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Journal of Thermal Spray Technology

, Volume 2, Issue 4, pp 345–350 | Cite as

Entrainaient and demixing in subsonic argon/helium thermal plasma jets

  • J. R. Fincke
  • W. D. Swank
  • D. C. Haggard
Reviewed Paper

Abstract

The velocity, temperature, entrained air fraction, and Ar/He concentration profiles were measured in a subsonic thermal plasma jet using an enthalpy probe and mass spectrometer. Through interaction with the surrounding atmosphere, air is quickly entrained into the jet, resulting in rapidly decreasing velocities and temperatures. Due to the difference in ionization potential, a significant diffusive separation or demixing of Ar and He is also observed in the large temperature gradients present. Near the exit of the torch, in the jet center, the relative He concentration is enhanced by approximately 50% over that of the premixed feed gases. Demixing occurs primarily in the discharge region and torch nozzle. As jet mixing progresses in the downstream direction, the Ar to He ratio approaches the initial input ratio.

Key words

argon/helium plasmas diagnostics enthalpy probe entrainment control mass spectrometer plasma jet 

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Copyright information

© ASM International 1993

Authors and Affiliations

  • J. R. Fincke
    • 1
  • W. D. Swank
    • 1
  • D. C. Haggard
    • 1
  1. 1.Idaho National Engineering LaboratoryE G & G Idaho, Inc.Idaho Falls

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