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Results of experimental determination of the average heat transfer coefficient upon condensation of pure steam αc and steam from air–steam mixture αas.m in tubes of a large-scale model of the emergency cooling heat exchanger in the system of passive heat removal through steam generators of AES-2006 project at Leningrad II NPP are presented. The model contained 16 parallel tubes with a diameter of 16 × 2 mm and a length of 2.9 m connected to the upper steam distributing and lower condensate gathering horizontal collectors; the distance between their axes was 2.28 m. The tube segments were vertical, horizontal, or inclined. The internal diameter of the collectors was 40 or 60 mm. The model was placed in the lower part of a tank with a height of 6.5 m and a volume of 5.85 m3 filled with boiling water at atmospheric pressure. The experimental parameters were as follows: pressure range 0.43–7.77 MPa, condensate Reynolds number Ref = (0.87–9.3) × 103, and average air volume fraction at the segment with air–steam mixture 0.18–0.85. The studies showed that nonuniformity of static pressure distribution along the steam-distributing collector strongly influences the reduction of αc value (ejecting effect). The agreement between experimental and calculated according to statutory guidelines values of αc for vertical tubes is achieved if the dynamic head of the steam flow at the input of the steam-distributing collector does not exceed 1 kPa. Equations for calculation of the diffusion heat transfer coefficient at steam condensation from the air–steam mixture αas.m on the internal tube surface are proposed. In the considered conditions, air is completely displaced by steam flow from the upper to the lower part of the tubes. The boundary between these regions is characterized by an average reduced steam velocity through this cross section of 1.6 ± 0.4 m/s. Above the boundary cross section, it is recommended to calculate αc. according to [1].

The conditions for the generation of subnanosecond and picosecond electron beams with a tunable pulse width are studied on an SLEP-150 generator with a tubular cathode at a voltage pulse rise time of 0.3 ns. The width and shape of the beam current pulse are varied by varying the pressure and gas kind in the diode. It is shown that in the vacuum diode mode, the beam current rise time decreases from ${\sim}{0.5}$ to ${\sim}{\rm 0.2}~{\rm ns}$ as the interelectrode gap is decreased from 12 to ${\sim}{\rm 2}~{\rm mm}$ . It is found that with a 3-mm interelectrode gap, increasing the air pressure in the diode of the SLEP-150 generator from 0.1 to 6 torr decreases the full width at half maximum (FWHM) of the current pulse from ${\sim}{1}$ to 0.18 ns, with the beam current amplitude greater than 400 A and the beam current rise time less delayed with respect to the voltage pulse rise time. It is confirmed that with a nanosecond voltage pulse, the residual pressure of helium, nitrogen, and air in the diode ( ${\sim}{0.1}$ torr or less) does not affect the beam current amplitude and pulse width. At low pressure of air in the gas diode, the attained beam current density at a beam current pulse FWHM of 0.18-1 and ${\sim}{\rm 0.1}~{\rm ns}$ is ${\sim}{500}$ and ${\sim}{100}~{\rm A}/{\rm cm}^{2}$ , respectively.

A high-pressure CO{sub 2} laser with a discharge initiated by an electron beam of sub-nanosecond duration in the laser gas mixture at a pressure up to 5 atm is fabricated. For the 20-ns pulses the energy from the active volume {approx} 4 cm{sup 3} amounted to 40 mJ. The laser operation at a pulse repetition rate up to 5 Hz is demonstrated. In the gas mixture CO{sub 2}:N{sub 2}:He = 1:1:6 at a pressure 5 atm, the specific energy deposition of {approx} 0.07 J cm{sup -3} atm{sup -1} is obtained in the process of a non-self-sustained discharge with ionisation amplification.

Electrochemical dissolution of an Al-In-Sn alloy in 2–4 M NaOH solutions containing 0–3 M of sodium aluminate at temperatures of 40 and 75°C was studied by measuring potentiodynamic curves and chronopotentiograms.

