Performance enhancement of a dielectric barrier discharge vacuum-ultraviolet photon source using short-pulsed electrical excitation

In this study, we investigate the use of novel electrical excitation techniques applied to a high-pressure argon excimer lamp based on a dielectric barrier discharge (DBD). The lamp emits λ=126-nm (10 eV) photons in the vacuum-ultraviolet (VUV) spectral region which are effective at ionizing many chemical analytes. The availability of improved VUV light sources could potentially make a big impact in the field of mass spectrometry ion sources. Because the ionization energies of common solvents such as water, acetonitrile, and methanol are higher than 10 eV and are not efficiently ionized by the lamp, 10 eV photoionization enables high signal-to-background measurements. The specific aim of this work is to boost the overall VUV output power and operating efficiency of the photon source by undertaking a detailed experimental characterisation of its performance using two different electrical excitation techniques based on short-pulse high-voltage drivers and conventional (sinusoidal) high-voltage drivers, and test them over a range of operating conditions of the DBD plasma (e.g. vs. argon pressure, waveform peak voltage, duty-cycle, and repetition frequency). A wide range of operating conditions have been tested up to the thermal loading limit of the air-cooled argon VUV lamp. Previously, we reported analogous studies on VUV excimer lamps using either Xenon (λ=172nm) or Neon (λ=84nmn) gas fills. [1]. Preliminary results will be reported which clearly show significant improvement of the overall lamp performance when utilizing short-pulsed voltage excitation techniques. Measurements of the lamp's spectral emission across the VUV/UV/visible range (λ=110−550nm) also clearly demonstrate that the lamp output is highly monochromatic, with the photon emission essentially consisting of a single VUV excimer band around λ∼126nm.