Infrared emission spectroscopy of atmospheric-pressure ball plasmoids

Scott E. Dubowsky, Bradley Deutsch, Rohit Bhargava, Benjamin J. McCall

Research output: Contribution to journalArticle

Abstract

We report the first (to our knowledge) infrared emission spectra collected from water-based laboratory ball plasmoid discharges. A "ball plasmoid" results from a unique type of pulsed DC plasma discharge in which a sphere of plasma is seen to grow and eventually separate from a central electrode and last for a few hundred milliseconds without an external power source before dissipating. Typical recombination rates for plasmas at ambient conditions are on the order of a millisecond or less, however ball plasmoids have been observed to last a few hundred milliseconds, and there is no explanation in the literature that fully accounts for this large discrepancy in lifetime. The spectra are dominated by emission from water and from hydroxyl radical; PGOPHER was used to fit the experimental spectra to extract rotational temperatures for these molecules. The temperatures of the bending and stretching modes of H 2 O were determined to be 1900 ± 300 K and 2400 ± 400 K, respectively and the rotational temperature of OH was found to be 9200 ± 1500 K.

Original languageEnglish (US)
Pages (from-to)1-8
Number of pages8
JournalJournal of Molecular Spectroscopy
Volume322
DOIs
StatePublished - Apr 1 2016

Keywords

  • Ball lightning
  • Infrared emission spectroscopy PGOPHER
  • Plasma diagnostics
  • Plasmoid
  • Rotational temperature

ASJC Scopus subject areas

  • Atomic and Molecular Physics, and Optics
  • Spectroscopy
  • Physical and Theoretical Chemistry

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