Arrays of Microplasma Jets Generated by Double Parabolic Microcavities in an Hourglass Configuration

Microplasma jets have been generated in double parabolic microcavities arranged in an hourglass structure with a 300-μm-diameter throat. Fabricated by micropowder blasting of nanoporous alumina grown on Al foil, the parabolic cavities are situated back-to-back and operated with a feedstock gas having a flow rate of ~ 1.5-6 standard L/min. Arrays as large as 6 × 6 jets have been demonstrated for which the jet pitch and fill factor are 1.25 mm and 17%, respectively. Images of the visible fluorescence produced by the expansion of He microplasma jets in laboratory air provide a vivid picture of the extent of the He(2³S) → N₂⁺ Penning ionization reaction zone.