Electron beam formation in krypton, neon, helium, and nitrogen at elevated pressures are experimentally investigated. It is shown that, when the krypton, neon, and helium pressures are varied, respectively, from 70 to 760 Torr, from 150 to 760 Torr, and from 300 to 4560 Torr, runaway electrons are beamed at the instant the plasma in the discharge gap approaches the anode and the nonlocal criterion for electron runaway is fulfilled. The fast-electron simulation of discharge gap preionization is performed. The simulation data demonstrate that preionization in the discharge gap is provided if the voltage pulse rise time is shorter than a nanosecond under atmospheric pressure.

Electrochemical dissolution of aluminum alloyed with tin, indium, and lead in a NaOH solution in the concentration range 4.4–12.0 M at 75°C was studied by the method of chronopotential and current-voltage curves. The influence exerted by alloying elements on the electrochemical parameters of the process was revealed.

Experiments are performed on the formation of coloured dots of a submillimetre size on the titanium foil surface irradiated by pulsed IR lasers. It is shown that the parameters of laser pulses can be selected so that the dots produced on the titanium foil surface will change their colour from yellow to blue with increasing exposure time. The threshold laser power densities required for the formation of contrast coloured dots on the titanium foil surface irradiated by laser pulses with low repetition rates are estimated as ~1.5 × 103 J cm-2 for a 1.73-μm Xe laser and ~2.3 × 103 J cm-2 for a 10.6-μm CO2 laser.

The formation of a beam of runaway electrons in a diode filled with helium at a pressure from 0.1 to 760 Torr was studied under conditions of a pulsed ≈4 ns) high ≈200 kV) voltage applied to the discharge gap. Both theoretical results and experimental data indicate that the electron beam is generated both at a large strength of the electric field, when the fraction of runaway electrons is large, and in a field of low strength, where intensive electron multiplication takes place. In the latter case, a high current can be obtained despite a small fraction of runaway electrons relative to their total number. The electron beams obtained in the helium-filled diode had a current amplitude of up to 140 A (corresponding to a current density above 10 A/cm2) at an electron energy of ∼150 keV.

The interaction of Xe (λ ∼ 1.73 μm) and XeCl (0.308 μm) laser radiation with surfaces of metal and TiN-ceramic coatings on glass and steel substrates has been studied. Correlation between parameters of surface erosion versus laser-specific energy was investigated. Monitoring of laser-induced erosion on smooth polished surfaces was performed using optical microscopy. The correlation has been revealed between characteristic zones of thin coatings damaged by irradiation and energy distribution over the laser beam cross section allowing evaluation of defects and adhesion of coatings. The interaction of pulsed periodical CO2 (λ ∼ 10.6 μm), and Xe (λ ∼ 1.73 μm) laser radiation with surfaces of teflon (polytetrafluoroethylene—PTFE) has been studied. Monitoring of erosion track on surfaces was performed through optical microscopy. It has been shown that at pulsed periodical CO2-radiation interaction with teflon the sputtering of polymer with formation of submicron-size particles occurs. Dependencies of particle sizes, form, and sputtering velocity on laser pulse duration and target temperature have been obtained.

Subnanosecond electron beams can be formed in gas-filled diodes at high pressures (up to 6 and 4 bar in helium and nitrogen, respectively). In a diode filled with air at atmospheric pressure, a beam current amplitude above 240 A was obtained at a pulse duration (FWHM) of ∼0.2 s and a beam current density of ∼40 A/cm2.

A technique for determining the amplitude and time parameters of pulsed electron beams is proposed. Using this technique, it is possible to measure weak currents. It is based on the non-self-sustained discharge initiated by the electron beam under investigation. The experimental results are presented for two electron beams formed in a gas-filled diode at the atmospheric pressure of air, nitrogen, a mixture of CO2 : N2 : He = 1 : 1 : 3, or helium and ejected through a foil or grid.

