EMISSION SPECTROSCOPY OF ATMOSPHERIC-PRESSURE BALL PLASMOIDS: HIGHER ENERGY REVEALS A RICH CHEMISTRY

Ball plasmoids (self-sustaining spherical plasmas) are a particularly unique example of a non-equilibrium air plasma. These plasmoids have lifetimes on the order of hundreds of milliseconds without an external power source, however, current models dictate that a ball plasmoid should recombine in a millisecond or less. Ball plasmoids are considered to be a laboratory analogue of natural ball lightning, a phenomenon that has eluded scientific explanation for centuries. We are searching for the underlying physicochemical mechanism(s) by which ball plasmoids and (by extension) ball lightning are stabilized using a variety of diagnostic techniques. _x000d_ _x000d_ This presentation will focus on optical emission spectroscopy (OES) of ball plasmoid discharges between 190-850 nm. The previous generation of OES measurements\footnote{Versteegh, A.; Behringer, K.; Fantz, U.; Fussman, G.; J\"{u}ttner, B.; Noack, S. \textit{Plas. Sour. Sci. Technol.} \textbf{2008}, 17(2), 024014}$^{,}$\footnote{Stephan, K. D.; Dumas, S.; Komala-Noor, L.; McMinn, J. \textit{Plas. Sour. Sci. Technol.} \textbf{2013}, 22(2), 025018} of this system showed emission from only a few atomic and molecular species, however, the energy available for the discharges in these experiments was limited by the size of the capacitor banks and voltages to which the capacitor banks were charged. We are capable of generating plasmoids at much higher energies, and as a result we are the first to report a very rich chemistry previously not observed in ball plasmoids. We have identified signals from species including NO A$^{2}$$\Sigma$$^{+}$$\rightarrow$X$^{2}$$\Pi$, OH A$^{2}$$\Sigma$$^{+}$$\rightarrow$X$^{2}$$\Pi$, NH A$^{3}$$\Pi$$\rightarrow$X$^{3}$$\Sigma$$^{-}$, AlO A$^{2}$$\Pi$$\rightarrow$X$^{2}$$\Sigma$$^{+}$, NH$^{+}$ B$^{2}$$\Delta$$\rightarrow$X$^{2}$$\Pi$, W I, Al I, Cu I, and H$_{\alpha}$, all of which have not yet been reported for this system. Analysis of the emission spectra and fitting procedures will be discussed, rotational temperatures of constituent species will be reported, and theories of ball plasmoid stabilization based upon these new results will be presented. _x000d