Determination of gas temperature of high-frequency low-temperature electrodeless plasma using molecular spectra of hydrogen and hydroxyl-radical

In this study we determine gas temperature of He+H2, Ar+H2 and Ne+H2 high frequency electrodeless lamps using intensity distribution in rotational spectra of hydrogen molecule and hydroxyl radical. The measurement results show that OH rotational spectra can be successfully used for estimation of gas temperature of the high-frequency electrodeless lamps at very small amounts of hydrogen present in plasma. The analysis of the measurement results leads to the conclusion that in “pure” plasma the applied energy is used to heat plasma, while for the plasma with hydrogen addition the energy is used in chemical reactions.

► We determine gas temperature of He+H2, Ar+H2 and Ne+H2 HFEDLs. ► We use rotational spectra of hydrogen molecule and hydroxyl radical. ► OH can be successfully used for gas temperature determination of HFEDLs. ► In HFEDLs excited neon atoms are supplying energy to OH radicals. ► In plasma with hydrogen addition the energy is used in chemical reactions.