The dynamics and macrostructure of near-surface vapor-plasma fluxes arising from condensed substances evaporation in the field of broadband radiation of the UV-VUV spectrum range are studied using double-exposure laser holographic interferometry and schlieren photography (the Toepler scheme in the light field mode). The experimental setup was created on the basis of the unique scientific facility "Beam-M". Broadband UV and VUV radiation was generated by a plasma-dynamic emitting discharge of an end geometry coaxial erosion-type magnetoplasma compressor with an ablating fluoroplastic plasma-forming insulating sleeve in a gas. To control the emission spectrum of the discharge, gas filters were used (Ar, Ne, air, Ne mixture with 5% air). The emitter operated in the following mode: U = 20 kV, the stored energy W = 3.6 kJ, the energy input to the discharge was up to 3.2 kJ, with 30% in the first half-cycle of current, the maximum current is 160 kA, the half-cycle of discharge is 6 μs; the total radiation energy from the discharge was 1.0-1.2 kJ; the fraction of radiation in the VUV range of the spectrum was about 50% in Ne (hν ≤ 20 eV) and about 45% in Ar (hν ≤ 16 eV). It was shown that the implemented scheme of electromagnetic compatibility and protection ensures reliable synchronization of the electric discharge circuit and optical diagnostics components in the whole range of discharge characteristics. Optical diagnostics of near-surface gas-plasma flows was implemented on the basis of a second harmonic (532 nm) of a solid-state Nd:YAG laser (Solar LQ-115), its versatility was shown for studying various pulsed plasma processes with characteristic changes in gas concentrations of about 10 17-10 18 cm-3 and gradients of 10 19-10 20 cm-3. On the schlieren-pictures and interferograms, the zones characteristic of the studied type of radiation effects on materials were recorded: the gas-dynamic evaporation mode was realized (plasma piston mode), there was a shock wave in the gas, the contact boundary between the shock-compressed gas and the vapor plasma. The analysis of interferograms indicates that the regime of developed evaporation was preceded by a regime of diffusion evaporation. The use of extended samples allowed us to observe successive stages in the development of gas-dynamic perturbations during evaporation (due to the different distances between the target areas and the discharge). On the interferograms above the target, at different distances from the source of irradiation, 3 types of gas-dynamic perturbations were observed: acoustic wave, simple wave (Riemann wave), and shock wave. The effect of the energy characteristics of the discharge and the spectral composition of the radiation on the evaporation pattern was experimentally shown.

The results of an experimental study of the plasma formed by the evaporation of the lead target in the field of powerful broadband VUV radiation are presented. A pulse light-erosion magnetoplasma compressor (MPC’s) discharge is used as a model source of VUV radiation. “Gas filtration” of radiation is used to control the spectral composition – the discharge takes place in pure inert gases: in argon at 200 torr and neon at 400 torr. This allows us to manage the spectral distribution of radiation energy and to limit the energy of quants which irradiate the lead target with the first ionization potential of buffer gas. Shadow photography, toeplergrathy, double exposure laser holographic interferometry are used for diagnostics. Experimentally established different distribution of parameters in the lead plasma depending on the spectral composition of the impact radiation (the composition of buffer gas). It is shown that when the energy of quants increases (above the lead second ionization potential), a more even heating of the plasma layer is realized.

The dynamics of the vapor-plasma flows formed at impact of erosion type magnetoplasma compressor (MPC) discharge radiation on Ti, Al and PTFE targets with use of methods of a holographic interferometry and schlieren photos (Toepler’s scheme in the light field mode) is investigated. In the schlieren and interferogram photos, zones characteristic of the studied process of radiation interaction with matter are well visible: the gas-dynamic evaporation mode is realized (plasma piston mode), there is a shock wave in the gas, the contact boundary between the shock-compressed gas and the vapor plasma. The interferograms analysis indicates that the regime of developed evaporation is preceded by a regime of diffusion evaporation. On the interferograms above the targets at different distances from the radiation source (from the MPC), we observe 3 types of gas-dynamic perturbations: an acoustic wave, a simple wave (Riemann wave), and a shock wave. Qualitative and quantitative description of processes in these zones is discussed in the report. The effect of the radiation spectral composition (we use the method of gas spectral selection), the targets materials, and the degree of surface treatment on the evaporation is shown experimentally.