Some problems with the development of combined generation of electricity and heat in Russia

The current state of cogeneration in Russia is analyzed. It is characterized by a sharp decrease in industrial heat consumption and a reduction in the demand for electricity. As a result many cogeneration plants presently operate under off-design conditions, which change their economic indexes to the worse. The ways of introducing small-scale cogeneration installations are considered, which show promise under the existing conditions of limited investments. The problems that accompany the introduction of modern highly efficient large-capacity power units at cogeneration plants are analyzed.     

Project of CW race-track microtron-recuperator for free-electronlasers

A project for a race-track microtron-the beam source for a free-electron laser (FEL)-is considered. Utilized in the FEL, the beam will liberate its energy to the RF microtron system when, being decelerated, it passes along the same microtron orbits in inverse sequence. The layout of the microtron is depicted. The microtron comprises an injector, two magnetic straight systems with 180° separating bend, a common straight section with RF cavities (the section is common to electrons of different energy), magnets for the injection and extraction systems, solenoidal magnetic lenses, four separated straight sections with magnetic quadrupole lenses, a FEL magnetic system placed in the fourth straight section, and a beam dump. The design energy of electrons is 35 MeV and the mean current ranges from 0.1 to 1 A     

Millimeter-wave Detectors Based on Antenna-coupled Low-barrier Schottky Diodes

The principles of construction of millimeter wave detectors based on low-barrier Schottky diodes and planar antennas are discussed. The modified planar slot antenna with low beam spillover at the resonant frequency of 94 GHz has been developed. Experiments have been carried out to investigate detecting characteristics of the diodes with differential contact resistances \( R_{j} = 1 \div 1000\;{\text{k}}\Omega \) at zero bias. Experimental data are well correspond to calculations in a simple model of detector. At \( R_{j} = 20 \div 100\;{\text{k}}\,\OmegaΩ \) the maximum of rf-to-dc voltage sensitivity - more than 10000 V/W - is obtained. At lower values of \( R_{j} = 2 \div 6\;{\text{k}}\,\Omega Ω \) a better noise equivalent power (NEP), around 10^?12 W Hz^?1/2, is predicted.     

Continuous-wave laser oscillation of Yb/sup 3+/ in monoclinic KLu(WO/sub 4/)/sub 2/

The strongly anisotropic monoclinic double tungstate crystal KLu(WO/sub 4/)/sub 2/ was doped with Yb/sup 3+/ ions and shown to be a highly efficient active laser medium in the 1-/spl mu/m spectral range for continuous-wave room-temperature operation, very suitable for pumping with InGaAs laser diodes.     

Compact all-diode-pumped femtosecond laser source based on chirpedpulse optical parametric amplification in periodically poledKTiOPO4

1 kHz chirped pulse optical parametric amplification in periodically poled KTiOPO₄ achieving 20 μJ amplified signal pulse energy at 1.573 μm and 320 fs pulse duration after recompression is reported     

MBE-grown nanoheterostructures with increased electron mobility

Multilayered nitride heterostructures AlN/AlGaN/GaN/AlGaN are grown using a Nanofab-100 multichamber domestic complex involving a STE3N3 specialized installation of molecular beam epitaxy. The obtained heterostructures have high structural quality, smooth morphology, and a low dislocation density, which demonstrates the high potential of the nanotechnological complex.     

Self‐Assembly of Nanostructured,Complex, Multication Films via Spontaneous Phase Separation and Strain‐Driven Ordering

Spontaneous self‐assembly of a multication nanophase in another multication matrix phase is a promising bottom‐up approach to fabricate novel, nanocomposite structures for a range of applications. In an effort to understand the mechanisms for such self‐assembly, complimentary experimental and theoretical studies are reported to first understand and then control or guide the self‐assembly of insulating BaZrO₃ (BZO) nanodots within REBa₂Cu₃O_7–δ (RE = rare earth elements including Y, REBCO) superconducting films. The strain field developed around BZO nanodots embedded in the REBCO matrix is a key driving force dictating the self‐assembly of BZO nanodots along REBCO c‐axis. The size selection and spatial ordering of BZO self‐assembly are simulated using thermodynamic and kinetic models. The BZO self‐assembly is controllable by tuning the interphase strain field. REBCO superconducting films with BZO defect arrays self‐assembled to align in both vertical (REBCO c‐axis) and horizontal (REBCO ab‐planes) directions result in the maximized pinning and J_c performance for all field angles with smaller angular J_c anisotropy. The work has broad implications for the fabrication of controlled self‐assembled nanostructures for a range of applications via strain‐tuning.     

Analysis of Linewidth Tunable Terahertz Wave Generation in Periodically Poled Lithium Niobate

A new scheme of optical rectification of femtosecond laser pulses in a periodically poled lithium niobate crystal, which generates high energy and linewidth tunable multicycle terahertz (THz) pulses, is analyzed. The developed simple theoretical model allows investigating the generated THz spectrum and its dependence on spot size of the pump beam. It is shown that the transformation of THz radiation from narrowband to broadband is possible by simply reducing the pump beam size. The temporal waveform and energy of the multicycle THz pulses were calculated as well. It is shown that THz energy is inversely proportional to the pump beam size r _y , whereas energy spectral density is independent of r _y . The efficiency of optical-to-THz energy conversion for pump pulse energy of 1?mJ is estimated to be 0.8?×?10^?4. The possibility of tuning the generation frequency by changing the direction of the pump beam propagation is analyzed.