A high-pressure CO2 laser with a discharge initiated by a subnanosecond electron beam formed in the laser operating medium under pressure 5 atm. Radiation energy of 40 mJ in active volume of ~ 4 cm3 at radiation duration of 20 ns has been obtained. Laser operation at pulse repetition rate (p.r.r.) of up to 5 Hz has been demonstrated. Specific energy input of ~0,07 J/cm3. atm have been realized in laser operating gas mixture CO2:N2:He = 1:1:6 under pressure of 5 atm on the course of a pulsed non-sustained discharge with pre-ionization.© (2006) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

In HIV-infected MT-4 cells,l-lysine-α-oxidase, an inhibitor of HIV reproduction, selectively inhibits the synthesis of histone proteins, including 18K antigen (H2B histone). This protein is the target for autoimmune suppression of helper T cells. The enzyme has a low effect on the synthesis of other proteins and DNA. In addition to 18K antigen,l-lysine-α-oxidase suppresses the synthesis of high-molecular-weight proteins (270, 220, 140, 100, 75, 70, and 60 kD).

Teflon plate is irradiated by pulsed CO/sub 2/ laser. A crater with even edges without traces of melt or blackening was formed after irradiation of the teflon plate surface by focussed pulsed radiation of CO/sub 2/-laser with p.r.r. of /spl sim/1 Hz. Increasing of PTFE surface temperature resulted in increase of efficiency of teflon mass removed from the crater. Increasing of teflon target surface temperature or laser pulse duration results in greater amount of PTFE mass sputtered per shot, increase in particle sizes and appearance of fiber-like formations. Teflon sputtering velocities and powder particles distribution by size at pulse duration of 100 ns and 15 /spl mu/s and specific power of 10/sup 8/ and 10/sup 6/ W/cm/sup 2/, correspondingly, have been define.

It has been shown that a volume discharge is forming in a non-uniform electric field at a short voltage pulse rise and pulse nanosecond duration without preionization in different gases under pressures above atmospheric (helium 6 atm, nitrogen 3 atm).

It has been shown that the use of gas diodes with cathode electric field enhancement and voltage pulses having a short leading edge allow to form high-current subnanosecond electron beams. An electron beam appears at voltage pulse leading edge with duration at FWHM not more than 0.3 ns. On the beam current termination the discharge is usually continued in a quasi-stationary mode having a volume character. With a diode filled in with air under atmospheric pressure, beam current amplitude over 240 A at a pulse duration at FWHM of 0.2 ns and current density of 40 A/cm 2 was obtained. It has been also shown that at a smal l gas diode inductance the subnanosecond electron beams are formed in various gases in a wide pressure range (up to 6 atm in helium, and up to 4 atm in nitrogen). It has been established that with the new method an electron beam is formed due to critical field reached between an anode and plasma propagating from a cathode. Key words: e-beam, running electrons, gas diode, volume discharge

Atmosphere pressure CO2-laser with e-beam initiated disch arge formed in laser operating mixture has been created. Energy of radiation as 18 mJ in active volume of ~6 cm3 has been obtained. Laser operation at pulse repetition rate of up to 5 Hz was demonstrated. Specific energy input as ~0.1 J/cm3 was realized in gas mixture CO2:N2:He = 1:1:4 under atmosphere pressure in the process of a pulsed non-self-sustained discharge with ionized amplification. This method of discharge initiation is rather promising for creation of short-pulse high-pressure lasers.© (2004) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

This paper reports on experimental study of subnanosecond e-beam formed in air under atmospheric pressure. An electron beam with amplitude of ~ 170 A with duration at FWHM ~0.3 ns has been obtained. Based on beam temporal characteristics and discharge spatial characteristics, the critical fields were supposed to be reached at plasma approach to anode. Simultaneously, the sharp high-energy pulse of e-beam current is generated. Of critical importance is cathode type and plasma protrusions occurred on the cathode. It is shown that in order to get maximum e-beam in gas diode, the discharge in gas diode should be volume.

