Confinement of nonequilibrium plasmas in microcavities with diamond or circular cross sections: Sealed arrays of Al∕Al2O3/glass microplasma devices with radiating areas above 20cm2

Abstract

Arrays of Al∕Al2O3/glass microplasma devices with microcavities having diamond or circular cross-sectional geometries and radiating (active) areas >20cm2 have been operated sealed-off in Ne, Ar, and Ar∕D2 gas mixtures. Microcavities are fabricated in only one of the two electrodes, and the thickness of the completed package is ∼170μm (excluding the quartz output window). Excited by a sinusoidal 20kHz voltage wave form, arrays with active areas of 4.5×3cm2 exhibit ignition voltages as low as 110±5V rms for Ne pressures of 400–700Torr. Mixtures of 1% D2 in Ar at a total pressure of 300Torr produce wavelength-integrated (λ∼250–400nm) intensities of ∼1mWcm−2 over a 25cm2 area. Optical micrographs show the operation of the microplasmas in two well-defined modes. For current densities below a threshold value (∼53mAcm−2 for 250μm dia. cavities and pNe=400Torr), diffuse uniform plasma is produced in each cavity but, with higher currents, a positive column having near-cylindrical geometry appears, as evidenced by the generation of intense emission localized in the region of weak electric field gradient near the axis of symmetry.

Mass Spectrometry: Recent Advances in Direct Open Air Surface Sampling/Ionization

“…156 The main emphasis has been on the use of microplasmas as excitation sources for elemental emission spectroscopy, 157 alternative geometries, 158 and arrayed devices. 159 The use of microplasmas for surface analysis in ambient sampling/ionization approaches is just emerging. Initial work involved the coupling of a microhollow configuration discharge microplasma (MHCD) to neutral desorption using a heated nitrogen stream for the analysis of model analytes.…”

“…The reduced power and gas consumption of these devices is their most attractive feature, which has led to their coupling to analyzers typically used for field work, such as ion mobility spectrometry (IMS) . The main emphasis has been on the use of microplasmas as excitation sources for elemental emission spectroscopy, alternative geometries, and arrayed devices . The use of microplasmas for surface analysis in ambient sampling/ionization approaches is just emerging.…”

Commercialization of microcavity plasma devices and arrays: Systems for VUV photolithography and nanopatterning, disinfection of drinking water and air, and biofilm deactivation for medical therapeutics

“…[11] From the outset, efforts focused on the development of flat lamps, and the "engine" of the first lamps was an array of dielectric barrier discharges (DBDs) generated within cavities in aluminum screen, any pattern woven with Al wire, or aluminum foil, for example, which was chemically treated to yield a surface layer of nanoporous alumina. [12][13][14] Serving as a dielectric having exceptional breakdown strength, the adoption of nanoporous Al 2 O 3 allowed for the driving voltage to be decreased relative to existing DBD lamps. [15] Figure 1 is a 2008 photograph of a newspaper illuminated by the green output of a secondgeneration lamp having 16 cm 2 of surface area and the phosphor coating applied to the front window.…”

Gap-dependent transitions of atmospheric microplasma in open air

“…[1][2][3][4][5][6][7][8][9][10][11][12] They are operated under different geometries of the electrodes, dielectric layer material, relative electrode distance, working ambient gas, pressure, temperature, driving voltage, waveform, and frequency. [10][11][12] For example, microplasmas have been observed in filamentary discharge [3][4][5]8,9 and uniform diffuse discharge.…”