Plasma Chemistry and Plasma Processing

, Volume 8, Issue 1, pp 101–110 | Cite as

Dynamics of the formation of excited hydrogen, H(n=2,3,4), during a pulse discharge in methane

  • Radoslaw Sobczynski
  • Hubert Lange
  • Stanislaw Kurowski
Article

Abstract

The dynamics of the formation and decay of excited hydrogen during a pulse discharge in methane at a pressure of 200 Pa and energy density of 0.05 J/cm3 has been studied. The population of hydrogen in the n=2 state was monitored by the laser absorption method. The time constant of the decay of the excited hydrogen was measured to be 95±15 ns. The concentration of free electrons reached a maximum value of 7×1014 cm−3, and the time constant of their recombination was 220±50 ns. The formation of appreciable amounts of atomic hydrogen in the ground state during the discharge, H(n=1)>1016 cm−3, was estimated on the basis of a kinetic model.

Key Words

Plasma laser diagnostics hydrocarbons free radicals kinetics 

Notation

\(\tilde{v}\)

absorption coefficient

\(\tilde{v}\)

wave number, cm−1

c

velocity of light

e

electron charge

me

mass of electron

Amn

Einstein coefficient

Fmn

collisional deexcitation rate constant

Sm

ionization rate constant

f24

oscillator strength

ne

electron concentration

nH(n=2,3,4)

excited-state hydrogen concentration

ve

electron velocity

qmn

excitation cross-section

(qmnve)

excitation rate constants

Te

electron temperature

E (t)

electrical field strength

j

current density

tei−1

electron-ion collision frequency

α2,m

two-body recombination rate constant

α3,m

three-body recombination rate constant

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Copyright information

© Plenum Publishing Corporation 1988

Authors and Affiliations

  • Radoslaw Sobczynski
    • 1
  • Hubert Lange
    • 1
  • Stanislaw Kurowski
    • 1
  1. 1.Department of Chemistry, Plasma Diagnostics LaboratoryThe University of WarsawWarsawPoland

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