Properties of plasma produced in volume nanosecond high-pressure discharge and its formation conditions under elevated pressure in air, nitrogen, krypton, argon, neon and gas mixtures Ar-N2, Ar-Xe, CO2-N2-He in the gap with the cathode having small curvature radius have been investigated. Time-amplitude characteristics and radiation spectra of plasma in different gases in the range of 230-600 nm were defined. Lasing in the gas mixture Ar-Xe at active length of 1.5 cm has been achieved by excitation through volume nanosecond high-pressure discharge. Comparison of spectral radiation in nitrogen, krypton, argon, and neon under pumping of mentioned gases by volume discharge in non-uniform electric field, by nanosecond e-beam, and by volume pulsed discharge in the uniform electric field with high initial voltage was made. Lasing has also been obtained in the gas mixture CO2-N2-He under pumping by e-beam initiated discharge. The electron beam was formed in a gas diode filled the same gas mixture.© (2004) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Investigation of the modes of thin metal and ceramic films (0,3-1 μm) removal from the glass and stainless steel substrate by IR and UV laser radiation has been performed. It is presented that the efficient film destruction and removal occurs due to laser induced thermal strength under laser fluxes of ~0.5 J/cm2 not sufficient for phase transformation.© (2004) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Formation of microscopic size colored dots on titanium foil surface by pulsed IR-laser irradiation was studied. It was found that the dot on titanium surface changes its color from yellow to blue as the exposure is increased. According to our numerical calculation, the colored dot formation is accompanying with titanium surface melting and partial evaporation. At pulse-periodical irradiation mode it can result in foil break-through.© (2003) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

The interaction of pulsed periodical CO2-(λ~10.6 ´m), and Xe-(λ~1.73 μm) lasers radiation with surfaces of polymers has been studied. Correlation between parameters of surface erosion (area of crater and amount of evaporated material versus laser focus position and number of pulses) was investigated using teflon (polytetrafluoroethylene-PTFE) and vinypros (plasticized semi-transparent polyvinylchloride) sample. Monitoring of erosion track on surfaces was performed through optical microscopy. It has been shown that at pulsed periodical CO2-radiation interaction with teflon and vinypros the sputtering of polymers with formation of submicron-size particles occurs. Dependencies of particle sizes, form and sputtering velocity on laser pulse duration and target temperature have been obtained.© (2003) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

The complex of experimental installations for studying of laser radiation interaction with surface of metals has been established. At titanium surface irradiating depending on the accumulated laser radiation energy, the surface color might be changed from bright yellow to red and deep-blue colors. The presented results testify to the possibility to use the change of titanium surface color at heating by laser irradiation in the open air to obtain dot raster images. Presently, form the world data available on interaction of laser radiation with metal and dielectric surfaces and development of experimental diagnostics techniques by itself it is allowed to raise a reverse question, i.e., restoration of laser radiation energy spatial distribution through surface imprint. Using imprints, it is also possible to make an express diagnostics of multi-layer surface coatings. With this in mind, we have made the detailed morphology of imprint of the pulsed HF-laser interaction with carbon steel surface through atomic force microscope.

The repetitively pulsed regime of an atomic xenon transition laser pumped by an electron beam with various pulse durations and an electron-beam-initiated discharge is studied experimentally. An average radiation power of 2.5 W has been achieved in a quasi-stationary regime for a pulse repetition rate of 5 Hz in a laser pumped by a radially convergent electron beam of duration 100 μs without circulation of the Ar — Xe working mixture. The average output power for a laser pumped by a planar electron beam in quasi-stationary regime is 2 W. It is shown that for a specific energy contribution not exceeding 50 J L-1 and laser excitation by a train of electron-beam pulses at a repetition rate of 50 Hz, the amplitude and duration of the second lasing pulse virtually coincide with those of the first. For a laser pumped by a discharge initiated by a nanosecond electron beam, an average lasing power of 380 mW is achieved under steady-state conditions upon transverse circulation of the working mixture and a pump pulse repetition rate of 25 Hz. Pumping by an electron beam from two accelerators with a pulse duration of a few tens of microseconds under an Ar — Xe mixture pressure of about 1 atm and a specific pump power of 1 — 3 kW cm-3 per pulse is proposed for the development of 1.73-μm repetitively pulsed Xe lasers with a high average output power.