Simultaneous measurement of nitrogen and hydrogen dissociation from vacuum ultraviolet self-absorption spectroscopy in a developing low temperature plasma at atmospheric pressure

George Laity, Andrew Fierro, James Dickens, Andreas Neuber, Klaus Frank

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Abstract

We demonstrate a method for determining the dissociation density of N and H atoms present in a developing low temperature plasma, based on the emission and self-absorption of vacuum ultraviolet radiation produced from the plasma. Spark plasmas are produced via pulsed discharge in N2/H2 mixtures at atmospheric pressure, where information on the dissociated densities of the constituent gas molecules is desired without employing invasive diagnostic techniques. By analyzing the self-absorption line profile of 121.5 nm Lyman-α H radiation emitted within the first ∼1.0 mm of plasma near the anode tip, a peak dissociated H atom concentration of 5.6 × 10 17 cm-3 was observed ∼100 ns into spark formation, with an estimated electron density of 2.65 × 1018 cm -3 determined from Stark broadening. Similarly, simultaneous line fitting of the N 120.0/124.3 nm emission profiles revealed a peak dissociated N atom concentration of 3.8 × 1017 cm-3 during the same discharge period.

Original languageEnglish
Article number184104
JournalApplied Physics Letters
Volume102
Issue number18
DOIs
StatePublished - May 6 2013

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