the so-called reflex configuration, where the cathode and anti-cathode are
biased to the same negative potential. The discharge is supported by thermal elec-
tron emission from the cathode. Electron and ion collisions, including ionization,
are fully accounted for. The emphasis is on a specific regime in which the plasma
potential at the center of the discharge is positive with respect to the chamber walls,
serving as an anode. Spatial and temporal scales of the observed azimuthal and
axial fluctuations and structures are characterized. It is suggested that azimuthal
structures are caused by the dissipative gradient-drift instability. We find that the
axial fluctuations related to the plasma-beam instabilities are weakly correlated with
the azimuthal perturbations of the density, so that the azimuthal modes rotate as
a whole and do not show any axial shear. The behavior of the electric potential is
more complex and involves intermittent structures in the r-z plane that modulate
the electron transport, producing the standing wave pattern (along the z-direction)
in the radial electron flux.
charge in the so-called reflex configuration, where the cathode and anti-cathode are
biased to the same negative potential. The discharge is supported by thermal elec-
tron emission from the cathode. Electron and ion collisions, including ionization,
are fully accounted for. The emphasis is on a specific regime in which the plasma
potential at the center of the discharge is positive with respect to the chamber walls,
serving as an anode. Spatial and temporal scales of the observed azimuthal and
axial fluctuations and structures are characterized. It is suggested that azimuthal
structures are caused by the dissipative gradient-drift instability. We find that the
axial fluctuations related to the plasma-beam instabilities are weakly correlated with
the azimuthal perturbations of the density, so that the azimuthal modes rotate as
a whole and do not show any axial shear. The behavior of the electric potential is
more complex and involves intermittent structures in the r-z plane that modulate
the electron transport, producing the standing wave pattern (along the z-direction)
in the radial electron flux.
*This work is supported in part by NSERC Canada, the Digital Research Alliance of31 Canada, and the Plasma Collaborative Research Facility at Princeton Plasma Physics Lab-oratory. This research used the VSim particle-in-cell code (https://www.txcorp.com/Vsim),developed by Tech-X Corporation. Simulations were performed on the Niagara supercom-puter at SciNet, the Digital Research Alliance of Canada (https://www.scinethpc.ca/niagara).
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Publication: Submitted to PSST
Presenters
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Mina Papahn Zadeh
- University of Saskatchewan