Experimental investigation of the role of fluid turbulent stresses and edge plasma flows for intrinsic rotation generation in DIII-D H-mode plasmas

The first measurements of turbulent stresses and flows inside the separatrix of a tokamak H-mode plasma are reported, using a reciprocating multitip Langmuir probe at the DIII-D tokamak. A strong co-current rotation layer at the separatrix is found to precede intrinsic rotation development in the core. The measured fluid turbulent stresses transport toroidal momentum outward against the velocity gradient and thus try to sustain the edge layer. However, large kinetic stresses must exist to explain the net inward momentum transport leading to co-current core plasma rotation. The importance of such kinetic stresses is corroborated by the success of a simple orbit loss model, representing a purely kinetic mechanism, in the prediction of features of the edge corotation layer.     

Density isotherms of binary solvents hexane-modifier for liquid chromatography

Isothermic dependences of density of binary mobile phases on volume fraction of modifiers for normal-phase liquid chromatography are studied by the example of hexane-modifier systems (dioxane, diethyl ester, ethyl acetate). The influence of temperature on density and deviations of density of mobile phases from additivity are discussed.     

Modified multipulse technique for the effective detection of pure nuclear quadrupole resonance

Modification of the steady-state free precession (SSFP) multipulse technique for the effective detection of nuclear quadrupole resonance (NQR) signals was studied. This modification is based on the use of the preparatory pulse in the SSFP pulse sequences. It was shown that under certain conditions the total intensity of accumulated NQR signal can be increased. Experimental results of applying the proposed technique to nitrogen-14 NQR in the sample of sodium nitrite (NaNO₂) are presented and convincingly demonstrate the technique’s effectiveness.     

Slow motion of a permeable sphere in a viscous fluid

Flow of a viscous fluid past a permeable sphere is investigated in the Stokes approximation. An example of such a flow is flow past a perforated or meshed spherical surface. The elements of the sphere contain rigid impermeable sections and openings through which the fluid can flow. The interaction of the sphere with the flow is described by two drag coefficients, which established the connection between the flow velocity of the fluid at the sphere and the stress tensor on it. The dependence of the flow pattern and also the drag and flow rate of the fluid on these coefficients is investigated. In special cases, the obtained solution describes flow past solid and liquid spheres.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 5, pp. 165–167, September–October, 1982.     

Convective instability of a horizontal layer of fluid between permeable membranes

The equilibrium stability is investigated of a system consisting of two semi-infinite isothermal masses of fluid divided by a horizontal layer of finite thickness of the same fluid with a vertical temperature gradient directed downwards. The transition layer is separated by thin permeable membranes. Neutral stability curves are constructed for different membrane resistances. In the case of high permeability, the equilibrium is absolutely unstable with respect to monotonic-type longwave perturbations. For low permeability membranes, instability with respect to monotonic finite-wavelength perturbations is characteristic.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 4, pp. 171–173, July–August, 1985.     

Thermal decomposition of tetraalkylammonium iodides

A number of tetramethylammonium (TMA) iodides, including mono-, tri-, and pentaiodide, were synthesized. Thermal decomposition of samples was investigated by simultaneous TG–DSC analysis accompanied by gaseous IR- and mass-spectrometry analyses. Two different reaction pathways have been observed for TMA pentaiodide at different heating rates. At low heating rates (1–5 K min^?1), a gradual mass loss takes place and a stability plateau due to monoiodide formation exists on TG curve. At high heating rates (10, 15 and 7 K min^?1 as the in-between stage), there are only two peaks on DTG curve (instead of three for lower heating rates) and no monoiodide formation is observed as the sample decomposes completely before 350 °C.     

Intellectual power supply and control system on the phasotron of the joint institute for nuclear research laboratory of nuclear problems implemented from one source at different currents in electromagnetic lenses

The intellectual power supply and control system is presented for the group of electromagnetic lenses in the phasotron-beam transport channel supplied from one power supply source. An intellectual power supply and control system is proposed to minimize power consumption upon the redistribution of the lens currents between the main power supply and additional local regulation power supply sources.     

Periodic solutions of a quasilinear wave equation with homogeneous boundary conditions

In this paper, we prove the existence of time-periodic weak solutions for the wave equation with homogeneous boundary conditions. This paper deals with the cases where a nonlinear term has a superlinear and sublinear growth. __________ Translated from Fundamentalnaya i Prikladnaya Matematika, Vol. 12, No. 5, pp. 189–201, 2005.     

The LEPTA diagnostics and control system

The Low Energy Particle Toroidal Accumulator (LEPTA) is expected to provide experiments with intense flux of positronium. The diagnostics and control system of LEPTA consists of PCs and electronic equipment grouped in accordance with their applications. Devices in CAMAC standard, instrumentation and specially designed control cards imbedded in the LEPTA equipment are used.