Superconducting Multipole Wigglers for Generating Synchrotron Radiation at the Budker Institute of Nuclear Physics

Physics of Particles and Nuclei Letters - Superconducting multipole insertion devices (wigglers and undulators) used to generate synchrotron radiation significantly increase the photon flux,...     

Maser based on cyclotron resonance in a decaying plasma

The features of generating electromagnetic radiation in a two-level cyclotron maser whose active medium is a decaying nonequilibrium plasma confined in a magnetic field with the mirror configuration have been examined. It has been shown that, even in the absence of a continuously acting source of nonequilibrium particles (inversion of the medium), the system can exhibit the regimes of the quasimonochromatic or pulse generation of radiation owing to a fast monotonic decrease in the instability threshold that is characteristic of the plasma decay. The theory is confirmed by the results of observations of the burst activity of the decaying pulsed-discharge plasma under the conditions of the electron cyclotron resonance in the direct axisymmetric magnetic trap.     

Kinetics of Gas Bubble Motion in a Capillary

Two flow regimes were discovered by measuring flow rate vof water through thin capillaries containing small gas bubble. The first regime is realized at a low pressure drop P, when the main resistance to flow is created by the wetting film. The estimate of its thickness makes it possible to determine the parameters of the isotherm of the electrostatic component of the disjoining pressure corresponding to the constant charge of the film–gas interface and potential of the quartz surface, which requires the application of a new calculation procedure. As Pincreases, an advancing meniscus forms contact angle of 50°–60° due to the film rupture when it reaches critical pressure in the thinnest part near the meniscus. In this case, the rate vis controlled by the flow in the filled part of a capillary, although some additional viscous drag is also created by the film moving in front of advancing meniscus. The longer the bubble, the greater this contribution.     

Capillary Flow of Cationic Polyelectrolyte Solutions

The flow rates and the dynamic contact angles of aqueous solutions of cationic polyelectrolyte (CPE) in quartz capillaries with radius of 3–4 m are measured. It is shown that the surface tension and viscosity of CPE solutions with concentrations from 10^–1 to 10^–5 g/l are the same as for water. Surface inactivity of CPE leads to the substantial difference between the capillary properties of their solutions and those of surfactant solutions. It is established that, as the solution concentration increases, the advancing contact angles are reduced from 83° to 75°; the receding contact angles lie between 10° and 20°. Large hysteresis of contact angle can probably be related to the formation of metastable wetting film behind the receding meniscus. Surface hydrophobization occurs as a result of the adsorption of CPE molecules on the negatively charged quartz surface. The specific features of the application of CPE solutions in the deposition technology of hydrophobic coatings, the capillary imbibition and displacement of oils from hydrophobic pores are discussed.     

Synthesis of (2<Emphasis Type="Italic">E</Emphasis>,4<Emphasis Type="Italic">E</Emphasis>)-dodeca-2,4-dien-1-yl isovalerate,the main component of rootstock oil of <Emphasis Type="Italic">Echinacea purpurea</Emphasis>

By phosphine-free Heck reaction a stereoselective synthesis was performed of (2E,4E)-dodeca-2,4-dien-1-yl isovalerate, the main component of the rootstock oil of Echinacea purpurea.     

Phase separation two polymers in a blend and selective degradation as a method for porous structure formation

A method is proposed for the formation of porous structures in polymers. The method is based on the phase separation of two polymers in a blend and selective degradation of one of them. Polymers hydrolyzable at a high rate in alkaline media (polyesters of oxalic acid) are synthesized, and their hydrolytic degradation and phase separation in mixed solutions with a polylactide are investigated. Porous polylactide samples are prepared by the selective hydrolysis of polylactide-polyoxalate blends.     

Enantioselective Biocatalytic Reduction of Hexan-2-one,Catalyzed by Petroselinum crispum Cells

Russian Journal of General Chemistry - A method for the synthesis of (2S)-(+)-hexan-2-ol, a precursor of a number of drugs, by the enantioselective biocatalytic reduction of a prochiral...     

Reaction of α-carbanions of lithium acylates with 1,2-dibromoethane

The reaction of 1,2-dibromoethane with α-carbanions of lithium acylates generated from acetic, butyric, isobutyric, and capronic acids with lithium diisopropylamide has been studied. Anion-radical and anionic pathways of the products formation have been discussed.     

Generation of a high-current beam of multiply charged ions from a dense plasma produced by high-power millimeter-wave gyrotron radiation under ECR conditions

Experimental data for generating intense beams of multiply charged heavy gas ions are reported. The beams are extracted from the dense plasma of an ECR discharge with quasi-gasdynamic confinement provided by the powerful microwave radiation of a gyrotron in a magnetic trap. The axisymmetric magnetic trap makes it possible to extract uniform (in transverse coordinates) plasma fluxes from it, and the use of a multiple-aperture extraction system makes it possible to increase the beam current by more than an order of magnitude compared with the ECP sources currently available. Multiply charged nitrogen ion beams with a current of 150 mA and a normalized emittance of 0.9π mm mrad are obtained.     

75GHz ECR等离子体

A Simple Mirror Ion Source with 75GHz pumping(SMIS 75)has been created.The confinement system is a mirror trap with magnetic field in the plug up to 5T,variable length 15—20cm and mirror ratio 3—5.Plasma heating is performed by the microwave radiation of a gyrotron(frequency 75GHz,power up to 200kW,pulse duration up to 150μs).The first results on plasma creation,heating and confinement are presented.Gas discharge conditions and charge state distributions are investigated.The main features of the plasma are high density and short confinement time.Plasma is confined in the trap in quasi-gas-dynamic regime.This means very short rising time and very dense plasma flux.