Abstract:
Using in situ laser surface probing, we study the interaction of broadband high-power radiation from a pulsed high-current discharge in background gas media (Ar and air) with the surface of a model dielectric mirror (ZrO2/SiO2). Sources based on pulsed high-current (I > 100 kA) plasma dynamic discharges generate high-brightness radiation fluxes, including those in the vacuum ultraviolet (VUV) spectrum. Changing the composition of the background gas enables radiative spectrum tuning, by controlling the short-wavelength emission limit. Characteristic values of the integrated (over the entire spectrum) radiant energy flux density at a distance of 78.6 cm from the source axis under the implemented conditions range from ∼14 – 25 kW/cm2 (discharges in air) to ∼37 – 112 kW/cm2 (discharges in argon). The obtained results indicate the occurrence of several gas-dynamic processes (evaporation, plasma layer formation, etc.) near the irradiated mirror, whose intensity reaches a maximum within 12 – 15 μs, which is confirmed by shielding the scanning laser beam. It is shown that the characteristic time of plasma flow emission above the surface is ∼30 – 40 μs.
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