Formation of active species in spark discharge and their possible use

The chemical effects of self-sustained spark discharge with an energy per pulse of 5.9 × 10⁻² J, a pulse repetition frequency of 10 Hz, and a spark-gap breakdown voltage of 6 kV have been studied. The discharge generated a UV photon flux of (2.5 ± 0.3) × 10¹⁵ cm⁻² s⁻¹ with an energy density of (2 ± 0.3) × 10⁻³ J cm⁻¹ s⁻¹ and the emission spectrum maximum at 220 nm. The action of the discharge on water samples leads to a decrease in pH and to buildup of oxidizing and reducing species. The formation of HO₂^· radicals with an initial yield of (1.2 ± 0.3) × 10⁻⁶ mol L⁻¹ s⁻¹ has been detected in the liquid. The initial yields of acid residues (increment in [H⁺]), oxidants, and reducing agents are (5.8 ± 1.6) × 10⁻⁷, (3.3 ± 1) × 10⁻⁶, and (4.2 ± 1) × 10⁻⁷ mol equiv L⁻¹s⁻¹, respectively. The formation of NO₃⁻ and NO₄⁺ ions, nitrosamines, and organic compounds has been established.     

Comparison of Chemistry Induced by Direct and Indirect Plasma Treatment of Water to the Effect of UV Radiation

Plasma Chemistry and Plasma Processing - The yield of redox reactions (Fe2+ oxidation and Mn7+ reduction in aqueous solutions) under the action of hot plasma radiation in liquid and species formed...     

The inertia of an S-shaped volt-ampere characteristic and the self-oscillation frequency limits in multilayered heterostructures

Radiophysics and Quantum Electronics -     

Photoproton cross section for 26Mg in the giant dipole resonance region

Using bremsstrahlung from the 35 MeV betatron the ²⁶Mg(γ, xp) reaction cross section has been obtained in the excitation energy region up to 29 MeV. The role of isospin splitting in the formation of a giant dipole resonance is discussed in the case of light nuclei.     

Effect of Spark Discharge Plasma on Water,Physiological Saline,and Hanks’ Solution

The effect of the duration of a current pulse of spark discharge in air on the composition of products formed in liquid both by the action of plasma radiation and with the participation of species formed in the discharge itself has been studied. The products formed in water, 0.9% NaCl, and in Hanks’ solution have been determined. It has been that in all the cases, nitrous acid is one of the primary products. The yield of nitrous acid is the same in all the three solutions. With a decrease in the current pulse duration, the influence of the species formed in the discharge itself on the yield of nitrous acid increases. The products formed in water decompose within up to 13 days. Peroxynitrite and N₂O₃ were identified as degradation products.     

The formation of ozone and UV radiation from high-power pulsed electric discharges

High-power electric discharges with pulse energies of from 0.15 J to 4 kJ were studied. The yields of UV photons and ozone were found to be approximately equal, which led us to conclude that discharge conditions under which UV radiation and ozone fully destroyed each other were possible. If ozone formation was suppressed, as when a negative volume charge was created in the spark gap region, the flux of UV photons reached 3 × 10²³ photons/(cm² s).     

Modification of tetrafluoroethylene-hexafluoropropylene copolymer films in direct-current discharge

The effect of dc discharge treatment at the anode and cathode on the surface properties of tetrafluoroethylene-hexafluoropropylene copolymer films was studied. It was found that the modification of the films under conditions that ensure the separation of the discharge active species acting on the polymer materials makes it possible to achieve substantially lower values for the contact angle and higher values for the work of adhesion and surface energy than in the case of other modes of discharge. A change in the composition and structure of the films was studied by means of IR and X-ray photoelectron spectroscopy. It was found that new oxygen-containing groups are formed on the polymer surface as a result of plasma discharge treatment.     

Modification of polypropylene films in a direct-current discharge

The surface properties of polypropylene (PP) films modified in a direct-current discharge at the anode and cathode, as well as their change during long-term storage were studied. It was shown that the greatest decrease in the contact angles and the increase in the total surface energy and the polar component are observed for the films treated at the anode. Changes in the chemical structure of PP films were investigated by means of Fourier-transform IR spectroscopy and X-ray photoelectron spectroscopy techniques.     

Modification of tetrafluoroethylene-perfluoropropylvinyl ether copolymer films in direct-current discharge

Changes induced in the surface properties of films of a tetrafluoroethylene copolymer with perfluoropropylvinyl ether by direct-current discharge have been investigated, depending on the discharge parameters. It has been shown that the treatment of the films at the anode is more effective than at the cathode. A change in the contact properties of the modified films during their storage in air under ambient conditions and upon heating to 150°C has been examined. The chemical composition of the surface of the films after modification, storage, and heating has been studied by X-ray photoelectron spectroscopy and Fouriertransform IR spectroscopy. It has been found that dc discharge treatment significantly improves the adhesion properties of the films and barely affects their light transmission.