Looking for a method to estimate the properties of atmospheric pressure plasmas (electron density and electron temperature) with various gas/gas mixtures (CH4, O2, CH4+O2, CH4+CO2, CH4+noble gases, etc.)
Do you have a monochromator ? What kind of sensors do you have in your disposal ?
Generally the non-disturbing approach would be to use observe Balmer series emission from excited Hydrogen. Hbeta is used up to densities of 10^15-10^16 cm^-3 , at higher densities it becomes usually to broad and Halpha commonly used. You need a monochromator with the sufficient spectral resolution and a CCD or ICCD sensor to record the line shape. The details and nuances of calculation of plasma electron density from the line shape can be found in books on plasma spectroscopy by Griem, Kunze , Hutchinson etc.
Since DBD discharge in atmospheric pressure generates non-equilibrium plasma you cannot use the ratio of Balmer lines intensities to get the Te from Boltzmann plot. Its very tricky to get the electron temperature in non-equlibrium plasma . The only method for direct measurement in open air discharge would be Thomson scattering. It also yileds electron density in addition to temperature however it requires a pulsed laser and either a triple grating spectrometer or Bragg notch filter + iCCD sensor and generally is an advanced and complex measurement technique. (see attached file )
Relatively simple microwave absorption tests are described in the literature. This can help to estimate the electron density if plasma is impedance matched to the measuring equipment.
https://researchonline.jcu.edu.au/6105/1/6105_Mphale_et_al._2008.pdf
http://rspa.royalsocietypublishing.org/content/211/1104/31
http://www.jstor.org/stable/98839
- Badges
- Science topic
- Similar topics
- Geoscience
- Asia
- India