Study of the feasibility of distributed cathodic arc as a plasma source for development of the technology for plasma separation of SNF and radioactive wastes

One of the key problems in the development of plasma separation technology is designing a plasma source which uses condensed spent nuclear fuel (SNF) or nuclear wastes as a raw material. This paper covers the experimental study of the evaporation and ionization of model materials (gadolinium, niobium oxide, and titanium oxide). For these purposes, a vacuum arc with a heated cathode on the studied material was initiated and its parameters in different regimes were studied. During the experiment, the cathode temperature, arc current, arc voltage, and plasma radiation spectra were measured, and also probe measurements were carried out. It was found that the increase in the cathode heating power leads to the decrease in the arc voltage (to 3 V). This fact makes it possible to reduce the electron energy and achieve singly ionized plasma with a high degree of ionization to fulfill one of the requirements for plasma separation of SNF. This finding is supported by the analysis of the plasma radiation spectrum and the results of the probe diagnostics.     

Supersonic flow past a cylindrical body with transverse jets at large angles of attack

Supersonic flow past a cylindrical body with a system of transverse jets ejected from its surface at angles of attack α=60–120^o is characterized by a complicated gasdynamic flow pattern [1]. The body surface is affected by both the oncoming flow and the ejected jets which shield a portion of the surface from the external flow. This results in considerable transverse and longitudinal pressure gradients appearing on the body surface. The experimental pressure distributions over a cylindrical model with four transverse jets at a Mach number M=4 and α=60°, 90°, and 120° make it possible to study the specific features of the flowfield and derive correlations for the "jet obstacle" dimensions. Moscow. Translated from Izvestiya Rossiiskoi Akademii Nauk, Mekhanika Zhidkosti i Gaza, No. 1, pp. 179–183, January–February, 1998.     

Interaction between monomethylolurea and sodium bicarbonate in water

Processes occurring in the ternary water-salt system containing monomethylolurea and sodium bicarbonate are studied using physicochemical (visual polythermal and isothermal) methods. The germinability and the energy of germination of cotton plant seeds in saline soils is shown to increase due to chemical binding of sodium bicarbonate with monomethylolurea.     

Ethylene oxidation under conditions of the oxidative coupling of methane

Ethylene conversion under conditions of the oxidative coupling of methane has been investigated. In an empty reactor above 740°C, ethylene oxidation occurs at a higher rate and its main product is carbon monoxide. Filling the reactor with an inert material (quartz) or a NaWMn/SiO₂ catalyst leads to a marked decrease in the ethylene conversion rate. Addition of methane to the reaction mixture dramatically slows down ethylene conversion rate and increases the C₃ hydrocarbon content of the reaction products. The kinetics of ethylene oxidation in the presence of methane over the NaWMn/SiO₂ catalyst is reported.     

Nonlinear pulse compression by the second-harmonic generation in quasiphase and group-velocity matched samples

We investigate numerically the second-harmonic generation from near infrared 100 fs pulses in periodically and aperiodically poled lithium niobate crystals, taking into account the group-velocity mismatch, the group-velocity dispersion, and self-action effects. For the first time, we show that a tenfold pulse compression can be obtained at both fundamental and second-harmonic frequencies. The mechanism of compression and the pertinent quality factors are discussed.     

Chemiluminescence of Ru(bpy)3 2+* in the reaction of electron transfer from Ph3CNa to Ru(bpy)3 3+ in a solution

Conditions for the generation of the Ru(bpy)₃ ³⁺ complex in organic solvents (Me₃CN or MeNO₂) in the presence of small amounts of H₂SO₄ were found. Chemiluminescence was observed in the reaction of Ru(bpy)₃ ³⁺ with Ph₃Na in a THF-MeCN mixture. The chemiluminescence emitter was identified as Ru(bpy)₃ ^2+*. This emitter forms in the excited state in the elementary reaction of electron transfer from the Ph₃C⁻ anion to Ru(bpy)₃ ³⁺. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 292–294, February, 1999.     

Influence of the scattering matrix elements on the gain of Stokes and anti-Stokes components in the nonstationary regime

The influence of the scattering matrix elements that are responsible for the amplification of the Stokes and anti-Stokes components on the process of stimulated Raman scattering in the essentially nonstationary regime is analyzed. It is demonstrated that the optimum proportion between the scattering matrix elements, which maximizes the anti-Stokes component, is determined by the ratio between the optical frequencies of the components and the initial proportion between the intensities of the pump and initiating pulses. In the case of the optimum proportion between the scattering matrix elements, the variation in the excitation of a medium compensates the self-induced modulation of gain, and the efficiency of converting the radiation energy into the Stokes and anti-Stokes components increases substantially.