A computationally assisted spectroscopic technique to measure secondary electron emission coefficients in radio frequency plasmas

M. Daksha, B. Berger, E. Schuengel, I. Korolov, A. Derzsi, M. Koepke, Z. Donkó, J. Schulze

Research output: Contribution to journalArticle

12 Citations (Scopus)

Abstract

A computationally assisted spectroscopic technique to measure secondary electron emission coefficients (γ-CAST) in capacitively-coupled radio-frequency plasmas is proposed. This non-intrusive, sensitive diagnostic is based on a combination of phase resolved optical emission spectroscopy and particle-based kinetic simulations. In such plasmas (under most conditions in electropositive gases) the spatio-temporally resolved electron-impact excitation/ionization rate features two distinct maxima adjacent to each electrode at different times within each RF period. While one maximum is the consequence of the energy gain of electrons due to sheath expansion, the second maximum is produced by secondary electrons accelerated towards the plasma bulk by the sheath electric field at the time of maximum voltage drop across the adjacent sheath. Due to these different excitation/ionization mechanisms, the ratio of the intensities of these maxima is very sensitive to the secondary electron emission coefficient γ. This sensitvity, in turn, allows γ to be determined by comparing experimental excitation profiles and simulation data obtained with various γ-coefficients. The diagnostic, tested here in a geometrically symmetric argon discharge, yields an effective secondary electron emission coefficient of for stainless steel electrodes.

Original languageEnglish
Article number234001
JournalJournal of Physics D: Applied Physics
Volume49
Issue number23
DOIs
Publication statusPublished - May 12 2016

Fingerprint

Electron emission
secondary emission
electron emission
radio frequencies
Plasmas
Ionization
sheaths
Electrons
coefficients
Plasma sheaths
Optical emission spectroscopy
Electrodes
Argon
Stainless Steel
excitation
Stainless steel
ionization
Gases
Electric fields
electrodes

Keywords

  • low temperature plasma science
  • particle in cell simulations
  • phase resolved optical emission spectroscopy
  • plasma diagnostics
  • radio frequency plasmas
  • secondary electron emission coefficients

ASJC Scopus subject areas

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

Cite this

A computationally assisted spectroscopic technique to measure secondary electron emission coefficients in radio frequency plasmas. / Daksha, M.; Berger, B.; Schuengel, E.; Korolov, I.; Derzsi, A.; Koepke, M.; Donkó, Z.; Schulze, J.

In: Journal of Physics D: Applied Physics, Vol. 49, No. 23, 234001, 12.05.2016.

Research output: Contribution to journalArticle

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AU - Berger, B.

AU - Schuengel, E.

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AU - Koepke, M.

AU - Donkó, Z.

AU - Schulze, J.

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