Gas Dynamics Processes above the Polymers Surface under Irradiation with Broadband High-Brightness Radiation in the Vacuum Ultraviolet Spectrum Region

Abstract

Obtaining new data on the gas-dynamic responses from the polymer samples (polytetrafluoroethylene, PTFE) irradiated by powerful VUV radiation from compressed plasma flows is in the focus of the present study. An erosion type magnetoplasma compressor (MPC), a type of plasma focus discharge, was used as a radiation source. The operating voltages of the MPC were between 15 and 25 kV, the maximum measured discharge current was 200 kA, and the radiation energy in the VUV range was ≈1–2 kJ. The VUV fluxes on the sample surface were high and equal to ≈1022–1024 photons cm−2·s−1. Double-exposure laser holographic interferometry and schlieren photography were used to diagnose and visualize the gas-dynamic structures. The spatial distribution of the parameters (temperature, pressure and concentrations of electrons and ions) was defined based on the assumption of local thermodynamic equilibrium. It has been demonstrated that the maximum temperature ranged from ≈ 10 to 15 kK in the plasma layer. The electron concentration was ≈ (0.7–1.6) × 1018 cm−3 in this region. The used techniques of optical diagnostics and procedures of result processing make it possible to obtain data on the dynamics of polymer ablation, which occurs when their surface is exposed to powerful energy fluxes (thermal, shock-wave, radiation, and other extreme loads).

Lightweight ZnO/Carbonated Cotton Fiber Nanocomposites for Electromagnetic Interference Applications: Preparation and Properties

“…The synergistic effects of impedance matching, scattering, multiple reflections, and dielectric loss led to outstanding EMI shielding efficiency. Consequently, dark samples of carbonated networks were obtained with considerable volume shrinkage and weight loss; their densities were also calculated to be between 1.02-1.08 g/cm 3 . The experimental results and characteristics of CF-0% ZnO, CF-10% ZnO, CF-30% ZnO, CF-50% ZnO, and CF-70% ZnO show that ZnO and carbonated fibers are the most influential synergistic materials.…”

“…Consequently, different dark-colored samples of CF-0% ZnO, CF-10% ZnO, CF-30% ZnO, CF-50% ZnO, and CF-70% ZnO after carbonization of networks with densities of 1.02-1.08 g/cm 3 were produced with significant weight loss and volume contraction. In comparison to CF-0% ZnO, the carbonated composites displayed relative flexibility, as presented previously in Figure 1.…”

“…To examine CF/ZnO functional groups and the changing of hydroxyl groups in cotton fibers both before and after carbonization treatment, the FTIR spectra of all samples (CF-0% ZnO, CF-10% ZnO, CF-30% ZnO, CF-50% ZnO, and CF-70% ZnO) are shown in Figure 4. Consequently, different dark-colored samples of CF-0% ZnO, CF-10% ZnO, CF-30% ZnO, CF-50% ZnO, and CF-70% ZnO after carbonization of networks with densities of 1.02-1.08 g/cm 3 were produced with significant weight loss and volume contraction. In comparison to CF-0% ZnO, the carbonated composites displayed relative flexibility, as presented previously in Figure 1.…”

“…With the prompt development of radar detection technology, wireless telecommunications, and related electronic equipment, the electromagnetic field unavoidably generates pollution, which has turned out to be one of the most severe problems, matching noise, water, and air pollution [ 1 , 2 , 3 , 4 , 5 ]. To solve the induced electromagnetic interference (EMI) problems, different applications of microwave-absorbing resources (MARs) have garnered considerable attention in the commercial and military fields because of their ability to absorb and shield against electromagnetic radiation [ 6 , 7 , 8 , 9 , 10 ].…”