Flexible, Lightweight Arrays of Microcavity Plasma Devices: Control of Cavity Geometry in Thin Substrates

Abstract

Adaptation of wet chemical processing or replica molding techniques to microcavity plasma device technology has yielded lightweight and flexible arrays in the Al/Al <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> materials system and plastic substrates, respectively. Microplasma arrays fabricated from two bonded sections of Al mesh with an integral dielectric barrier of nanoporous alumina have an overall thickness of <100 mum, resulting in lamps that are flexible and conformable to a variety of surfaces. Operating these arrays in both flat and curved configurations reveals few changes to the voltage-current characteristics but a reduction of a factor of two in the luminance of curved or bent structures relative to that for a flat array. Truncated paraboloid cavities have also been formed in 30-70-mum-thick Al foil by a sequence of wet chemical processes. Microcavities with an emitting aperture diameter as small as 50 mum have been realized, and arrays comprising 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sup> cavities exhibit ignition voltages of ~140-150 V (rms) for Ne pressures between 400 and 700 torr and a 20-kHz sinusoidal voltage waveform. Mixtures of Ne and Xe with Xe content up to 67% have been operated successfully. Ignition voltages of only 70-90 V (rms) have been measured for 30 times 30 arrays of 200 times 200-mum <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> microcavities formed in ultraviolet curable polymer by replica molding and operating in 400-600 torr of Ne. For 3% N <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> /Ar mixtures at total pressures of 400-700 torr, the ignition voltages rise to ~150-220 V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">RMS</sub> for a driving frequency of 20 kHz, the array emission is spatially uniform, and rms currents above 85 mA can be drawn in the steady state by these plastic-based arrays.