Boltzmann analysis of electron swarm parameters in CHF₃+CF₄ mixtures

Authors: HIDIR DÜZKAYA, SÜLEYMAN SUNGUR TEZCAN

Abstract: The electron drift velocity, mean energy, ionization, attachment, effective ionization coefficient, limit electrical field, and synergism of pure CHF₃ (fluoroform), pure CF₄ (tetrafluoromethane), and CHF₃+CF₄ gas mixtures are calculated by Boltzmann equation analysis in a wide range of density normalized electrical fields (E/N). The finite difference method is used to solve the two-term approximation of the Boltzmann equation under steady-state Townsend conditions. To our knowledge, no previous electron swarm parameters of these mixtures have been published. At constant E/N values, the electron mean energies and drift velocities increase with decreasing CHF₃ content. The addition of CF₄ into the mixture increases the attachment coefficient but reduces the ionization coefficient since CF₄ is more electronegative than CHF₃. Furthermore, the limit electrical fields increase with increasing CF₄ concentration.

Keywords: Gas discharge characteristics, fluoroform, tetrafluoromethane, Boltzmann equations

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