Max-Planck Institut f

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Max-Planck Institut für Plasmaphysik, EURATOM
Association, 17491 Greifswald, Germany
Particle in Cell simulations of sheath
dynamics in capacitive RF discharges in Oxygen,
Hydrogen and Argon
Konstantin Matyash
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Max-Planck Institut für Plasmaphysik, EURATOM
Association, 17491 Greifswald, Germany Oxygen
discharge
Oxygen 844.6 nm line excitation
simulation (electron impact only)
experiment
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Max-Planck Institut für Plasmaphysik, EURATOM
Association, 17491 Greifswald, Germany
Oxygen Dynamic during RF cycle
First maximum is during the electrons expelled
from the growing sheath Second maximum is
originated by the electrons detached from the
negative ions due to collisions with neutrals.
This electrons are starting the ionization
avelanche, which reaches its maximum when the
sheath drop is highest
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Max-Planck Institut für Plasmaphysik, EURATOM
Association, 17491 Greifswald, Germany Oxygen
discharge
Field reversal effect
experiment
simulation
Due to reduced mobility of the electrons
(electron-neutral collisions) negative space
charge pops-up iat the sheath edge, causing the
field reversal during the short time at the
sheath collaps phase. This reversed field is
accelerating the electrons in the sheath toward
the wall, self-consistently maintaining the
ion-electron current ballance. Electrons,
accelerated in this reversed field originate the
third emmision maximum close to the electrode
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Max-Planck Institut für Plasmaphysik, EURATOM
Association, 17491 Greifswald, Germany Oxygen
discharge
Heavy particles excitation
Oxygen 844.6 nm line electronion-impact
excitation (simulation)
model cross-section for
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Max-Planck Institut für Plasmaphysik, EURATOM
Association, 17491 Greifswald, Germany Oxygen
discharge
RF cycle averaged experimental axial profile of
844 nm excitation
simulation
experiment
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Max-Planck Institut für Plasmaphysik, EURATOM
Association, 17491 Greifswald, Germany Hydrogen
discharge
Hydrogen 656.3 nm line excitation
simulation (electron impact only)
experiment
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Max-Planck Institut für Plasmaphysik, EURATOM
Association, 17491 Greifswald, Germany Hydrogen
Dynamic during RF cycle
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Max-Planck Institut für Plasmaphysik, EURATOM
Association, 17491 Greifswald, Germany Argon
discharge
Argon 840.8 842.5 nm line electron-impact
excitation
simulation
experiment