25 W of average power at 172 nm in the vacuum ultraviolet from flat, efficient lamps driven by interlaced arrays of microcavity plasmas

Abstract

More than 25 W of average power and >800 W of peak power have been generated at λ=172 nm (hν=7.2 eV) in the vacuum ultraviolet (VUV) from the Xe2 molecule in flat, 10 × 10 cm2 lamps having an active area and volume of 80 cm2 and 20%. For a bipolar voltage waveform driving frequency of 137 kHz and a 54% Xe/Ne gas fill mixture at a 300 K pressure of 550 Torr, the lamp generates as much as 31.5 W of average power and intensities >350 mW cm−2 in 40–60 μJ, 70±10 ns FWHM pulses produced in a burst mode−four pulses of 600–850 W peak power in every cycle of the driving waveform. The lamp intensity is uniform to within ±2.5% at ≥10 mm from its surface and average power varies linearly with pulse repetition frequency throughout the 18−135 kHz interval. The spectral breadth of the Xe dimer emission is ∼9 nm FWHM and time-resolved, spatial intensity maps show improved utilization of the power pulse (V⋅I) with two or more microcavity arrays that are interleaved. This photonic source technology is capable of generating unprecedented power levels in the VUV spectral region (e.g., ∼2.5 kW m−2) with tiled lamps.