Corona-glow transition in the atmospheric pressure RF-excited plasma needle

Y. Sakiyama, D. B. Graves

Research output: Contribution to journalArticlepeer-review

77 Scopus citations

Abstract

We present clear evidence of two different discharge modes of the atmospheric pressure RF-excited plasma needle and the transition mechanism by the finite element method. The gas used is helium with 0.1% nitrogen addition. The needle has a point-to-plane geometry with a radius of 30 νm at the tip, 150 νm at the base and an inter-electrode gap of 1 mm. We employ the one-moment fluid model with the local field approximation. Our simulation results indicate that the plasma needle operates as a corona discharge at low power and that the discharge mode transitions to a glow discharge at a critical power. The discharge power increases but the discharge voltage drops abruptly by a factor of about 2 in the corona-glow transition. The plasma density and ionization is confined near the needle tip in corona-mode while it spreads back along the needle surface in glow-mode. The corona-glow transition is also characterized by a dramatic decrease in sheath thickness and an order of magnitude increase in plasma density and volume-averaged ionization. The transition is observed whether or not secondary electron emission is included in the model, and therefore we suggest that this is not an α -γ transition.

Original languageEnglish (US)
Article number018
Pages (from-to)3644-3652
Number of pages9
JournalJournal of Physics D: Applied Physics
Volume39
Issue number16
DOIs
StatePublished - Aug 21 2006
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Acoustics and Ultrasonics
  • Surfaces, Coatings and Films

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