Sterilization efficacy of a coaxial microwave plasma flow at atmospheric pressure

Takehiko Sato, Kazunari Fujioka, Raju Ramasamy, Takuya Urayama, Shuitsu Fujii

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37 Citations (Scopus)


A coaxial cable for microwave transmission type of atmospheric low-temperature plasma source was developed. The plasma source has the advantages of portability, simple configuration, and ability to operate with a wide range of gases and mixtures of such gases. It mainly consists of a cavity, a quartz discharge tube, a coaxial cable, a microwave power source, and a gas supply system. Using this plasma source, the authors tried to clarify its sterilization efficacy against Geobacillus stearothermophilus. A log reduction number of G. stearothermophilus of at least 5 (10-5) was obtained under the following operating conditions: gas flow rate of argon of 14 SL/min, input power is 400 W, and substrate surface temperature of 353 K. Distributions of temperature and velocities of gas were also measured two-dimensionally by using an E-type thermocouple and a Pitot tube, respectively. The temperature distributions and the peak value of temperature were found to be influenced by the gas flow rate and the kinds of gas mixtures.

Original languageEnglish
Pages (from-to)399-404
Number of pages6
JournalIEEE Transactions on Industry Applications
Issue number2
Publication statusPublished - 2006 Mar


  • Argon
  • Atmospheric pressure
  • Coaxial microwave plasma
  • Geobacilllus stearothermophilus
  • Sterilization


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