Low-temperature atmospheric-pressure plasma measurement -- Selected as a Highlight paper

More than 20 years have already passed since atmospheric-pressure non-equilibrium plasmas were frequently discussed at the forefront of science and technology. They can also be generated by underwater or submerged discharge, and new applications are increasing in the field of medical, agriculture, food industry, and textile industry, etc. However, a standard method that can be easily performed on a laboratory scale has not yet been established for the measurement of their electron temperature Te and density Ne. Therefore, a general-purpose means for measuring their Te and Ne is absolutely necessary. We also generated atmospheric pressure non-equilibrium plasma, and planned and executed research to measure electron temperature and density from the continuum spectrum measurement due to electron-atom bremsstrahlung. As an electron energy distribution function, assuming a specific shape, the theoretical calculation and the measured spectrum were compared, and the electron temperature Te and density Ne can be obtained as the best fitting parameters. In addition, the validity of the obtained values ​​is confirmed by the comparison with the line spectral intensity and the excited-state density with a reliable calculation model called "collisional radiative model". Consequently, the electron temperature and density of the atmospheric pressure non-equilibrium plasma are confirmed to be obtained by practical and simple continuum spectrum measurement.

This paper was selected as a Spotlight paper of Japanese Journal of Applied Physics in 2021, but in 2022, it was further selected as the "Highlight paper" from the Plasma field. Furthermore, it was selected and awarded for the "20th (March 2022) Plasma Electronics Award" by the Plasma Electronics Division of the Japan Society of Applied Physics.

In the future, I hope that the measurement method based on this research will spread to various applications such as agriculture and medical care as well as electrical and electronic engineering.