Electron heating mode transitions in a low pressure capacitively coupled oxygen discharge

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Abstract

Using particle-in-cell Monte Carlo collision simulations we have demonstrated an electron heating mode transition from drift-ambipolar (DA) mode to α-mode in the capacitively coupled oxygen discharge as the operating pressure and/or electrode separation are increased. Here we explore further the transition as pressure and electrode separation are varied. At fixed electrode spacing of 45 mm when operating at low pressure (10 mTorr) the electron heating is a combination of DA- and α-mode heating while at higher pressures (>30 mTorr) electron heating in the sheath regions dominates. When varying the electrode spacing from 25 to 60 mm at fixed operating pressure at the higher pressures (50 mTorr) the electron heating is a combination of DA- and α-mode heating for small electrode spacing and it transitions to pure α-mode heating as the electrode spacing is increased. We relate the transition to increased electronegativity and generation of drift and ambipolar electric field within the electronegative core when the discharge pressure is low or electrode spacing is small.

Original languageEnglish
Article number045012
JournalPlasma Sources Science and Technology
Volume28
Issue number4
DOIs
Publication statusPublished - 24 Apr 2019

Bibliographical note

Publisher Copyright:
© 2019 IOP Publishing Ltd.

Other keywords

  • cpacitively coupled discharge
  • detachment
  • electron heating
  • oxygen
  • particle-in-cell Monte Carlo collision

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